Virtualization - Jul 2022 - [PATCH v11 24/40] virtio_pci: struct virtio_pci_common_cfg add queue_notify_data

The virtio spec already supports the virtio queue reset function. This patch set
is to add this function to the kernel. The relevant virtio spec information is
here:

    https://github.com/oasis-tcs/virtio-spec/issues/124
    https://github.com/oasis-tcs/virtio-spec/issues/139

Also regarding MMIO support for queue reset, I plan to support it after this
patch is passed.

This patch set implements the refactoring of vring. Finally, the
virtuque_resize() interface is provided based on the reset function of the
transport layer.

Test environment:
    Host: 4.19.91
    Qemu: QEMU emulator version 6.2.50 (with vq reset support)
    Test Cmd:  ethtool -G eth1 rx $1 tx $2; ethtool -g eth1

    The default is split mode, modify Qemu virtio-net to add PACKED feature to
test
    packed mode.

Qemu code:
   
https://github.com/fengidri/qemu/compare/89f3bfa3265554d1d591ee4d7f1197b6e3397e84...master

In order to simplify the review of this patch set, the function of reusing
the old buffers after resize will be introduced in subsequent patch sets.

Please review. Thanks.

v11:
  1. struct virtio_pci_common_cfg to virtio_pci_modern.h
  2. conflict resolution

v10:
  1. on top of the harden vring IRQ
  2. factor out split and packed from struct vring_virtqueue
  3. some suggest from @Jason Wang

v9:
  1. Provide a virtqueue_resize() interface directly
  2. A patch set including vring resize, virtio pci reset, virtio-net resize
  3. No more separate structs

v8:
  1. Provide a virtqueue_reset() interface directly
  2. Split the two patch sets, this is the first part
  3. Add independent allocation helper for allocating state, extra

v7:
  1. fix #6 subject typo
  2. fix #6 ring_size_in_bytes is uninitialized
  3. check by: make W=12

v6:
  1. virtio_pci: use synchronize_irq(irq) to sync the irq callbacks
  2. Introduce virtqueue_reset_vring() to implement the reset of vring during
     the reset process. May use the old vring if num of the vq not change.
  3. find_vqs() support sizes to special the max size of each vq

v5:
  1. add virtio-net support set_ringparam

v4:
  1. just the code of virtio, without virtio-net
  2. Performing reset on a queue is divided into these steps:
    1. reset_vq: reset one vq
    2. recycle the buffer from vq by virtqueue_detach_unused_buf()
    3. release the ring of the vq by vring_release_virtqueue()
    4. enable_reset_vq: re-enable the reset queue
  3. Simplify the parameters of enable_reset_vq()
  4. add container structures for virtio_pci_common_cfg

v3:
  1. keep vq, irq unreleased

Xuan Zhuo (40):
  virtio: add helper virtqueue_get_vring_max_size()
  virtio: struct virtio_config_ops add callbacks for queue_reset
  virtio_ring: update the document of the virtqueue_detach_unused_buf
    for queue reset
  virtio_ring: extract the logic of freeing vring
  virtio_ring: split vring_virtqueue
  virtio_ring: introduce virtqueue_init()
  virtio_ring: split: introduce vring_free_split()
  virtio_ring: split: extract the logic of alloc queue
  virtio_ring: split: extract the logic of alloc state and extra
  virtio_ring: split: extract the logic of attach vring
  virtio_ring: split: extract the logic of vring init
  virtio_ring: split: introduce virtqueue_reinit_split()
  virtio_ring: split: reserve vring_align, may_reduce_num
  virtio_ring: split: introduce virtqueue_resize_split()
  virtio_ring: packed: introduce vring_free_packed
  virtio_ring: packed: extract the logic of alloc queue
  virtio_ring: packed: extract the logic of alloc state and extra
  virtio_ring: packed: extract the logic of attach vring
  virtio_ring: packed: extract the logic of vring init
  virtio_ring: packed: introduce virtqueue_reinit_packed()
  virtio_ring: packed: introduce virtqueue_resize_packed()
  virtio_ring: introduce virtqueue_resize()
  virtio_pci: move struct virtio_pci_common_cfg to virtio_pci_modern.h
  virtio_pci: struct virtio_pci_common_cfg add queue_notify_data
  virtio: allow to unbreak/break virtqueue individually
  virtio: queue_reset: add VIRTIO_F_RING_RESET
  virtio_pci: struct virtio_pci_common_cfg add queue_reset
  virtio_pci: introduce helper to get/set queue reset
  virtio_pci: extract the logic of active vq for modern pci
  virtio_pci: support VIRTIO_F_RING_RESET
  virtio: find_vqs() add arg sizes
  virtio_pci: support the arg sizes of find_vqs()
  virtio_mmio: support the arg sizes of find_vqs()
  virtio: add helper virtio_find_vqs_ctx_size()
  virtio_net: set the default max ring size by find_vqs()
  virtio_net: get ringparam by virtqueue_get_vring_max_size()
  virtio_net: split free_unused_bufs()
  virtio_net: support rx queue resize
  virtio_net: support tx queue resize
  virtio_net: support set_ringparam

 arch/um/drivers/virtio_uml.c             |   3 +-
 drivers/net/virtio_net.c                 | 209 +++++-
 drivers/platform/mellanox/mlxbf-tmfifo.c |   3 +
 drivers/remoteproc/remoteproc_virtio.c   |   3 +
 drivers/s390/virtio/virtio_ccw.c         |   4 +
 drivers/virtio/virtio_mmio.c             |  11 +-
 drivers/virtio/virtio_pci_common.c       |  32 +-
 drivers/virtio/virtio_pci_common.h       |   3 +-
 drivers/virtio/virtio_pci_legacy.c       |   8 +-
 drivers/virtio/virtio_pci_modern.c       | 161 ++++-
 drivers/virtio/virtio_pci_modern_dev.c   |  35 +
 drivers/virtio/virtio_ring.c             | 785 +++++++++++++++++------
 drivers/virtio/virtio_vdpa.c             |   3 +
 include/linux/virtio.h                   |   9 +
 include/linux/virtio_config.h            |  38 +-
 include/linux/virtio_pci_modern.h        |  30 +
 include/uapi/linux/virtio_config.h       |   7 +-
 include/uapi/linux/virtio_pci.h          |  28 +-
 18 files changed, 1068 insertions(+), 304 deletions(-)

--
2.31.0

Record the maximum queue num supported by the device.

virtio-net can display the maximum (supported by hardware) ring size in
ethtool -g eth0.

When the subsequent patch implements vring reset, it can judge whether
the ring size passed by the driver is legal based on this.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 arch/um/drivers/virtio_uml.c             |  1 +
 drivers/platform/mellanox/mlxbf-tmfifo.c |  2 ++
 drivers/remoteproc/remoteproc_virtio.c   |  2 ++
 drivers/s390/virtio/virtio_ccw.c         |  3 +++
 drivers/virtio/virtio_mmio.c             |  2 ++
 drivers/virtio/virtio_pci_legacy.c       |  2 ++
 drivers/virtio/virtio_pci_modern.c       |  2 ++
 drivers/virtio/virtio_ring.c             | 14 ++++++++++++++
 drivers/virtio/virtio_vdpa.c             |  2 ++
 include/linux/virtio.h                   |  2 ++
 10 files changed, 32 insertions(+)

diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index 82ff3785bf69..e719af8bdf56 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -958,6 +958,7 @@ static struct virtqueue *vu_setup_vq(struct virtio_device
*vdev,
 		goto error_create;
 	}
 	vq->priv = info;
+	vq->num_max = num;
 	num = virtqueue_get_vring_size(vq);
 
 	if (vu_dev->protocol_features &
diff --git a/drivers/platform/mellanox/mlxbf-tmfifo.c
b/drivers/platform/mellanox/mlxbf-tmfifo.c
index 38800e86ed8a..1ae3c56b66b0 100644
--- a/drivers/platform/mellanox/mlxbf-tmfifo.c
+++ b/drivers/platform/mellanox/mlxbf-tmfifo.c
@@ -959,6 +959,8 @@ static int mlxbf_tmfifo_virtio_find_vqs(struct virtio_device
*vdev,
 			goto error;
 		}
 
+		vq->num_max = vring->num;
+
 		vqs[i] = vq;
 		vring->vq = vq;
 		vq->priv = vring;
diff --git a/drivers/remoteproc/remoteproc_virtio.c
b/drivers/remoteproc/remoteproc_virtio.c
index d43d74733f0a..0f7706e23eb9 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -125,6 +125,8 @@ static struct virtqueue *rp_find_vq(struct virtio_device
*vdev,
 		return ERR_PTR(-ENOMEM);
 	}
 
+	vq->num_max = num;
+
 	rvring->vq = vq;
 	vq->priv = rvring;
 
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index 161d3b141f0d..6b86d0280d6b 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -530,6 +530,9 @@ static struct virtqueue *virtio_ccw_setup_vq(struct
virtio_device *vdev,
 		err = -ENOMEM;
 		goto out_err;
 	}
+
+	vq->num_max = info->num;
+
 	/* it may have been reduced */
 	info->num = virtqueue_get_vring_size(vq);
 
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 083ff1eb743d..a20d5a6b5819 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -403,6 +403,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device
*vdev, unsigned int in
 		goto error_new_virtqueue;
 	}
 
+	vq->num_max = num;
+
 	/* Activate the queue */
 	writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
 	if (vm_dev->version == 1) {
diff --git a/drivers/virtio/virtio_pci_legacy.c
b/drivers/virtio/virtio_pci_legacy.c
index a5e5721145c7..2257f1b3d8ae 100644
--- a/drivers/virtio/virtio_pci_legacy.c
+++ b/drivers/virtio/virtio_pci_legacy.c
@@ -135,6 +135,8 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 	if (!vq)
 		return ERR_PTR(-ENOMEM);
 
+	vq->num_max = num;
+
 	q_pfn = virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT;
 	if (q_pfn >> 32) {
 		dev_err(&vp_dev->pci_dev->dev,
diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
index 623906b4996c..e7e0b8c850f6 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -218,6 +218,8 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 	if (!vq)
 		return ERR_PTR(-ENOMEM);
 
+	vq->num_max = num;
+
 	/* activate the queue */
 	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
 	vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a5ec724c01d8..4cac600856ad 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2385,6 +2385,20 @@ void vring_transport_features(struct virtio_device *vdev)
 }
 EXPORT_SYMBOL_GPL(vring_transport_features);
 
+/**
+ * virtqueue_get_vring_max_size - return the max size of the virtqueue's
vring
+ * @_vq: the struct virtqueue containing the vring of interest.
+ *
+ * Returns the max size of the vring.
+ *
+ * Unlike other operations, this need not be serialized.
+ */
+unsigned int virtqueue_get_vring_max_size(struct virtqueue *_vq)
+{
+	return _vq->num_max;
+}
+EXPORT_SYMBOL_GPL(virtqueue_get_vring_max_size);
+
 /**
  * virtqueue_get_vring_size - return the size of the virtqueue's vring
  * @_vq: the struct virtqueue containing the vring of interest.
diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
index c40f7deb6b5a..9670cc79371d 100644
--- a/drivers/virtio/virtio_vdpa.c
+++ b/drivers/virtio/virtio_vdpa.c
@@ -183,6 +183,8 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned
int index,
 		goto error_new_virtqueue;
 	}
 
+	vq->num_max = max_num;
+
 	/* Setup virtqueue callback */
 	cb.callback = callback ? virtio_vdpa_virtqueue_cb : NULL;
 	cb.private = info;
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index d8fdf170637c..a82620032e43 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -31,6 +31,7 @@ struct virtqueue {
 	struct virtio_device *vdev;
 	unsigned int index;
 	unsigned int num_free;
+	unsigned int num_max;
 	void *priv;
 };
 
@@ -80,6 +81,7 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *vq);
 
 void *virtqueue_detach_unused_buf(struct virtqueue *vq);
 
+unsigned int virtqueue_get_vring_max_size(struct virtqueue *vq);
 unsigned int virtqueue_get_vring_size(struct virtqueue *vq);
 
 bool virtqueue_is_broken(struct virtqueue *vq);
-- 
2.31.0

reset can be divided into the following four steps (example):
 1. transport: notify the device to reset the queue
 2. vring:     recycle the buffer submitted
 3. vring:     reset/resize the vring (may re-alloc)
 4. transport: mmap vring to device, and enable the queue

In order to support queue reset, add two callbacks(reset_vq,
enable_reset_vq) in struct virtio_config_ops to implement steps 1 and 4.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 include/linux/virtio_config.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index b47c2e7ed0ee..ded51b0d4823 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -78,6 +78,16 @@ struct virtio_shm_region {
  * @set_vq_affinity: set the affinity for a virtqueue (optional).
  * @get_vq_affinity: get the affinity for a virtqueue (optional).
  * @get_shm_region: get a shared memory region based on the index.
+ * @reset_vq: reset a queue individually (optional).
+ *	vq: the virtqueue
+ *	Returns 0 on success or error status
+ *	reset_vq will guarantee that the callbacks are disabled and synchronized.
+ *	Except for the callback, the caller should guarantee that the vring is
+ *	not accessed by any functions of virtqueue.
+ * @enable_reset_vq: enable a reset queue
+ *	vq: the virtqueue
+ *	Returns 0 on success or error status
+ *	If reset_vq is set, then enable_reset_vq must also be set.
  */
 typedef void vq_callback_t(struct virtqueue *);
 struct virtio_config_ops {
@@ -104,6 +114,8 @@ struct virtio_config_ops {
 			int index);
 	bool (*get_shm_region)(struct virtio_device *vdev,
 			       struct virtio_shm_region *region, u8 id);
+	int (*reset_vq)(struct virtqueue *vq);
+	int (*enable_reset_vq)(struct virtqueue *vq);
 };
 
 /* If driver didn't advertise the feature, it will never appear. */
-- 
2.31.0

Added documentation for virtqueue_detach_unused_buf, allowing it to be
called on queue reset.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/virtio/virtio_ring.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 4cac600856ad..4ed51bc05a51 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2130,8 +2130,8 @@ EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed);
  * @_vq: the struct virtqueue we're talking about.
  *
  * Returns NULL or the "data" token handed to virtqueue_add_*().
- * This is not valid on an active queue; it is useful only for device
- * shutdown.
+ * This is not valid on an active queue; it is useful for device
+ * shutdown or the reset queue.
  */
 void *virtqueue_detach_unused_buf(struct virtqueue *_vq)
 {
-- 
2.31.0

Introduce vring_free() to free the vring of vq.

Subsequent patches will use vring_free() alone.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/virtio/virtio_ring.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 4ed51bc05a51..bb4e8ae09c9b 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2316,14 +2316,10 @@ struct virtqueue *vring_new_virtqueue(unsigned int
index,
 }
 EXPORT_SYMBOL_GPL(vring_new_virtqueue);
 
-void vring_del_virtqueue(struct virtqueue *_vq)
+static void vring_free(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
 
-	spin_lock(&vq->vq.vdev->vqs_list_lock);
-	list_del(&_vq->list);
-	spin_unlock(&vq->vq.vdev->vqs_list_lock);
-
 	if (vq->we_own_ring) {
 		if (vq->packed_ring) {
 			vring_free_queue(vq->vq.vdev,
@@ -2354,6 +2350,18 @@ void vring_del_virtqueue(struct virtqueue *_vq)
 		kfree(vq->split.desc_state);
 		kfree(vq->split.desc_extra);
 	}
+}
+
+void vring_del_virtqueue(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	spin_lock(&vq->vq.vdev->vqs_list_lock);
+	list_del(&_vq->list);
+	spin_unlock(&vq->vq.vdev->vqs_list_lock);
+
+	vring_free(_vq);
+
 	kfree(vq);
 }
 EXPORT_SYMBOL_GPL(vring_del_virtqueue);
-- 
2.31.0

Separate the two inline structures(split and packed) from the structure
vring_virtqueue.

In this way, we can use these two structures later to pass parameters
and retain temporary variables.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 116 ++++++++++++++++++-----------------
 1 file changed, 60 insertions(+), 56 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index bb4e8ae09c9b..2806e033a651 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -85,6 +85,64 @@ struct vring_desc_extra {
 	u16 next;			/* The next desc state in a list. */
 };
 
+struct vring_virtqueue_split {
+	/* Actual memory layout for this queue. */
+	struct vring vring;
+
+	/* Last written value to avail->flags */
+	u16 avail_flags_shadow;
+
+	/*
+	 * Last written value to avail->idx in
+	 * guest byte order.
+	 */
+	u16 avail_idx_shadow;
+
+	/* Per-descriptor state. */
+	struct vring_desc_state_split *desc_state;
+	struct vring_desc_extra *desc_extra;
+
+	/* DMA address and size information */
+	dma_addr_t queue_dma_addr;
+	size_t queue_size_in_bytes;
+};
+
+struct vring_virtqueue_packed {
+	/* Actual memory layout for this queue. */
+	struct {
+		unsigned int num;
+		struct vring_packed_desc *desc;
+		struct vring_packed_desc_event *driver;
+		struct vring_packed_desc_event *device;
+	} vring;
+
+	/* Driver ring wrap counter. */
+	bool avail_wrap_counter;
+
+	/* Avail used flags. */
+	u16 avail_used_flags;
+
+	/* Index of the next avail descriptor. */
+	u16 next_avail_idx;
+
+	/*
+	 * Last written value to driver->flags in
+	 * guest byte order.
+	 */
+	u16 event_flags_shadow;
+
+	/* Per-descriptor state. */
+	struct vring_desc_state_packed *desc_state;
+	struct vring_desc_extra *desc_extra;
+
+	/* DMA address and size information */
+	dma_addr_t ring_dma_addr;
+	dma_addr_t driver_event_dma_addr;
+	dma_addr_t device_event_dma_addr;
+	size_t ring_size_in_bytes;
+	size_t event_size_in_bytes;
+};
+
 struct vring_virtqueue {
 	struct virtqueue vq;
 
@@ -124,64 +182,10 @@ struct vring_virtqueue {
 
 	union {
 		/* Available for split ring */
-		struct {
-			/* Actual memory layout for this queue. */
-			struct vring vring;
-
-			/* Last written value to avail->flags */
-			u16 avail_flags_shadow;
-
-			/*
-			 * Last written value to avail->idx in
-			 * guest byte order.
-			 */
-			u16 avail_idx_shadow;
-
-			/* Per-descriptor state. */
-			struct vring_desc_state_split *desc_state;
-			struct vring_desc_extra *desc_extra;
-
-			/* DMA address and size information */
-			dma_addr_t queue_dma_addr;
-			size_t queue_size_in_bytes;
-		} split;
+		struct vring_virtqueue_split split;
 
 		/* Available for packed ring */
-		struct {
-			/* Actual memory layout for this queue. */
-			struct {
-				unsigned int num;
-				struct vring_packed_desc *desc;
-				struct vring_packed_desc_event *driver;
-				struct vring_packed_desc_event *device;
-			} vring;
-
-			/* Driver ring wrap counter. */
-			bool avail_wrap_counter;
-
-			/* Avail used flags. */
-			u16 avail_used_flags;
-
-			/* Index of the next avail descriptor. */
-			u16 next_avail_idx;
-
-			/*
-			 * Last written value to driver->flags in
-			 * guest byte order.
-			 */
-			u16 event_flags_shadow;
-
-			/* Per-descriptor state. */
-			struct vring_desc_state_packed *desc_state;
-			struct vring_desc_extra *desc_extra;
-
-			/* DMA address and size information */
-			dma_addr_t ring_dma_addr;
-			dma_addr_t driver_event_dma_addr;
-			dma_addr_t device_event_dma_addr;
-			size_t ring_size_in_bytes;
-			size_t event_size_in_bytes;
-		} packed;
+		struct vring_virtqueue_packed packed;
 	};
 
 	/* How to notify other side. FIXME: commonalize hcalls! */
-- 
2.31.0

Separate the logic of virtqueue initialization. This logic is irrelevant
to ring layout.

