Re: [Qemu-devel] [PATCH] virtio-9p: add savem handlers

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Thu, 12 Nov 2015 09:28:21 +0100
Greg Kurz <gkurz@linux.vnet.ibm.com> wrote:

> On Thu, 22 Oct 2015 19:38:42 +0200
> Greg Kurz <gkurz@linux.vnet.ibm.com> wrote:
> 
> > We don't support migration of mounted 9p shares. This is handled by a
> > migration blocker.
> > 
> > One would expect, however, to be able to migrate if the share is unmounted.
> > Unfortunately virtio-9p-device does not register savevm handlers at all !
> > Migration succeeds and leaves the guest with a dangling device...
> > 
> > This patch simply registers migration handlers for virtio-9p-device. Whether
> > migration is possible or not still depends on the migration blocker.
> > 
> > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > ---
> 
> Ping ?
> 
> > Michael, Aneesh,
> > 
> > This is the same patch minus the call to unregister_savevm() since we don't
> > have an unrealize handler.
> > 
> > I decided to simply drop all the other patches. Hot-unplug support is totally
> > missing and definitely needs more work. I'll try to come up with a solution
> > in its own series.
> > 
> > Cheers.
> > 
> > --
> > Greg
> > 
> > ---
> >  hw/9pfs/virtio-9p-device.c |   11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
> > index 93a407c45926..e3abcfaffb2a 100644
> > --- a/hw/9pfs/virtio-9p-device.c
> > +++ b/hw/9pfs/virtio-9p-device.c
> > @@ -43,6 +43,16 @@ static void virtio_9p_get_config(VirtIODevice *vdev, uint8_t *config)
> >      g_free(cfg);
> >  }
> > 
> > +static void virtio_9p_save(QEMUFile *f, void *opaque)
> > +{
> > +    virtio_save(VIRTIO_DEVICE(opaque), f);
> > +}
> > +
> > +static int virtio_9p_load(QEMUFile *f, void *opaque, int version_id)
> > +{
> > +    return virtio_load(VIRTIO_DEVICE(opaque), f, version_id);
> > +}
> > +
> >  static void virtio_9p_device_realize(DeviceState *dev, Error **errp)
> >  {
> >      VirtIODevice *vdev = VIRTIO_DEVICE(dev);
> > @@ -130,6 +140,7 @@ static void virtio_9p_device_realize(DeviceState *dev, Error **errp)
> >      }
> >      v9fs_path_free(&path);
> > 
> > +    register_savevm(dev, "virtio-9p", -1, 1, virtio_9p_save, virtio_9p_load, s);
> >      return;
> >  out:
> >      g_free(s->ctx.fs_root);

Probably dumb question: Is there no state in the V9fsState, or is it
simply irrelevant if there are no mounts?