Add a redzone to our context image and check the HW does not write into
after a context save, to verify that we have the correct context size.
(This does vary with feature bits, so test with a live setup that should
match how we run userspace.)
v2: Check the redzone on every context unpin
v3: Use a kernel context to prevent loading garbage for ringbuffer
submission
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_lrc.c | 34 +++++
drivers/gpu/drm/i915/gt/selftest_context.c | 141 +++++++++++++++++++++
2 files changed, 175 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
index 2978cf16fb9b..d2800dc7fa4f 100644
--- a/drivers/gpu/drm/i915/gt/intel_lrc.c
+++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
@@ -1617,8 +1617,38 @@ static void execlists_context_destroy(struct kref *kref)
intel_context_free(ce);
}
+static void
+set_redzone(void *vaddr, const struct intel_engine_cs *engine)
+{
+ if (!IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
+ return;
+
+ vaddr += LRC_HEADER_PAGES * PAGE_SIZE;
+ vaddr += engine->context_size;
+
+ memset(vaddr, POISON_INUSE, I915_GTT_PAGE_SIZE);
+}
+
+static void
+check_redzone(const void *vaddr, const struct intel_engine_cs *engine)
+{
+ if (!IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
+ return;
+
+ vaddr += LRC_HEADER_PAGES * PAGE_SIZE;
+ vaddr += engine->context_size;
+
+ if (memchr_inv(vaddr, POISON_INUSE, I915_GTT_PAGE_SIZE))
+ dev_err_once(engine->i915->drm.dev,
+ "%s context redzone overwritten!\n",
+ engine->name);
+}
+
static void execlists_context_unpin(struct intel_context *ce)
{
+ check_redzone((void *)ce->lrc_reg_state - LRC_STATE_PN * PAGE_SIZE,
+ ce->engine);
+
i915_gem_context_unpin_hw_id(ce->gem_context);
i915_gem_object_unpin_map(ce->state->obj);
intel_ring_reset(ce->ring, ce->ring->tail);
@@ -3157,6 +3187,8 @@ populate_lr_context(struct intel_context *ce,
return ret;
}
+ set_redzone(vaddr, engine);
+
if (engine->default_state) {
/*
* We only want to copy over the template context state;
@@ -3211,6 +3243,8 @@ static int __execlists_context_alloc(struct intel_context *ce,
* for our own use and for sharing with the GuC.
*/
context_size += LRC_HEADER_PAGES * PAGE_SIZE;
+ if (IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM))
+ context_size += I915_GTT_PAGE_SIZE; /* for redzone */
ctx_obj = i915_gem_object_create_shmem(engine->i915, context_size);
if (IS_ERR(ctx_obj))
diff --git a/drivers/gpu/drm/i915/gt/selftest_context.c b/drivers/gpu/drm/i915/gt/selftest_context.c
index 6fbc72bc290e..9d1ea26c7a2d 100644
--- a/drivers/gpu/drm/i915/gt/selftest_context.c
+++ b/drivers/gpu/drm/i915/gt/selftest_context.c
@@ -5,6 +5,7 @@
*/
#include "i915_selftest.h"
+#include "intel_engine_pm.h"
#include "intel_gt.h"
#include "gem/selftests/mock_context.h"
@@ -64,6 +65,145 @@ static int context_sync(struct intel_context *ce)
return err;
}
+static int __live_context_size(struct intel_engine_cs *engine,
+ struct i915_gem_context *fixme)
+{
+ struct intel_context *ce;
+ struct i915_request *rq;
+ void *vaddr;
+ int err;
+
+ ce = intel_context_create(fixme, engine);
+ if (IS_ERR(ce))
+ return PTR_ERR(ce);
+
+ err = intel_context_pin(ce);
+ if (err)
+ goto err;
+
+ vaddr = i915_gem_object_pin_map(ce->state->obj,
+ i915_coherent_map_type(engine->i915));
+ if (IS_ERR(vaddr)) {
+ err = PTR_ERR(vaddr);
+ intel_context_unpin(ce);
+ goto err;
+ }
+
+ /*
+ * Note that execlists also applies a redzone which it checks on
+ * context unpin when debugging. We are using the same location
+ * and same poison value so that our checks overlap. Despite the
+ * redundancy, we want to keep this little selftest so that we
+ * get coverage of any and all submission backends, and we can
+ * always extend this test to ensure we trick the HW into a
+ * compromising position wrt to the various sections that need
+ * to be written into the context state.
