Re: [Qemu-devel] [PATCH] virtio/vhost: drop unnecessary VHOST_SET_VRING call

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

On Wed, Aug 12, 2015 at 01:19:51PM +0300, Marcel Apfelbaum wrote:
> No need to send VHOST_SET_VRING_CALL to backend
> before the negotiation with the guest is finished.
> 
> Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>

Well - we do need to set it to the masked notifier initially to avoid
losing events.  You can't just drop it - need to move this call
somewhere else.

> ---
>  hw/virtio/vhost.c | 13 +------------
>  1 file changed, 1 insertion(+), 12 deletions(-)
> 
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 2712c6f..b448542 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -875,24 +875,13 @@ static void vhost_eventfd_del(MemoryListener *listener,
>  static int vhost_virtqueue_init(struct vhost_dev *dev,
>                                  struct vhost_virtqueue *vq, int n)
>  {
> -    struct vhost_vring_file file = {
> -        .index = n,
> -    };
>      int r = event_notifier_init(&vq->masked_notifier, 0);
> +
>      if (r < 0) {
>          return r;
>      }
>  
> -    file.fd = event_notifier_get_fd(&vq->masked_notifier);
> -    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_CALL, &file);
> -    if (r) {
> -        r = -errno;
> -        goto fail_call;
> -    }
>      return 0;
> -fail_call:
> -    event_notifier_cleanup(&vq->masked_notifier);
> -    return r;
>  }
>  
>  static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
> -- 
> 2.1.0