Re: [PATCH v11 02/40] virtio: struct virtio_config_ops add callbacks for queue_reset

Michael S. Tsirkin
2022-07-01T06:29:31Z

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@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