This logic can be called independently when implementing resize/reset
later.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 61 ++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 30 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 2806e033a651..986dbd9294d6 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -368,6 +368,34 @@ static int vring_mapping_error(const struct vring_virtqueue
*vq,
 	return dma_mapping_error(vring_dma_dev(vq), addr);
 }
 
+static void virtqueue_init(struct vring_virtqueue *vq, u32 num)
+{
+	struct virtio_device *vdev;
+
+	vdev = vq->vq.vdev;
+
+	vq->vq.num_free = num;
+	if (vq->packed_ring)
+		vq->last_used_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR);
+	else
+		vq->last_used_idx = 0;
+	vq->event_triggered = false;
+	vq->num_added = 0;
+	vq->use_dma_api = vring_use_dma_api(vdev);
+#ifdef DEBUG
+	vq->in_use = false;
+	vq->last_add_time_valid = false;
+#endif
+
+	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
+
+	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
+		vq->weak_barriers = false;
+
+	/* Put everything in free lists. */
+	vq->free_head = 0;
+}
+
 
 /*
  * Split ring specific functions - *_split().
@@ -1706,7 +1734,6 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	vq->vq.callback = callback;
 	vq->vq.vdev = vdev;
 	vq->vq.name = name;
-	vq->vq.num_free = num;
 	vq->vq.index = index;
 	vq->we_own_ring = true;
 	vq->notify = notify;
@@ -1716,22 +1743,10 @@ static struct virtqueue *vring_create_virtqueue_packed(
 #else
 	vq->broken = false;
 #endif
-	vq->last_used_idx = 0 | (1 << VRING_PACKED_EVENT_F_WRAP_CTR);
-	vq->event_triggered = false;
-	vq->num_added = 0;
 	vq->packed_ring = true;
-	vq->use_dma_api = vring_use_dma_api(vdev);
-#ifdef DEBUG
-	vq->in_use = false;
-	vq->last_add_time_valid = false;
-#endif
 
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
 		!context;
-	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
-
-	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
-		vq->weak_barriers = false;
 
 	vq->packed.ring_dma_addr = ring_dma_addr;
 	vq->packed.driver_event_dma_addr = driver_event_dma_addr;
@@ -1759,8 +1774,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	memset(vq->packed.desc_state, 0,
 		num * sizeof(struct vring_desc_state_packed));
 
-	/* Put everything in free lists. */
-	vq->free_head = 0;
+	virtqueue_init(vq, num);
 
 	vq->packed.desc_extra = vring_alloc_desc_extra(num);
 	if (!vq->packed.desc_extra)
@@ -2205,7 +2219,6 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 	vq->vq.callback = callback;
 	vq->vq.vdev = vdev;
 	vq->vq.name = name;
-	vq->vq.num_free = vring.num;
 	vq->vq.index = index;
 	vq->we_own_ring = false;
 	vq->notify = notify;
@@ -2215,21 +2228,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 #else
 	vq->broken = false;
 #endif
-	vq->last_used_idx = 0;
-	vq->event_triggered = false;
-	vq->num_added = 0;
-	vq->use_dma_api = vring_use_dma_api(vdev);
-#ifdef DEBUG
-	vq->in_use = false;
-	vq->last_add_time_valid = false;
-#endif
 
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
 		!context;
-	vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
-
-	if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
-		vq->weak_barriers = false;
 
 	vq->split.queue_dma_addr = 0;
 	vq->split.queue_size_in_bytes = 0;
@@ -2255,11 +2256,11 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 	if (!vq->split.desc_extra)
 		goto err_extra;
 
-	/* Put everything in free lists. */
-	vq->free_head = 0;
 	memset(vq->split.desc_state, 0, vring.num *
 			sizeof(struct vring_desc_state_split));
 
+	virtqueue_init(vq, vq->split.vring.num);
+
 	spin_lock(&vdev->vqs_list_lock);
 	list_add_tail(&vq->vq.list, &vdev->vqs);
 	spin_unlock(&vdev->vqs_list_lock);
-- 
2.31.0

Free the structure struct vring_vritqueue_split.

Subsequent patches require it.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 986dbd9294d6..49d61e412dc6 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -939,6 +939,16 @@ static void *virtqueue_detach_unused_buf_split(struct
virtqueue *_vq)
 	return NULL;
 }
 
+static void vring_free_split(struct vring_virtqueue_split *vring,
+			     struct virtio_device *vdev)
+{
+	vring_free_queue(vdev, vring->queue_size_in_bytes, vring->vring.desc,
+			 vring->queue_dma_addr);
+
+	kfree(vring->desc_state);
+	kfree(vring->desc_extra);
+}
+
 static struct virtqueue *vring_create_virtqueue_split(
 	unsigned int index,
 	unsigned int num,
-- 
2.31.0

Separate the logic of split to create vring queue.

This feature is required for subsequent virtuqueue reset vring.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 68 ++++++++++++++++++++++--------------
 1 file changed, 42 insertions(+), 26 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 49d61e412dc6..a9ceb9c16c54 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -949,28 +949,19 @@ static void vring_free_split(struct vring_virtqueue_split
*vring,
 	kfree(vring->desc_extra);
 }
 
-static struct virtqueue *vring_create_virtqueue_split(
-	unsigned int index,
-	unsigned int num,
-	unsigned int vring_align,
-	struct virtio_device *vdev,
-	bool weak_barriers,
-	bool may_reduce_num,
-	bool context,
-	bool (*notify)(struct virtqueue *),
-	void (*callback)(struct virtqueue *),
-	const char *name)
+static int vring_alloc_queue_split(struct vring_virtqueue_split *vring,
+				   struct virtio_device *vdev,
+				   u32 num,
+				   unsigned int vring_align,
+				   bool may_reduce_num)
 {
-	struct virtqueue *vq;
 	void *queue = NULL;
 	dma_addr_t dma_addr;
-	size_t queue_size_in_bytes;
-	struct vring vring;
 
 	/* We assume num is a power of 2. */
 	if (num & (num - 1)) {
 		dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
-		return NULL;
+		return -EINVAL;
 	}
 
 	/* TODO: allocate each queue chunk individually */
@@ -981,11 +972,11 @@ static struct virtqueue *vring_create_virtqueue_split(
 		if (queue)
 			break;
 		if (!may_reduce_num)
-			return NULL;
+			return -ENOMEM;
 	}
 
 	if (!num)
-		return NULL;
+		return -ENOMEM;
 
 	if (!queue) {
 		/* Try to get a single page. You are my only hope! */
@@ -993,21 +984,46 @@ static struct virtqueue *vring_create_virtqueue_split(
 					  &dma_addr, GFP_KERNEL|__GFP_ZERO);
 	}
 	if (!queue)
-		return NULL;
+		return -ENOMEM;
+
+	vring_init(&vring->vring, num, queue, vring_align);
 
-	queue_size_in_bytes = vring_size(num, vring_align);
-	vring_init(&vring, num, queue, vring_align);
+	vring->queue_dma_addr = dma_addr;
+	vring->queue_size_in_bytes = vring_size(num, vring_align);
+
+	return 0;
+}
+
+static struct virtqueue *vring_create_virtqueue_split(
+	unsigned int index,
+	unsigned int num,
+	unsigned int vring_align,
+	struct virtio_device *vdev,
+	bool weak_barriers,
+	bool may_reduce_num,
+	bool context,
+	bool (*notify)(struct virtqueue *),
+	void (*callback)(struct virtqueue *),
+	const char *name)
+{
+	struct vring_virtqueue_split vring = {};
+	struct virtqueue *vq;
+	int err;
+
+	err = vring_alloc_queue_split(&vring, vdev, num, vring_align,
+				      may_reduce_num);
+	if (err)
+		return NULL;
 
-	vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
-				   notify, callback, name);
+	vq = __vring_new_virtqueue(index, vring.vring, vdev, weak_barriers,
+				   context, notify, callback, name);
 	if (!vq) {
-		vring_free_queue(vdev, queue_size_in_bytes, queue,
-				 dma_addr);
+		vring_free_split(&vring, vdev);
 		return NULL;
 	}
 
-	to_vvq(vq)->split.queue_dma_addr = dma_addr;
-	to_vvq(vq)->split.queue_size_in_bytes = queue_size_in_bytes;
+	to_vvq(vq)->split.queue_dma_addr = vring.queue_dma_addr;
+	to_vvq(vq)->split.queue_size_in_bytes = vring.queue_size_in_bytes;
 	to_vvq(vq)->we_own_ring = true;
 
 	return vq;
-- 
2.31.0

Separate the logic of creating desc_state, desc_extra, and subsequent
patches will call it independently.

Since only the structure vring is passed into __vring_new_virtqueue(),
when creating the function vring_alloc_state_extra_split(), we prefer to
use vring_virtqueue_split as a parameter, and it will be more convenient
to pass vring_virtqueue_split to some subsequent functions.

So a new vring_virtqueue_split variable is added in
__vring_new_virtqueue().

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 58 +++++++++++++++++++++++++-----------
 1 file changed, 40 insertions(+), 18 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index a9ceb9c16c54..cedd340d6db7 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -204,6 +204,7 @@ struct vring_virtqueue {
 #endif
 };
 
+static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num);
 
 /*
  * Helpers.
@@ -939,6 +940,32 @@ static void *virtqueue_detach_unused_buf_split(struct
virtqueue *_vq)
 	return NULL;
 }
 
+static int vring_alloc_state_extra_split(struct vring_virtqueue_split *vring)
+{
+	struct vring_desc_state_split *state;
+	struct vring_desc_extra *extra;
+	u32 num = vring->vring.num;
+
+	state = kmalloc_array(num, sizeof(struct vring_desc_state_split), GFP_KERNEL);
+	if (!state)
+		goto err_state;
+
+	extra = vring_alloc_desc_extra(num);
+	if (!extra)
+		goto err_extra;
+
+	memset(state, 0, num * sizeof(struct vring_desc_state_split));
+
+	vring->desc_state = state;
+	vring->desc_extra = extra;
+	return 0;
+
+err_extra:
+	kfree(state);
+err_state:
+	return -ENOMEM;
+}
+
 static void vring_free_split(struct vring_virtqueue_split *vring,
 			     struct virtio_device *vdev)
 {
@@ -2224,7 +2251,7 @@ EXPORT_SYMBOL_GPL(vring_interrupt);
 
 /* Only available for split ring */
 struct virtqueue *__vring_new_virtqueue(unsigned int index,
-					struct vring vring,
+					struct vring _vring,
 					struct virtio_device *vdev,
 					bool weak_barriers,
 					bool context,
@@ -2232,7 +2259,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 					void (*callback)(struct virtqueue *),
 					const char *name)
 {
+	struct vring_virtqueue_split vring = {};
 	struct vring_virtqueue *vq;
+	int err;
 
 	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
 		return NULL;
@@ -2261,7 +2290,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 	vq->split.queue_dma_addr = 0;
 	vq->split.queue_size_in_bytes = 0;
 
-	vq->split.vring = vring;
+	vq->split.vring = _vring;
 	vq->split.avail_flags_shadow = 0;
 	vq->split.avail_idx_shadow = 0;
 
@@ -2273,30 +2302,23 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 					vq->split.avail_flags_shadow);
 	}
 
-	vq->split.desc_state = kmalloc_array(vring.num,
-			sizeof(struct vring_desc_state_split), GFP_KERNEL);
-	if (!vq->split.desc_state)
-		goto err_state;
+	vring.vring = _vring;
 
-	vq->split.desc_extra = vring_alloc_desc_extra(vring.num);
-	if (!vq->split.desc_extra)
-		goto err_extra;
+	err = vring_alloc_state_extra_split(&vring);
+	if (err) {
+		kfree(vq);
+		return NULL;
+	}
 
-	memset(vq->split.desc_state, 0, vring.num *
-			sizeof(struct vring_desc_state_split));
+	vq->split.desc_state = vring.desc_state;
+	vq->split.desc_extra = vring.desc_extra;
 
-	virtqueue_init(vq, vq->split.vring.num);
+	virtqueue_init(vq, vring.vring.num);
 
 	spin_lock(&vdev->vqs_list_lock);
 	list_add_tail(&vq->vq.list, &vdev->vqs);
 	spin_unlock(&vdev->vqs_list_lock);
 	return &vq->vq;
-
-err_extra:
-	kfree(vq->split.desc_state);
-err_state:
-	kfree(vq);
-	return NULL;
 }
 EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
 
-- 
2.31.0

Separate the logic of attach vring, subsequent patches will call it
separately.

Since the "struct vring_virtqueue_split split" is created on the
stack and has been initialized to 0. So using
split->queue_dma_addr/split->queue_size_in_bytes assignment for
queue_dma_addr/queue_size_in_bytes can keep the same as the original
code.

On the other hand, subsequent patches can use the "struct
vring_virtqueue_split split" obtained by vring_alloc_queue_split() to
directly complete the attach operation.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index cedd340d6db7..9025bd373d3b 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -940,6 +940,18 @@ static void *virtqueue_detach_unused_buf_split(struct
virtqueue *_vq)
 	return NULL;
 }
 
+static void virtqueue_vring_attach_split(struct vring_virtqueue *vq,
+					 struct vring_virtqueue_split *vring)
+{
+	vq->split.queue_dma_addr = vring->queue_dma_addr;
+	vq->split.queue_size_in_bytes = vring->queue_size_in_bytes;
+
+	vq->split.vring = vring->vring;
+
+	vq->split.desc_state = vring->desc_state;
+	vq->split.desc_extra = vring->desc_extra;
+}
+
 static int vring_alloc_state_extra_split(struct vring_virtqueue_split *vring)
 {
 	struct vring_desc_state_split *state;
@@ -2287,10 +2299,6 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
 		!context;
 
-	vq->split.queue_dma_addr = 0;
-	vq->split.queue_size_in_bytes = 0;
-
-	vq->split.vring = _vring;
 	vq->split.avail_flags_shadow = 0;
 	vq->split.avail_idx_shadow = 0;
 
@@ -2310,10 +2318,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 		return NULL;
 	}
 
-	vq->split.desc_state = vring.desc_state;
-	vq->split.desc_extra = vring.desc_extra;
-
 	virtqueue_init(vq, vring.vring.num);
+	virtqueue_vring_attach_split(vq, &vring);
 
 	spin_lock(&vdev->vqs_list_lock);
 	list_add_tail(&vq->vq.list, &vdev->vqs);
-- 
2.31.0

Separate the logic of initializing vring, and subsequent patches will
call it separately.

This function completes the variable initialization of split vring. It
together with the logic of atatch constitutes the initialization of
vring.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 9025bd373d3b..35540daaa1e7 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -940,6 +940,24 @@ static void *virtqueue_detach_unused_buf_split(struct
virtqueue *_vq)
 	return NULL;
 }
 
+static void virtqueue_vring_init_split(struct vring_virtqueue *vq)
+{
+	struct virtio_device *vdev;
+
+	vdev = vq->vq.vdev;
+
+	vq->split.avail_flags_shadow = 0;
+	vq->split.avail_idx_shadow = 0;
+
+	/* No callback?  Tell other side not to bother us. */
+	if (!vq->vq.callback) {
+		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
+		if (!vq->event)
+			vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
+					vq->split.avail_flags_shadow);
+	}
+}
+
 static void virtqueue_vring_attach_split(struct vring_virtqueue *vq,
 					 struct vring_virtqueue_split *vring)
 {
@@ -2299,17 +2317,6 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
 		!context;
 
-	vq->split.avail_flags_shadow = 0;
-	vq->split.avail_idx_shadow = 0;
-
-	/* No callback?  Tell other side not to bother us. */
-	if (!callback) {
-		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
-		if (!vq->event)
-			vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
-					vq->split.avail_flags_shadow);
-	}
-
 	vring.vring = _vring;
 
 	err = vring_alloc_state_extra_split(&vring);
@@ -2320,6 +2327,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 
 	virtqueue_init(vq, vring.vring.num);
 	virtqueue_vring_attach_split(vq, &vring);
+	virtqueue_vring_init_split(vq);
 
 	spin_lock(&vdev->vqs_list_lock);
 	list_add_tail(&vq->vq.list, &vdev->vqs);
-- 
2.31.0

Introduce a function to initialize vq without allocating new ring,
desc_state, desc_extra.

Subsequent patches will call this function after reset vq to
reinitialize vq.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/virtio/virtio_ring.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 35540daaa1e7..4c8972da5423 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -958,6 +958,25 @@ static void virtqueue_vring_init_split(struct
vring_virtqueue *vq)
 	}
 }
 
+static void virtqueue_reinit_split(struct vring_virtqueue *vq)
+{
+	int size, i;
+
+	memset(vq->split.vring.desc, 0, vq->split.queue_size_in_bytes);
+
+	size = sizeof(struct vring_desc_state_split) * vq->split.vring.num;
+	memset(vq->split.desc_state, 0, size);
+
+	size = sizeof(struct vring_desc_extra) * vq->split.vring.num;
+	memset(vq->split.desc_extra, 0, size);
+
+	for (i = 0; i < vq->split.vring.num - 1; i++)
+		vq->split.desc_extra[i].next = i + 1;
+
+	virtqueue_init(vq, vq->split.vring.num);
+	virtqueue_vring_init_split(vq);
+}
+
 static void virtqueue_vring_attach_split(struct vring_virtqueue *vq,
 					 struct vring_virtqueue_split *vring)
 {
-- 
2.31.0

In vring_create_virtqueue_split() save vring_align, may_reduce_num to
structure vring_virtqueue_split. Used to create a new vring when
implementing resize .

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 4c8972da5423..9c83c5e6d5a9 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -105,6 +105,13 @@ struct vring_virtqueue_split {
 	/* DMA address and size information */
 	dma_addr_t queue_dma_addr;
 	size_t queue_size_in_bytes;
+
+	/*
+	 * The parameters for creating vrings are reserved for creating new
+	 * vring.
+	 */
+	u32 vring_align;
+	bool may_reduce_num;
 };
 
 struct vring_virtqueue_packed {
@@ -1098,6 +1105,8 @@ static struct virtqueue *vring_create_virtqueue_split(
 		return NULL;
 	}
 
+	to_vvq(vq)->split.vring_align = vring_align;
+	to_vvq(vq)->split.may_reduce_num = may_reduce_num;
 	to_vvq(vq)->split.queue_dma_addr = vring.queue_dma_addr;
 	to_vvq(vq)->split.queue_size_in_bytes = vring.queue_size_in_bytes;
 	to_vvq(vq)->we_own_ring = true;
-- 
2.31.0

virtio ring split supports resize.

Only after the new vring is successfully allocated based on the new num,
we will release the old vring. In any case, an error is returned,
indicating that the vring still points to the old vring.

In the case of an error, re-initialize(virtqueue_reinit_split()) the
virtqueue to ensure that the vring can be used.

In addition, vring_align, may_reduce_num are necessary for reallocating
vring, so they are retained for creating vq.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 9c83c5e6d5a9..1aaa1e5f9991 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -212,6 +212,7 @@ struct vring_virtqueue {
 };
 
 static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num);
+static void vring_free(struct virtqueue *_vq);
 
 /*
  * Helpers.
@@ -1114,6 +1115,37 @@ static struct virtqueue *vring_create_virtqueue_split(
 	return vq;
 }
 
+static int virtqueue_resize_split(struct virtqueue *_vq, u32 num)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct vring_virtqueue_split vring = {};
+	struct virtio_device *vdev = _vq->vdev;
+	int err;
+
+	err = vring_alloc_queue_split(&vring, vdev, num, vq->split.vring_align,
+				      vq->split.may_reduce_num);
+	if (err)
+		goto err;
+
+	err = vring_alloc_state_extra_split(&vring);
+	if (err) {
+		vring_free_split(&vring, vdev);
+		goto err;
+	}
+
+	vring_free(&vq->vq);
+
+	virtqueue_init(vq, vring.vring.num);
+	virtqueue_vring_attach_split(vq, &vring);
+	virtqueue_vring_init_split(vq);
+
+	return 0;
+
+err:
+	virtqueue_reinit_split(vq);
+	return -ENOMEM;
+}
+
 
 /*
  * Packed ring specific functions - *_packed().
-- 
2.31.0

Free the structure struct vring_vritqueue_packed.

