drm/i915: Perform GGTT restore much earlier during resume

As soon as we re-enable the various functions within the HW, they may go
off and read data via a GGTT offset. Hence, if we have not yet restored
the GGTT PTE before then, they may read and even *write* random locations
in memory.

Detected by DMAR faults during resume.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Martin Peres <martin.peres@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: stable@vger.kernel.org
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190909110011.8958-4-chris@chris-wilson.co.uk
(cherry picked from commit cec5ca08e3)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/i915/selftests/i915_gem.c

@@ -118,6 +118,12 @@ static void pm_resume(struct drm_i915_private *i915)
 	with_intel_runtime_pm(&i915->runtime_pm, wakeref) {
 		intel_gt_sanitize(&i915->gt, false);
 		i915_gem_sanitize(i915);
+
+		mutex_lock(&i915->drm.struct_mutex);
+		i915_gem_restore_gtt_mappings(i915);
+		i915_gem_restore_fences(i915);
+		mutex_unlock(&i915->drm.struct_mutex);
+
 		i915_gem_resume(i915);
 	}
 }