Re: [Qemu-devel] [PATCH V2 1/3] virtio: guard against NULL pfn

[Jason Wang]

On 2017年03月13日 18:18, Paolo Bonzini wrote:
> On 13/03/2017 10:55, Cornelia Huck wrote:
> > On Mon, 13 Mar 2017 14:29:41 +0800
> > Jason Wang <address@hidden> wrote:
> >
> > > To avoid access stale memory region cache after reset, this patch
> > > check the existence of virtqueue pfn for all exported virtqueue access
> > > helpers before trying to use them.
> > >
> > > Cc: Cornelia Huck <address@hidden>
> > > Cc: Paolo Bonzini <address@hidden>
> > > Signed-off-by: Jason Wang <address@hidden>
> > > ---
> > >   hw/virtio/virtio.c | 21 +++++++++++++++++++++
> > >   1 file changed, 21 insertions(+)
> > >
> > > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> > > index efce4b3..76cc81b 100644
> > > --- a/hw/virtio/virtio.c
> > > +++ b/hw/virtio/virtio.c
> > > @@ -322,6 +322,10 @@ static int virtio_queue_empty_rcu(VirtQueue *vq)
> > >           return 0;
> > >       }
> > >
> > > +    if (unlikely(!vq->vring.avail)) {
> > > +        return 0;
> > Shouldn't that rather return !0 (denoting a non-existing queue as
> > empty)?
> Yes, and the check should also go first (before the function can return 0).
>
> Paolo

Yes, will fix in V3.

Thanks