Re: [Qemu-devel] [PATCH for-2.5 1/1] vhost-user: do not send SET_VRING_ENABLE at start

[Michael S. Tsirkin]

On Tue, Nov 24, 2015 at 05:10:36PM +0100, Thibaut Collet wrote:
> This patch reverts partially commit 3a12f32229a.
> 
> In case of live migration several queues can be enabled and not only the first
> one. So inform backend that only the first queue is enabled is wrong.
> 
> Since commit 7263a0ad7899 backend is already notified of the state of the 
> vring
> through the vring attach operation. This function, called during the startup
> sequence, provides the correct state of the vring, even in case of live
> migration.
> 
> So nothing has to be added to give the vring state to the backend at the 
> startup.
> 
> Signed-off-by: Thibaut Collet <address@hidden>
> ---
>  hw/virtio/vhost.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 1794f0d..870cd12 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1226,11 +1226,6 @@ int vhost_dev_start(struct vhost_dev *hdev, 
> VirtIODevice *vdev)
>          }
>      }
>  
> -    if (hdev->vhost_ops->vhost_set_vring_enable) {
> -        /* only enable first vq pair by default */
> -        hdev->vhost_ops->vhost_set_vring_enable(hdev, hdev->vq_index == 0);
> -    }
> -
>      return 0;
>  fail_log:
>      vhost_log_put(hdev, false);
> -- 
> 2.1.4

Yes - and I'm beginning to think that maybe we should revert
all of 3a12f32229a then, for symmetry.

Yunnan, Victor - what do you think?

-- 
MST