[PATCH] drm/i915/selftests: scrub 64K

[Matthew Auld <matthew.auld@intel.com>]

We write out all PTEs when operating in 64K mode, which is acceptable
given the assertion that the hw only cares about every 16th PTE and so
will ignore everything else.  However this may hide potential issues,
for example the hw could be sneakily operating in 4K mode and we would
be none the wiser, so make sure this doesn't escape us in the selftests.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Changbin Du <changbin.du@intel.com>
---
 drivers/gpu/drm/i915/i915_gem_gtt.c         | 20 ++++++++++++++++++++
 drivers/gpu/drm/i915/i915_gem_gtt.h         |  1 +
 drivers/gpu/drm/i915/selftests/huge_pages.c |  3 +++
 3 files changed, 24 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index c879bfd9294f..5deef6044944 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -1161,6 +1161,26 @@ static void gen8_ppgtt_insert_huge_entries(struct i915_vma *vma,
 			vaddr[idx.pde] |= GEN8_PDE_IPS_64K;
 			kunmap_atomic(vaddr);
 			page_size = I915_GTT_PAGE_SIZE_64K;
+
+			/*
+			 * For simplicity we choose to write out all PTEs when
+			 * operating in 64K mode, which is acceptable given the
+			 * assertion that the hw only cares about every 16th PTE
+			 * and so will ignore everything else.  However this may
+			 * hide potential issues, so make sure this doesn't
+			 * escape us in the selftests.
+			 */
+			if (I915_SELFTEST_ONLY(vma->vm->scrub_64K)) {
+				u16 i;
+
+				encode = pte_encode | vma->vm->scratch_page.daddr;
+				vaddr = kmap_atomic_px(pd->page_table[idx.pde]);
+
+				for (i = 1; i < index; i += 16)
+					memset64(vaddr + i, encode, 15);
+
+				kunmap_atomic(vaddr);
+			}
 		}
 
 		vma->page_sizes.gtt |= page_size;
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 1db0dedb4059..aec4f73574f4 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -342,6 +342,7 @@ struct i915_address_space {
 	void (*clear_pages)(struct i915_vma *vma);
 
 	I915_SELFTEST_DECLARE(struct fault_attr fault_attr);
+	I915_SELFTEST_DECLARE(bool scrub_64K);
 };
 
 #define i915_is_ggtt(V) (!(V)->file)
diff --git a/drivers/gpu/drm/i915/selftests/huge_pages.c b/drivers/gpu/drm/i915/selftests/huge_pages.c
index d7c8ef8e6764..91c72911be3c 100644
--- a/drivers/gpu/drm/i915/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/selftests/huge_pages.c
@@ -1757,6 +1757,9 @@ int i915_gem_huge_page_live_selftests(struct drm_i915_private *dev_priv)
 		goto out_unlock;
 	}
 
+	if (ctx->ppgtt)
+		ctx->ppgtt->base.scrub_64K = true;
+
 	err = i915_subtests(tests, ctx);
 
 out_unlock:
-- 
2.17.0

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