Linux Virtualization - Apr 2023 - [PATCH v2] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

Add VIRTIO_F_NOTIFICATION_DATA support for vDPA transport.
If this feature is negotiated, the driver passes extra data when kicking
a virtqueue.

A device that offers this feature needs to implement the
kick_vq_with_data callback.

kick_vq_with_data receives the vDPA device and data.
data includes:
16 bits vqn and 16 bits next available index for split virtqueues.
16 bits vqs, 15 least significant bits of next available index
and 1 bit next_wrap for packed virtqueues.

This patch follows a patch [1] by Viktor Prutyanov which adds support
for the MMIO, channel I/O and modern PCI transports.

This patch needs to be applied on top of Viktor's patch.

[1] https://lore.kernel.org/lkml/20230324195029.2410503-1-viktor at daynix.com/

Signed-off-by: Alvaro Karsz <alvaro.karsz at solid-run.com>
---
v2:
	- clear the feature bit if kick_vq_with_data is not implemented.
	- Fix kick_vq_with_data comment in include/linux/vdpa.h
	- Write in more detail about the extra data in the commit log

 drivers/virtio/virtio_vdpa.c | 23 +++++++++++++++++++++--
 include/linux/vdpa.h         |  9 +++++++++
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
index d7f5af62dda..737c1f36d32 100644
--- a/drivers/virtio/virtio_vdpa.c
+++ b/drivers/virtio/virtio_vdpa.c
@@ -112,6 +112,17 @@ static bool virtio_vdpa_notify(struct virtqueue *vq)
 	return true;
 }
 
+static bool virtio_vdpa_notify_with_data(struct virtqueue *vq)
+{
+	struct vdpa_device *vdpa = vd_get_vdpa(vq->vdev);
+	const struct vdpa_config_ops *ops = vdpa->config;
+	u32 data = vring_notification_data(vq);
+
+	ops->kick_vq_with_data(vdpa, data);
+
+	return true;
+}
+
 static irqreturn_t virtio_vdpa_config_cb(void *private)
 {
 	struct virtio_vdpa_device *vd_dev = private;
@@ -138,6 +149,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned
int index,
 	struct device *dma_dev;
 	const struct vdpa_config_ops *ops = vdpa->config;
 	struct virtio_vdpa_vq_info *info;
+	bool (*notify)(struct virtqueue *vq) = virtio_vdpa_notify;
 	struct vdpa_callback cb;
 	struct virtqueue *vq;
 	u64 desc_addr, driver_addr, device_addr;
@@ -154,6 +166,14 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned
int index,
 	if (index >= vdpa->nvqs)
 		return ERR_PTR(-ENOENT);
 
+	/* We cannot accept VIRTIO_F_NOTIFICATION_DATA without kick_vq_with_data */
+	if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA)) {
+		if (ops->kick_vq_with_data)
+			notify = virtio_vdpa_notify_with_data;
+		else
+			__virtio_clear_bit(vdev, VIRTIO_F_NOTIFICATION_DATA);
+	}
+
 	/* Queue shouldn't already be set up. */
 	if (ops->get_vq_ready(vdpa, index))
 		return ERR_PTR(-ENOENT);
@@ -183,8 +203,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned
int index,
 		dma_dev = vdpa_get_dma_dev(vdpa);
 	vq = vring_create_virtqueue_dma(index, max_num, align, vdev,
 					true, may_reduce_num, ctx,
-					virtio_vdpa_notify, callback,
-					name, dma_dev);
+					notify, callback, name, dma_dev);
 	if (!vq) {
 		err = -ENOMEM;
 		goto error_new_virtqueue;
diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 43f59ef10cc..04cdaad77dd 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -143,6 +143,14 @@ struct vdpa_map_file {
  * @kick_vq:			Kick the virtqueue
  *				@vdev: vdpa device
  *				@idx: virtqueue index
+ * @kick_vq_with_data:		Kick the virtqueue and supply extra data
+ *				(only if VIRTIO_F_NOTIFICATION_DATA is negotiated)
+ *				@vdev: vdpa device
+ *				@data for split virtqueue:
+ *				16 bits vqn and 16 bits next available index.
+ *				@data for packed virtqueue:
+ *				16 bits vqn, 15 least significant bits of
+ *				next available index and 1 bit next_wrap.
  * @set_vq_cb:			Set the interrupt callback function for
  *				a virtqueue
  *				@vdev: vdpa device
@@ -300,6 +308,7 @@ struct vdpa_config_ops {
 			      u64 device_area);
 	void (*set_vq_num)(struct vdpa_device *vdev, u16 idx, u32 num);
 	void (*kick_vq)(struct vdpa_device *vdev, u16 idx);
+	void (*kick_vq_with_data)(struct vdpa_device *vdev, u32 data);
 	void (*set_vq_cb)(struct vdpa_device *vdev, u16 idx,
 			  struct vdpa_callback *cb);
 	void (*set_vq_ready)(struct vdpa_device *vdev, u16 idx, bool ready);
-- 
2.34.1

