On 2017.03.20 14:58:06 +0800, Jike Song wrote: > On 03/20/2017 10:38 AM, Alex Williamson wrote: > > The kvmgt code keeps a pointer to the struct kvm associated with the > > device, but doesn't actually hold a reference to it. If we do unclean > > shutdown testing (ie. killing the user process), then we can see the > > kvm association to the device unset, which causes kvmgt to trigger a > > device release via a work queue. Naturally we cannot guarantee that > > the cached struct kvm pointer is still valid at this point without > > holding a reference. The observed failure in this case is a stuck > > cpu trying to acquire the spinlock from the invalid reference, but > > other failure modes are clearly possible. Hold a reference to avoid > > this. > > > > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > > Cc: stable@xxxxxxxxxxxxxxx #v4.10 > > Cc: Jike Song <jike.song@xxxxxxxxx> > > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > > Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx> > > Cc: Zhi Wang <zhi.a.wang@xxxxxxxxx> > > --- > > Reviewed-by: Jike Song <jike.song@xxxxxxxxx> > > Thanks for the fix! > queued in fixes tree, thanks! > > > drivers/gpu/drm/i915/gvt/kvmgt.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c > > index 84d801638ede..142b8bd4ba6b 100644 > > --- a/drivers/gpu/drm/i915/gvt/kvmgt.c > > +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c > > @@ -1324,6 +1324,7 @@ static int kvmgt_guest_init(struct mdev_device *mdev) > > vgpu->handle = (unsigned long)info; > > info->vgpu = vgpu; > > info->kvm = kvm; > > + kvm_get_kvm(info->kvm); > > > > kvmgt_protect_table_init(info); > > gvt_cache_init(vgpu); > > @@ -1343,6 +1344,7 @@ static bool kvmgt_guest_exit(struct kvmgt_guest_info *info) > > } > > > > kvm_page_track_unregister_notifier(info->kvm, &info->track_node); > > + kvm_put_kvm(info->kvm); > > kvmgt_protect_table_destroy(info); > > gvt_cache_destroy(info->vgpu); > > vfree(info); > > -- Open Source Technology Center, Intel ltd. $gpg --keyserver wwwkeys.pgp.net --recv-keys 4D781827
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