Subsequent patches require it.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 1aaa1e5f9991..4f497b6f2d04 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1830,6 +1830,27 @@ static struct vring_desc_extra
*vring_alloc_desc_extra(unsigned int num)
 	return desc_extra;
 }
 
+static void vring_free_packed(struct vring_virtqueue_packed *vring,
+			      struct virtio_device *vdev)
+{
+	if (vring->vring.desc)
+		vring_free_queue(vdev, vring->ring_size_in_bytes,
+				 vring->vring.desc, vring->ring_dma_addr);
+
+	if (vring->vring.driver)
+		vring_free_queue(vdev, vring->event_size_in_bytes,
+				 vring->vring.driver,
+				 vring->driver_event_dma_addr);
+
+	if (vring->vring.device)
+		vring_free_queue(vdev, vring->event_size_in_bytes,
+				 vring->vring.device,
+				 vring->device_event_dma_addr);
+
+	kfree(vring->desc_state);
+	kfree(vring->desc_extra);
+}
+
 static struct virtqueue *vring_create_virtqueue_packed(
 	unsigned int index,
 	unsigned int num,
-- 
2.31.0

Separate the logic of packed to create vring queue.

For the convenience of passing parameters, add a structure
vring_packed.

This feature is required for subsequent virtuqueue reset vring.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 80 +++++++++++++++++++++++-------------
 1 file changed, 51 insertions(+), 29 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 4f497b6f2d04..891257d9cdf8 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1851,19 +1851,10 @@ static void vring_free_packed(struct
vring_virtqueue_packed *vring,
 	kfree(vring->desc_extra);
 }
 
-static struct virtqueue *vring_create_virtqueue_packed(
-	unsigned int index,
-	unsigned int num,
-	unsigned int vring_align,
-	struct virtio_device *vdev,
-	bool weak_barriers,
-	bool may_reduce_num,
-	bool context,
-	bool (*notify)(struct virtqueue *),
-	void (*callback)(struct virtqueue *),
-	const char *name)
+static int vring_alloc_queue_packed(struct vring_virtqueue_packed *vring,
+				    struct virtio_device *vdev,
+				    u32 num)
 {
-	struct vring_virtqueue *vq;
 	struct vring_packed_desc *ring;
 	struct vring_packed_desc_event *driver, *device;
 	dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
@@ -1875,7 +1866,11 @@ static struct virtqueue *vring_create_virtqueue_packed(
 				 &ring_dma_addr,
 				 GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
 	if (!ring)
-		goto err_ring;
+		goto err;
+
+	vring->vring.desc         = ring;
+	vring->ring_dma_addr      = ring_dma_addr;
+	vring->ring_size_in_bytes = ring_size_in_bytes;
 
 	event_size_in_bytes = sizeof(struct vring_packed_desc_event);
 
@@ -1883,13 +1878,47 @@ static struct virtqueue *vring_create_virtqueue_packed(
 				   &driver_event_dma_addr,
 				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
 	if (!driver)
-		goto err_driver;
+		goto err;
+
+	vring->vring.driver          = driver;
+	vring->event_size_in_bytes   = event_size_in_bytes;
+	vring->driver_event_dma_addr = driver_event_dma_addr;
 
 	device = vring_alloc_queue(vdev, event_size_in_bytes,
 				   &device_event_dma_addr,
 				   GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
 	if (!device)
-		goto err_device;
+		goto err;
+
+	vring->vring.device          = device;
+	vring->device_event_dma_addr = device_event_dma_addr;
+
+	vring->vring.num    = num;
+
+	return 0;
+
+err:
+	vring_free_packed(vring, vdev);
+	return -ENOMEM;
+}
+
+static struct virtqueue *vring_create_virtqueue_packed(
+	unsigned int index,
+	unsigned int num,
+	unsigned int vring_align,
+	struct virtio_device *vdev,
+	bool weak_barriers,
+	bool may_reduce_num,
+	bool context,
+	bool (*notify)(struct virtqueue *),
+	void (*callback)(struct virtqueue *),
+	const char *name)
+{
+	struct vring_virtqueue_packed vring = {};
+	struct vring_virtqueue *vq;
+
+	if (vring_alloc_queue_packed(&vring, vdev, num))
+		goto err_ring;
 
 	vq = kmalloc(sizeof(*vq), GFP_KERNEL);
 	if (!vq)
@@ -1912,17 +1941,14 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
 		!context;
 
-	vq->packed.ring_dma_addr = ring_dma_addr;
-	vq->packed.driver_event_dma_addr = driver_event_dma_addr;
-	vq->packed.device_event_dma_addr = device_event_dma_addr;
+	vq->packed.ring_dma_addr = vring.ring_dma_addr;
+	vq->packed.driver_event_dma_addr = vring.driver_event_dma_addr;
+	vq->packed.device_event_dma_addr = vring.device_event_dma_addr;
 
-	vq->packed.ring_size_in_bytes = ring_size_in_bytes;
-	vq->packed.event_size_in_bytes = event_size_in_bytes;
+	vq->packed.ring_size_in_bytes = vring.ring_size_in_bytes;
+	vq->packed.event_size_in_bytes = vring.event_size_in_bytes;
 
-	vq->packed.vring.num = num;
-	vq->packed.vring.desc = ring;
-	vq->packed.vring.driver = driver;
-	vq->packed.vring.device = device;
+	vq->packed.vring = vring.vring;
 
 	vq->packed.next_avail_idx = 0;
 	vq->packed.avail_wrap_counter = 1;
@@ -1961,11 +1987,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
 err_desc_state:
 	kfree(vq);
 err_vq:
-	vring_free_queue(vdev, event_size_in_bytes, device, device_event_dma_addr);
-err_device:
-	vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_dma_addr);
-err_driver:
-	vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
+	vring_free_packed(&vring, vdev);
 err_ring:
 	return NULL;
 }
-- 
2.31.0

Separate the logic for alloc desc_state and desc_extra, which will
be called separately by subsequent patches.

Use struct vring_packed to pass desc_state, desc_extra.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 48 +++++++++++++++++++++++++-----------
 1 file changed, 34 insertions(+), 14 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 891257d9cdf8..0c4109eb6c6c 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1902,6 +1902,33 @@ static int vring_alloc_queue_packed(struct
vring_virtqueue_packed *vring,
 	return -ENOMEM;
 }
 
+static int vring_alloc_state_extra_packed(struct vring_virtqueue_packed *vring)
+{
+	struct vring_desc_state_packed *state;
+	struct vring_desc_extra *extra;
+	u32 num = vring->vring.num;
+
+	state = kmalloc_array(num, sizeof(struct vring_desc_state_packed),
GFP_KERNEL);
+	if (!state)
+		goto err_desc_state;
+
+	memset(state, 0, num * sizeof(struct vring_desc_state_packed));
+
+	extra = vring_alloc_desc_extra(num);
+	if (!extra)
+		goto err_desc_extra;
+
+	vring->desc_state = state;
+	vring->desc_extra = extra;
+
+	return 0;
+
+err_desc_extra:
+	kfree(state);
+err_desc_state:
+	return -ENOMEM;
+}
+
 static struct virtqueue *vring_create_virtqueue_packed(
 	unsigned int index,
 	unsigned int num,
@@ -1916,6 +1943,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
 {
 	struct vring_virtqueue_packed vring = {};
 	struct vring_virtqueue *vq;
+	int err;
 
 	if (vring_alloc_queue_packed(&vring, vdev, num))
 		goto err_ring;
@@ -1955,21 +1983,15 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	vq->packed.event_flags_shadow = 0;
 	vq->packed.avail_used_flags = 1 << VRING_PACKED_DESC_F_AVAIL;
 
-	vq->packed.desc_state = kmalloc_array(num,
-			sizeof(struct vring_desc_state_packed),
-			GFP_KERNEL);
-	if (!vq->packed.desc_state)
-		goto err_desc_state;
+	err = vring_alloc_state_extra_packed(&vring);
+	if (err)
+		goto err_state_extra;
 
-	memset(vq->packed.desc_state, 0,
-		num * sizeof(struct vring_desc_state_packed));
+	vq->packed.desc_state = vring.desc_state;
+	vq->packed.desc_extra = vring.desc_extra;
 
 	virtqueue_init(vq, num);
 
-	vq->packed.desc_extra = vring_alloc_desc_extra(num);
-	if (!vq->packed.desc_extra)
-		goto err_desc_extra;
-
 	/* No callback?  Tell other side not to bother us. */
 	if (!callback) {
 		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
@@ -1982,9 +2004,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	spin_unlock(&vdev->vqs_list_lock);
 	return &vq->vq;
 
-err_desc_extra:
-	kfree(vq->packed.desc_state);
-err_desc_state:
+err_state_extra:
 	kfree(vq);
 err_vq:
 	vring_free_packed(&vring, vdev);
-- 
2.31.0

Separate the logic of attach vring, the subsequent patch will call it
separately.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 29 +++++++++++++++++------------
 1 file changed, 17 insertions(+), 12 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 0c4109eb6c6c..91ac99f99bff 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1929,6 +1929,22 @@ static int vring_alloc_state_extra_packed(struct
vring_virtqueue_packed *vring)
 	return -ENOMEM;
 }
 
+static void virtqueue_vring_attach_packed(struct vring_virtqueue *vq,
+					  struct vring_virtqueue_packed *vring)
+{
+	vq->packed.ring_dma_addr = vring->ring_dma_addr;
+	vq->packed.driver_event_dma_addr = vring->driver_event_dma_addr;
+	vq->packed.device_event_dma_addr = vring->device_event_dma_addr;
+
+	vq->packed.ring_size_in_bytes = vring->ring_size_in_bytes;
+	vq->packed.event_size_in_bytes = vring->event_size_in_bytes;
+
+	vq->packed.vring = vring->vring;
+
+	vq->packed.desc_state = vring->desc_state;
+	vq->packed.desc_extra = vring->desc_extra;
+}
+
 static struct virtqueue *vring_create_virtqueue_packed(
 	unsigned int index,
 	unsigned int num,
@@ -1969,15 +1985,6 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
 		!context;
 
-	vq->packed.ring_dma_addr = vring.ring_dma_addr;
-	vq->packed.driver_event_dma_addr = vring.driver_event_dma_addr;
-	vq->packed.device_event_dma_addr = vring.device_event_dma_addr;
-
-	vq->packed.ring_size_in_bytes = vring.ring_size_in_bytes;
-	vq->packed.event_size_in_bytes = vring.event_size_in_bytes;
-
-	vq->packed.vring = vring.vring;
-
 	vq->packed.next_avail_idx = 0;
 	vq->packed.avail_wrap_counter = 1;
 	vq->packed.event_flags_shadow = 0;
@@ -1987,10 +1994,8 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	if (err)
 		goto err_state_extra;
 
-	vq->packed.desc_state = vring.desc_state;
-	vq->packed.desc_extra = vring.desc_extra;
-
 	virtqueue_init(vq, num);
+	virtqueue_vring_attach_packed(vq, &vring);
 
 	/* No callback?  Tell other side not to bother us. */
 	if (!callback) {
-- 
2.31.0

Separate the logic of initializing vring, and subsequent patches will
call it separately.

This function completes the variable initialization of packed vring. It
together with the logic of atatch constitutes the initialization of
vring.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 91ac99f99bff..2f58266539eb 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1945,6 +1945,21 @@ static void virtqueue_vring_attach_packed(struct
vring_virtqueue *vq,
 	vq->packed.desc_extra = vring->desc_extra;
 }
 
+static void virtqueue_vring_init_packed(struct vring_virtqueue *vq)
+{
+	vq->packed.next_avail_idx = 0;
+	vq->packed.avail_wrap_counter = 1;
+	vq->packed.event_flags_shadow = 0;
+	vq->packed.avail_used_flags = 1 << VRING_PACKED_DESC_F_AVAIL;
+
+	/* No callback?  Tell other side not to bother us. */
+	if (!vq->vq.callback) {
+		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
+		vq->packed.vring.driver->flags +		
cpu_to_le16(vq->packed.event_flags_shadow);
+	}
+}
+
 static struct virtqueue *vring_create_virtqueue_packed(
 	unsigned int index,
 	unsigned int num,
@@ -1985,24 +2000,13 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
 		!context;
 
-	vq->packed.next_avail_idx = 0;
-	vq->packed.avail_wrap_counter = 1;
-	vq->packed.event_flags_shadow = 0;
-	vq->packed.avail_used_flags = 1 << VRING_PACKED_DESC_F_AVAIL;
-
 	err = vring_alloc_state_extra_packed(&vring);
 	if (err)
 		goto err_state_extra;
 
 	virtqueue_init(vq, num);
 	virtqueue_vring_attach_packed(vq, &vring);
-
-	/* No callback?  Tell other side not to bother us. */
-	if (!callback) {
-		vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
-		vq->packed.vring.driver->flags -		
cpu_to_le16(vq->packed.event_flags_shadow);
-	}
+	virtqueue_vring_init_packed(vq);
 
 	spin_lock(&vdev->vqs_list_lock);
 	list_add_tail(&vq->vq.list, &vdev->vqs);
-- 
2.31.0

Introduce a function to initialize vq without allocating new ring,
desc_state, desc_extra.

Subsequent patches will call this function after reset vq to
reinitialize vq.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 2f58266539eb..650f701a5480 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1960,6 +1960,27 @@ static void virtqueue_vring_init_packed(struct
vring_virtqueue *vq)
 	}
 }
 
+static void virtqueue_reinit_packed(struct vring_virtqueue *vq)
+{
+	int size, i;
+
+	memset(vq->packed.vring.device, 0, vq->packed.event_size_in_bytes);
+	memset(vq->packed.vring.driver, 0, vq->packed.event_size_in_bytes);
+	memset(vq->packed.vring.desc, 0, vq->packed.ring_size_in_bytes);
+
+	size = sizeof(struct vring_desc_state_packed) * vq->packed.vring.num;
+	memset(vq->packed.desc_state, 0, size);
+
+	size = sizeof(struct vring_desc_extra) * vq->packed.vring.num;
+	memset(vq->packed.desc_extra, 0, size);
+
+	for (i = 0; i < vq->packed.vring.num - 1; i++)
+		vq->packed.desc_extra[i].next = i + 1;
+
+	virtqueue_init(vq, vq->packed.vring.num);
+	virtqueue_vring_init_packed(vq);
+}
+
 static struct virtqueue *vring_create_virtqueue_packed(
 	unsigned int index,
 	unsigned int num,
-- 
2.31.0

virtio ring packed supports resize.

Only after the new vring is successfully allocated based on the new num,
we will release the old vring. In any case, an error is returned,
indicating that the vring still points to the old vring.

In the case of an error, re-initialize(by virtqueue_reinit_packed()) the
virtqueue to ensure that the vring can be used.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 650f701a5480..4860787286db 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2042,6 +2042,35 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	return NULL;
 }
 
+static int virtqueue_resize_packed(struct virtqueue *_vq, u32 num)
+{
+	struct vring_virtqueue_packed vring = {};
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct virtio_device *vdev = _vq->vdev;
+	int err;
+
+	if (vring_alloc_queue_packed(&vring, vdev, num))
+		goto err_ring;
+
+	err = vring_alloc_state_extra_packed(&vring);
+	if (err)
+		goto err_state_extra;
+
+	vring_free(&vq->vq);
+
+	virtqueue_init(vq, vring.vring.num);
+	virtqueue_vring_attach_packed(vq, &vring);
+	virtqueue_vring_init_packed(vq);
+
+	return 0;
+
+err_state_extra:
+	vring_free_packed(&vring, vdev);
+err_ring:
+	virtqueue_reinit_packed(vq);
+	return -ENOMEM;
+}
+
 
 /*
  * Generic functions and exported symbols.
-- 
2.31.0

Introduce virtqueue_resize() to implement the resize of vring.
Based on these, the driver can dynamically adjust the size of the vring.
For example: ethtool -G.

virtqueue_resize() implements resize based on the vq reset function. In
case of failure to allocate a new vring, it will give up resize and use
the original vring.

During this process, if the re-enable reset vq fails, the vq can no
longer be used. Although the probability of this situation is not high.

The parameter recycle is used to recycle the buffer that is no longer
used.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 72 ++++++++++++++++++++++++++++++++++++
 include/linux/virtio.h       |  3 ++
 2 files changed, 75 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 4860787286db..5ec43607cc15 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2542,6 +2542,78 @@ struct virtqueue *vring_create_virtqueue(
 }
 EXPORT_SYMBOL_GPL(vring_create_virtqueue);
 
+/**
+ * virtqueue_resize - resize the vring of vq
+ * @_vq: the struct virtqueue we're talking about.
+ * @num: new ring num
+ * @recycle: callback for recycle the useless buffer
+ *
+ * When it is really necessary to create a new vring, it will set the current
vq
+ * into the reset state. Then call the passed callback to recycle the buffer
+ * that is no longer used. Only after the new vring is successfully created,
the
+ * old vring will be released.
+ *
+ * Caller must ensure we don't call this with other virtqueue operations
+ * at the same time (except where noted).
+ *
+ * Returns zero or a negative error.
+ * 0: success.
+ * -ENOMEM: Failed to allocate a new ring, fall back to the original ring size.
+ *  vq can still work normally
+ * -EBUSY: Failed to sync with device, vq may not work properly
+ * -ENOENT: Transport or device not supported
+ * -E2BIG/-EINVAL: num error
+ * -EPERM: Operation not permitted
+ *
+ */
+int virtqueue_resize(struct virtqueue *_vq, u32 num,
+		     void (*recycle)(struct virtqueue *vq, void *buf))
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+	struct virtio_device *vdev = vq->vq.vdev;
+	bool packed;
+	void *buf;
+	int err;
+
+	if (!vq->we_own_ring)
+		return -EPERM;
+
+	if (num > vq->vq.num_max)
+		return -E2BIG;
+
+	if (!num)
+		return -EINVAL;
+
+	packed = virtio_has_feature(vdev, VIRTIO_F_RING_PACKED) ? true : false;
+
+	if ((packed ? vq->packed.vring.num : vq->split.vring.num) == num)
+		return 0;
+
+	if (!vdev->config->reset_vq)
+		return -ENOENT;
+
+	if (!vdev->config->enable_reset_vq)
+		return -ENOENT;
+
+	err = vdev->config->reset_vq(_vq);
+	if (err)
+		return err;
+
+	while ((buf = virtqueue_detach_unused_buf(_vq)) != NULL)
+		recycle(_vq, buf);
+
+	if (packed)
+		err = virtqueue_resize_packed(_vq, num);
+	else
+		err = virtqueue_resize_split(_vq, num);
+
+	if (vdev->config->enable_reset_vq(_vq))
+		return -EBUSY;
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(virtqueue_resize);
+
 /* Only available for split ring */
 struct virtqueue *vring_new_virtqueue(unsigned int index,
 				      unsigned int num,
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index a82620032e43..1272566adec6 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -91,6 +91,9 @@ dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq);
 dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq);
 dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq);
 
+int virtqueue_resize(struct virtqueue *vq, u32 num,
+		     void (*recycle)(struct virtqueue *vq, void *buf));
+
 /**
  * virtio_device - representation of a device using virtio
  * @index: unique position on the virtio bus
-- 
2.31.0

In order to facilitate the expansion of virtio_pci_common_cfg in the
future, move it from uapi to virtio_pci_modern.h. In this way, we can
freely expand virtio_pci_common_cfg in the future.

