drm/msm/gem: Add metadata

The EXT_external_objects extension is a bit awkward as it doesn't pass
explicit modifiers, leaving the importer to guess with incomplete
information.  In the case of vk (turnip) exporting and gl (freedreno)
importing, the "OPTIMAL_TILING_EXT" layout depends on VkImageCreateInfo
flags (among other things), which the importer does not know.  Which
unfortunately leaves us with the need for a metadata back-channel.

The contents of the metadata are defined by userspace.  The
EXT_external_objects extension is only required to work between
compatible versions of gl and vk drivers, as defined by device and
driver UUIDs.

v2: add missing metadata kfree
v3: Rework to move copy_from/to_user out from under gem obj lock
    to avoid angering lockdep about deadlocks against fs-reclaim

Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/566157/

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index db1e748daa75..32303cc8e646 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -1058,6 +1058,7 @@ static void msm_gem_free_object(struct drm_gem_object *obj)
 
 	drm_gem_object_release(obj);
 
+	kfree(msm_obj->metadata);
 	kfree(msm_obj);
 }