From 0437bad8f396041b513ceacc62dc7cd1cbc31df0 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 2 Jan 2020 13:17:07 +0000
Subject: drm/i915/gt: Always poison the kernel_context image before unparking
Git-commit: 1d0e2c9359fec6212af8c5fb29d5d56269f96968
Patch-mainline: v5.6-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

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@intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Imre Deak <imre.deak@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200102131707.1463945-5-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 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, &ce->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 709836edbed0..dde8e10c46d8 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -2507,7 +2507,7 @@ 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
@@ -2518,7 +2518,7 @@ 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);
-- 
2.28.0