Other projects using virtio_pci_common_cfg in uapi need to maintain a
separate virtio_pci_common_cfg or use the offset macro defined in uapi.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 include/linux/virtio_pci_modern.h | 26 ++++++++++++++++++++++++++
 include/uapi/linux/virtio_pci.h   | 26 --------------------------
 2 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
index eb2bd9b4077d..c4f7ffbacb4e 100644
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -5,6 +5,32 @@
 #include <linux/pci.h>
 #include <linux/virtio_pci.h>
 
+/* Fields in VIRTIO_PCI_CAP_COMMON_CFG: */
+struct virtio_pci_common_cfg {
+	/* About the whole device. */
+	__le32 device_feature_select;	/* read-write */
+	__le32 device_feature;		/* read-only */
+	__le32 guest_feature_select;	/* read-write */
+	__le32 guest_feature;		/* read-write */
+	__le16 msix_config;		/* read-write */
+	__le16 num_queues;		/* read-only */
+	__u8 device_status;		/* read-write */
+	__u8 config_generation;		/* read-only */
+
+	/* About a specific virtqueue. */
+	__le16 queue_select;		/* read-write */
+	__le16 queue_size;		/* read-write, power of 2. */
+	__le16 queue_msix_vector;	/* read-write */
+	__le16 queue_enable;		/* read-write */
+	__le16 queue_notify_off;	/* read-only */
+	__le32 queue_desc_lo;		/* read-write */
+	__le32 queue_desc_hi;		/* read-write */
+	__le32 queue_avail_lo;		/* read-write */
+	__le32 queue_avail_hi;		/* read-write */
+	__le32 queue_used_lo;		/* read-write */
+	__le32 queue_used_hi;		/* read-write */
+};
+
 struct virtio_pci_modern_device {
 	struct pci_dev *pci_dev;
 
diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
index 3a86f36d7e3d..247ec42af2c8 100644
--- a/include/uapi/linux/virtio_pci.h
+++ b/include/uapi/linux/virtio_pci.h
@@ -140,32 +140,6 @@ struct virtio_pci_notify_cap {
 	__le32 notify_off_multiplier;	/* Multiplier for queue_notify_off. */
 };
 
-/* Fields in VIRTIO_PCI_CAP_COMMON_CFG: */
-struct virtio_pci_common_cfg {
-	/* About the whole device. */
-	__le32 device_feature_select;	/* read-write */
-	__le32 device_feature;		/* read-only */
-	__le32 guest_feature_select;	/* read-write */
-	__le32 guest_feature;		/* read-write */
-	__le16 msix_config;		/* read-write */
-	__le16 num_queues;		/* read-only */
-	__u8 device_status;		/* read-write */
-	__u8 config_generation;		/* read-only */
-
-	/* About a specific virtqueue. */
-	__le16 queue_select;		/* read-write */
-	__le16 queue_size;		/* read-write, power of 2. */
-	__le16 queue_msix_vector;	/* read-write */
-	__le16 queue_enable;		/* read-write */
-	__le16 queue_notify_off;	/* read-only */
-	__le32 queue_desc_lo;		/* read-write */
-	__le32 queue_desc_hi;		/* read-write */
-	__le32 queue_avail_lo;		/* read-write */
-	__le32 queue_avail_hi;		/* read-write */
-	__le32 queue_used_lo;		/* read-write */
-	__le32 queue_used_hi;		/* read-write */
-};
-
 /* Fields in VIRTIO_PCI_CAP_PCI_CFG: */
 struct virtio_pci_cfg_cap {
 	struct virtio_pci_cap cap;
-- 
2.31.0

Add queue_notify_data in struct virtio_pci_common_cfg, which comes from
here https://github.com/oasis-tcs/virtio-spec/issues/89

Since I want to add queue_reset after queue_notify_data, I submitted
this patch first.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 include/linux/virtio_pci_modern.h | 2 ++
 include/uapi/linux/virtio_pci.h   | 1 +
 2 files changed, 3 insertions(+)

diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
index c4f7ffbacb4e..9f31dde46f57 100644
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -29,6 +29,8 @@ struct virtio_pci_common_cfg {
 	__le32 queue_avail_hi;		/* read-write */
 	__le32 queue_used_lo;		/* read-write */
 	__le32 queue_used_hi;		/* read-write */
+	__le16 queue_notify_data;	/* read-write */
+	__le16 padding;
 };
 
 struct virtio_pci_modern_device {
diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
index 247ec42af2c8..748b3eb62d2f 100644
--- a/include/uapi/linux/virtio_pci.h
+++ b/include/uapi/linux/virtio_pci.h
@@ -176,6 +176,7 @@ struct virtio_pci_cfg_cap {
 #define VIRTIO_PCI_COMMON_Q_AVAILHI	44
 #define VIRTIO_PCI_COMMON_Q_USEDLO	48
 #define VIRTIO_PCI_COMMON_Q_USEDHI	52
+#define VIRTIO_PCI_COMMON_Q_NDATA	56
 
 #endif /* VIRTIO_PCI_NO_MODERN */
 
-- 
2.31.0

This patch allows the new introduced
__virtqueue_break()/__virtqueue_unbreak() to break/unbreak the
virtqueue.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_ring.c | 24 ++++++++++++++++++++++++
 include/linux/virtio.h       |  3 +++
 2 files changed, 27 insertions(+)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 5ec43607cc15..7b02be7fce67 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2744,6 +2744,30 @@ unsigned int virtqueue_get_vring_size(struct virtqueue
*_vq)
 }
 EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);
 
+/*
+ * This function should only be called by the core, not directly by the driver.
+ */
+void __virtqueue_break(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	/* Pairs with READ_ONCE() in virtqueue_is_broken(). */
+	WRITE_ONCE(vq->broken, true);
+}
+EXPORT_SYMBOL_GPL(__virtqueue_break);
+
+/*
+ * This function should only be called by the core, not directly by the driver.
+ */
+void __virtqueue_unbreak(struct virtqueue *_vq)
+{
+	struct vring_virtqueue *vq = to_vvq(_vq);
+
+	/* Pairs with READ_ONCE() in virtqueue_is_broken(). */
+	WRITE_ONCE(vq->broken, false);
+}
+EXPORT_SYMBOL_GPL(__virtqueue_unbreak);
+
 bool virtqueue_is_broken(struct virtqueue *_vq)
 {
 	struct vring_virtqueue *vq = to_vvq(_vq);
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 1272566adec6..dc474a0d48d1 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -138,6 +138,9 @@ bool is_virtio_device(struct device *dev);
 void virtio_break_device(struct virtio_device *dev);
 void __virtio_unbreak_device(struct virtio_device *dev);
 
+void __virtqueue_break(struct virtqueue *_vq);
+void __virtqueue_unbreak(struct virtqueue *_vq);
+
 void virtio_config_changed(struct virtio_device *dev);
 #ifdef CONFIG_PM_SLEEP
 int virtio_device_freeze(struct virtio_device *dev);
-- 
2.31.0

Added VIRTIO_F_RING_RESET, it came from here

https://github.com/oasis-tcs/virtio-spec/issues/124
https://github.com/oasis-tcs/virtio-spec/issues/139

This feature indicates that the driver can reset a queue individually.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 include/uapi/linux/virtio_config.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/virtio_config.h
b/include/uapi/linux/virtio_config.h
index f0fb0ae021c0..3c05162bc988 100644
--- a/include/uapi/linux/virtio_config.h
+++ b/include/uapi/linux/virtio_config.h
@@ -52,7 +52,7 @@
  * rest are per-device feature bits.
  */
 #define VIRTIO_TRANSPORT_F_START	28
-#define VIRTIO_TRANSPORT_F_END		38
+#define VIRTIO_TRANSPORT_F_END		41
 
 #ifndef VIRTIO_CONFIG_NO_LEGACY
 /* Do we get callbacks when the ring is completely used, even if we've
@@ -98,4 +98,9 @@
  * Does the device support Single Root I/O Virtualization?
  */
 #define VIRTIO_F_SR_IOV			37
+
+/*
+ * This feature indicates that the driver can reset a queue individually.
+ */
+#define VIRTIO_F_RING_RESET		40
 #endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
-- 
2.31.0

Add queue_reset in virtio_pci_common_cfg.

 https://github.com/oasis-tcs/virtio-spec/issues/124
 https://github.com/oasis-tcs/virtio-spec/issues/139

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 include/linux/virtio_pci_modern.h | 2 +-
 include/uapi/linux/virtio_pci.h   | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
index 9f31dde46f57..beebc7a4a31d 100644
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -30,7 +30,7 @@ struct virtio_pci_common_cfg {
 	__le32 queue_used_lo;		/* read-write */
 	__le32 queue_used_hi;		/* read-write */
 	__le16 queue_notify_data;	/* read-write */
-	__le16 padding;
+	__le16 queue_reset;		/* read-write */
 };
 
 struct virtio_pci_modern_device {
diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h
index 748b3eb62d2f..4f0a8d86cb11 100644
--- a/include/uapi/linux/virtio_pci.h
+++ b/include/uapi/linux/virtio_pci.h
@@ -177,6 +177,7 @@ struct virtio_pci_cfg_cap {
 #define VIRTIO_PCI_COMMON_Q_USEDLO	48
 #define VIRTIO_PCI_COMMON_Q_USEDHI	52
 #define VIRTIO_PCI_COMMON_Q_NDATA	56
+#define VIRTIO_PCI_COMMON_Q_RESET	58
 
 #endif /* VIRTIO_PCI_NO_MODERN */
 
-- 
2.31.0

Introduce new helpers to implement queue reset and get queue reset
status.

 https://github.com/oasis-tcs/virtio-spec/issues/124
 https://github.com/oasis-tcs/virtio-spec/issues/139

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_pci_modern_dev.c | 35 ++++++++++++++++++++++++++
 include/linux/virtio_pci_modern.h      |  2 ++
 2 files changed, 37 insertions(+)

diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
index fa2a9445bb18..07415654247c 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -3,6 +3,7 @@
 #include <linux/virtio_pci_modern.h>
 #include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/delay.h>
 
 /*
  * vp_modern_map_capability - map a part of virtio pci capability
@@ -474,6 +475,40 @@ void vp_modern_set_status(struct virtio_pci_modern_device
*mdev,
 }
 EXPORT_SYMBOL_GPL(vp_modern_set_status);
 
+/*
+ * vp_modern_get_queue_reset - get the queue reset status
+ * @mdev: the modern virtio-pci device
+ * @index: queue index
+ */
+int vp_modern_get_queue_reset(struct virtio_pci_modern_device *mdev, u16 index)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	vp_iowrite16(index, &cfg->queue_select);
+	return vp_ioread16(&cfg->queue_reset);
+}
+EXPORT_SYMBOL_GPL(vp_modern_get_queue_reset);
+
+/*
+ * vp_modern_set_queue_reset - reset the queue
+ * @mdev: the modern virtio-pci device
+ * @index: queue index
+ */
+void vp_modern_set_queue_reset(struct virtio_pci_modern_device *mdev, u16
index)
+{
+	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
+
+	vp_iowrite16(index, &cfg->queue_select);
+	vp_iowrite16(1, &cfg->queue_reset);
+
+	while (vp_ioread16(&cfg->queue_reset))
+		msleep(1);
+
+	while (vp_ioread16(&cfg->queue_enable))
+		msleep(1);
+}
+EXPORT_SYMBOL_GPL(vp_modern_set_queue_reset);
+
 /*
  * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
  * @mdev: the modern virtio-pci device
diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
index beebc7a4a31d..ded01157f864 100644
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -134,4 +134,6 @@ void __iomem * vp_modern_map_vq_notify(struct
virtio_pci_modern_device *mdev,
 				       u16 index, resource_size_t *pa);
 int vp_modern_probe(struct virtio_pci_modern_device *mdev);
 void vp_modern_remove(struct virtio_pci_modern_device *mdev);
+int vp_modern_get_queue_reset(struct virtio_pci_modern_device *mdev, u16
index);
+void vp_modern_set_queue_reset(struct virtio_pci_modern_device *mdev, u16
index);
 #endif
-- 
2.31.0

Introduce vp_active_vq() to configure vring to backend after vq attach
vring. And configure vq vector if necessary.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/virtio/virtio_pci_modern.c | 46 ++++++++++++++++++------------
 1 file changed, 28 insertions(+), 18 deletions(-)

diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
index e7e0b8c850f6..9041d9a41b7d 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -176,6 +176,29 @@ static void vp_reset(struct virtio_device *vdev)
 	vp_synchronize_vectors(vdev);
 }
 
+static int vp_active_vq(struct virtqueue *vq, u16 msix_vec)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
+	unsigned long index;
+
+	index = vq->index;
+
+	/* activate the queue */
+	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
+	vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
+				virtqueue_get_avail_addr(vq),
+				virtqueue_get_used_addr(vq));
+
+	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
+		msix_vec = vp_modern_queue_vector(mdev, index, msix_vec);
+		if (msix_vec == VIRTIO_MSI_NO_VECTOR)
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
 static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
 {
 	return vp_modern_config_vector(&vp_dev->mdev, vector);
@@ -220,32 +243,19 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 
 	vq->num_max = num;
 
-	/* activate the queue */
-	vp_modern_set_queue_size(mdev, index, virtqueue_get_vring_size(vq));
-	vp_modern_queue_address(mdev, index, virtqueue_get_desc_addr(vq),
-				virtqueue_get_avail_addr(vq),
-				virtqueue_get_used_addr(vq));
+	err = vp_active_vq(vq, msix_vec);
+	if (err)
+		goto err;
 
 	vq->priv = (void __force *)vp_modern_map_vq_notify(mdev, index, NULL);
 	if (!vq->priv) {
 		err = -ENOMEM;
-		goto err_map_notify;
-	}
-
-	if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
-		msix_vec = vp_modern_queue_vector(mdev, index, msix_vec);
-		if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
-			err = -EBUSY;
-			goto err_assign_vector;
-		}
+		goto err;
 	}
 
 	return vq;
 
-err_assign_vector:
-	if (!mdev->notify_base)
-		pci_iounmap(mdev->pci_dev, (void __iomem __force *)vq->priv);
-err_map_notify:
+err:
 	vring_del_virtqueue(vq);
 	return ERR_PTR(err);
 }
-- 
2.31.0

This patch implements virtio pci support for QUEUE RESET.

Performing reset on a queue is divided into these steps:

 1. notify the device to reset the queue
 2. recycle the buffer submitted
 3. reset the vring (may re-alloc)
 4. mmap vring to device, and enable the queue

This patch implements virtio_reset_vq(), virtio_enable_resetq() in the
pci scenario.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_pci_common.c | 12 +++-
 drivers/virtio/virtio_pci_modern.c | 96 ++++++++++++++++++++++++++++++
 drivers/virtio/virtio_ring.c       |  2 +
 include/linux/virtio.h             |  1 +
 4 files changed, 108 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
index ca51fcc9daab..ad258a9d3b9f 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -214,9 +214,15 @@ static void vp_del_vq(struct virtqueue *vq)
 	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
 	unsigned long flags;
 
-	spin_lock_irqsave(&vp_dev->lock, flags);
-	list_del(&info->node);
-	spin_unlock_irqrestore(&vp_dev->lock, flags);
+	/*
+	 * If it fails during re-enable reset vq. This way we won't rejoin
+	 * info->node to the queue. Prevent unexpected irqs.
+	 */
+	if (!vq->reset) {
+		spin_lock_irqsave(&vp_dev->lock, flags);
+		list_del(&info->node);
+		spin_unlock_irqrestore(&vp_dev->lock, flags);
+	}
 
 	vp_dev->del_vq(info);
 	kfree(info);
diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
index 9041d9a41b7d..754e5e10386b 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -34,6 +34,9 @@ static void vp_transport_features(struct virtio_device *vdev,
u64 features)
 	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
 			pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
 		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
+
+	if (features & BIT_ULL(VIRTIO_F_RING_RESET))
+		__virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
 }
 
 /* virtio config->finalize_features() implementation */
@@ -199,6 +202,95 @@ static int vp_active_vq(struct virtqueue *vq, u16 msix_vec)
 	return 0;
 }
 
+static int vp_modern_reset_vq(struct virtqueue *vq)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
+	struct virtio_pci_vq_info *info;
+	unsigned long flags;
+
+	if (!virtio_has_feature(vq->vdev, VIRTIO_F_RING_RESET))
+		return -ENOENT;
+
+	vp_modern_set_queue_reset(mdev, vq->index);
+
+	info = vp_dev->vqs[vq->index];
+
+	/* delete vq from irq handler */
+	spin_lock_irqsave(&vp_dev->lock, flags);
+	list_del(&info->node);
+	spin_unlock_irqrestore(&vp_dev->lock, flags);
+
+	INIT_LIST_HEAD(&info->node);
+
+	/* For the case where vq has an exclusive irq, to prevent the irq from
+	 * being received again and the pending irq, call synchronize_irq(), and
+	 * break it.
+	 *
+	 * We can't use disable_irq() since it conflicts with the affinity
+	 * managed IRQ that is used by some drivers. So this is done on top of
+	 * IRQ hardening.
+	 *
+	 * In the scenario based on shared interrupts, vq will be searched from
+	 * the queue virtqueues. Since the previous list_del() has been deleted
+	 * from the queue, it is impossible for vq to be called in this case.
+	 * There is no need to close the corresponding interrupt.
+	 */
+	if (vp_dev->per_vq_vectors && info->msix_vector !=
VIRTIO_MSI_NO_VECTOR) {
+#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
+		__virtqueue_break(vq);
+#endif
+		synchronize_irq(pci_irq_vector(vp_dev->pci_dev, info->msix_vector));
+	}
+
+	vq->reset = true;
+
+	return 0;
+}
+
+static int vp_modern_enable_reset_vq(struct virtqueue *vq)
+{
+	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
+	struct virtio_pci_vq_info *info;
+	unsigned long flags, index;
+	int err;
+
+	if (!vq->reset)
+		return -EBUSY;
+
+	index = vq->index;
+	info = vp_dev->vqs[index];
+
+	if (vp_modern_get_queue_reset(mdev, index))
+		return -EBUSY;
+
+	if (vp_modern_get_queue_enable(mdev, index))
+		return -EBUSY;
+
+	err = vp_active_vq(vq, info->msix_vector);
+	if (err)
+		return err;
+
+	if (vq->callback) {
+		spin_lock_irqsave(&vp_dev->lock, flags);
+		list_add(&info->node, &vp_dev->virtqueues);
+		spin_unlock_irqrestore(&vp_dev->lock, flags);
+	} else {
+		INIT_LIST_HEAD(&info->node);
+	}
+
+#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
+	if (vp_dev->per_vq_vectors && info->msix_vector !=
VIRTIO_MSI_NO_VECTOR)
+		__virtqueue_unbreak(vq);
+#endif
+
+	vp_modern_set_queue_enable(&vp_dev->mdev, index, true);
+	vq->reset = false;
+
+	return 0;
+}
+
 static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
 {
 	return vp_modern_config_vector(&vp_dev->mdev, vector);
@@ -413,6 +505,8 @@ static const struct virtio_config_ops
virtio_pci_config_nodev_ops = {
 	.set_vq_affinity = vp_set_vq_affinity,
 	.get_vq_affinity = vp_get_vq_affinity,
 	.get_shm_region  = vp_get_shm_region,
+	.reset_vq	 = vp_modern_reset_vq,
+	.enable_reset_vq = vp_modern_enable_reset_vq,
 };
 
 static const struct virtio_config_ops virtio_pci_config_ops = {
@@ -431,6 +525,8 @@ static const struct virtio_config_ops virtio_pci_config_ops
= {
 	.set_vq_affinity = vp_set_vq_affinity,
 	.get_vq_affinity = vp_get_vq_affinity,
 	.get_shm_region  = vp_get_shm_region,
+	.reset_vq	 = vp_modern_reset_vq,
+	.enable_reset_vq = vp_modern_enable_reset_vq,
 };
 
 /* the PCI probing function */
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 7b02be7fce67..82b058e8ce34 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -2008,6 +2008,7 @@ static struct virtqueue *vring_create_virtqueue_packed(
 	vq->vq.vdev = vdev;
 	vq->vq.name = name;
 	vq->vq.index = index;
+	vq->vq.reset = false;
 	vq->we_own_ring = true;
 	vq->notify = notify;
 	vq->weak_barriers = weak_barriers;
@@ -2487,6 +2488,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
 	vq->vq.vdev = vdev;
 	vq->vq.name = name;
 	vq->vq.index = index;
+	vq->vq.reset = false;
 	vq->we_own_ring = false;
 	vq->notify = notify;
 	vq->weak_barriers = weak_barriers;
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index dc474a0d48d1..88f21796b1c3 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -33,6 +33,7 @@ struct virtqueue {
 	unsigned int num_free;
 	unsigned int num_max;
 	void *priv;
+	bool reset;
 };
 
 int virtqueue_add_outbuf(struct virtqueue *vq,
-- 
2.31.0

find_vqs() adds a new parameter sizes to specify the size of each vq
vring.

