Re: [PATCH] vdpa net: zero vhost_vdpa iova_tree pointer at cleanup

[Lei Yang <leiyang@redhat.com>]

QE tested this patch with real nic,guest can works well after
cancelling migration.

Tested-by: Lei Yang <leiyang@redhat.com>

On Thu, Sep 14, 2023 at 11:23 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Wed, Sep 13, 2023 at 8:34 PM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
> > Not zeroing it causes a SIGSEGV if the live migration is cancelled, at
> > net device restart.
> >
> > This is caused because CVQ tries to reuse the iova_tree that is present
> > in the first vhost_vdpa device at the end of vhost_vdpa_net_cvq_start.
> > As a consequence, it tries to access an iova_tree that has been already
> > free.
> >
> > Fixes: 00ef422e9fbf ("vdpa net: move iova tree creation from init to start")
> > Reported-by: Yanhui Ma <yama@redhat.com>
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
>
> Acked-by: Jason Wang <jasowang@redhat.com>
>
> Thanks
>
> > ---
> >  net/vhost-vdpa.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
> > index 34202ca009..1714ff4b11 100644
> > --- a/net/vhost-vdpa.c
> > +++ b/net/vhost-vdpa.c
> > @@ -385,6 +385,8 @@ static void vhost_vdpa_net_client_stop(NetClientState *nc)
> >      dev = s->vhost_vdpa.dev;
> >      if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
> >          g_clear_pointer(&s->vhost_vdpa.iova_tree, vhost_iova_tree_delete);
> > +    } else {
> > +        s->vhost_vdpa.iova_tree = NULL;
> >      }
> >  }
> >
> > --
> > 2.39.3
> >
>