Re: [PATCH] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Apr 02, 2023 at 11:10:34AM +0300, Alvaro Karsz 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 the vqn, next_off and 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@daynix.com/
> 
> Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>

Hmm so I conclude that drivers without kick_vq_with_data
should not accept VIRTIO_F_NOTIFICATION_DATA then?


> ---
>  drivers/virtio/virtio_vdpa.c | 20 ++++++++++++++++++--
>  include/linux/vdpa.h         |  6 ++++++
>  2 files changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> index d7f5af62dda..bdaf30f7fbf 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);
>  	struct vdpa_callback cb;
>  	struct virtqueue *vq;
>  	u64 desc_addr, driver_addr, device_addr;
> @@ -154,6 +166,11 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index,
>  	if (index >= vdpa->nvqs)
>  		return ERR_PTR(-ENOENT);
>  
> +	if (__virtio_test_bit(vdev, VIRTIO_F_NOTIFICATION_DATA))
> +		notify = virtio_vdpa_notify_with_data;
> +	else
> +		notify = virtio_vdpa_notify;
> +
>  	/* Queue shouldn't already be set up. */
>  	if (ops->get_vq_ready(vdpa, index))
>  		return ERR_PTR(-ENOENT);
> @@ -183,8 +200,7 @@ 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..a83bb0501c5 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -143,6 +143,11 @@ 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: includes vqn, next_off and next_wrap for
> + *				packed virtqueues
>   * @set_vq_cb:			Set the interrupt callback function for
>   *				a virtqueue
>   *				@vdev: vdpa device
> @@ -300,6 +305,7 @@ 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

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