drm/virtio: Add PM notifier to restore objects after hibernation

Register a PM notifier in virtio-gpu to handle suspend/hibernate
events. On PM_POST_HIBERNATION, restore all GPU objects so that the
driver can properly recover after resume.

Suggested-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patch.msgid.link/20260526192814.179673-4-dongwon.kim@intel.com
[dmitry.osipenko@collabora.com: rename vgdev->hibernation -> hibernated]
[dmitry.osipenko@collabora.com: restore objs on suspend error]
[dmitry.osipenko@collabora.com: no_cb int -> bool]
[dmitry.osipenko@collabora.com: don't include pm_runtime.h]
[dmitry.osipenko@collabora.com: proeprly handle failing register_pm_notifier]

drivers/gpu/drm/virtio/virtgpu_drv.c

@@ -167,6 +167,14 @@ static unsigned int features[] = {
 };
 
 #ifdef CONFIG_PM_SLEEP
+static void virtgpu_hibernation_restore(struct virtio_gpu_device *vgdev)
+{
+	if (vgdev->hibernated) {
+		vgdev->hibernated = false;
+		virtio_gpu_object_restore_all(vgdev);
+	}
+}
+
 static int virtgpu_freeze(struct virtio_device *vdev)
 {
 	struct drm_device *dev = vdev->priv;
@@ -179,6 +187,9 @@ static int virtgpu_freeze(struct virtio_device *vdev)
 		return error;
 	}
 
+	if (vgdev->hibernated)
+		virtio_gpu_object_unref_all(vgdev);
+
 	flush_work(&vgdev->obj_free_work);
 	flush_work(&vgdev->ctrlq.dequeue_work);
 	flush_work(&vgdev->cursorq.dequeue_work);
@@ -201,6 +212,8 @@ static int virtgpu_freeze(struct virtio_device *vdev)
 	return 0;
 
 err_resume:
+	virtgpu_hibernation_restore(vgdev);
+
 	drm_mode_config_helper_resume(dev);
 
 	return error;
@@ -220,6 +233,8 @@ static int virtgpu_restore(struct virtio_device *vdev)
 
 	virtio_device_ready(vdev);
 
+	virtgpu_hibernation_restore(vgdev);
+
 	error = drm_mode_config_helper_resume(dev);
 	if (error) {
 		DRM_ERROR("resume error: %d\n", error);

drivers/gpu/drm/virtio/virtgpu_drv.h

@@ -263,6 +263,7 @@ struct virtio_gpu_device {
 	bool has_host_visible;
 	bool has_context_init;
 	bool has_blob_alignment;
+	bool hibernated;
 	struct virtio_shm_region host_visible_region;
 	struct drm_mm host_visible_mm;
 
@@ -280,6 +281,8 @@ struct virtio_gpu_device {
 	struct list_head cap_cache;
 	uint32_t blob_alignment;
 
+	struct notifier_block pm_nb;
+
 	/* protects uuid state when exporting */
 	spinlock_t resource_export_lock;
 	/* protects map state and host_visible_mm */
@@ -345,7 +348,8 @@ void virtio_gpu_cmd_create_resource(struct virtio_gpu_device *vgdev,
 				    struct virtio_gpu_object_array *objs,
 				    struct virtio_gpu_fence *fence);
 void virtio_gpu_cmd_unref_resource(struct virtio_gpu_device *vgdev,
-				   struct virtio_gpu_object *bo);
+				   struct virtio_gpu_object *bo,
+				   bool no_cb);
 int virtio_gpu_panic_cmd_transfer_to_host_2d(struct virtio_gpu_device *vgdev,
 					     uint64_t offset,
 					     uint32_t width, uint32_t height,
@@ -497,6 +501,8 @@ void virtio_gpu_add_object_to_restore_list(struct virtio_gpu_device *vgdev,
 
 int virtio_gpu_object_restore_all(struct virtio_gpu_device *vgdev);
 
+void virtio_gpu_object_unref_all(struct virtio_gpu_device *vgdev);
+
 /* virtgpu_prime.c */
 int virtio_gpu_resource_assign_uuid(struct virtio_gpu_device *vgdev,
 				    struct virtio_gpu_object *bo);

drivers/gpu/drm/virtio/virtgpu_kms.c

@@ -23,6 +23,7 @@
  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 
+#include <linux/suspend.h>
 #include <linux/virtio.h>
 #include <linux/virtio_config.h>
 #include <linux/virtio_ring.h>
@@ -134,6 +135,31 @@ int virtio_gpu_find_vqs(struct virtio_gpu_device *vgdev)
 	return 0;
 }
 
