drm/virtio: Add support for saving and restoring virtio_gpu_objects

When the host KVM/QEMU resumes from hibernation, it loses all graphics
resources previously submitted by the guest OS, as the QEMU process is
terminated during the suspend-resume cycle. This leads to invalid resource
errors when the guest OS attempts to interact with the host using those
resources after resumption.

To resolve this, the virtio-gpu driver now tracks all active virtio_gpu_objects
and provides a mechanism to restore them by re-submitting the objects to QEMU
when needed (e.g., during resume from hibernation).

Cc: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Cc: Nirmoy Das <nirmoyd@nvidia.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>
Link: https://patch.msgid.link/20260526192814.179673-3-dongwon.kim@intel.com
[dmitry.osipenko@collabora.com: remove extra blank line]
[dmitry.osipenko@collabora.com: move err msg to virtio_gpu_object_restore_all]

drivers/gpu/drm/virtio/virtgpu_drv.h

@@ -99,6 +99,10 @@ struct virtio_gpu_object {
 
 	int uuid_state;
 	uuid_t uuid;
+
+	/* for restoration of objects after hibernation */
+	struct virtio_gpu_object_params params;
+	struct list_head restore_node;
 };
 #define gem_to_virtio_gpu_obj(gobj) \
 	container_of((gobj), struct virtio_gpu_object, base.base)
@@ -267,6 +271,8 @@ struct virtio_gpu_device {
 	struct work_struct obj_free_work;
 	spinlock_t obj_free_lock;
 	struct list_head obj_free_list;
+	struct mutex obj_restore_lock;
+	struct list_head obj_restore_list;
 
 	struct virtio_gpu_drv_capset *capsets;
 	uint32_t num_capsets;
@@ -472,6 +478,7 @@ void virtio_gpu_fence_event_process(struct virtio_gpu_device *vdev,
 				    u64 fence_id);
 
 /* virtgpu_object.c */
+void virtio_gpu_remove_from_restore_list(struct virtio_gpu_object *bo);
 void virtio_gpu_cleanup_object(struct virtio_gpu_object *bo);
 struct drm_gem_object *virtio_gpu_create_object(struct drm_device *dev,
 						size_t size);
@@ -484,6 +491,12 @@ bool virtio_gpu_is_shmem(struct virtio_gpu_object *bo);
 
 int virtio_gpu_resource_id_get(struct virtio_gpu_device *vgdev,
 			       uint32_t *resid);
+
+void virtio_gpu_add_object_to_restore_list(struct virtio_gpu_device *vgdev,
+					   struct virtio_gpu_object *bo);
+
+int virtio_gpu_object_restore_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);
@@ -498,6 +511,8 @@ int virtgpu_dma_buf_import_sgt(struct virtio_gpu_mem_entry **ents,
 			       unsigned int *nents,
 			       struct virtio_gpu_object *bo,
 			       struct dma_buf_attachment *attach);
+int virtgpu_dma_buf_obj_resubmit(struct virtio_gpu_device *vgdev,
+				 struct virtio_gpu_object *bo);
 
 /* virtgpu_debugfs.c */
 void virtio_gpu_debugfs_init(struct drm_minor *minor);

drivers/gpu/drm/virtio/virtgpu_kms.c

@@ -171,6 +171,8 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 		  virtio_gpu_array_put_free_work);
 	INIT_LIST_HEAD(&vgdev->obj_free_list);
 	spin_lock_init(&vgdev->obj_free_lock);
+	INIT_LIST_HEAD(&vgdev->obj_restore_list);
+	mutex_init(&vgdev->obj_restore_lock);
 