NULL as sizes means that all queues in find_vqs() use the maximum size.
A value in the array is 0, which means that the corresponding queue uses
the maximum size.

In the split scenario, the meaning of size is the largest size, because
it may be limited by memory, the virtio core will try a smaller size.
And the size is power of 2.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Hans de Goede <hdegoede at redhat.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier at linaro.org>
---
 arch/um/drivers/virtio_uml.c             |  2 +-
 drivers/platform/mellanox/mlxbf-tmfifo.c |  1 +
 drivers/remoteproc/remoteproc_virtio.c   |  1 +
 drivers/s390/virtio/virtio_ccw.c         |  1 +
 drivers/virtio/virtio_mmio.c             |  1 +
 drivers/virtio/virtio_pci_common.c       |  2 +-
 drivers/virtio/virtio_pci_common.h       |  2 +-
 drivers/virtio/virtio_pci_modern.c       |  7 +++++--
 drivers/virtio/virtio_vdpa.c             |  1 +
 include/linux/virtio_config.h            | 14 +++++++++-----
 10 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index e719af8bdf56..79e38afd4b91 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -1011,7 +1011,7 @@ static struct virtqueue *vu_setup_vq(struct virtio_device
*vdev,
 
 static int vu_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 		       struct virtqueue *vqs[], vq_callback_t *callbacks[],
-		       const char * const names[], const bool *ctx,
+		       const char * const names[], u32 sizes[], const bool *ctx,
 		       struct irq_affinity *desc)
 {
 	struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
diff --git a/drivers/platform/mellanox/mlxbf-tmfifo.c
b/drivers/platform/mellanox/mlxbf-tmfifo.c
index 1ae3c56b66b0..8be13d416f48 100644
--- a/drivers/platform/mellanox/mlxbf-tmfifo.c
+++ b/drivers/platform/mellanox/mlxbf-tmfifo.c
@@ -928,6 +928,7 @@ static int mlxbf_tmfifo_virtio_find_vqs(struct virtio_device
*vdev,
 					struct virtqueue *vqs[],
 					vq_callback_t *callbacks[],
 					const char * const names[],
+					u32 sizes[],
 					const bool *ctx,
 					struct irq_affinity *desc)
 {
diff --git a/drivers/remoteproc/remoteproc_virtio.c
b/drivers/remoteproc/remoteproc_virtio.c
index 0f7706e23eb9..81c4f5776109 100644
--- a/drivers/remoteproc/remoteproc_virtio.c
+++ b/drivers/remoteproc/remoteproc_virtio.c
@@ -158,6 +158,7 @@ static int rproc_virtio_find_vqs(struct virtio_device *vdev,
unsigned int nvqs,
 				 struct virtqueue *vqs[],
 				 vq_callback_t *callbacks[],
 				 const char * const names[],
+				 u32 sizes[],
 				 const bool * ctx,
 				 struct irq_affinity *desc)
 {
diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index 6b86d0280d6b..72500cd2dbf5 100644
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -635,6 +635,7 @@ static int virtio_ccw_find_vqs(struct virtio_device *vdev,
unsigned nvqs,
 			       struct virtqueue *vqs[],
 			       vq_callback_t *callbacks[],
 			       const char * const names[],
+			       u32 sizes[],
 			       const bool *ctx,
 			       struct irq_affinity *desc)
 {
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index a20d5a6b5819..5e3ba3cc7fd0 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -474,6 +474,7 @@ static int vm_find_vqs(struct virtio_device *vdev, unsigned
int nvqs,
 		       struct virtqueue *vqs[],
 		       vq_callback_t *callbacks[],
 		       const char * const names[],
+		       u32 sizes[],
 		       const bool *ctx,
 		       struct irq_affinity *desc)
 {
diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
index ad258a9d3b9f..7ad734584823 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -396,7 +396,7 @@ static int vp_find_vqs_intx(struct virtio_device *vdev,
unsigned int nvqs,
 /* the config->find_vqs() implementation */
 int vp_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
 		struct virtqueue *vqs[], vq_callback_t *callbacks[],
-		const char * const names[], const bool *ctx,
+		const char * const names[], u32 sizes[], const bool *ctx,
 		struct irq_affinity *desc)
 {
 	int err;
diff --git a/drivers/virtio/virtio_pci_common.h
b/drivers/virtio/virtio_pci_common.h
index 23112d84218f..a5ff838b85a5 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -110,7 +110,7 @@ void vp_del_vqs(struct virtio_device *vdev);
 /* the config->find_vqs() implementation */
 int vp_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
 		struct virtqueue *vqs[], vq_callback_t *callbacks[],
-		const char * const names[], const bool *ctx,
+		const char * const names[], u32 sizes[], const bool *ctx,
 		struct irq_affinity *desc);
 const char *vp_bus_name(struct virtio_device *vdev);
 
diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
index 754e5e10386b..287cb3c2b55f 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -355,12 +355,15 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 static int vp_modern_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
 			      struct virtqueue *vqs[],
 			      vq_callback_t *callbacks[],
-			      const char * const names[], const bool *ctx,
+			      const char * const names[],
+			      u32 sizes[],
+			      const bool *ctx,
 			      struct irq_affinity *desc)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	struct virtqueue *vq;
-	int rc = vp_find_vqs(vdev, nvqs, vqs, callbacks, names, ctx, desc);
+	int rc = vp_find_vqs(vdev, nvqs, vqs, callbacks, names, sizes, ctx,
+			     desc);
 
 	if (rc)
 		return rc;
diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
index 9670cc79371d..832d2c5b1b19 100644
--- a/drivers/virtio/virtio_vdpa.c
+++ b/drivers/virtio/virtio_vdpa.c
@@ -269,6 +269,7 @@ static int virtio_vdpa_find_vqs(struct virtio_device *vdev,
unsigned int nvqs,
 				struct virtqueue *vqs[],
 				vq_callback_t *callbacks[],
 				const char * const names[],
+				u32 sizes[],
 				const bool *ctx,
 				struct irq_affinity *desc)
 {
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index ded51b0d4823..31b04ac8284b 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -55,6 +55,7 @@ struct virtio_shm_region {
  *		include a NULL entry for vqs that do not need a callback
  *	names: array of virtqueue names (mainly for debugging)
  *		include a NULL entry for vqs unused by driver
+ *	sizes: array of virtqueue sizes
  *	Returns 0 on success or error status
  * @del_vqs: free virtqueues found by find_vqs().
  * @synchronize_cbs: synchronize with the virtqueue callbacks (optional)
@@ -101,7 +102,9 @@ struct virtio_config_ops {
 	void (*reset)(struct virtio_device *vdev);
 	int (*find_vqs)(struct virtio_device *, unsigned nvqs,
 			struct virtqueue *vqs[], vq_callback_t *callbacks[],
-			const char * const names[], const bool *ctx,
+			const char * const names[],
+			u32 sizes[],
+			const bool *ctx,
 			struct irq_affinity *desc);
 	void (*del_vqs)(struct virtio_device *);
 	void (*synchronize_cbs)(struct virtio_device *);
@@ -210,7 +213,7 @@ struct virtqueue *virtio_find_single_vq(struct virtio_device
*vdev,
 	const char *names[] = { n };
 	struct virtqueue *vq;
 	int err = vdev->config->find_vqs(vdev, 1, &vq, callbacks, names,
NULL,
-					 NULL);
+					 NULL, NULL);
 	if (err < 0)
 		return ERR_PTR(err);
 	return vq;
@@ -222,7 +225,8 @@ int virtio_find_vqs(struct virtio_device *vdev, unsigned
nvqs,
 			const char * const names[],
 			struct irq_affinity *desc)
 {
-	return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, NULL,
desc);
+	return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, NULL,
+				      NULL, desc);
 }
 
 static inline
@@ -231,8 +235,8 @@ int virtio_find_vqs_ctx(struct virtio_device *vdev, unsigned
nvqs,
 			const char * const names[], const bool *ctx,
 			struct irq_affinity *desc)
 {
-	return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, ctx,
-				      desc);
+	return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, NULL,
+				      ctx, desc);
 }
 
 /**
-- 
2.31.0

Virtio PCI supports new parameter sizes of find_vqs().

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/virtio/virtio_pci_common.c | 18 ++++++++++--------
 drivers/virtio/virtio_pci_common.h |  1 +
 drivers/virtio/virtio_pci_legacy.c |  6 +++++-
 drivers/virtio/virtio_pci_modern.c | 10 +++++++---
 4 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
index 7ad734584823..00ad476a815d 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -174,6 +174,7 @@ static int vp_request_msix_vectors(struct virtio_device
*vdev, int nvectors,
 static struct virtqueue *vp_setup_vq(struct virtio_device *vdev, unsigned int
index,
 				     void (*callback)(struct virtqueue *vq),
 				     const char *name,
+				     u32 size,
 				     bool ctx,
 				     u16 msix_vec)
 {
@@ -186,7 +187,7 @@ static struct virtqueue *vp_setup_vq(struct virtio_device
*vdev, unsigned int in
 	if (!info)
 		return ERR_PTR(-ENOMEM);
 
-	vq = vp_dev->setup_vq(vp_dev, info, index, callback, name, ctx,
+	vq = vp_dev->setup_vq(vp_dev, info, index, callback, name, size, ctx,
 			      msix_vec);
 	if (IS_ERR(vq))
 		goto out_info;
@@ -283,7 +284,7 @@ void vp_del_vqs(struct virtio_device *vdev)
 
 static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned int nvqs,
 		struct virtqueue *vqs[], vq_callback_t *callbacks[],
-		const char * const names[], bool per_vq_vectors,
+		const char * const names[], u32 sizes[], bool per_vq_vectors,
 		const bool *ctx,
 		struct irq_affinity *desc)
 {
@@ -326,8 +327,8 @@ static int vp_find_vqs_msix(struct virtio_device *vdev,
unsigned int nvqs,
 		else
 			msix_vec = VP_MSIX_VQ_VECTOR;
 		vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
-				     ctx ? ctx[i] : false,
-				     msix_vec);
+				     sizes ? sizes[i] : 0,
+				     ctx ? ctx[i] : false, msix_vec);
 		if (IS_ERR(vqs[i])) {
 			err = PTR_ERR(vqs[i]);
 			goto error_find;
@@ -357,7 +358,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev,
unsigned int nvqs,
 
 static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned int nvqs,
 		struct virtqueue *vqs[], vq_callback_t *callbacks[],
-		const char * const names[], const bool *ctx)
+		const char * const names[], u32 sizes[], const bool *ctx)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	int i, err, queue_idx = 0;
@@ -379,6 +380,7 @@ static int vp_find_vqs_intx(struct virtio_device *vdev,
unsigned int nvqs,
 			continue;
 		}
 		vqs[i] = vp_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
+				     sizes ? sizes[i] : 0,
 				     ctx ? ctx[i] : false,
 				     VIRTIO_MSI_NO_VECTOR);
 		if (IS_ERR(vqs[i])) {
@@ -402,15 +404,15 @@ int vp_find_vqs(struct virtio_device *vdev, unsigned int
nvqs,
 	int err;
 
 	/* Try MSI-X with one vector per queue. */
-	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true, ctx, desc);
+	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, sizes, true, ctx,
desc);
 	if (!err)
 		return 0;
 	/* Fallback: MSI-X with one vector for config, one shared for queues. */
-	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, false, ctx, desc);
+	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, sizes, false, ctx,
desc);
 	if (!err)
 		return 0;
 	/* Finally fall back to regular interrupts. */
-	return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, ctx);
+	return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, sizes, ctx);
 }
 
 const char *vp_bus_name(struct virtio_device *vdev)
diff --git a/drivers/virtio/virtio_pci_common.h
b/drivers/virtio/virtio_pci_common.h
index a5ff838b85a5..c0448378b698 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -80,6 +80,7 @@ struct virtio_pci_device {
 				      unsigned int idx,
 				      void (*callback)(struct virtqueue *vq),
 				      const char *name,
+				      u32 size,
 				      bool ctx,
 				      u16 msix_vec);
 	void (*del_vq)(struct virtio_pci_vq_info *info);
diff --git a/drivers/virtio/virtio_pci_legacy.c
b/drivers/virtio/virtio_pci_legacy.c
index 2257f1b3d8ae..d75e5c4e637f 100644
--- a/drivers/virtio/virtio_pci_legacy.c
+++ b/drivers/virtio/virtio_pci_legacy.c
@@ -112,6 +112,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 				  unsigned int index,
 				  void (*callback)(struct virtqueue *vq),
 				  const char *name,
+				  u32 size,
 				  bool ctx,
 				  u16 msix_vec)
 {
@@ -125,10 +126,13 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 	if (!num || vp_legacy_get_queue_enable(&vp_dev->ldev, index))
 		return ERR_PTR(-ENOENT);
 
+	if (!size || size > num)
+		size = num;
+
 	info->msix_vector = msix_vec;
 
 	/* create the vring */
-	vq = vring_create_virtqueue(index, num,
+	vq = vring_create_virtqueue(index, size,
 				    VIRTIO_PCI_VRING_ALIGN, &vp_dev->vdev,
 				    true, false, ctx,
 				    vp_notify, callback, name);
diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
index 287cb3c2b55f..781e40d8ba0d 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -301,6 +301,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 				  unsigned int index,
 				  void (*callback)(struct virtqueue *vq),
 				  const char *name,
+				  u32 size,
 				  bool ctx,
 				  u16 msix_vec)
 {
@@ -318,15 +319,18 @@ static struct virtqueue *setup_vq(struct virtio_pci_device
*vp_dev,
 	if (!num || vp_modern_get_queue_enable(mdev, index))
 		return ERR_PTR(-ENOENT);
 
-	if (num & (num - 1)) {
-		dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u",
num);
+	if (!size || size > num)
+		size = num;
+
+	if (size & (size - 1)) {
+		dev_warn(&vp_dev->pci_dev->dev, "bad queue size %u",
size);
 		return ERR_PTR(-EINVAL);
 	}
 
 	info->msix_vector = msix_vec;
 
 	/* create the vring */
-	vq = vring_create_virtqueue(index, num,
+	vq = vring_create_virtqueue(index, size,
 				    SMP_CACHE_BYTES, &vp_dev->vdev,
 				    true, true, ctx,
 				    vp_notify, callback, name);
-- 
2.31.0

Virtio MMIO support the new parameter sizes of find_vqs().

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/virtio/virtio_mmio.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 5e3ba3cc7fd0..c888fee18caf 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -360,7 +360,7 @@ static void vm_synchronize_cbs(struct virtio_device *vdev)
 
 static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned int
index,
 				  void (*callback)(struct virtqueue *vq),
-				  const char *name, bool ctx)
+				  const char *name, u32 size, bool ctx)
 {
 	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 	struct virtio_mmio_vq_info *info;
@@ -395,8 +395,11 @@ static struct virtqueue *vm_setup_vq(struct virtio_device
*vdev, unsigned int in
 		goto error_new_virtqueue;
 	}
 
+	if (!size || size > num)
+		size = num;
+
 	/* Create the vring */
-	vq = vring_create_virtqueue(index, num, VIRTIO_MMIO_VRING_ALIGN, vdev,
+	vq = vring_create_virtqueue(index, size, VIRTIO_MMIO_VRING_ALIGN, vdev,
 				 true, true, ctx, vm_notify, callback, name);
 	if (!vq) {
 		err = -ENOMEM;
@@ -497,6 +500,7 @@ static int vm_find_vqs(struct virtio_device *vdev, unsigned
int nvqs,
 		}
 
 		vqs[i] = vm_setup_vq(vdev, queue_idx++, callbacks[i], names[i],
+				     sizes ? sizes[i] : 0,
 				     ctx ? ctx[i] : false);
 		if (IS_ERR(vqs[i])) {
 			vm_del_vqs(vdev);
-- 
2.31.0

Introduce helper virtio_find_vqs_ctx_size() to call find_vqs and specify
the maximum size of each vq ring.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 include/linux/virtio_config.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 31b04ac8284b..aa6cdf353748 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -239,6 +239,18 @@ int virtio_find_vqs_ctx(struct virtio_device *vdev,
unsigned nvqs,
 				      ctx, desc);
 }
 
+static inline
+int virtio_find_vqs_ctx_size(struct virtio_device *vdev, u32 nvqs,
+			     struct virtqueue *vqs[],
+			     vq_callback_t *callbacks[],
+			     const char * const names[],
+			     u32 sizes[],
+			     const bool *ctx, struct irq_affinity *desc)
+{
+	return vdev->config->find_vqs(vdev, nvqs, vqs, callbacks, names, sizes,
+				      ctx, desc);
+}
+
 /**
  * virtio_synchronize_cbs - synchronize with virtqueue callbacks
  * @vdev: the device
-- 
2.31.0

Use virtio_find_vqs_ctx_size() to specify the maximum ring size of tx,
rx at the same time.

                         | rx/tx ring size
-------------------------------------------
speed == UNKNOWN or < 10G| 1024
speed < 40G              | 4096
speed >= 40G             | 8192

Call virtnet_update_settings() once before calling init_vqs() to update
speed.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/net/virtio_net.c | 42 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 38 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 8a5810bcb839..40532ecbe7fc 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3208,6 +3208,29 @@ static unsigned int mergeable_min_buf_len(struct
virtnet_info *vi, struct virtqu
 		   (unsigned int)GOOD_PACKET_LEN);
 }
 
+static void virtnet_config_sizes(struct virtnet_info *vi, u32 *sizes)
+{
+	u32 i, rx_size, tx_size;
+
+	if (vi->speed == SPEED_UNKNOWN || vi->speed < SPEED_10000) {
+		rx_size = 1024;
+		tx_size = 1024;
+
+	} else if (vi->speed < SPEED_40000) {
+		rx_size = 1024 * 4;
+		tx_size = 1024 * 4;
+
+	} else {
+		rx_size = 1024 * 8;
+		tx_size = 1024 * 8;
+	}
+
+	for (i = 0; i < vi->max_queue_pairs; i++) {
+		sizes[rxq2vq(i)] = rx_size;
+		sizes[txq2vq(i)] = tx_size;
+	}
+}
+
 static int virtnet_find_vqs(struct virtnet_info *vi)
 {
 	vq_callback_t **callbacks;
@@ -3215,6 +3238,7 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 	int ret = -ENOMEM;
 	int i, total_vqs;
 	const char **names;
+	u32 *sizes;
 	bool *ctx;
 
 	/* We expect 1 RX virtqueue followed by 1 TX virtqueue, followed by
@@ -3242,10 +3266,15 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 		ctx = NULL;
 	}
 
+	sizes = kmalloc_array(total_vqs, sizeof(*sizes), GFP_KERNEL);
+	if (!sizes)
+		goto err_sizes;
+
 	/* Parameters for control virtqueue, if any */
 	if (vi->has_cvq) {
 		callbacks[total_vqs - 1] = NULL;
 		names[total_vqs - 1] = "control";
+		sizes[total_vqs - 1] = 64;
 	}
 
 	/* Allocate/initialize parameters for send/receive virtqueues */
@@ -3260,8 +3289,10 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 			ctx[rxq2vq(i)] = true;
 	}
 
-	ret = virtio_find_vqs_ctx(vi->vdev, total_vqs, vqs, callbacks,
-				  names, ctx, NULL);
+	virtnet_config_sizes(vi, sizes);
+
+	ret = virtio_find_vqs_ctx_size(vi->vdev, total_vqs, vqs, callbacks,
+				       names, sizes, ctx, NULL);
 	if (ret)
 		goto err_find;
 
@@ -3281,6 +3312,8 @@ static int virtnet_find_vqs(struct virtnet_info *vi)
 
 
 err_find:
+	kfree(sizes);
+err_sizes:
 	kfree(ctx);
 err_ctx:
 	kfree(names);
@@ -3630,6 +3663,9 @@ static int virtnet_probe(struct virtio_device *vdev)
 		vi->curr_queue_pairs = num_online_cpus();
 	vi->max_queue_pairs = max_queue_pairs;
 
+	virtnet_init_settings(dev);
+	virtnet_update_settings(vi);
+
 	/* Allocate/initialize the rx/tx queues, and invoke find_vqs */
 	err = init_vqs(vi);
 	if (err)
@@ -3642,8 +3678,6 @@ static int virtnet_probe(struct virtio_device *vdev)
 	netif_set_real_num_tx_queues(dev, vi->curr_queue_pairs);
 	netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);
 
-	virtnet_init_settings(dev);
-
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_STANDBY)) {
 		vi->failover = net_failover_create(vi->dev);
 		if (IS_ERR(vi->failover)) {
-- 
2.31.0

Use virtqueue_get_vring_max_size() in virtnet_get_ringparam() to set
tx,rx_max_pending.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/net/virtio_net.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 40532ecbe7fc..63f990bdc302 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2254,10 +2254,10 @@ static void virtnet_get_ringparam(struct net_device
*dev,
 {
 	struct virtnet_info *vi = netdev_priv(dev);
 
-	ring->rx_max_pending = virtqueue_get_vring_size(vi->rq[0].vq);
-	ring->tx_max_pending = virtqueue_get_vring_size(vi->sq[0].vq);
-	ring->rx_pending = ring->rx_max_pending;
-	ring->tx_pending = ring->tx_max_pending;
+	ring->rx_max_pending = virtqueue_get_vring_max_size(vi->rq[0].vq);
+	ring->tx_max_pending = virtqueue_get_vring_max_size(vi->sq[0].vq);
+	ring->rx_pending = virtqueue_get_vring_size(vi->rq[0].vq);
+	ring->tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
 }
 
 static bool virtnet_commit_rss_command(struct virtnet_info *vi)
-- 
2.31.0

This patch separates two functions for freeing sq buf and rq buf from
free_unused_bufs().

