On Sat, Jul 16, 2022 at 7:34 PM Eugenio Pérez <epere...@redhat.com> wrote:
>
> Migration with SVQ already migrate the inflight descriptors,
How is this done?
> so the
> destination can perform the work.
>
> This makes easier to migrate between backends or to recover them in
> vhost devices that support set in flight descriptors.
>
> Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> ---
> hw/virtio/vhost-vdpa.c | 24 +++++++++++-------------
> 1 file changed, 11 insertions(+), 13 deletions(-)
>
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 18820498b3..4458c8d23e 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -1178,7 +1178,18 @@ static int vhost_vdpa_set_vring_base(struct vhost_dev
> *dev,
> struct vhost_vring_state *ring)
> {
> struct vhost_vdpa *v = dev->opaque;
> + VirtQueue *vq = virtio_get_queue(dev->vdev, ring->index);
>
> + /*
> + * vhost-vdpa devices does not support in-flight requests. Set all of
> them
> + * as available.
> + *
> + * TODO: This is ok for networking, but other kinds of devices might
> + * have problems with these retransmissions.
> + */
> + while (virtqueue_rewind(vq, 1)) {
> + continue;
> + }
> if (v->shadow_vqs_enabled) {
> /*
> * Device vring base was set at device start. SVQ base is handled by
> @@ -1197,19 +1208,6 @@ static int vhost_vdpa_get_vring_base(struct vhost_dev
> *dev,
> int ret;
>
> if (v->shadow_vqs_enabled) {
> - VirtQueue *vq = virtio_get_queue(dev->vdev, 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.
> - */
> - while (virtqueue_rewind(vq, 1)) {
> - continue;
> - }
I think it's not a good idea to partially revert the code that was
just introduced in the previous patch (unless it can be backported to
-stable independently).
We probably need to squash the changes.
Thanks
> ring->num = virtio_queue_get_last_avail_idx(dev->vdev, ring->index);
> return 0;
> }
> --
> 2.31.1
>
