Linux Virtualization - Oct 2023 - [PATCH vhost v2 1/2] virtio_pci: fix the common map size and add check for common size

1. fix the length of the pci_iomap_range() to the common cfg
2. add size check for the vq-reset
3. add build size check to the new common cfg items


Xuan Zhuo (2):
  virtio_pci: fix the common map size and add check for common size
  virtio_pci: add build offset check for the new common cfg items

 drivers/virtio/virtio_pci_modern.c     | 20 +++++++++++++++++++-
 drivers/virtio/virtio_pci_modern_dev.c |  8 ++++++--
 include/linux/virtio_pci_modern.h      |  1 +
 3 files changed, 26 insertions(+), 3 deletions(-)

-- 
2.32.0.3.g01195cf9f

Now, the function vp_modern_map_capability() takes the size parameter,
which corresponds to the size of virtio_pci_common_cfg. As a result,
this indicates the size of memory area to map.

However, if the _F_RING_RESET is negotiated, the extra items will be
used. Therefore, we need to use the size of virtio_pci_modern_common_cfg
to map more space.

Meanwhile, this patch removes the feature(_F_RING_ERSET and
_F_NOTIFICATION_DATA) when the common cfg size does not match
the corresponding feature.

Fixes: 0b50cece0b78 ("virtio_pci: introduce helper to get/set queue
reset")
Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
---
 drivers/virtio/virtio_pci_modern.c     | 20 +++++++++++++++++++-
 drivers/virtio/virtio_pci_modern_dev.c |  4 ++--
 include/linux/virtio_pci_modern.h      |  1 +
 3 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_pci_modern.c
b/drivers/virtio/virtio_pci_modern.c
index d6bb68ba84e5..c0b9d2363ddb 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -22,8 +22,26 @@
 static u64 vp_get_features(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+	u64 features = vp_modern_get_features(&vp_dev->mdev);
+
+#define check_feature(feature, field)								\
+	do {											\
+		if (features & BIT_ULL(feature)) {						\
+			u32 offset = offsetofend(struct virtio_pci_modern_common_cfg, field);	\
+			if (unlikely(vp_dev->mdev.common_len < offset))				\
+				features &= ~BIT_ULL(feature);					\
+		}										\
+	} while (0)
+
+	/* For buggy devices, if the common len does not match the feature, we
+	 * remove the feature.
+	 */
+	check_feature(VIRTIO_F_NOTIFICATION_DATA, queue_notify_data);
+	check_feature(VIRTIO_F_RING_RESET, queue_reset);
+
+#undef check_feature
 
-	return vp_modern_get_features(&vp_dev->mdev);
+	return features;
 }
 
 static void vp_transport_features(struct virtio_device *vdev, u64 features)
diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
index aad7d9296e77..33f319da1558 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -291,8 +291,8 @@ int vp_modern_probe(struct virtio_pci_modern_device *mdev)
 	err = -EINVAL;
 	mdev->common = vp_modern_map_capability(mdev, common,
 				      sizeof(struct virtio_pci_common_cfg), 4,
-				      0, sizeof(struct virtio_pci_common_cfg),
-				      NULL, NULL);
+				      0, sizeof(struct virtio_pci_modern_common_cfg),
+				      &mdev->common_len, NULL);
 	if (!mdev->common)
 		goto err_map_common;
 	mdev->isr = vp_modern_map_capability(mdev, isr, sizeof(u8), 1,
diff --git a/include/linux/virtio_pci_modern.h
b/include/linux/virtio_pci_modern.h
index 067ac1d789bc..edf62bae0474 100644
--- a/include/linux/virtio_pci_modern.h
+++ b/include/linux/virtio_pci_modern.h
@@ -28,6 +28,7 @@ struct virtio_pci_modern_device {
 	/* So we can sanity-check accesses. */
 	size_t notify_len;
 	size_t device_len;
+	size_t common_len;
 
 	/* Capability for when we need to map notifications per-vq. */
 	int notify_map_cap;
-- 
2.32.0.3.g01195cf9f

Add checks to the check_offsets(void) for queue_notify_data and
queue_reset.

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 | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/virtio/virtio_pci_modern_dev.c
b/drivers/virtio/virtio_pci_modern_dev.c
index 33f319da1558..e2a1fe7bb66c 100644
--- a/drivers/virtio/virtio_pci_modern_dev.c
+++ b/drivers/virtio/virtio_pci_modern_dev.c
@@ -203,6 +203,10 @@ static inline void check_offsets(void)
 		     offsetof(struct virtio_pci_common_cfg, queue_used_lo));
 	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_USEDHI ! 		     offsetof(struct
virtio_pci_common_cfg, queue_used_hi));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_NDATA !+		     offsetof(struct
virtio_pci_modern_common_cfg, queue_notify_data));
+	BUILD_BUG_ON(VIRTIO_PCI_COMMON_Q_RESET !+		     offsetof(struct
virtio_pci_modern_common_cfg, queue_reset));
 }
 
 /*
-- 
2.32.0.3.g01195cf9f