Re: [Qemu-devel] [PULL for-1.6 3/4] virtio: clear signalled_used_valid when switching from dataplane

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Aug 13, 2013 at 09:26:39AM -0500, Michael Roth wrote:
> Quoting Michael S. Tsirkin (2013-08-12 07:02:42)
> > From: Stefan Hajnoczi <stefanha@redhat.com>
> > 
> > When the dataplane thread stops, its vring.c implementation synchronizes
> > vring state back to virtio.c so we can continue emulating the virtio
> > device.
> > 
> > This patch ensures that virtio.c's signalled_used_valid flag is reset so
> > that we do not suppress guest notifications due to stale signalled_used
> > values.
> > 
> > Suggested-by: Kevin Wolf <kwolf@redhat.com>
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> 
> Is this applicable for qemu-stable? It's a dependency of 4/4 of this series
> which I'm planning on pulling in.

Certainly does no harm there.

> > ---
> >  hw/virtio/dataplane/vring.c | 1 +
> >  hw/virtio/virtio.c          | 5 +++++
> >  include/hw/virtio/virtio.h  | 1 +
> >  3 files changed, 7 insertions(+)
> > 
> > diff --git a/hw/virtio/dataplane/vring.c b/hw/virtio/dataplane/vring.c
> > index 82cc151..351a343 100644
> > --- a/hw/virtio/dataplane/vring.c
> > +++ b/hw/virtio/dataplane/vring.c
> > @@ -52,6 +52,7 @@ bool vring_setup(Vring *vring, VirtIODevice *vdev, int n)
> >  void vring_teardown(Vring *vring, VirtIODevice *vdev, int n)
> >  {
> >      virtio_queue_set_last_avail_idx(vdev, n, vring->last_avail_idx);
> > +    virtio_queue_invalidate_signalled_used(vdev, n);
> > 
> >      hostmem_finalize(&vring->hostmem);
> >  }
> > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > index 09f62c6..706bdf4 100644
> > --- a/hw/virtio/virtio.c
> > +++ b/hw/virtio/virtio.c
> > @@ -1059,6 +1059,11 @@ void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
> >      vdev->vq[n].last_avail_idx = idx;
> >  }
> > 
> > +void virtio_queue_invalidate_signalled_used(VirtIODevice *vdev, int n)
> > +{
> > +    vdev->vq[n].signalled_used_valid = false;
> > +}
> > +
> >  VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n)
> >  {
> >      return vdev->vq + n;
> > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> > index d7e9e0f..a90522d 100644
> > --- a/include/hw/virtio/virtio.h
> > +++ b/include/hw/virtio/virtio.h
> > @@ -237,6 +237,7 @@ hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n);
> >  hwaddr virtio_queue_get_ring_size(VirtIODevice *vdev, int n);
> >  uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n);
> >  void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx);
> > +void virtio_queue_invalidate_signalled_used(VirtIODevice *vdev, int n);
> >  VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n);
> >  uint16_t virtio_get_queue_index(VirtQueue *vq);
> >  int virtio_queue_get_id(VirtQueue *vq);
> > -- 
> > MST