When supporting the enable/disable tx/rq queue in the future, it is
necessary to support separate recovery of a sq buf or a rq buf.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/net/virtio_net.c | 41 ++++++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 16 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 63f990bdc302..9fe222a3663a 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -3151,6 +3151,27 @@ static void free_receive_page_frags(struct virtnet_info
*vi)
 			put_page(vi->rq[i].alloc_frag.page);
 }
 
+static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
+{
+	if (!is_xdp_frame(buf))
+		dev_kfree_skb(buf);
+	else
+		xdp_return_frame(ptr_to_xdp(buf));
+}
+
+static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
+{
+	struct virtnet_info *vi = vq->vdev->priv;
+	int i = vq2rxq(vq);
+
+	if (vi->mergeable_rx_bufs)
+		put_page(virt_to_head_page(buf));
+	else if (vi->big_packets)
+		give_pages(&vi->rq[i], buf);
+	else
+		put_page(virt_to_head_page(buf));
+}
+
 static void free_unused_bufs(struct virtnet_info *vi)
 {
 	void *buf;
@@ -3158,26 +3179,14 @@ static void free_unused_bufs(struct virtnet_info *vi)
 
 	for (i = 0; i < vi->max_queue_pairs; i++) {
 		struct virtqueue *vq = vi->sq[i].vq;
-		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) {
-			if (!is_xdp_frame(buf))
-				dev_kfree_skb(buf);
-			else
-				xdp_return_frame(ptr_to_xdp(buf));
-		}
+		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
+			virtnet_sq_free_unused_buf(vq, buf);
 	}
 
 	for (i = 0; i < vi->max_queue_pairs; i++) {
 		struct virtqueue *vq = vi->rq[i].vq;
-
-		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL) {
-			if (vi->mergeable_rx_bufs) {
-				put_page(virt_to_head_page(buf));
-			} else if (vi->big_packets) {
-				give_pages(&vi->rq[i], buf);
-			} else {
-				put_page(virt_to_head_page(buf));
-			}
-		}
+		while ((buf = virtqueue_detach_unused_buf(vq)) != NULL)
+			virtnet_rq_free_unused_buf(vq, buf);
 	}
 }
 
-- 
2.31.0

This patch implements the resize function of the rx queues.
Based on this function, it is possible to modify the ring num of the
queue.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/net/virtio_net.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 9fe222a3663a..6ab16fd193e5 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -278,6 +278,8 @@ struct padded_vnet_hdr {
 	char padding[12];
 };
 
+static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
+
 static bool is_xdp_frame(void *ptr)
 {
 	return (unsigned long)ptr & VIRTIO_XDP_FLAG;
@@ -1846,6 +1848,26 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct
net_device *dev)
 	return NETDEV_TX_OK;
 }
 
+static int virtnet_rx_resize(struct virtnet_info *vi,
+			     struct receive_queue *rq, u32 ring_num)
+{
+	int err, qindex;
+
+	qindex = rq - vi->rq;
+
+	napi_disable(&rq->napi);
+
+	err = virtqueue_resize(rq->vq, ring_num, virtnet_rq_free_unused_buf);
+	if (err)
+		netdev_err(vi->dev, "resize rx fail: rx queue index: %d err:
%d\n", qindex, err);
+
+	if (!try_fill_recv(vi, rq, GFP_KERNEL))
+		schedule_delayed_work(&vi->refill, 0);
+
+	virtnet_napi_enable(rq->vq, &rq->napi);
+	return err;
+}
+
 /*
  * Send command via the control virtqueue and check status.  Commands
  * supported by the hypervisor, as indicated by feature bits, should
-- 
2.31.0

This patch implements the resize function of the tx queues.
Based on this function, it is possible to modify the ring num of the
queue.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/net/virtio_net.c | 48 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 6ab16fd193e5..fd358462f802 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -135,6 +135,9 @@ struct send_queue {
 	struct virtnet_sq_stats stats;
 
 	struct napi_struct napi;
+
+	/* Record whether sq is in reset state. */
+	bool reset;
 };
 
 /* Internal representation of a receive virtqueue */
@@ -279,6 +282,7 @@ struct padded_vnet_hdr {
 };
 
 static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
+static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
 
 static bool is_xdp_frame(void *ptr)
 {
@@ -1603,6 +1607,11 @@ static void virtnet_poll_cleantx(struct receive_queue
*rq)
 		return;
 
 	if (__netif_tx_trylock(txq)) {
+		if (READ_ONCE(sq->reset)) {
+			__netif_tx_unlock(txq);
+			return;
+		}
+
 		do {
 			virtqueue_disable_cb(sq->vq);
 			free_old_xmit_skbs(sq, true);
@@ -1868,6 +1877,45 @@ static int virtnet_rx_resize(struct virtnet_info *vi,
 	return err;
 }
 
+static int virtnet_tx_resize(struct virtnet_info *vi,
+			     struct send_queue *sq, u32 ring_num)
+{
+	struct netdev_queue *txq;
+	int err, qindex;
+
+	qindex = sq - vi->sq;
+
+	virtnet_napi_tx_disable(&sq->napi);
+
+	txq = netdev_get_tx_queue(vi->dev, qindex);
+
+	/* 1. wait all ximt complete
+	 * 2. fix the race of netif_stop_subqueue() vs netif_start_subqueue()
+	 */
+	__netif_tx_lock_bh(txq);
+
+	/* Prevent rx poll from accessing sq. */
+	WRITE_ONCE(sq->reset, true);
+
+	/* Prevent the upper layer from trying to send packets. */
+	netif_stop_subqueue(vi->dev, qindex);
+
+	__netif_tx_unlock_bh(txq);
+
+	err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf);
+	if (err)
+		netdev_err(vi->dev, "resize tx fail: tx queue index: %d err:
%d\n", qindex, err);
+
+	/* Memory barrier before set reset and start subqueue. */
+	smp_mb();
+
+	WRITE_ONCE(sq->reset, false);
+	netif_tx_wake_queue(txq);
+
+	virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
+	return err;
+}
+
 /*
  * Send command via the control virtqueue and check status.  Commands
  * supported by the hypervisor, as indicated by feature bits, should
-- 
2.31.0

Support set_ringparam based on virtio queue reset.

Users can use ethtool -G eth0 <ring_num> to modify the ring size of
virtio-net.

Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
Acked-by: Jason Wang <jasowang at redhat.com>
---
 drivers/net/virtio_net.c | 48 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index fd358462f802..cc554cbac431 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2330,6 +2330,53 @@ static void virtnet_get_ringparam(struct net_device *dev,
 	ring->tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
 }
 
+static int virtnet_set_ringparam(struct net_device *dev,
+				 struct ethtool_ringparam *ring,
+				 struct kernel_ethtool_ringparam *kernel_ring,
+				 struct netlink_ext_ack *extack)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+	u32 rx_pending, tx_pending;
+	struct receive_queue *rq;
+	struct send_queue *sq;
+	int i, err;
+
+	if (ring->rx_mini_pending || ring->rx_jumbo_pending)
+		return -EINVAL;
+
+	rx_pending = virtqueue_get_vring_size(vi->rq[0].vq);
+	tx_pending = virtqueue_get_vring_size(vi->sq[0].vq);
+
+	if (ring->rx_pending == rx_pending &&
+	    ring->tx_pending == tx_pending)
+		return 0;
+
+	if (ring->rx_pending > virtqueue_get_vring_max_size(vi->rq[0].vq))
+		return -EINVAL;
+
+	if (ring->tx_pending > virtqueue_get_vring_max_size(vi->sq[0].vq))
+		return -EINVAL;
+
+	for (i = 0; i < vi->max_queue_pairs; i++) {
+		rq = vi->rq + i;
+		sq = vi->sq + i;
+
+		if (ring->tx_pending != tx_pending) {
+			err = virtnet_tx_resize(vi, sq, ring->tx_pending);
+			if (err)
+				return err;
+		}
+
+		if (ring->rx_pending != rx_pending) {
+			err = virtnet_rx_resize(vi, rq, ring->rx_pending);
+			if (err)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
 static bool virtnet_commit_rss_command(struct virtnet_info *vi)
 {
 	struct net_device *dev = vi->dev;
@@ -2817,6 +2864,7 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
 	.get_drvinfo = virtnet_get_drvinfo,
 	.get_link = ethtool_op_get_link,
 	.get_ringparam = virtnet_get_ringparam,
+	.set_ringparam = virtnet_set_ringparam,
 	.get_strings = virtnet_get_strings,
 	.get_sset_count = virtnet_get_sset_count,
 	.get_ethtool_stats = virtnet_get_ethtool_stats,
-- 
2.31.0

On Wed, Jun 29, 2022 at 02:56:18PM +0800, Xuan Zhuo
wrote:
> reset can be divided into the following four steps (example):
>  1. transport: notify the device to reset the queue
>  2. vring:     recycle the buffer submitted
>  3. vring:     reset/resize the vring (may re-alloc)
>  4. transport: mmap vring to device, and enable the queue
> 
> In order to support queue reset, add two callbacks(reset_vq,
> enable_reset_vq) in struct virtio_config_ops to implement steps 1 and 4.
> 
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>  include/linux/virtio_config.h | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
> index b47c2e7ed0ee..ded51b0d4823 100644
> --- a/include/linux/virtio_config.h
> +++ b/include/linux/virtio_config.h
> @@ -78,6 +78,16 @@ struct virtio_shm_region {
>   * @set_vq_affinity: set the affinity for a virtqueue (optional).
>   * @get_vq_affinity: get the affinity for a virtqueue (optional).
>   * @get_shm_region: get a shared memory region based on the index.
> + * @reset_vq: reset a queue individually (optional).
> + *	vq: the virtqueue
> + *	Returns 0 on success or error status
> + *	reset_vq will guarantee that the callbacks are disabled and
synchronized.
> + *	Except for the callback, the caller should guarantee that the vring is
> + *	not accessed by any functions of virtqueue.
> + * @enable_reset_vq: enable a reset queue
> + *	vq: the virtqueue
> + *	Returns 0 on success or error status
> + *	If reset_vq is set, then enable_reset_vq must also be set.
>   */
>  typedef void vq_callback_t(struct virtqueue *);
>  struct virtio_config_ops {
> @@ -104,6 +114,8 @@ struct virtio_config_ops {
>  			int index);
>  	bool (*get_shm_region)(struct virtio_device *vdev,
>  			       struct virtio_shm_region *region, u8 id);
> +	int (*reset_vq)(struct virtqueue *vq);
> +	int (*enable_reset_vq)(struct virtqueue *vq);
>  };
The names need some tweaking.
I came up with
 	int (*disable_vq_and_reset)(struct virtqueue *vq);
 	int (*enable_vq_after_reset)(struct virtqueue *vq);

>  /* If driver didn't advertise the feature, it will never appear. */
> -- 
> 2.31.0

On Wed, Jun 29, 2022 at 02:56:41PM +0800, Xuan Zhuo
wrote:
> This patch allows the new introduced
> __virtqueue_break()/__virtqueue_unbreak() to break/unbreak the
> virtqueue.
> 
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
I wonder how this interacts with the hardening patches.
Jason?
> ---
>  drivers/virtio/virtio_ring.c | 24 ++++++++++++++++++++++++
>  include/linux/virtio.h       |  3 +++
>  2 files changed, 27 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 5ec43607cc15..7b02be7fce67 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2744,6 +2744,30 @@ unsigned int virtqueue_get_vring_size(struct
virtqueue *_vq)
>  }
>  EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);
>  
> +/*
> + * This function should only be called by the core, not directly by the
driver.
> + */
> +void __virtqueue_break(struct virtqueue *_vq)
> +{
> +	struct vring_virtqueue *vq = to_vvq(_vq);
> +
> +	/* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> +	WRITE_ONCE(vq->broken, true);
> +}
> +EXPORT_SYMBOL_GPL(__virtqueue_break);
> +
> +/*
> + * This function should only be called by the core, not directly by the
driver.
> + */
> +void __virtqueue_unbreak(struct virtqueue *_vq)
> +{
> +	struct vring_virtqueue *vq = to_vvq(_vq);
> +
> +	/* Pairs with READ_ONCE() in virtqueue_is_broken(). */
> +	WRITE_ONCE(vq->broken, false);
> +}
I don't think these "Pairs" comments have any value.

> +EXPORT_SYMBOL_GPL(__virtqueue_unbreak);
> +
>  bool virtqueue_is_broken(struct virtqueue *_vq)
>  {
>  	struct vring_virtqueue *vq = to_vvq(_vq);
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index 1272566adec6..dc474a0d48d1 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -138,6 +138,9 @@ bool is_virtio_device(struct device *dev);
>  void virtio_break_device(struct virtio_device *dev);
>  void __virtio_unbreak_device(struct virtio_device *dev);
>  
> +void __virtqueue_break(struct virtqueue *_vq);
> +void __virtqueue_unbreak(struct virtqueue *_vq);
> +
>  void virtio_config_changed(struct virtio_device *dev);
>  #ifdef CONFIG_PM_SLEEP
>  int virtio_device_freeze(struct virtio_device *dev);
> -- 
> 2.31.0

? 2022/6/29 14:56, Xuan Zhuo ??:
> Separate the logic of split to create vring queue.
>
> This feature is required for subsequent virtuqueue reset vring.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   drivers/virtio/virtio_ring.c | 68 ++++++++++++++++++++++--------------
>   1 file changed, 42 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 49d61e412dc6..a9ceb9c16c54 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -949,28 +949,19 @@ static void vring_free_split(struct
vring_virtqueue_split *vring,
>   	kfree(vring->desc_extra);
>   }
>   
> -static struct virtqueue *vring_create_virtqueue_split(
> -	unsigned int index,
> -	unsigned int num,
> -	unsigned int vring_align,
> -	struct virtio_device *vdev,
> -	bool weak_barriers,
> -	bool may_reduce_num,
> -	bool context,
> -	bool (*notify)(struct virtqueue *),
> -	void (*callback)(struct virtqueue *),
> -	const char *name)
> +static int vring_alloc_queue_split(struct vring_virtqueue_split *vring,
> +				   struct virtio_device *vdev,
> +				   u32 num,
> +				   unsigned int vring_align,
> +				   bool may_reduce_num)
>   {
> -	struct virtqueue *vq;
>   	void *queue = NULL;
>   	dma_addr_t dma_addr;
> -	size_t queue_size_in_bytes;
> -	struct vring vring;
>   
>   	/* We assume num is a power of 2. */
>   	if (num & (num - 1)) {
>   		dev_warn(&vdev->dev, "Bad virtqueue length %u\n",
num);
> -		return NULL;
> +		return -EINVAL;
>   	}
>   
>   	/* TODO: allocate each queue chunk individually */
> @@ -981,11 +972,11 @@ static struct virtqueue
*vring_create_virtqueue_split(
>   		if (queue)
>   			break;
>   		if (!may_reduce_num)
> -			return NULL;
> +			return -ENOMEM;
>   	}
>   
>   	if (!num)
> -		return NULL;
> +		return -ENOMEM;
>   
>   	if (!queue) {
>   		/* Try to get a single page. You are my only hope! */
> @@ -993,21 +984,46 @@ static struct virtqueue
*vring_create_virtqueue_split(
>   					  &dma_addr, GFP_KERNEL|__GFP_ZERO);
>   	}
>   	if (!queue)
> -		return NULL;
> +		return -ENOMEM;
> +
> +	vring_init(&vring->vring, num, queue, vring_align);
>   
> -	queue_size_in_bytes = vring_size(num, vring_align);
> -	vring_init(&vring, num, queue, vring_align);
> +	vring->queue_dma_addr = dma_addr;
> +	vring->queue_size_in_bytes = vring_size(num, vring_align);
> +
> +	return 0;
> +}
> +
> +static struct virtqueue *vring_create_virtqueue_split(
> +	unsigned int index,
> +	unsigned int num,
> +	unsigned int vring_align,
> +	struct virtio_device *vdev,
> +	bool weak_barriers,
> +	bool may_reduce_num,
> +	bool context,
> +	bool (*notify)(struct virtqueue *),
> +	void (*callback)(struct virtqueue *),
> +	const char *name)
> +{
> +	struct vring_virtqueue_split vring = {};
> +	struct virtqueue *vq;
> +	int err;
> +
> +	err = vring_alloc_queue_split(&vring, vdev, num, vring_align,
> +				      may_reduce_num);
> +	if (err)
> +		return NULL;
>   
> -	vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
> -				   notify, callback, name);
> +	vq = __vring_new_virtqueue(index, vring.vring, vdev, weak_barriers,
> +				   context, notify, callback, name);
>   	if (!vq) {
> -		vring_free_queue(vdev, queue_size_in_bytes, queue,
> -				 dma_addr);
> +		vring_free_split(&vring, vdev);
>   		return NULL;
>   	}
>   
> -	to_vvq(vq)->split.queue_dma_addr = dma_addr;
> -	to_vvq(vq)->split.queue_size_in_bytes = queue_size_in_bytes;
> +	to_vvq(vq)->split.queue_dma_addr = vring.queue_dma_addr;

Nit: having two queue_dma_addr seems redundant (so did queue_size_in_bytes).