+static int virtio_gpu_pm_notifier(struct notifier_block *nb, unsigned long mode,
+				  void *data)
+{
+	struct virtio_gpu_device *vgdev = container_of(nb,
+						struct virtio_gpu_device,
+						pm_nb);
+
+	switch (mode) {
+	case PM_HIBERNATION_PREPARE:
+		if (vgdev->has_virgl_3d) {
+			DRM_ERROR("S4 not allowed when VIRGL is enabled\n");
+			return notifier_from_errno(-EPERM);
+		}
+
+		vgdev->hibernated = true;
+		break;
+
+	case PM_POST_HIBERNATION:
+		vgdev->hibernated = false;
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
 int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 {
 	struct virtio_gpu_device *vgdev;
@@ -278,8 +304,16 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 		wait_event_timeout(vgdev->resp_wq, !vgdev->display_info_pending,
 				   5 * HZ);
 	}
+
+	vgdev->pm_nb.notifier_call = virtio_gpu_pm_notifier;
+	ret = register_pm_notifier(&vgdev->pm_nb);
+	if (ret)
+		goto err_modeset_fini;
+
 	return 0;
 
+err_modeset_fini:
+	virtio_gpu_modeset_fini(vgdev);
 err_scanouts:
 	virtio_gpu_free_vbufs(vgdev);
 err_vbufs:
@@ -303,6 +337,7 @@ void virtio_gpu_deinit(struct drm_device *dev)
 {
 	struct virtio_gpu_device *vgdev = dev->dev_private;
 
+	unregister_pm_notifier(&vgdev->pm_nb);
 	flush_work(&vgdev->obj_free_work);
 	flush_work(&vgdev->ctrlq.dequeue_work);
 	flush_work(&vgdev->cursorq.dequeue_work);

drivers/gpu/drm/virtio/virtgpu_object.c

@@ -104,7 +104,7 @@ static void virtio_gpu_free_object(struct drm_gem_object *obj)
 
 	if (bo->created) {
 		virtio_gpu_remove_from_restore_list(bo);
-		virtio_gpu_cmd_unref_resource(vgdev, bo);
+		virtio_gpu_cmd_unref_resource(vgdev, bo, false);
 		virtio_gpu_notify(vgdev);
 		/* completion handler calls virtio_gpu_cleanup_object() */
 		return;
@@ -344,3 +344,18 @@ int virtio_gpu_object_restore_all(struct virtio_gpu_device *vgdev)
 
 	return ret;
 }
+
+void virtio_gpu_object_unref_all(struct virtio_gpu_device *vgdev)
+{
+	struct virtio_gpu_object *bo, *tmp;
+
+	mutex_lock(&vgdev->obj_restore_lock);
+	list_for_each_entry_safe(bo, tmp, &vgdev->obj_restore_list,
+				 restore_node)
+		if (bo->created) {
+			virtio_gpu_cmd_unref_resource(vgdev, bo, true);
+			virtio_gpu_notify(vgdev);
+		}
+
+	mutex_unlock(&vgdev->obj_restore_lock);
+}

drivers/gpu/drm/virtio/virtgpu_prime.c

@@ -218,7 +218,7 @@ static void virtgpu_dma_buf_free_obj(struct drm_gem_object *obj)
 
 	if (bo->created) {
 		virtio_gpu_remove_from_restore_list(bo);
-		virtio_gpu_cmd_unref_resource(vgdev, bo);
+		virtio_gpu_cmd_unref_resource(vgdev, bo, false);
 		virtio_gpu_notify(vgdev);
 		return;
 	}

drivers/gpu/drm/virtio/virtgpu_vq.c

@@ -640,14 +640,21 @@ static void virtio_gpu_cmd_unref_cb(struct virtio_gpu_device *vgdev,
 }
 
 void virtio_gpu_cmd_unref_resource(struct virtio_gpu_device *vgdev,
-				   struct virtio_gpu_object *bo)
+				   struct virtio_gpu_object *bo,
+				   bool no_cb)
 {
 	struct virtio_gpu_resource_unref *cmd_p;
 	struct virtio_gpu_vbuffer *vbuf;
 	int ret;
 
-	cmd_p = virtio_gpu_alloc_cmd_cb(vgdev, &vbuf, sizeof(*cmd_p),
-					virtio_gpu_cmd_unref_cb);
+	if (no_cb) {
+		cmd_p = virtio_gpu_alloc_cmd_cb(vgdev, &vbuf, sizeof(*cmd_p),
+						NULL);
+	} else {
+		cmd_p = virtio_gpu_alloc_cmd_cb(vgdev, &vbuf, sizeof(*cmd_p),
+						virtio_gpu_cmd_unref_cb);
+	}
+
 	memset(cmd_p, 0, sizeof(*cmd_p));
 
 	cmd_p->hdr.type = cpu_to_le32(VIRTIO_GPU_CMD_RESOURCE_UNREF);

drivers/gpu/drm/virtio/virtgpu_vram.c

@@ -21,7 +21,7 @@ static void virtio_gpu_vram_free(struct drm_gem_object *obj)
 			virtio_gpu_cmd_unmap(vgdev, bo);
 
 		virtio_gpu_remove_from_restore_list(bo);
-		virtio_gpu_cmd_unref_resource(vgdev, bo);
+		virtio_gpu_cmd_unref_resource(vgdev, bo, false);
 		virtio_gpu_notify(vgdev);
 		return;
 	}