Re: [PATCH v2 1/3] vdpa: do not block migration if device has cvq and x-svq=on

[Lei Yang]

QE tested this series with vhost_vdpa and x-svq=on, guest can migrate
and everything works well.

Tested-by: Lei Yang <leiyang@redhat.com>

On Fri, Jun 2, 2023 at 10:39 PM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> It was a mistake to forbid in all cases, as SVQ is already able to send
> all the CVQ messages before start forwarding data vqs.  It actually
> caused a regression, making impossible to migrate device previously
> migratable.
>
> Fixes: 36e4647247f2 ("vdpa: add vhost_vdpa_net_valid_svq_features")
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>  net/vhost-vdpa.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> index 37cdc84562..c63456ff7c 100644
> --- a/net/vhost-vdpa.c
> +++ b/net/vhost-vdpa.c
> @@ -837,13 +837,16 @@ static NetClientState 
> *net_vhost_vdpa_init(NetClientState *peer,
>          s->vhost_vdpa.shadow_vq_ops_opaque = s;
>
>          /*
> -         * TODO: We cannot migrate devices with CVQ as there is no way to set
> -         * the device state (MAC, MQ, etc) before starting the datapath.
> +         * TODO: We cannot migrate devices with CVQ and no x-svq enabled as
> +         * there is no way to set the device state (MAC, MQ, etc) before
> +         * starting the datapath.
>           *
>           * Migration blocker ownership now belongs to s->vhost_vdpa.
>           */
> -        error_setg(&s->vhost_vdpa.migration_blocker,
> -                   "net vdpa cannot migrate with CVQ feature");
> +        if (!svq) {
> +            error_setg(&s->vhost_vdpa.migration_blocker,
> +                       "net vdpa cannot migrate with CVQ feature");
> +        }
>      }
>      ret = vhost_vdpa_add(nc, (void *)&s->vhost_vdpa, queue_pair_index, nvqs);
>      if (ret) {
> --
> 2.31.1
>