Re: [PATCH v2 11/14] vdpa: Adapt vhost_vdpa_get_vring_base to SVQ

[Jason Wang]

在 2022/2/27 下午9:41, Eugenio Pérez 写道:
> This is needed to achieve migration, so the destination can restore its
> index.


I suggest to duplicate the comment below here.

Thanks


> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> ---
>   hw/virtio/vhost-vdpa.c | 17 +++++++++++++++++
>   1 file changed, 17 insertions(+)
>
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 56f9f125cd..accc4024c2 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -1180,8 +1180,25 @@ static int vhost_vdpa_set_vring_base(struct vhost_dev 
> *dev,
>   static int vhost_vdpa_get_vring_base(struct vhost_dev *dev,
>                                          struct vhost_vring_state *ring)
>   {
> +    struct vhost_vdpa *v = dev->opaque;
>       int ret;
>   
> +    if (v->shadow_vqs_enabled) {
> +        VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs,
> +                                                      ring->index);
> +
> +        /*
> +         * Setting base as last used idx, so destination will see as available
> +         * all the entries that the device did not use, including the in-flight
> +         * processing ones.
> +         *
> +         * TODO: This is ok for networking, but other kinds of devices might
> +         * have problems with these retransmissions.
> +         */
> +        ring->num = svq->last_used_idx;
> +        return 0;
> +    }
> +
>       ret = vhost_vdpa_call(dev, VHOST_GET_VRING_BASE, ring);
>       trace_vhost_vdpa_get_vring_base(dev, ring->index, ring->num);
>       return ret;