Keep scrubbing the kernel_context image with poison before we reset it
in order to demonstrate that we will be resilient in the case where it
is accidentally overwritten on idle.
Suggested-by: Imre Deak <imre.deak@xxxxxxxxx>
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_engine_pm.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
index b9444ce29a3a..86970bbff8bb 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
@@ -35,6 +35,20 @@ static int __engine_unpark(struct intel_wakeref *wf)
if (!IS_ERR_OR_NULL(map))
engine->pinned_default_state = map;
+ /* Poison the kernel_context image to verify we never fully trust it */
+ if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM) &&
+ engine->kernel_context->state) {
+ struct drm_i915_gem_object *obj =
+ engine->kernel_context->state->obj;
+
+ map = i915_gem_object_pin_map(obj, i915_coherent_map_type(engine->i915));
+ if (!IS_ERR(map)) {
+ memset(map, POISON_INUSE, obj->base.size);
+ i915_gem_object_flush_map(obj);
+ i915_gem_object_unpin_map(obj);
+ }
+ }
+
/* Discard stale context state from across idling */
ce = engine->kernel_context;
if (ce)
--
2.24.1
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