On Sun, Apr 9, 2023 at 3:07?PM Alvaro Karsz <alvaro.karsz at
solid-run.com> wrote:
>
> Add VIRTIO_F_NOTIFICATION_DATA support for vDPA transport.
> If this feature is negotiated, the driver passes extra data when kicking
> a virtqueue.
>
> A device that offers this feature needs to implement the
> kick_vq_with_data callback.
>
> kick_vq_with_data receives the vDPA device and data.
> data includes:
> 16 bits vqn and 16 bits next available index for split virtqueues.
> 16 bits vqs, 15 least significant bits of next available index
> and 1 bit next_wrap for packed virtqueues.
>
> This patch follows a patch [1] by Viktor Prutyanov which adds support
> for the MMIO, channel I/O and modern PCI transports.
>
> This patch needs to be applied on top of Viktor's patch.
>
> [1] https://lore.kernel.org/lkml/20230324195029.2410503-1-viktor at
daynix.com/
>
> Signed-off-by: Alvaro Karsz <alvaro.karsz at solid-run.com>
> ---
> v2:
>         - clear the feature bit if kick_vq_with_data is not implemented.
>         - Fix kick_vq_with_data comment in include/linux/vdpa.h
>         - Write in more detail about the extra data in the commit log
>
>  drivers/virtio/virtio_vdpa.c | 23 +++++++++++++++++++++--
>  include/linux/vdpa.h         |  9 +++++++++
>  2 files changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> index d7f5af62dda..737c1f36d32 100644
> --- a/drivers/virtio/virtio_vdpa.c
> +++ b/drivers/virtio/virtio_vdpa.c
> @@ -112,6 +112,17 @@ static bool virtio_vdpa_notify(struct virtqueue *vq)
>         return true;
>  }
>
> +static bool virtio_vdpa_notify_with_data(struct virtqueue *vq)
> +{
> +       struct vdpa_device *vdpa = vd_get_vdpa(vq->vdev);
> +       const struct vdpa_config_ops *ops = vdpa->config;
> +       u32 data = vring_notification_data(vq);
> +
> +       ops->kick_vq_with_data(vdpa, data);
> +
> +       return true;
> +}
> +
>  static irqreturn_t virtio_vdpa_config_cb(void *private)
>  {
>         struct virtio_vdpa_device *vd_dev = private;
> @@ -138,6 +149,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev,
unsigned int index,
>         struct device *dma_dev;
>         const struct vdpa_config_ops *ops = vdpa->config;
>         struct virtio_vdpa_vq_info *info;
> +       bool (*notify)(struct virtqueue *vq) = virtio_vdpa_notify;
>         struct vdpa_callback cb;
>         struct virtqueue *vq;
>         u64 desc_addr, driver_addr, device_addr;
> @@ -154,6 +166,14 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev,
unsigned int index,
>         if (index >= vdpa->nvqs)
>                 return ERR_PTR(-ENOENT);
>
> +       /* We cannot accept VIRTIO_F_NOTIFICATION_DATA without
kick_vq_with_data */
> +       if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA)) {
> +               if (ops->kick_vq_with_data)
> +                       notify = virtio_vdpa_notify_with_data;
> +               else
If we do this, I wonder if we need to fail or at least warn in this case.

Thanks
> +                       __virtio_clear_bit(vdev,
VIRTIO_F_NOTIFICATION_DATA);
> +       }
> +
>         /* Queue shouldn't already be set up. */
>         if (ops->get_vq_ready(vdpa, index))
>                 return ERR_PTR(-ENOENT);
> @@ -183,8 +203,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev,
unsigned int index,
>                 dma_dev = vdpa_get_dma_dev(vdpa);
>         vq = vring_create_virtqueue_dma(index, max_num, align, vdev,
>                                         true, may_reduce_num, ctx,
> -                                       virtio_vdpa_notify, callback,
> -                                       name, dma_dev);
> +                                       notify, callback, name, dma_dev);
>         if (!vq) {
>                 err = -ENOMEM;
>                 goto error_new_virtqueue;
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 43f59ef10cc..04cdaad77dd 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -143,6 +143,14 @@ struct vdpa_map_file {
>   * @kick_vq:                   Kick the virtqueue
>   *                             @vdev: vdpa device
>   *                             @idx: virtqueue index
> + * @kick_vq_with_data:         Kick the virtqueue and supply extra data
> + *                             (only if VIRTIO_F_NOTIFICATION_DATA is
negotiated)
> + *                             @vdev: vdpa device
> + *                             @data for split virtqueue:
> + *                             16 bits vqn and 16 bits next available
index.
> + *                             @data for packed virtqueue:
> + *                             16 bits vqn, 15 least significant bits of
> + *                             next available index and 1 bit next_wrap.
>   * @set_vq_cb:                 Set the interrupt callback function for
>   *                             a virtqueue
>   *                             @vdev: vdpa device
> @@ -300,6 +308,7 @@ struct vdpa_config_ops {
>                               u64 device_area);
>         void (*set_vq_num)(struct vdpa_device *vdev, u16 idx, u32 num);
>         void (*kick_vq)(struct vdpa_device *vdev, u16 idx);
> +       void (*kick_vq_with_data)(struct vdpa_device *vdev, u32 data);
>         void (*set_vq_cb)(struct vdpa_device *vdev, u16 idx,
>                           struct vdpa_callback *cb);
>         void (*set_vq_ready)(struct vdpa_device *vdev, u16 idx, bool
ready);
> --
> 2.34.1
>