Thanks

> +	to_vvq(vq)->split.queue_size_in_bytes = vring.queue_size_in_bytes;
>   	to_vvq(vq)->we_own_ring = true;
>   
>   	return vq;

? 2022/6/29 14:56, Xuan Zhuo ??:
> Separate the logic of creating desc_state, desc_extra, and subsequent
> patches will call it independently.
>
> Since only the structure vring is passed into __vring_new_virtqueue(),
> when creating the function vring_alloc_state_extra_split(), we prefer to
> use vring_virtqueue_split as a parameter, and it will be more convenient
> to pass vring_virtqueue_split to some subsequent functions.
>
> So a new vring_virtqueue_split variable is added in
> __vring_new_virtqueue().
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   drivers/virtio/virtio_ring.c | 58 +++++++++++++++++++++++++-----------
>   1 file changed, 40 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index a9ceb9c16c54..cedd340d6db7 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -204,6 +204,7 @@ struct vring_virtqueue {
>   #endif
>   };
>   
> +static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num);
>   
>   /*
>    * Helpers.
> @@ -939,6 +940,32 @@ static void *virtqueue_detach_unused_buf_split(struct
virtqueue *_vq)
>   	return NULL;
>   }
>   
> +static int vring_alloc_state_extra_split(struct vring_virtqueue_split
*vring)
> +{
> +	struct vring_desc_state_split *state;
> +	struct vring_desc_extra *extra;
> +	u32 num = vring->vring.num;
> +
> +	state = kmalloc_array(num, sizeof(struct vring_desc_state_split),
GFP_KERNEL);
> +	if (!state)
> +		goto err_state;
> +
> +	extra = vring_alloc_desc_extra(num);
> +	if (!extra)
> +		goto err_extra;
> +
> +	memset(state, 0, num * sizeof(struct vring_desc_state_split));
> +
> +	vring->desc_state = state;
> +	vring->desc_extra = extra;
> +	return 0;
> +
> +err_extra:
> +	kfree(state);
> +err_state:
> +	return -ENOMEM;
> +}
> +
>   static void vring_free_split(struct vring_virtqueue_split *vring,
>   			     struct virtio_device *vdev)
>   {
> @@ -2224,7 +2251,7 @@ EXPORT_SYMBOL_GPL(vring_interrupt);
>   
>   /* Only available for split ring */
>   struct virtqueue *__vring_new_virtqueue(unsigned int index,
> -					struct vring vring,
> +					struct vring _vring,
>   					struct virtio_device *vdev,
>   					bool weak_barriers,
>   					bool context,
> @@ -2232,7 +2259,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>   					void (*callback)(struct virtqueue *),
>   					const char *name)
>   {
> +	struct vring_virtqueue_split vring = {};

Nit: to reduce the change-set, let's use vring_split here?

Other looks good.

Thanks

>   	struct vring_virtqueue *vq;
> +	int err;
>   
>   	if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
>   		return NULL;
> @@ -2261,7 +2290,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>   	vq->split.queue_dma_addr = 0;
>   	vq->split.queue_size_in_bytes = 0;
>   
> -	vq->split.vring = vring;
> +	vq->split.vring = _vring;
>   	vq->split.avail_flags_shadow = 0;
>   	vq->split.avail_idx_shadow = 0;
>   
> @@ -2273,30 +2302,23 @@ struct virtqueue *__vring_new_virtqueue(unsigned
int index,
>   					vq->split.avail_flags_shadow);
>   	}
>   
> -	vq->split.desc_state = kmalloc_array(vring.num,
> -			sizeof(struct vring_desc_state_split), GFP_KERNEL);
> -	if (!vq->split.desc_state)
> -		goto err_state;
> +	vring.vring = _vring;
>   
> -	vq->split.desc_extra = vring_alloc_desc_extra(vring.num);
> -	if (!vq->split.desc_extra)
> -		goto err_extra;
> +	err = vring_alloc_state_extra_split(&vring);
> +	if (err) {
> +		kfree(vq);
> +		return NULL;
> +	}
>   
> -	memset(vq->split.desc_state, 0, vring.num *
> -			sizeof(struct vring_desc_state_split));
> +	vq->split.desc_state = vring.desc_state;
> +	vq->split.desc_extra = vring.desc_extra;
>   
> -	virtqueue_init(vq, vq->split.vring.num);
> +	virtqueue_init(vq, vring.vring.num);
>   
>   	spin_lock(&vdev->vqs_list_lock);
>   	list_add_tail(&vq->vq.list, &vdev->vqs);
>   	spin_unlock(&vdev->vqs_list_lock);
>   	return &vq->vq;
> -
> -err_extra:
> -	kfree(vq->split.desc_state);
> -err_state:
> -	kfree(vq);
> -	return NULL;
>   }
>   EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
>

? 2022/6/29 14:56, Xuan Zhuo ??:
> Separate the logic of attach vring, subsequent patches will call it
> separately.
>
> Since the "struct vring_virtqueue_split split" is created on the
> stack and has been initialized to 0. So using
> split->queue_dma_addr/split->queue_size_in_bytes assignment for
> queue_dma_addr/queue_size_in_bytes can keep the same as the original
> code.
>
> On the other hand, subsequent patches can use the "struct
> vring_virtqueue_split split" obtained by vring_alloc_queue_split() to
> directly complete the attach operation.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>

Acked-by: Jason Wang <jasowang at redhat.com>

> ---
>   drivers/virtio/virtio_ring.c | 20 +++++++++++++-------
>   1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index cedd340d6db7..9025bd373d3b 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -940,6 +940,18 @@ static void *virtqueue_detach_unused_buf_split(struct
virtqueue *_vq)
>   	return NULL;
>   }
>   
> +static void virtqueue_vring_attach_split(struct vring_virtqueue *vq,
> +					 struct vring_virtqueue_split *vring)
> +{
> +	vq->split.queue_dma_addr = vring->queue_dma_addr;
> +	vq->split.queue_size_in_bytes = vring->queue_size_in_bytes;
> +
> +	vq->split.vring = vring->vring;
> +
> +	vq->split.desc_state = vring->desc_state;
> +	vq->split.desc_extra = vring->desc_extra;
> +}
> +
>   static int vring_alloc_state_extra_split(struct vring_virtqueue_split
*vring)
>   {
>   	struct vring_desc_state_split *state;
> @@ -2287,10 +2299,6 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>   	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
>   		!context;
>   
> -	vq->split.queue_dma_addr = 0;
> -	vq->split.queue_size_in_bytes = 0;
> -
> -	vq->split.vring = _vring;
>   	vq->split.avail_flags_shadow = 0;
>   	vq->split.avail_idx_shadow = 0;
>   
> @@ -2310,10 +2318,8 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>   		return NULL;
>   	}
>   
> -	vq->split.desc_state = vring.desc_state;
> -	vq->split.desc_extra = vring.desc_extra;
> -
>   	virtqueue_init(vq, vring.vring.num);
> +	virtqueue_vring_attach_split(vq, &vring);
>   
>   	spin_lock(&vdev->vqs_list_lock);
>   	list_add_tail(&vq->vq.list, &vdev->vqs);

? 2022/6/29 14:56, Xuan Zhuo ??:
> Separate the logic of initializing vring, and subsequent patches will
> call it separately.
>
> This function completes the variable initialization of split vring. It
> together with the logic of atatch constitutes the initialization of
> vring.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>

Acked-by: Jason Wang <jasowang at redhat.com>

> ---
>   drivers/virtio/virtio_ring.c | 30 +++++++++++++++++++-----------
>   1 file changed, 19 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 9025bd373d3b..35540daaa1e7 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -940,6 +940,24 @@ static void *virtqueue_detach_unused_buf_split(struct
virtqueue *_vq)
>   	return NULL;
>   }
>   
> +static void virtqueue_vring_init_split(struct vring_virtqueue *vq)
> +{
> +	struct virtio_device *vdev;
> +
> +	vdev = vq->vq.vdev;
> +
> +	vq->split.avail_flags_shadow = 0;
> +	vq->split.avail_idx_shadow = 0;
> +
> +	/* No callback?  Tell other side not to bother us. */
> +	if (!vq->vq.callback) {
> +		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
> +		if (!vq->event)
> +			vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
> +					vq->split.avail_flags_shadow);
> +	}
> +}
> +
>   static void virtqueue_vring_attach_split(struct vring_virtqueue *vq,
>   					 struct vring_virtqueue_split *vring)
>   {
> @@ -2299,17 +2317,6 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>   	vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC)
&&
>   		!context;
>   
> -	vq->split.avail_flags_shadow = 0;
> -	vq->split.avail_idx_shadow = 0;
> -
> -	/* No callback?  Tell other side not to bother us. */
> -	if (!callback) {
> -		vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
> -		if (!vq->event)
> -			vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
> -					vq->split.avail_flags_shadow);
> -	}
> -
>   	vring.vring = _vring;
>   
>   	err = vring_alloc_state_extra_split(&vring);
> @@ -2320,6 +2327,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>   
>   	virtqueue_init(vq, vring.vring.num);
>   	virtqueue_vring_attach_split(vq, &vring);
> +	virtqueue_vring_init_split(vq);
>   
>   	spin_lock(&vdev->vqs_list_lock);
>   	list_add_tail(&vq->vq.list, &vdev->vqs);

? 2022/6/29 14:56, Xuan Zhuo ??:
> In vring_create_virtqueue_split() save vring_align, may_reduce_num to
> structure vring_virtqueue_split. Used to create a new vring when
> implementing resize .
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>

Acked-by: Jason Wang <jasowang at redhat.com>

> ---
>   drivers/virtio/virtio_ring.c | 9 +++++++++
>   1 file changed, 9 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 4c8972da5423..9c83c5e6d5a9 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -105,6 +105,13 @@ struct vring_virtqueue_split {
>   	/* DMA address and size information */
>   	dma_addr_t queue_dma_addr;
>   	size_t queue_size_in_bytes;
> +
> +	/*
> +	 * The parameters for creating vrings are reserved for creating new
> +	 * vring.
> +	 */
> +	u32 vring_align;
> +	bool may_reduce_num;
>   };
>   
>   struct vring_virtqueue_packed {
> @@ -1098,6 +1105,8 @@ static struct virtqueue
*vring_create_virtqueue_split(
>   		return NULL;
>   	}
>   
> +	to_vvq(vq)->split.vring_align = vring_align;
> +	to_vvq(vq)->split.may_reduce_num = may_reduce_num;
>   	to_vvq(vq)->split.queue_dma_addr = vring.queue_dma_addr;
>   	to_vvq(vq)->split.queue_size_in_bytes = vring.queue_size_in_bytes;
>   	to_vvq(vq)->we_own_ring = true;

? 2022/6/29 14:56, Xuan Zhuo ??:
> virtio ring split supports resize.
>
> Only after the new vring is successfully allocated based on the new num,
> we will release the old vring. In any case, an error is returned,
> indicating that the vring still points to the old vring.
>
> In the case of an error, re-initialize(virtqueue_reinit_split()) the
> virtqueue to ensure that the vring can be used.
>
> In addition, vring_align, may_reduce_num are necessary for reallocating
> vring, so they are retained for creating vq.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   drivers/virtio/virtio_ring.c | 32 ++++++++++++++++++++++++++++++++
>   1 file changed, 32 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 9c83c5e6d5a9..1aaa1e5f9991 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -212,6 +212,7 @@ struct vring_virtqueue {
>   };
>   
>   static struct vring_desc_extra *vring_alloc_desc_extra(unsigned int num);
> +static void vring_free(struct virtqueue *_vq);
>   
>   /*
>    * Helpers.
> @@ -1114,6 +1115,37 @@ static struct virtqueue
*vring_create_virtqueue_split(
>   	return vq;
>   }
>   
> +static int virtqueue_resize_split(struct virtqueue *_vq, u32 num)
> +{
> +	struct vring_virtqueue *vq = to_vvq(_vq);
> +	struct vring_virtqueue_split vring = {};
> +	struct virtio_device *vdev = _vq->vdev;
> +	int err;
> +
> +	err = vring_alloc_queue_split(&vring, vdev, num,
vq->split.vring_align,
> +				      vq->split.may_reduce_num);
> +	if (err)
> +		goto err;

It's better to have decouple the allocation future more to avoid any 
rewind here in the future.

But the patch should be fine.

So

Acked-by: Jason Wang <jasowang at redhat.com>

> +
> +	err = vring_alloc_state_extra_split(&vring);
> +	if (err) {
> +		vring_free_split(&vring, vdev);
> +		goto err;
> +	}
> +
> +	vring_free(&vq->vq);
> +
> +	virtqueue_init(vq, vring.vring.num);
> +	virtqueue_vring_attach_split(vq, &vring);
> +	virtqueue_vring_init_split(vq);
> +
> +	return 0;
> +
> +err:
> +	virtqueue_reinit_split(vq);
> +	return -ENOMEM;
> +}
> +
>   
>   /*
>    * Packed ring specific functions - *_packed().

? 2022/6/29 14:56, Xuan Zhuo ??:
> virtio ring packed supports resize.
>
> Only after the new vring is successfully allocated based on the new num,
> we will release the old vring. In any case, an error is returned,
> indicating that the vring still points to the old vring.
>
> In the case of an error, re-initialize(by virtqueue_reinit_packed()) the
> virtqueue to ensure that the vring can be used.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   drivers/virtio/virtio_ring.c | 29 +++++++++++++++++++++++++++++
>   1 file changed, 29 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 650f701a5480..4860787286db 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2042,6 +2042,35 @@ static struct virtqueue
*vring_create_virtqueue_packed(
>   	return NULL;
>   }
>   
> +static int virtqueue_resize_packed(struct virtqueue *_vq, u32 num)
> +{
> +	struct vring_virtqueue_packed vring = {};
> +	struct vring_virtqueue *vq = to_vvq(_vq);
> +	struct virtio_device *vdev = _vq->vdev;
> +	int err;
> +
> +	if (vring_alloc_queue_packed(&vring, vdev, num))
> +		goto err_ring;
> +
> +	err = vring_alloc_state_extra_packed(&vring);
> +	if (err)
> +		goto err_state_extra;
> +
> +	vring_free(&vq->vq);
> +
> +	virtqueue_init(vq, vring.vring.num);
> +	virtqueue_vring_attach_packed(vq, &vring);
> +	virtqueue_vring_init_packed(vq);
> +
> +	return 0;
> +
> +err_state_extra:
> +	vring_free_packed(&vring, vdev);
> +err_ring:
> +	virtqueue_reinit_packed(vq);

So desc_state and desc_extra has been freed vring_free_packed() when 
vring_alloc_state_extra_packed() fails. We might get use-after-free here?

Actually, I think for resize we need

1) detach old
2) allocate new
3) if 2) succeed, attach new otherwise attach old

This seems more clearer than the current logic?

Thanks

> +	return -ENOMEM;
> +}
> +
>   
>   /*
>    * Generic functions and exported symbols.

? 2022/6/29 14:56, Xuan Zhuo ??:
> Introduce virtqueue_resize() to implement the resize of vring.
> Based on these, the driver can dynamically adjust the size of the vring.
> For example: ethtool -G.
>
> virtqueue_resize() implements resize based on the vq reset function. In
> case of failure to allocate a new vring, it will give up resize and use
> the original vring.
>
> During this process, if the re-enable reset vq fails, the vq can no
> longer be used. Although the probability of this situation is not high.
>
> The parameter recycle is used to recycle the buffer that is no longer
> used.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   drivers/virtio/virtio_ring.c | 72 ++++++++++++++++++++++++++++++++++++
>   include/linux/virtio.h       |  3 ++
>   2 files changed, 75 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 4860787286db..5ec43607cc15 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2542,6 +2542,78 @@ struct virtqueue *vring_create_virtqueue(
>   }
>   EXPORT_SYMBOL_GPL(vring_create_virtqueue);
>   
> +/**
> + * virtqueue_resize - resize the vring of vq
> + * @_vq: the struct virtqueue we're talking about.
> + * @num: new ring num
> + * @recycle: callback for recycle the useless buffer
> + *
> + * When it is really necessary to create a new vring, it will set the
current vq
> + * into the reset state. Then call the passed callback to recycle the
buffer
> + * that is no longer used. Only after the new vring is successfully
created, the
> + * old vring will be released.
> + *
> + * Caller must ensure we don't call this with other virtqueue
operations
> + * at the same time (except where noted).
> + *
> + * Returns zero or a negative error.
> + * 0: success.
> + * -ENOMEM: Failed to allocate a new ring, fall back to the original ring
size.
> + *  vq can still work normally
> + * -EBUSY: Failed to sync with device, vq may not work properly
> + * -ENOENT: Transport or device not supported
> + * -E2BIG/-EINVAL: num error
> + * -EPERM: Operation not permitted
> + *
> + */
> +int virtqueue_resize(struct virtqueue *_vq, u32 num,
> +		     void (*recycle)(struct virtqueue *vq, void *buf))
> +{
> +	struct vring_virtqueue *vq = to_vvq(_vq);
> +	struct virtio_device *vdev = vq->vq.vdev;
> +	bool packed;
> +	void *buf;
> +	int err;
> +
> +	if (!vq->we_own_ring)
> +		return -EPERM;
> +
> +	if (num > vq->vq.num_max)
> +		return -E2BIG;
> +
> +	if (!num)
> +		return -EINVAL;
> +
> +	packed = virtio_has_feature(vdev, VIRTIO_F_RING_PACKED) ? true : false;

vq->packed_ring?

> +
> +	if ((packed ? vq->packed.vring.num : vq->split.vring.num) == num)
> +		return 0;
> +
> +	if (!vdev->config->reset_vq)
> +		return -ENOENT;
> +
> +	if (!vdev->config->enable_reset_vq)
> +		return -ENOENT;

Not sure this is useful, e.g driver may choose to resize after a reset 
of the device?

Thanks

> +
> +	err = vdev->config->reset_vq(_vq);
> +	if (err)
> +		return err;
> +
> +	while ((buf = virtqueue_detach_unused_buf(_vq)) != NULL)
> +		recycle(_vq, buf);
> +
> +	if (packed)
> +		err = virtqueue_resize_packed(_vq, num);
> +	else
> +		err = virtqueue_resize_split(_vq, num);
> +
> +	if (vdev->config->enable_reset_vq(_vq))
> +		return -EBUSY;
> +
> +	return err;
> +}
> +EXPORT_SYMBOL_GPL(virtqueue_resize);
> +
>   /* Only available for split ring */
>   struct virtqueue *vring_new_virtqueue(unsigned int index,
>   				      unsigned int num,
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index a82620032e43..1272566adec6 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -91,6 +91,9 @@ dma_addr_t virtqueue_get_desc_addr(struct virtqueue *vq);
>   dma_addr_t virtqueue_get_avail_addr(struct virtqueue *vq);
>   dma_addr_t virtqueue_get_used_addr(struct virtqueue *vq);
>   
> +int virtqueue_resize(struct virtqueue *vq, u32 num,
> +		     void (*recycle)(struct virtqueue *vq, void *buf));
> +
>   /**
>    * virtio_device - representation of a device using virtio
>    * @index: unique position on the virtio bus

? 2022/6/29 14:56, Xuan Zhuo ??:
> In order to facilitate the expansion of virtio_pci_common_cfg in the
> future, move it from uapi to virtio_pci_modern.h. In this way, we can
> freely expand virtio_pci_common_cfg in the future.
>
> Other projects using virtio_pci_common_cfg in uapi need to maintain a
> separate virtio_pci_common_cfg or use the offset macro defined in uapi.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   include/linux/virtio_pci_modern.h | 26 ++++++++++++++++++++++++++
>   include/uapi/linux/virtio_pci.h   | 26 --------------------------
>   2 files changed, 26 insertions(+), 26 deletions(-)
>
> diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
> index eb2bd9b4077d..c4f7ffbacb4e 100644
> --- a/include/linux/virtio_pci_modern.h
> +++ b/include/linux/virtio_pci_modern.h
> @@ -5,6 +5,32 @@
>   #include <linux/pci.h>
>   #include <linux/virtio_pci.h>
>   
> +/* Fields in VIRTIO_PCI_CAP_COMMON_CFG: */
> +struct virtio_pci_common_cfg {
> +	/* About the whole device. */
> +	__le32 device_feature_select;	/* read-write */
> +	__le32 device_feature;		/* read-only */
> +	__le32 guest_feature_select;	/* read-write */
> +	__le32 guest_feature;		/* read-write */
> +	__le16 msix_config;		/* read-write */
> +	__le16 num_queues;		/* read-only */
> +	__u8 device_status;		/* read-write */
> +	__u8 config_generation;		/* read-only */
> +
> +	/* About a specific virtqueue. */
> +	__le16 queue_select;		/* read-write */
> +	__le16 queue_size;		/* read-write, power of 2. */
> +	__le16 queue_msix_vector;	/* read-write */
> +	__le16 queue_enable;		/* read-write */
> +	__le16 queue_notify_off;	/* read-only */
> +	__le32 queue_desc_lo;		/* read-write */
> +	__le32 queue_desc_hi;		/* read-write */
> +	__le32 queue_avail_lo;		/* read-write */
> +	__le32 queue_avail_hi;		/* read-write */
> +	__le32 queue_used_lo;		/* read-write */
> +	__le32 queue_used_hi;		/* read-write */
> +};
> +
>   struct virtio_pci_modern_device {
>   	struct pci_dev *pci_dev;
>   
> diff --git a/include/uapi/linux/virtio_pci.h
b/include/uapi/linux/virtio_pci.h
> index 3a86f36d7e3d..247ec42af2c8 100644
> --- a/include/uapi/linux/virtio_pci.h
> +++ b/include/uapi/linux/virtio_pci.h
> @@ -140,32 +140,6 @@ struct virtio_pci_notify_cap {
>   	__le32 notify_off_multiplier;	/* Multiplier for queue_notify_off. */
>   };
>   
> -/* Fields in VIRTIO_PCI_CAP_COMMON_CFG: */
> -struct virtio_pci_common_cfg {
> -	/* About the whole device. */
> -	__le32 device_feature_select;	/* read-write */
> -	__le32 device_feature;		/* read-only */
> -	__le32 guest_feature_select;	/* read-write */
> -	__le32 guest_feature;		/* read-write */
> -	__le16 msix_config;		/* read-write */
> -	__le16 num_queues;		/* read-only */
> -	__u8 device_status;		/* read-write */
> -	__u8 config_generation;		/* read-only */
> -
> -	/* About a specific virtqueue. */
> -	__le16 queue_select;		/* read-write */
> -	__le16 queue_size;		/* read-write, power of 2. */
> -	__le16 queue_msix_vector;	/* read-write */
> -	__le16 queue_enable;		/* read-write */
> -	__le16 queue_notify_off;	/* read-only */
> -	__le32 queue_desc_lo;		/* read-write */
> -	__le32 queue_desc_hi;		/* read-write */
> -	__le32 queue_avail_lo;		/* read-write */
> -	__le32 queue_avail_hi;		/* read-write */
> -	__le32 queue_used_lo;		/* read-write */
> -	__le32 queue_used_hi;		/* read-write */
> -};
> -

I think it's better not delete those from uAPI. We can embed this struct 
in the private virito_pci_moden.h anyhow.

