Re: [Intel-gfx] [PATCH 7/7] drm/i915/gt: Always poison the kernel_context image before unparking

2019-12-30 Thread Matthew Auld
On Sun, 29 Dec 2019 at 18:32, Chris Wilson  wrote:
>
> 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 
> Signed-off-by: Chris Wilson 
> Cc: Imre Deak 
Reviewed-by: Matthew Auld 
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[Intel-gfx] [PATCH 7/7] drm/i915/gt: Always poison the kernel_context image before unparking

2019-12-29 Thread Chris Wilson
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 
Signed-off-by: Chris Wilson 
Cc: Imre Deak 
---
 drivers/gpu/drm/i915/gt/intel_context_types.h |  2 ++
 drivers/gpu/drm/i915/gt/intel_engine_pm.c | 18 +-
 drivers/gpu/drm/i915/gt/intel_lrc.c   |  4 ++--
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h 
b/drivers/gpu/drm/i915/gt/intel_context_types.h
index 9527a659546c..ca1420fb8b53 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -17,6 +17,8 @@
 #include "intel_engine_types.h"
 #include "intel_sseu.h"
 
+#define CONTEXT_REDZONE POISON_INUSE
+
 struct i915_gem_context;
 struct i915_vma;
 struct intel_context;
diff --git a/drivers/gpu/drm/i915/gt/intel_engine_pm.c 
b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
index 1b9f73948f22..ea90ab3e396e 100644
--- a/drivers/gpu/drm/i915/gt/intel_engine_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_engine_pm.c
@@ -37,8 +37,24 @@ static int __engine_unpark(struct intel_wakeref *wf)
 
/* Discard stale context state from across idling */
ce = engine->kernel_context;
-   if (ce)
+   if (ce) {
+   GEM_BUG_ON(test_bit(CONTEXT_VALID_BIT, >flags));
+
+   /* First poison the image to verify we never fully trust it */
+   if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM) && ce->state) {
+   struct drm_i915_gem_object *obj = ce->state->obj;
+   int type = i915_coherent_map_type(engine->i915);
+
+   map = i915_gem_object_pin_map(obj, type);
+   if (!IS_ERR(map)) {
+   memset(map, CONTEXT_REDZONE, obj->base.size);
+   i915_gem_object_flush_map(obj);
+   i915_gem_object_unpin_map(obj);
+   }
+   }
+
ce->ops->reset(ce);
+   }
 
if (engine->unpark)
engine->unpark(engine);
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c 
b/drivers/gpu/drm/i915/gt/intel_lrc.c
index b1508dbd1063..b7c963cfad04 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -2399,7 +2399,7 @@ set_redzone(void *vaddr, const struct intel_engine_cs 
*engine)
 
vaddr += engine->context_size;
 
-   memset(vaddr, POISON_INUSE, I915_GTT_PAGE_SIZE);
+   memset(vaddr, CONTEXT_REDZONE, I915_GTT_PAGE_SIZE);
 }
 
 static void
@@ -2410,7 +2410,7 @@ check_redzone(const void *vaddr, const struct 
intel_engine_cs *engine)
 
vaddr += engine->context_size;
 
-   if (memchr_inv(vaddr, POISON_INUSE, I915_GTT_PAGE_SIZE))
+   if (memchr_inv(vaddr, CONTEXT_REDZONE, I915_GTT_PAGE_SIZE))
dev_err_once(engine->i915->drm.dev,
 "%s context redzone overwritten!\n",
 engine->name);
-- 
2.25.0.rc0

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