GVT is not propagating the PTE bits, and is always setting the
read-write bit, thus breaking read-only support.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.william.auld@gmail.com>
Reviewed-by: Jon Bloomfield <jon.bloomfield@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180712185315.3288-3-chris@chris-wilson.co.uk
(backported from commit c9e66688)
Signed-off-by: Jon Bloomfield <jon.bloomfield@intel.com>

CVE-2019-0155
Signed-off-by: Timo Aaltonen <timo.aaltonen@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>