Re: [PATCH v4 2/7] vhost: check queue state in the vhost_dev_set_log routine

[Raphael Norwitz]

On Fri, Sep 4, 2020 at 5:32 AM Dima Stepanov <dimastep@yandex-team.ru> wrote:
>
> If the vhost-user-blk daemon provides only one virtqueue, but device was
> added with several queues, then QEMU will send more VHOST-USER command
> than expected by daemon side. The vhost_virtqueue_start() routine
> handles such case by checking the return value from the
> virtio_queue_get_desc_addr() function call. Add the same check to the
> vhost_dev_set_log() routine.
>
> Signed-off-by: Dima Stepanov <dimastep@yandex-team.ru>

Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>


> ---
>  hw/virtio/vhost.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index ffef7ab..a08b7d8 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -825,12 +825,24 @@ static int vhost_dev_set_features(struct vhost_dev *dev,
>  static int vhost_dev_set_log(struct vhost_dev *dev, bool enable_log)
>  {
>      int r, i, idx;
> +    hwaddr addr;
> +
>      r = vhost_dev_set_features(dev, enable_log);
>      if (r < 0) {
>          goto err_features;
>      }
>      for (i = 0; i < dev->nvqs; ++i) {
>          idx = dev->vhost_ops->vhost_get_vq_index(dev, dev->vq_index + i);
> +        addr = virtio_queue_get_desc_addr(dev->vdev, idx);
> +        if (!addr) {
> +            /*
> +             * The queue might not be ready for start. If this
> +             * is the case there is no reason to continue the process.
> +             * The similar logic is used by the vhost_virtqueue_start()
> +             * routine.
> +             */
> +            continue;
> +        }
>          r = vhost_virtqueue_set_addr(dev, dev->vqs + i, idx,
>                                       enable_log);
>          if (r < 0) {
> --
> 2.7.4
>
>