drm/virtio: Support virtgpu exported resources

Add support for UUID-based resource sharing mechanism to virtgpu. This
implements the new virtgpu commands and hooks them up to dma-buf's
get_uuid callback.
Signed-off-by: David Stevens <stevensd@chromium.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200818071343.3461203-4-stevensd@chromium.orgSigned-off-by: Gerd Hoffmann <kraxel@redhat.com>

drivers/gpu/drm/virtio/virtgpu_drv.c

@@ -165,6 +165,7 @@ static unsigned int features[] = {
 	VIRTIO_GPU_F_VIRGL,
 #endif
 	VIRTIO_GPU_F_EDID,
+	VIRTIO_GPU_F_RESOURCE_UUID,
 };
 static struct virtio_driver virtio_gpu_driver = {
 	.feature_table = features,
@@ -202,6 +203,8 @@ static struct drm_driver driver = {
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_mmap = drm_gem_prime_mmap,
+	.gem_prime_export = virtgpu_gem_prime_export,
+	.gem_prime_import = virtgpu_gem_prime_import,
 	.gem_prime_import_sg_table = virtgpu_gem_prime_import_sg_table,
 
 	.gem_create_object = virtio_gpu_create_object,

drivers/gpu/drm/virtio/virtgpu_drv.h

@@ -49,6 +49,10 @@
 #define DRIVER_MINOR 1
 #define DRIVER_PATCHLEVEL 0
 
+#define UUID_INITIALIZING 0
+#define UUID_INITIALIZED 1
+#define UUID_INITIALIZATION_FAILED 2
+
 struct virtio_gpu_object_params {
 	uint32_t format;
 	uint32_t width;
@@ -71,6 +75,9 @@ struct virtio_gpu_object {
 	uint32_t hw_res_handle;
 	bool dumb;
 	bool created;
+
+	int uuid_state;
+	uuid_t uuid;
 };
 #define gem_to_virtio_gpu_obj(gobj) \
 	container_of((gobj), struct virtio_gpu_object, base.base)
@@ -200,6 +207,7 @@ struct virtio_gpu_device {
 	bool has_virgl_3d;
 	bool has_edid;
 	bool has_indirect;
+	bool has_resource_assign_uuid;
 
 	struct work_struct config_changed_work;
 
@@ -210,6 +218,9 @@ struct virtio_gpu_device {
 	struct virtio_gpu_drv_capset *capsets;
 	uint32_t num_capsets;
 	struct list_head cap_cache;
+
+	/* protects resource state when exporting */
+	spinlock_t resource_export_lock;
 };
 
 struct virtio_gpu_fpriv {
@@ -336,6 +347,10 @@ void virtio_gpu_dequeue_fence_func(struct work_struct *work);
 
 void virtio_gpu_notify(struct virtio_gpu_device *vgdev);
 
+int
+virtio_gpu_cmd_resource_assign_uuid(struct virtio_gpu_device *vgdev,
+				    struct virtio_gpu_object_array *objs);
+
 /* virtgpu_display.c */
 void virtio_gpu_modeset_init(struct virtio_gpu_device *vgdev);
 void virtio_gpu_modeset_fini(struct virtio_gpu_device *vgdev);
@@ -367,6 +382,12 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
 bool virtio_gpu_is_shmem(struct virtio_gpu_object *bo);
 
 /* virtgpu_prime.c */
+struct dma_buf *virtgpu_gem_prime_export(struct drm_gem_object *obj,
+					 int flags);
+struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,
+						struct dma_buf *buf);
+int virtgpu_gem_prime_get_uuid(struct drm_gem_object *obj,
+			       uuid_t *uuid);
 struct drm_gem_object *virtgpu_gem_prime_import_sg_table(
 	struct drm_device *dev, struct dma_buf_attachment *attach,
 	struct sg_table *sgt);

