drm/virtio: implement blob resources: probe for host visible region

The availability of the host visible region means host 3D
allocations can be directly mapped in the guest.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200924003214.662-9-gurchetansingh@chromium.org
Co-developed-by: Gurchetan Singh <gurchetansingh@chromium.org>
Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>

drivers/gpu/drm/virtio/virtgpu_debugfs.c

@@ -52,6 +52,11 @@ static int virtio_gpu_features(struct seq_file *m, void *data)
 	virtio_add_bool(m, "blob resources", vgdev->has_resource_blob);
 	virtio_add_int(m, "cap sets", vgdev->num_capsets);
 	virtio_add_int(m, "scanouts", vgdev->num_scanouts);
+	if (vgdev->host_visible_region.len) {
+		seq_printf(m, "%-16s : 0x%lx +0x%lx\n", "host visible region",
+			   (unsigned long)vgdev->host_visible_region.addr,
+			   (unsigned long)vgdev->host_visible_region.len);
+	}
 	return 0;
 }
 

drivers/gpu/drm/virtio/virtgpu_drv.h

@@ -209,6 +209,8 @@ struct virtio_gpu_device {
 	bool has_indirect;
 	bool has_resource_assign_uuid;
 	bool has_resource_blob;
+	bool has_host_visible;
+	struct virtio_shm_region host_visible_region;
 
 	struct work_struct config_changed_work;
 

drivers/gpu/drm/virtio/virtgpu_kms.c

@@ -155,11 +155,27 @@ int virtio_gpu_init(struct drm_device *dev)
 	if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_RESOURCE_BLOB)) {
 		vgdev->has_resource_blob = true;
 	}
+	if (virtio_get_shm_region(vgdev->vdev, &vgdev->host_visible_region,
+				  VIRTIO_GPU_SHM_ID_HOST_VISIBLE)) {
+		if (!devm_request_mem_region(&vgdev->vdev->dev,
+					     vgdev->host_visible_region.addr,
+					     vgdev->host_visible_region.len,
+					     dev_name(&vgdev->vdev->dev))) {
+			DRM_ERROR("Could not reserve host visible region\n");
+			goto err_vqs;
+		}
 
-	DRM_INFO("features: %cvirgl %cedid %cresource_blob\n",
+		DRM_INFO("Host memory window: 0x%lx +0x%lx\n",
+			 (unsigned long)vgdev->host_visible_region.addr,
+			 (unsigned long)vgdev->host_visible_region.len);
+		vgdev->has_host_visible = true;
+	}
+
+	DRM_INFO("features: %cvirgl %cedid %cresource_blob %chost_visible\n",
 		 vgdev->has_virgl_3d    ? '+' : '-',
 		 vgdev->has_edid        ? '+' : '-',
-		 vgdev->has_resource_blob ? '+' : '-');
+		 vgdev->has_resource_blob ? '+' : '-',
+		 vgdev->has_host_visible ? '+' : '-');
 
 	ret = virtio_find_vqs(vgdev->vdev, 2, vqs, callbacks, names, NULL);
 	if (ret) {