drm/virtio: fix mmap page attributes

virtio-gpu uses cached mappings, set
drm_gem_shmem_object.map_cached accordingly.

Cc: [email protected]
Fixes: c66df70 ("drm/virtio: switch from ttm to gem shmem helpers")
Reported-by: Gurchetan Singh <[email protected]>
Reported-by: Guillaume Gardet <[email protected]>
Signed-off-by: Gerd Hoffmann <[email protected]>
Reviewed-by: Gurchetan Singh <[email protected]>
Tested-by: Guillaume Gardet <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: kraxel

drivers/gpu/drm/virtio/virtgpu_object.c

@@ -99,6 +99,7 @@ struct drm_gem_object *virtio_gpu_create_object(struct drm_device *dev,
 		return NULL;
 
 	bo->base.base.funcs = &virtio_gpu_gem_funcs;
+	bo->base.map_cached = true;
 	return &bo->base.base;
 }