drm/virtio: add virtio_gpu_object_array & helpers

Some helper functions to manage an array of gem objects.

v9: use dma_resv_lock_interruptible.
v6:
 - add ticket to struct virtio_gpu_object_array.
 - add virtio_gpu_array_{lock,unlock}_resv helpers.
 - add virtio_gpu_array_add_fence helper.
v5: some small optimizations (Chia-I Wu).
v4: make them virtio-private instead of generic helpers.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Chia-I Wu <olvaffe@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20190829103301.3539-8-kraxel@redhat.com

drivers/gpu/drm/virtio/virtgpu_drv.h

@@ -84,6 +84,12 @@ struct virtio_gpu_object {
 #define gem_to_virtio_gpu_obj(gobj) \
 	container_of((gobj), struct virtio_gpu_object, gem_base)
 
+struct virtio_gpu_object_array {
+	struct ww_acquire_ctx ticket;
+	u32 nents, total;
+	struct drm_gem_object *objs[];
+};
+
 struct virtio_gpu_vbuffer;
 struct virtio_gpu_device;
 
@@ -251,6 +257,17 @@ int virtio_gpu_mode_dumb_mmap(struct drm_file *file_priv,
 			      struct drm_device *dev,
 			      uint32_t handle, uint64_t *offset_p);
 
+struct virtio_gpu_object_array *virtio_gpu_array_alloc(u32 nents);
+struct virtio_gpu_object_array*
+virtio_gpu_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents);
+void virtio_gpu_array_add_obj(struct virtio_gpu_object_array *objs,
+			      struct drm_gem_object *obj);
+int virtio_gpu_array_lock_resv(struct virtio_gpu_object_array *objs);
+void virtio_gpu_array_unlock_resv(struct virtio_gpu_object_array *objs);
+void virtio_gpu_array_add_fence(struct virtio_gpu_object_array *objs,
+				struct dma_fence *fence);
+void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs);
+
 /* virtio vg */
 int virtio_gpu_alloc_vbufs(struct virtio_gpu_device *vgdev);
 void virtio_gpu_free_vbufs(struct virtio_gpu_device *vgdev);

drivers/gpu/drm/virtio/virtgpu_gem.c

@@ -171,3 +171,96 @@ void virtio_gpu_gem_object_close(struct drm_gem_object *obj,
 						qobj->hw_res_handle);
 	virtio_gpu_object_unreserve(qobj);
 }
+
+struct virtio_gpu_object_array *virtio_gpu_array_alloc(u32 nents)
+{
+	struct virtio_gpu_object_array *objs;
+	size_t size = sizeof(*objs) + sizeof(objs->objs[0]) * nents;
+
+	objs = kmalloc(size, GFP_KERNEL);
+	if (!objs)
+		return NULL;
+
+	objs->nents = 0;
+	objs->total = nents;
+	return objs;
+}
+
+static void virtio_gpu_array_free(struct virtio_gpu_object_array *objs)
+{
+	kfree(objs);
+}
+
+struct virtio_gpu_object_array*
+virtio_gpu_array_from_handles(struct drm_file *drm_file, u32 *handles, u32 nents)
+{
+	struct virtio_gpu_object_array *objs;
+	u32 i;
+
+	objs = virtio_gpu_array_alloc(nents);
+	if (!objs)
+		return NULL;
+
+	for (i = 0; i < nents; i++) {
+		objs->objs[i] = drm_gem_object_lookup(drm_file, handles[i]);
+		if (!objs->objs[i]) {
+			objs->nents = i;
+			virtio_gpu_array_put_free(objs);
+			return NULL;
+		}
+	}
+	objs->nents = i;
+	return objs;
+}
+
+void virtio_gpu_array_add_obj(struct virtio_gpu_object_array *objs,
+			      struct drm_gem_object *obj)
+{
+	if (WARN_ON_ONCE(objs->nents == objs->total))
+		return;
+
+	drm_gem_object_get(obj);
+	objs->objs[objs->nents] = obj;
+	objs->nents++;
+}
+
+int virtio_gpu_array_lock_resv(struct virtio_gpu_object_array *objs)
+{
+	int ret;
+
+	if (objs->nents == 1) {
+		ret = dma_resv_lock_interruptible(objs->objs[0]->resv, NULL);
+	} else {
+		ret = drm_gem_lock_reservations(objs->objs, objs->nents,
+						&objs->ticket);
+	}
+	return ret;
+}
+
+void virtio_gpu_array_unlock_resv(struct virtio_gpu_object_array *objs)
+{
+	if (objs->nents == 1) {
+		dma_resv_unlock(objs->objs[0]->resv);
+	} else {
+		drm_gem_unlock_reservations(objs->objs, objs->nents,
+					    &objs->ticket);
+	}
+}
+
+void virtio_gpu_array_add_fence(struct virtio_gpu_object_array *objs,
+				struct dma_fence *fence)
+{
+	int i;
+
+	for (i = 0; i < objs->nents; i++)
+		dma_resv_add_excl_fence(objs->objs[i]->resv, fence);
+}
+
+void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs)
+{
+	u32 i;
+
+	for (i = 0; i < objs->nents; i++)
+		drm_gem_object_put_unlocked(objs->objs[i]);
+	virtio_gpu_array_free(objs);
+}