drivers/gpu/drm/virtio/virtgpu_kms.c

@@ -118,6 +118,7 @@ int virtio_gpu_init(struct drm_device *dev)
 	vgdev->dev = dev->dev;
 
 	spin_lock_init(&vgdev->display_info_lock);
+	spin_lock_init(&vgdev->resource_export_lock);
 	ida_init(&vgdev->ctx_id_ida);
 	ida_init(&vgdev->resource_ida);
 	init_waitqueue_head(&vgdev->resp_wq);
@@ -146,6 +147,9 @@ int virtio_gpu_init(struct drm_device *dev)
 	if (virtio_has_feature(vgdev->vdev, VIRTIO_RING_F_INDIRECT_DESC)) {
 		vgdev->has_indirect = true;
 	}
+	if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_RESOURCE_UUID)) {
+		vgdev->has_resource_assign_uuid = true;
+	}
 
 	DRM_INFO("features: %cvirgl %cedid\n",
 		 vgdev->has_virgl_3d ? '+' : '-',

drivers/gpu/drm/virtio/virtgpu_prime.c

@@ -23,12 +23,102 @@
  */
 
 #include <drm/drm_prime.h>
+#include <linux/virtio_dma_buf.h>
 
 #include "virtgpu_drv.h"
 
-/* Empty Implementations as there should not be any other driver for a virtual
- * device that might share buffers with virtgpu
+static int virtgpu_virtio_get_uuid(struct dma_buf *buf,
+				   uuid_t *uuid)
+{
+	struct drm_gem_object *obj = buf->priv;
+	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
+	struct virtio_gpu_device *vgdev = obj->dev->dev_private;
+
+	wait_event(vgdev->resp_wq, bo->uuid_state != UUID_INITIALIZING);
+	if (bo->uuid_state != UUID_INITIALIZED)
+		return -ENODEV;
+
+	uuid_copy(uuid, &bo->uuid);
+
+	return 0;
+}
+
+const struct virtio_dma_buf_ops virtgpu_dmabuf_ops =  {
+	.ops = {
+		.cache_sgt_mapping = true,
+		.attach = virtio_dma_buf_attach,
+		.detach = drm_gem_map_detach,
+		.map_dma_buf = drm_gem_map_dma_buf,
+		.unmap_dma_buf = drm_gem_unmap_dma_buf,
+		.release = drm_gem_dmabuf_release,
+		.mmap = drm_gem_dmabuf_mmap,
+		.vmap = drm_gem_dmabuf_vmap,
+		.vunmap = drm_gem_dmabuf_vunmap,
+	},
+	.device_attach = drm_gem_map_attach,
+	.get_uuid = virtgpu_virtio_get_uuid,
+};
+
+struct dma_buf *virtgpu_gem_prime_export(struct drm_gem_object *obj,
+					 int flags)
+{
+	struct dma_buf *buf;
+	struct drm_device *dev = obj->dev;
+	struct virtio_gpu_device *vgdev = dev->dev_private;
+	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
+	struct virtio_gpu_object_array *objs;
+	int ret = 0;
+	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+
+	if (vgdev->has_resource_assign_uuid) {
+		objs = virtio_gpu_array_alloc(1);
+		if (!objs)
+			return ERR_PTR(-ENOMEM);
+		virtio_gpu_array_add_obj(objs, &bo->base.base);
+
+		ret = virtio_gpu_cmd_resource_assign_uuid(vgdev, objs);
+		if (ret)
+			return ERR_PTR(ret);
+		virtio_gpu_notify(vgdev);
+	} else {
+		bo->uuid_state = UUID_INITIALIZATION_FAILED;
+	}
+
+	exp_info.ops = &virtgpu_dmabuf_ops.ops;
+	exp_info.size = obj->size;
+	exp_info.flags = flags;
+	exp_info.priv = obj;
+	exp_info.resv = obj->resv;
+
+	buf = virtio_dma_buf_export(&exp_info);
+	if (IS_ERR(buf))
+		return buf;
+
+	drm_dev_get(dev);
+	drm_gem_object_get(obj);
+
+	return buf;
+}
+
+struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev,
+						struct dma_buf *buf)
+{
+	struct drm_gem_object *obj;
+
+	if (buf->ops == &virtgpu_dmabuf_ops.ops) {
+		obj = buf->priv;
+		if (obj->dev == dev) {
+			/*
+			 * Importing dmabuf exported from our own gem increases
+			 * refcount on gem itself instead of f_count of dmabuf.
 			 */
+			drm_gem_object_get(obj);
+			return obj;
+		}
+	}
+
+	return drm_gem_prime_import(dev, buf);
+}
 