+ *
+ * TLDR; this overlaps with the execlists redzone.
+ */
+ if (HAS_EXECLISTS(engine->i915))
+ vaddr += LRC_HEADER_PAGES * PAGE_SIZE;
+
+ vaddr += engine->context_size - I915_GTT_PAGE_SIZE;
+ memset(vaddr, POISON_INUSE, I915_GTT_PAGE_SIZE);
+
+ rq = intel_context_create_request(ce);
+ intel_context_unpin(ce);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto err_unpin;
+ }
+
+ err = request_sync(rq);
+ if (err)
+ goto err_unpin;
+
+ /* Force the context switch */
+ rq = i915_request_create(engine->kernel_context);
+ if (IS_ERR(rq)) {
+ err = PTR_ERR(rq);
+ goto err_unpin;
+ }
+ err = request_sync(rq);
+ if (err)
+ goto err_unpin;
+
+ if (memchr_inv(vaddr, POISON_INUSE, I915_GTT_PAGE_SIZE)) {
+ pr_err("%s context overwrote trailing red-zone!", engine->name);
+ err = -EINVAL;
+ }
+
+err_unpin:
+ i915_gem_object_unpin_map(ce->state->obj);
+err:
+ intel_context_put(ce);
+ return err;
+}
+
+static int live_context_size(void *arg)
+{
+ struct intel_gt *gt = arg;
+ struct intel_engine_cs *engine;
+ struct i915_gem_context *fixme;
+ enum intel_engine_id id;
+ int err = 0;
+
+ /*
+ * Check that our context sizes are correct by seeing if the
+ * HW tries to write past the end of one.
+ */
+
+ mutex_lock(>->i915->drm.struct_mutex);
+
+ fixme = kernel_context(gt->i915);
+ if (IS_ERR(fixme)) {
+ err = PTR_ERR(fixme);
+ goto unlock;
+ }
+
+ for_each_engine(engine, gt->i915, id) {
+ struct {
+ struct drm_i915_gem_object *state;
+ void *pinned;
+ } saved;
+
+ if (!engine->context_size)
+ continue;
+
+ intel_engine_pm_get(engine);
+
+ /*
+ * Hide the old default state -- we lie about the context size
+ * and get confused when the default state is smaller than
+ * expected. For our do nothing request, inheriting the
+ * active state is sufficient, we are only checking that we
+ * don't use more than we planned.
+ */
+ saved.state = fetch_and_zero(&engine->default_state);
+ saved.pinned = fetch_and_zero(&engine->pinned_default_state);
+
+ /* Overlaps with the execlists redzone */
+ engine->context_size += I915_GTT_PAGE_SIZE;
+
+ err = __live_context_size(engine, fixme);
+
+ engine->context_size -= I915_GTT_PAGE_SIZE;
+
+ engine->pinned_default_state = saved.pinned;
+ engine->default_state = saved.state;
+
+ intel_engine_pm_put(engine);
+
+ if (err)
+ break;
+ }
+
+ kernel_context_close(fixme);
+unlock:
+ mutex_unlock(>->i915->drm.struct_mutex);
+ return err;
+}
+
static int __live_active_context(struct intel_engine_cs *engine,
struct i915_gem_context *fixme)
{
@@ -303,6 +443,7 @@ static int live_remote_context(void *arg)
int intel_context_live_selftests(struct drm_i915_private *i915)
{
static const struct i915_subtest tests[] = {
+ SUBTEST(live_context_size),
SUBTEST(live_active_context),
SUBTEST(live_remote_context),
};
--
2.23.0.rc1
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