Re: [PATCH 2/2] virtio-vdpa: add VIRTIO_F_NOTIFICATION_DATA feature support

[Jason Wang]

On Thu, Apr 13, 2023 at 4:19 PM Alvaro Karsz <alvaro.karsz@xxxxxxxxxxxxx> 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.
>
> Signed-off-by: Alvaro Karsz <alvaro.karsz@xxxxxxxxxxxxx>

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>

Thanks

> ---
>  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
>