drm/etnaviv: reap idle mapping if it doesn't match the softpin address

drm/etnaviv: reap idle mapping if it doesn't match the softpin address

commit 332f847212e43d584019a8264895f25cf92aa647 upstream.

When a idle BO, which is held open by another process, gets freed by
userspace and subsequently referenced again by e.g. importing it again,
userspace may assign a different softpin VA than the last time around.
As the kernel GEM object still exists, we likely have a idle mapping
with the old VA still cached, if it hasn't been reaped in the meantime.

As the context matches, we then simply try to resurrect this mapping by
increasing the refcount. As the VA in this mapping does not match the
new softpin address, we consequently fail the otherwise valid submit.
Instead of failing, reap the idle mapping.

Cc: stable@vger.kernel.org # 5.19
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Guido Günther <agx@sigxcpu.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>