 struct drm_gem_object *virtgpu_gem_prime_import_sg_table(
 	struct drm_device *dev, struct dma_buf_attachment *attach,

drivers/gpu/drm/virtio/virtgpu_vq.c

@@ -1107,3 +1107,58 @@ void virtio_gpu_cursor_ping(struct virtio_gpu_device *vgdev,
 	memcpy(cur_p, &output->cursor, sizeof(output->cursor));
 	virtio_gpu_queue_cursor(vgdev, vbuf);
 }
+
+static void virtio_gpu_cmd_resource_uuid_cb(struct virtio_gpu_device *vgdev,
+					    struct virtio_gpu_vbuffer *vbuf)
+{
+	struct virtio_gpu_object *obj =
+		gem_to_virtio_gpu_obj(vbuf->objs->objs[0]);
+	struct virtio_gpu_resp_resource_uuid *resp =
+		(struct virtio_gpu_resp_resource_uuid *)vbuf->resp_buf;
+	uint32_t resp_type = le32_to_cpu(resp->hdr.type);
+
+	spin_lock(&vgdev->resource_export_lock);
+	WARN_ON(obj->uuid_state != UUID_INITIALIZING);
+
+	if (resp_type == VIRTIO_GPU_RESP_OK_RESOURCE_UUID &&
+	    obj->uuid_state == UUID_INITIALIZING) {
+		memcpy(&obj->uuid.b, resp->uuid, sizeof(obj->uuid.b));
+		obj->uuid_state = UUID_INITIALIZED;
+	} else {
+		obj->uuid_state = UUID_INITIALIZATION_FAILED;
+	}
+	spin_unlock(&vgdev->resource_export_lock);
+
+	wake_up_all(&vgdev->resp_wq);
+}
+
+int
+virtio_gpu_cmd_resource_assign_uuid(struct virtio_gpu_device *vgdev,
+				    struct virtio_gpu_object_array *objs)
+{
+	struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(objs->objs[0]);
+	struct virtio_gpu_resource_assign_uuid *cmd_p;
+	struct virtio_gpu_vbuffer *vbuf;
+	struct virtio_gpu_resp_resource_uuid *resp_buf;
+
+	resp_buf = kzalloc(sizeof(*resp_buf), GFP_KERNEL);
+	if (!resp_buf) {
+		spin_lock(&vgdev->resource_export_lock);
+		bo->uuid_state = UUID_INITIALIZATION_FAILED;
+		spin_unlock(&vgdev->resource_export_lock);
+		virtio_gpu_array_put_free(objs);
+		return -ENOMEM;
+	}
+
+	cmd_p = virtio_gpu_alloc_cmd_resp
+		(vgdev, virtio_gpu_cmd_resource_uuid_cb, &vbuf, sizeof(*cmd_p),
+		 sizeof(struct virtio_gpu_resp_resource_uuid), resp_buf);
+	memset(cmd_p, 0, sizeof(*cmd_p));
+
+	cmd_p->hdr.type = cpu_to_le32(VIRTIO_GPU_CMD_RESOURCE_ASSIGN_UUID);
+	cmd_p->resource_id = cpu_to_le32(bo->hw_res_handle);
+
+	vbuf->objs = objs;
+	virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
+	return 0;
+}