On Thu, Feb 15, 2024 at 5:15 PM Eugenio Perez Martin
<epere...@redhat.com> wrote:
>
> On Wed, Feb 14, 2024 at 1:39 PM Si-Wei Liu <si-wei....@oracle.com> wrote:
> >
> > Fix an issue where cancellation of ongoing migration ends up
> > with no network connectivity.
> >
> > When canceling migration, SVQ will be switched back to the
> > passthrough mode, but the right call fd is not programed to
> > the device and the svq's own call fd is still used. At the
> > point of this transitioning period, the shadow_vqs_enabled
> > hadn't been set back to false yet, causing the installation
> > of call fd inadvertently bypassed.
> >
> > Fixes: a8ac88585da1 ("vhost: Add Shadow VirtQueue call forwarding
> > capabilities")
> > Cc: Eugenio Pérez <epere...@redhat.com>
> > Acked-by: Jason Wang <jasow...@redhat.com>
> > Signed-off-by: Si-Wei Liu <si-wei....@oracle.com>
> > ---
> > hw/virtio/vhost-vdpa.c | 10 +++++++++-
> > 1 file changed, 9 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> > index 004110f..dfeca8b 100644
> > --- a/hw/virtio/vhost-vdpa.c
> > +++ b/hw/virtio/vhost-vdpa.c
> > @@ -1468,7 +1468,15 @@ static int vhost_vdpa_set_vring_call(struct
> > vhost_dev *dev,
> >
> > /* Remember last call fd because we can switch to SVQ anytime. */
> > vhost_svq_set_svq_call_fd(svq, file->fd);
> > - if (v->shadow_vqs_enabled) {
> > + /*
> > + * When SVQ is transitioning to off, shadow_vqs_enabled has
> > + * not been set back to false yet, but the underlying call fd
> > + * will have to switch back to the guest notifier to signal the
> > + * passthrough virtqueues. In other situations, SVQ's own call
> > + * fd shall be used to signal the device model.
> > + */
> > + if (v->shadow_vqs_enabled &&
> > + v->shared->svq_switching != SVQ_TSTATE_DISABLING) {
>
> I think it would be great to not need to add more status variables to
> vhost_vdpa (or any struct).
>
> What if we recover the call file descriptor at vhost_vdpa_svqs_stop?
> This way everything is more symmetrical as kick and call are set by
> vhost_vdpa_svqs_start.
>
Also, we could check for dev->started.
> Thanks!
>
> > return 0;
> > }
> >
> > --
> > 1.8.3.1
> >