 #ifdef __LITTLE_ENDIAN
 	if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_VIRGL))
@@ -307,6 +309,7 @@ void virtio_gpu_deinit(struct drm_device *dev)
 	flush_work(&vgdev->config_changed_work);
 	virtio_reset_device(vgdev->vdev);
 	vgdev->vdev->config->del_vqs(vgdev->vdev);
+	mutex_destroy(&vgdev->obj_restore_lock);
 }
 
 void virtio_gpu_release(struct drm_device *dev)

drivers/gpu/drm/virtio/virtgpu_object.c

@@ -63,6 +63,15 @@ static void virtio_gpu_resource_id_put(struct virtio_gpu_device *vgdev, uint32_t
 		ida_free(&vgdev->resource_ida, id - 1);
 }
 
+void virtio_gpu_remove_from_restore_list(struct virtio_gpu_object *bo)
+{
+	struct virtio_gpu_device *vgdev = bo->base.base.dev->dev_private;
+
+	mutex_lock(&vgdev->obj_restore_lock);
+	list_del_init(&bo->restore_node);
+	mutex_unlock(&vgdev->obj_restore_lock);
+}
+
 void virtio_gpu_cleanup_object(struct virtio_gpu_object *bo)
 {
 	struct virtio_gpu_device *vgdev = bo->base.base.dev->dev_private;
@@ -94,6 +103,7 @@ static void virtio_gpu_free_object(struct drm_gem_object *obj)
 	struct virtio_gpu_device *vgdev = bo->base.base.dev->dev_private;
 
 	if (bo->created) {
+		virtio_gpu_remove_from_restore_list(bo);
 		virtio_gpu_cmd_unref_resource(vgdev, bo);
 		virtio_gpu_notify(vgdev);
 		/* completion handler calls virtio_gpu_cleanup_object() */
@@ -220,6 +230,8 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
 		return PTR_ERR(shmem_obj);
 	bo = gem_to_virtio_gpu_obj(&shmem_obj->base);
 
+	INIT_LIST_HEAD(&bo->restore_node);
+
 	ret = virtio_gpu_resource_id_get(vgdev, &bo->hw_res_handle);
 	if (ret < 0)
 		goto err_free_gem;
@@ -258,6 +270,12 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
 		virtio_gpu_object_attach(vgdev, bo, ents, nents);
 	}
 
+	if (!params->virgl) {
+		/* store non-virgl object with its param to the restore list */
+		bo->params = *params;
+		virtio_gpu_add_object_to_restore_list(vgdev, bo);
+	}
+
 	*bo_ptr = bo;
 	return 0;
 
@@ -271,3 +289,58 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
 	drm_gem_shmem_free(shmem_obj);
 	return ret;
 }
+
+void virtio_gpu_add_object_to_restore_list(struct virtio_gpu_device *vgdev,
+					   struct virtio_gpu_object *bo)
+{
+	mutex_lock(&vgdev->obj_restore_lock);
+	list_add_tail(&bo->restore_node, &vgdev->obj_restore_list);
+	mutex_unlock(&vgdev->obj_restore_lock);
+}
+
+int virtio_gpu_object_restore_all(struct virtio_gpu_device *vgdev)
+{
+	struct virtio_gpu_object *bo, *tmp;
+	struct virtio_gpu_mem_entry *ents;
+	unsigned int nents;
+	int ret = 0;
+
+	mutex_lock(&vgdev->obj_restore_lock);
+	list_for_each_entry_safe(bo, tmp, &vgdev->obj_restore_list,
+				 restore_node) {
+		if (drm_gem_is_imported(&bo->base.base)) {
+			ret = virtgpu_dma_buf_obj_resubmit(vgdev, bo);
+			if (ret)
+				break;
+
+			continue;
+		}
+
+		if (bo->params.blob || bo->attached) {
+			ret = virtio_gpu_object_shmem_init(vgdev, bo, &ents,
+							   &nents);
+			if (ret)
+				break;
+		}
+
+		if (bo->params.blob) {
+			virtio_gpu_cmd_resource_create_blob(vgdev, bo,
+							    &bo->params,
+							    ents, nents);
+		} else {
+			virtio_gpu_cmd_create_resource(vgdev, bo, &bo->params,
+						       NULL, NULL);
+			if (bo->attached) {
+				bo->attached = false;
+				virtio_gpu_object_attach(vgdev, bo, ents,
+							 nents);
+			}
+		}
+	}
+	mutex_unlock(&vgdev->obj_restore_lock);
+
+	if (ret)
+		DRM_ERROR("failed to restore virtio-gpu objects: %d\n", ret);
+
+	return ret;
+}