Thanks

>   /* Fields in VIRTIO_PCI_CAP_PCI_CFG: */
>   struct virtio_pci_cfg_cap {
>   	struct virtio_pci_cap cap;

? 2022/6/29 14:56, Xuan Zhuo ??:
> Add queue_notify_data in struct virtio_pci_common_cfg, which comes from
> here https://github.com/oasis-tcs/virtio-spec/issues/89
>
> Since I want to add queue_reset after queue_notify_data, I submitted
> this patch first.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> Acked-by: Jason Wang <jasowang at redhat.com>
> ---
>   include/linux/virtio_pci_modern.h | 2 ++
>   include/uapi/linux/virtio_pci.h   | 1 +
>   2 files changed, 3 insertions(+)
>
> diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
> index c4f7ffbacb4e..9f31dde46f57 100644
> --- a/include/linux/virtio_pci_modern.h
> +++ b/include/linux/virtio_pci_modern.h
> @@ -29,6 +29,8 @@ struct virtio_pci_common_cfg {
>   	__le32 queue_avail_hi;		/* read-write */
>   	__le32 queue_used_lo;		/* read-write */
>   	__le32 queue_used_hi;		/* read-write */
> +	__le16 queue_notify_data;	/* read-write */
> +	__le16 padding;
>   };

As previous patch, I think it's better to simple embed the uAPI 
structure here.

Thanks

>   
>   struct virtio_pci_modern_device {
> diff --git a/include/uapi/linux/virtio_pci.h
b/include/uapi/linux/virtio_pci.h
> index 247ec42af2c8..748b3eb62d2f 100644
> --- a/include/uapi/linux/virtio_pci.h
> +++ b/include/uapi/linux/virtio_pci.h
> @@ -176,6 +176,7 @@ struct virtio_pci_cfg_cap {
>   #define VIRTIO_PCI_COMMON_Q_AVAILHI	44
>   #define VIRTIO_PCI_COMMON_Q_USEDLO	48
>   #define VIRTIO_PCI_COMMON_Q_USEDHI	52
> +#define VIRTIO_PCI_COMMON_Q_NDATA	56
>   
>   #endif /* VIRTIO_PCI_NO_MODERN */
>

? 2022/6/29 14:56, Xuan Zhuo ??:
> Introduce new helpers to implement queue reset and get queue reset
> status.
>
>   https://github.com/oasis-tcs/virtio-spec/issues/124
>   https://github.com/oasis-tcs/virtio-spec/issues/139
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>

Acked-by: Jason Wang <jasowang at redhat.com>

> ---
>   drivers/virtio/virtio_pci_modern_dev.c | 35 ++++++++++++++++++++++++++
>   include/linux/virtio_pci_modern.h      |  2 ++
>   2 files changed, 37 insertions(+)
>
> diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
> index fa2a9445bb18..07415654247c 100644
> --- a/drivers/virtio/virtio_pci_modern_dev.c
> +++ b/drivers/virtio/virtio_pci_modern_dev.c
> @@ -3,6 +3,7 @@
>   #include <linux/virtio_pci_modern.h>
>   #include <linux/module.h>
>   #include <linux/pci.h>
> +#include <linux/delay.h>
>   
>   /*
>    * vp_modern_map_capability - map a part of virtio pci capability
> @@ -474,6 +475,40 @@ void vp_modern_set_status(struct
virtio_pci_modern_device *mdev,
>   }
>   EXPORT_SYMBOL_GPL(vp_modern_set_status);
>   
> +/*
> + * vp_modern_get_queue_reset - get the queue reset status
> + * @mdev: the modern virtio-pci device
> + * @index: queue index
> + */
> +int vp_modern_get_queue_reset(struct virtio_pci_modern_device *mdev, u16
index)
> +{
> +	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
> +
> +	vp_iowrite16(index, &cfg->queue_select);
> +	return vp_ioread16(&cfg->queue_reset);
> +}
> +EXPORT_SYMBOL_GPL(vp_modern_get_queue_reset);
> +
> +/*
> + * vp_modern_set_queue_reset - reset the queue
> + * @mdev: the modern virtio-pci device
> + * @index: queue index
> + */
> +void vp_modern_set_queue_reset(struct virtio_pci_modern_device *mdev, u16
index)
> +{
> +	struct virtio_pci_common_cfg __iomem *cfg = mdev->common;
> +
> +	vp_iowrite16(index, &cfg->queue_select);
> +	vp_iowrite16(1, &cfg->queue_reset);
> +
> +	while (vp_ioread16(&cfg->queue_reset))
> +		msleep(1);
> +
> +	while (vp_ioread16(&cfg->queue_enable))
> +		msleep(1);
> +}
> +EXPORT_SYMBOL_GPL(vp_modern_set_queue_reset);
> +
>   /*
>    * vp_modern_queue_vector - set the MSIX vector for a specific virtqueue
>    * @mdev: the modern virtio-pci device
> diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
> index beebc7a4a31d..ded01157f864 100644
> --- a/include/linux/virtio_pci_modern.h
> +++ b/include/linux/virtio_pci_modern.h
> @@ -134,4 +134,6 @@ void __iomem * vp_modern_map_vq_notify(struct
virtio_pci_modern_device *mdev,
>   				       u16 index, resource_size_t *pa);
>   int vp_modern_probe(struct virtio_pci_modern_device *mdev);
>   void vp_modern_remove(struct virtio_pci_modern_device *mdev);
> +int vp_modern_get_queue_reset(struct virtio_pci_modern_device *mdev, u16
index);
> +void vp_modern_set_queue_reset(struct virtio_pci_modern_device *mdev, u16
index);
>   #endif

? 2022/6/29 14:56, Xuan Zhuo ??:
> This patch implements virtio pci support for QUEUE RESET.
>
> Performing reset on a queue is divided into these steps:
>
>   1. notify the device to reset the queue
>   2. recycle the buffer submitted
>   3. reset the vring (may re-alloc)
>   4. mmap vring to device, and enable the queue
>
> This patch implements virtio_reset_vq(), virtio_enable_resetq() in the
> pci scenario.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   drivers/virtio/virtio_pci_common.c | 12 +++-
>   drivers/virtio/virtio_pci_modern.c | 96 ++++++++++++++++++++++++++++++
>   drivers/virtio/virtio_ring.c       |  2 +
>   include/linux/virtio.h             |  1 +
>   4 files changed, 108 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c
b/drivers/virtio/virtio_pci_common.c
> index ca51fcc9daab..ad258a9d3b9f 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -214,9 +214,15 @@ static void vp_del_vq(struct virtqueue *vq)
>   	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
>   	unsigned long flags;
>   
> -	spin_lock_irqsave(&vp_dev->lock, flags);
> -	list_del(&info->node);
> -	spin_unlock_irqrestore(&vp_dev->lock, flags);
> +	/*
> +	 * If it fails during re-enable reset vq. This way we won't rejoin
> +	 * info->node to the queue. Prevent unexpected irqs.
> +	 */
> +	if (!vq->reset) {
> +		spin_lock_irqsave(&vp_dev->lock, flags);
> +		list_del(&info->node);
> +		spin_unlock_irqrestore(&vp_dev->lock, flags);
> +	}
>   
>   	vp_dev->del_vq(info);
>   	kfree(info);
> diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
> index 9041d9a41b7d..754e5e10386b 100644
> --- a/drivers/virtio/virtio_pci_modern.c
> +++ b/drivers/virtio/virtio_pci_modern.c
> @@ -34,6 +34,9 @@ static void vp_transport_features(struct virtio_device
*vdev, u64 features)
>   	if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
>   			pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
>   		__virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
> +
> +	if (features & BIT_ULL(VIRTIO_F_RING_RESET))
> +		__virtio_set_bit(vdev, VIRTIO_F_RING_RESET);
>   }
>   
>   /* virtio config->finalize_features() implementation */
> @@ -199,6 +202,95 @@ static int vp_active_vq(struct virtqueue *vq, u16
msix_vec)
>   	return 0;
>   }
>   
> +static int vp_modern_reset_vq(struct virtqueue *vq)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> +	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> +	struct virtio_pci_vq_info *info;
> +	unsigned long flags;
> +
> +	if (!virtio_has_feature(vq->vdev, VIRTIO_F_RING_RESET))
> +		return -ENOENT;
> +
> +	vp_modern_set_queue_reset(mdev, vq->index);
> +
> +	info = vp_dev->vqs[vq->index];
> +
> +	/* delete vq from irq handler */
> +	spin_lock_irqsave(&vp_dev->lock, flags);
> +	list_del(&info->node);
> +	spin_unlock_irqrestore(&vp_dev->lock, flags);
> +
> +	INIT_LIST_HEAD(&info->node);
> +
> +	/* For the case where vq has an exclusive irq, to prevent the irq from
> +	 * being received again and the pending irq, call synchronize_irq(), and
> +	 * break it.
> +	 *
> +	 * We can't use disable_irq() since it conflicts with the affinity
> +	 * managed IRQ that is used by some drivers. So this is done on top of
> +	 * IRQ hardening.
> +	 *
> +	 * In the scenario based on shared interrupts, vq will be searched from
> +	 * the queue virtqueues. Since the previous list_del() has been deleted
> +	 * from the queue, it is impossible for vq to be called in this case.
> +	 * There is no need to close the corresponding interrupt.
> +	 */
> +	if (vp_dev->per_vq_vectors && info->msix_vector !=
VIRTIO_MSI_NO_VECTOR) {
> +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
> +		__virtqueue_break(vq);
> +#endif
> +		synchronize_irq(pci_irq_vector(vp_dev->pci_dev,
info->msix_vector));
> +	}
> +
> +	vq->reset = true;
> +
> +	return 0;
> +}
> +
> +static int vp_modern_enable_reset_vq(struct virtqueue *vq)
> +{
> +	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
> +	struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> +	struct virtio_pci_vq_info *info;
> +	unsigned long flags, index;
> +	int err;
> +
> +	if (!vq->reset)
> +		return -EBUSY;
> +
> +	index = vq->index;
> +	info = vp_dev->vqs[index];
> +
> +	if (vp_modern_get_queue_reset(mdev, index))
> +		return -EBUSY;
> +
> +	if (vp_modern_get_queue_enable(mdev, index))
> +		return -EBUSY;
> +
> +	err = vp_active_vq(vq, info->msix_vector);
> +	if (err)
> +		return err;
> +
> +	if (vq->callback) {
> +		spin_lock_irqsave(&vp_dev->lock, flags);
> +		list_add(&info->node, &vp_dev->virtqueues);
> +		spin_unlock_irqrestore(&vp_dev->lock, flags);
> +	} else {
> +		INIT_LIST_HEAD(&info->node);
> +	}
> +
> +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION
> +	if (vp_dev->per_vq_vectors && info->msix_vector !=
VIRTIO_MSI_NO_VECTOR)
> +		__virtqueue_unbreak(vq);
> +#endif
> +
> +	vp_modern_set_queue_enable(&vp_dev->mdev, index, true);
> +	vq->reset = false;
> +
> +	return 0;
> +}
> +
>   static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
>   {
>   	return vp_modern_config_vector(&vp_dev->mdev, vector);
> @@ -413,6 +505,8 @@ static const struct virtio_config_ops
virtio_pci_config_nodev_ops = {
>   	.set_vq_affinity = vp_set_vq_affinity,
>   	.get_vq_affinity = vp_get_vq_affinity,
>   	.get_shm_region  = vp_get_shm_region,
> +	.reset_vq	 = vp_modern_reset_vq,
> +	.enable_reset_vq = vp_modern_enable_reset_vq,
>   };
>   
>   static const struct virtio_config_ops virtio_pci_config_ops = {
> @@ -431,6 +525,8 @@ static const struct virtio_config_ops
virtio_pci_config_ops = {
>   	.set_vq_affinity = vp_set_vq_affinity,
>   	.get_vq_affinity = vp_get_vq_affinity,
>   	.get_shm_region  = vp_get_shm_region,
> +	.reset_vq	 = vp_modern_reset_vq,
> +	.enable_reset_vq = vp_modern_enable_reset_vq,
>   };
>   
>   /* the PCI probing function */
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index 7b02be7fce67..82b058e8ce34 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -2008,6 +2008,7 @@ static struct virtqueue
*vring_create_virtqueue_packed(
>   	vq->vq.vdev = vdev;
>   	vq->vq.name = name;
>   	vq->vq.index = index;
> +	vq->vq.reset = false;
>   	vq->we_own_ring = true;
>   	vq->notify = notify;
>   	vq->weak_barriers = weak_barriers;
> @@ -2487,6 +2488,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int
index,
>   	vq->vq.vdev = vdev;
>   	vq->vq.name = name;
>   	vq->vq.index = index;
> +	vq->vq.reset = false;
>   	vq->we_own_ring = false;
>   	vq->notify = notify;
>   	vq->weak_barriers = weak_barriers;
> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
> index dc474a0d48d1..88f21796b1c3 100644
> --- a/include/linux/virtio.h
> +++ b/include/linux/virtio.h
> @@ -33,6 +33,7 @@ struct virtqueue {
>   	unsigned int num_free;
>   	unsigned int num_max;
>   	void *priv;
> +	bool reset;
>   };

I wonder if it's better to move virtio_ring part into a separate patch.

Other looks good.

Thanks

>   
>   int virtqueue_add_outbuf(struct virtqueue *vq,

? 2022/6/29 14:56, Xuan Zhuo ??:
> This patch implements the resize function of the rx queues.
> Based on this function, it is possible to modify the ring num of the
> queue.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   drivers/net/virtio_net.c | 22 ++++++++++++++++++++++
>   1 file changed, 22 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 9fe222a3663a..6ab16fd193e5 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -278,6 +278,8 @@ struct padded_vnet_hdr {
>   	char padding[12];
>   };
>   
> +static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
> +
>   static bool is_xdp_frame(void *ptr)
>   {
>   	return (unsigned long)ptr & VIRTIO_XDP_FLAG;
> @@ -1846,6 +1848,26 @@ static netdev_tx_t start_xmit(struct sk_buff *skb,
struct net_device *dev)
>   	return NETDEV_TX_OK;
>   }
>   
> +static int virtnet_rx_resize(struct virtnet_info *vi,
> +			     struct receive_queue *rq, u32 ring_num)
> +{
> +	int err, qindex;
> +
> +	qindex = rq - vi->rq;
> +
> +	napi_disable(&rq->napi);

Do we need to cancel the refill work here?

Thanks

> +
> +	err = virtqueue_resize(rq->vq, ring_num, virtnet_rq_free_unused_buf);
> +	if (err)
> +		netdev_err(vi->dev, "resize rx fail: rx queue index: %d err:
%d\n", qindex, err);
> +
> +	if (!try_fill_recv(vi, rq, GFP_KERNEL))
> +		schedule_delayed_work(&vi->refill, 0);
> +
> +	virtnet_napi_enable(rq->vq, &rq->napi);
> +	return err;
> +}
> +
>   /*
>    * Send command via the control virtqueue and check status.  Commands
>    * supported by the hypervisor, as indicated by feature bits, should

? 2022/6/29 14:56, Xuan Zhuo ??:
> This patch implements the resize function of the tx queues.
> Based on this function, it is possible to modify the ring num of the
> queue.
>
> Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> ---
>   drivers/net/virtio_net.c | 48 ++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 48 insertions(+)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 6ab16fd193e5..fd358462f802 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -135,6 +135,9 @@ struct send_queue {
>   	struct virtnet_sq_stats stats;
>   
>   	struct napi_struct napi;
> +
> +	/* Record whether sq is in reset state. */
> +	bool reset;
>   };
>   
>   /* Internal representation of a receive virtqueue */
> @@ -279,6 +282,7 @@ struct padded_vnet_hdr {
>   };
>   
>   static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
> +static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
>   
>   static bool is_xdp_frame(void *ptr)
>   {
> @@ -1603,6 +1607,11 @@ static void virtnet_poll_cleantx(struct
receive_queue *rq)
>   		return;
>   
>   	if (__netif_tx_trylock(txq)) {
> +		if (READ_ONCE(sq->reset)) {
> +			__netif_tx_unlock(txq);
> +			return;
> +		}
> +
>   		do {
>   			virtqueue_disable_cb(sq->vq);
>   			free_old_xmit_skbs(sq, true);
> @@ -1868,6 +1877,45 @@ static int virtnet_rx_resize(struct virtnet_info
*vi,
>   	return err;
>   }
>   
> +static int virtnet_tx_resize(struct virtnet_info *vi,
> +			     struct send_queue *sq, u32 ring_num)
> +{
> +	struct netdev_queue *txq;
> +	int err, qindex;
> +
> +	qindex = sq - vi->sq;
> +
> +	virtnet_napi_tx_disable(&sq->napi);
> +
> +	txq = netdev_get_tx_queue(vi->dev, qindex);
> +
> +	/* 1. wait all ximt complete
> +	 * 2. fix the race of netif_stop_subqueue() vs netif_start_subqueue()
> +	 */
> +	__netif_tx_lock_bh(txq);
> +
> +	/* Prevent rx poll from accessing sq. */
> +	WRITE_ONCE(sq->reset, true);

Can we simply disable RX NAPI here?

Thanks

> +
> +	/* Prevent the upper layer from trying to send packets. */
> +	netif_stop_subqueue(vi->dev, qindex);
> +
> +	__netif_tx_unlock_bh(txq);
> +
> +	err = virtqueue_resize(sq->vq, ring_num, virtnet_sq_free_unused_buf);
> +	if (err)
> +		netdev_err(vi->dev, "resize tx fail: tx queue index: %d err:
%d\n", qindex, err);
> +
> +	/* Memory barrier before set reset and start subqueue. */
> +	smp_mb();
> +
> +	WRITE_ONCE(sq->reset, false);
> +	netif_tx_wake_queue(txq);
> +
> +	virtnet_napi_tx_enable(vi, sq->vq, &sq->napi);
> +	return err;
> +}
> +
>   /*
>    * Send command via the control virtqueue and check status.  Commands
>    * supported by the hypervisor, as indicated by feature bits, should