4.10-stable review patch. If anyone has any objections, please let me know.
------------------ From: Alex Williamson <[email protected]> commit 93a15b58cfb8a24e666ffca432f19fe65c1cd7d1 upstream. 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 <[email protected]> Cc: Jike Song <[email protected]> Cc: Paolo Bonzini <[email protected]> Cc: Zhenyu Wang <[email protected]> Cc: Zhi Wang <[email protected]> Reviewed-by: Jike Song <[email protected]> Signed-off-by: Zhenyu Wang <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- drivers/gpu/drm/i915/gvt/kvmgt.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/gpu/drm/i915/gvt/kvmgt.c +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c @@ -1334,6 +1334,7 @@ static int kvmgt_guest_init(struct 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); @@ -1353,6 +1354,7 @@ static bool kvmgt_guest_exit(struct kvmg } 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);