drivers/gpu/drm/virtio/virtgpu_prime.c

@@ -23,6 +23,7 @@
  */
 
 #include <drm/drm_prime.h>
+#include <drm/drm_print.h>
 #include <linux/virtio_dma_buf.h>
 
 #include "virtgpu_drv.h"
@@ -216,6 +217,7 @@ 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_notify(vgdev);
 		return;
@@ -262,6 +264,13 @@ static int virtgpu_dma_buf_init_obj(struct drm_device *dev,
 	dma_buf_unpin(attach);
 	dma_resv_unlock(resv);
 
+	/*
+	 * Store the dmabuf imported object with its params to the
+	 * restore list.
+	 */
+	bo->params = params;
+	virtio_gpu_add_object_to_restore_list(vgdev, bo);
+
 	return 0;
 
 err_import:
@@ -272,6 +281,38 @@ static int virtgpu_dma_buf_init_obj(struct drm_device *dev,
 	return ret;
 }
 
+int virtgpu_dma_buf_obj_resubmit(struct virtio_gpu_device *vgdev,
+				 struct virtio_gpu_object *bo)
+{
+	struct virtio_gpu_mem_entry *ents;
+	struct scatterlist *sl;
+	int i;
+
+	if (!bo->sgt) {
+		DRM_ERROR("no sgt bound to virtio_gpu_object\n");
+		return -ENOMEM;
+	}
+
+	ents = kvmalloc_array(bo->sgt->nents,
+			      sizeof(struct virtio_gpu_mem_entry),
+			      GFP_KERNEL);
+	if (!ents) {
+		DRM_ERROR("failed to allocate ent list\n");
+		return -ENOMEM;
+	}
+
+	for_each_sgtable_dma_sg(bo->sgt, sl, i) {
+		ents[i].addr = cpu_to_le64(sg_dma_address(sl));
+		ents[i].length = cpu_to_le32(sg_dma_len(sl));
+		ents[i].padding = 0;
+	}
+
+	virtio_gpu_cmd_resource_create_blob(vgdev, bo, &bo->params,
+					    ents, bo->sgt->nents);
+
+	return 0;
+}
+
 static const struct drm_gem_object_funcs virtgpu_gem_dma_buf_funcs = {
 	.free = virtgpu_dma_buf_free_obj,
 };
@@ -317,6 +358,8 @@ struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,
 	if (!bo)
 		return ERR_PTR(-ENOMEM);
 
+	INIT_LIST_HEAD(&bo->restore_node);
+
 	obj = &bo->base.base;
 	obj->resv = buf->resv;
 	obj->funcs = &virtgpu_gem_dma_buf_funcs;

drivers/gpu/drm/virtio/virtgpu_vram.c

@@ -20,6 +20,7 @@ static void virtio_gpu_vram_free(struct drm_gem_object *obj)
 		if (unmap)
 			virtio_gpu_cmd_unmap(vgdev, bo);
 
+		virtio_gpu_remove_from_restore_list(bo);
 		virtio_gpu_cmd_unref_resource(vgdev, bo);
 		virtio_gpu_notify(vgdev);
 		return;
@@ -207,6 +208,8 @@ int virtio_gpu_vram_create(struct virtio_gpu_device *vgdev,
 	obj = &vram->base.base.base;
 	obj->funcs = &virtio_gpu_vram_funcs;
 
+	INIT_LIST_HEAD(&vram->base.restore_node);
+
 	params->size = PAGE_ALIGN(params->size);
 	drm_gem_private_object_init(vgdev->ddev, obj, params->size);