drm/i915/gvt: Free dmabuf_obj list in intel_vgpu_dmabuf_cleanup

The per vGPU dmabuf_obj list should be released in intel_vgpu_dmabuf_
cleanup, which is invoked either in the process of closing a VM or in
the process of removing a vGPU.

Fixes: e3a0d7976c53 ("drm/i915/gvt: Handle orphan dmabuf_objs")
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>

drivers/gpu/drm/i915/gvt/dmabuf.c

@@ -90,7 +90,7 @@ static void dmabuf_gem_object_free(struct kref *kref)
 	struct list_head *pos;
 	struct intel_vgpu_dmabuf_obj *dmabuf_obj;
 
-	if (vgpu) {
+	if (vgpu && vgpu->active && !list_empty(&vgpu->dmabuf_obj_list_head)) {
 		list_for_each(pos, &vgpu->dmabuf_obj_list_head) {
 			dmabuf_obj = container_of(pos,
 					struct intel_vgpu_dmabuf_obj, list);
@@ -530,6 +530,7 @@ void intel_vgpu_dmabuf_cleanup(struct intel_vgpu *vgpu)
 		if (dmabuf_obj->vgpu)
 			intel_gvt_hypervisor_put_vfio_device(vgpu);
 
+		list_del(pos);
 		dmabuf_obj->vgpu = NULL;
 
 	}