Re: [Qemu-devel] [PATCH 1/2] KVM: page track: add a new notifier type: track_flush_slot

[Xiao Guangrong]

On 10/19/2016 10:32 AM, Jike Song wrote:
+EXPORT_SYMBOL_GPL(vfio_group_set_usrdata);
> > > +
> > > +void *vfio_group_get_usrdata(struct vfio_group *group)
> > > +{
> > > +       return group->usrdata;
> > > +}
> > > +EXPORT_SYMBOL_GPL(vfio_group_get_usrdata);
> > > +
> > > +void *vfio_group_get_usrdata_by_device(struct device *dev)
> > > +{
> > > +       struct vfio_group *vfio_group;
> > > +
> > > +       vfio_group = __vfio_group_get_from_iommu(dev->iommu_group);
> >
> > We actually need to use iommu_group_get() here.  Kirti adds a
> > vfio_group_get_from_dev() in v9 03/12 that does this properly.
> >
> > > +       if (!vfio_group)
> > > +               return NULL;
> > > +
> > > +       return vfio_group_get_usrdata(vfio_group);

I am worrying if the kvm instance got from group->usrdata is safe
enough? What happens if you get the instance after kvm released
kvm-vfio device?