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Commit 34db79ae authored by David Riley's avatar David Riley Committed by Greg Kroah-Hartman
Browse files

drm/virtio: Add memory barriers for capset cache. 



[ Upstream commit 9ff3a5c88e1f1ab17a31402b96d45abe14aab9d7 ]

After data is copied to the cache entry, atomic_set is used indicate
that the data is the entry is valid without appropriate memory barriers.
Similarly the read side was missing the corresponding memory barriers.

Signed-off-by: default avatarDavid Riley <davidriley@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20190610211810.253227-5-davidriley@chromium.org


Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent bd36de4d

drivers/gpu/drm/virtio/virtgpu_ioctl.c

+3 −0
Original line number Diff line number Diff line
@@ -521,6 +521,9 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev, 
	ret = wait_event_timeout(vgdev->resp_wq,

				 atomic_read(&cache_ent->is_valid), 5 * HZ);



	/* is_valid check must proceed before copy of the cache entry. */

	smp_rmb();



	ptr = cache_ent->caps_cache;



copy_exit:

drivers/gpu/drm/virtio/virtgpu_vq.c

+2 −0
Original line number Diff line number Diff line
@@ -618,6 +618,8 @@ static void virtio_gpu_cmd_capset_cb(struct virtio_gpu_device *vgdev, 
		    cache_ent->id == le32_to_cpu(cmd->capset_id)) {

			memcpy(cache_ent->caps_cache, resp->capset_data,

			       cache_ent->size);

			/* Copy must occur before is_valid is signalled. */

			smp_wmb();

			atomic_set(&cache_ent->is_valid, 1);

			break;

		}