Re: [PATCH v1 1/2] virtio: struct VirtQueue introduce reset

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

subject seems wrong.

On Sun, Jan 29, 2023 at 10:51:49AM +0800, Xuan Zhuo wrote:
> In the current design, we stop the device from operating on the vring
> during per-queue reset by resetting the structure VirtQueue.
> 
> But before the reset operation, when recycling some resources, we should
> stop referencing new vring resources. For example, when recycling
> virtio-net's asynchronous sending resources, virtio-net should be able
> to perceive that the current queue is in the per-queue reset state, and
> stop sending new packets from the tx queue.
> 
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
>  hw/virtio/virtio.c         | 15 +++++++++++++++
>  include/hw/virtio/virtio.h |  1 +
>  2 files changed, 16 insertions(+)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index f35178f5fc..c954f2a2b3 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -142,6 +142,8 @@ struct VirtQueue
>      /* Notification enabled? */
>      bool notification;
>  
> +    bool disabled_by_reset;
> +
>      uint16_t queue_index;
>  
>      unsigned int inuse;
> @@ -2079,6 +2081,12 @@ void virtio_queue_reset(VirtIODevice *vdev, uint32_t queue_index)
>  {
>      VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
>  
> +    /*
> +     * Mark this queue is per-queue reset status. The device should release the
> +     * references of the vring, and not refer more new vring item.

items

> +     */
> +    vdev->vq[queue_index].disabled_by_reset = true;
> +
>      if (k->queue_reset) {
>          k->queue_reset(vdev, queue_index);
>      }

can we set this after calling queue_reset? For symmetry with enable.

> @@ -2102,11 +2110,18 @@ void virtio_queue_enable(VirtIODevice *vdev, uint32_t queue_index)
>      }
>      */
>  
> +    vdev->vq[queue_index].disabled_by_reset = false;
> +
>      if (k->queue_enable) {
>          k->queue_enable(vdev, queue_index);
>      }
>  }
>  
> +bool virtio_queue_reset_state(VirtQueue *vq)
> +{
> +    return vq->disabled_by_reset;
> +}
> +
>  void virtio_reset(void *opaque)
>  {
>      VirtIODevice *vdev = opaque;
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index 77c6c55929..00e91af7c4 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -319,6 +319,7 @@ int virtio_set_status(VirtIODevice *vdev, uint8_t val);
>  void virtio_reset(void *opaque);
>  void virtio_queue_reset(VirtIODevice *vdev, uint32_t queue_index);
>  void virtio_queue_enable(VirtIODevice *vdev, uint32_t queue_index);
> +bool virtio_queue_reset_state(VirtQueue *vq);
>  void virtio_update_irq(VirtIODevice *vdev);
>  int virtio_set_features(VirtIODevice *vdev, uint64_t val);

OK I guess ... what about migration. This state won't be
set correctly will it?


>  
> -- 
> 2.32.0.3.g01195cf9f