[Intel-gfx] [PATCH] drm/i915: Guard against i915_ggtt_disable_guc() being invoked unconditionally

[Joonas Lahtinen]

On ke, 2017-05-31 at 20:05 +0100, Chris Wilson wrote:
> Commit 7c3f86b6dc51 ("drm/i915: Invalidate the guc ggtt TLB upon
> insertion") added the restoration of the invalidation routine after the
> GuC was disabled, but missed that the GuC was unconditionally disabled
> when not used. This then overwrites the invalidate routine for the older
> chipsets, causing havoc and breaking resume as the most obvious victim.
> 
> We place the guard inside i915_ggtt_disable_guc() to be backport
> friendly (the bug was introduced into v4.11) but it would be preferred
> to be in more control over when this was guard (i.e. do not try and
> teardown the data structures before we have enabled them). That should
> be true with the reorganisation of the guc loaders.
> 
> Reported-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Fixes: 7c3f86b6dc51 ("drm/i915: Invalidate the guc ggtt TLB upon insertion")
> Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Oscar Mateo <oscar.mateo at intel.com>
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Arkadiusz Hiler <arkadiusz.hiler at intel.com>
> Cc: <stable at vger.kernel.org> # v4.11+

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation