[PATCH v2 20/38] drm/i915: Test coherency of and barriers between cache domains

[Chris Wilson <chris@chris-wilson.co.uk>]

Write into an object using WB, WC, GTT, and GPU paths and make sure that
our internal API is sufficient to ensure coherent reads and writes.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
---
 drivers/gpu/drm/i915/i915_gem.c                    |   1 +
 .../gpu/drm/i915/selftests/i915_gem_coherency.c    | 363 +++++++++++++++++++++
 .../gpu/drm/i915/selftests/i915_live_selftests.h   |   1 +
 3 files changed, 365 insertions(+)
 create mode 100644 drivers/gpu/drm/i915/selftests/i915_gem_coherency.c

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0772a4e0e3ef..2b6c0f9b02d0 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4944,4 +4944,5 @@ i915_gem_object_get_dma_address(struct drm_i915_gem_object *obj,
 #include "selftests/mock_gem_device.c"
 #include "selftests/huge_gem_object.c"
 #include "selftests/i915_gem_object.c"
+#include "selftests/i915_gem_coherency.c"
 #endif
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c b/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c
new file mode 100644
index 000000000000..0a5ef721c501
--- /dev/null
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_coherency.c
@@ -0,0 +1,363 @@
+/*
+ * Copyright © 2017 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ */
+
+#include <linux/prime_numbers.h>
+
+#include "i915_selftest.h"
+#include "i915_random.h"
+
+static int cpu_set(struct drm_i915_gem_object *obj,
+		   unsigned long offset,
+		   u32 v)
+{
+	unsigned int needs_clflush;
+	struct page *page;
+	typeof(v) *map;
+	int err;
+
+	err = i915_gem_obj_prepare_shmem_write(obj, &needs_clflush);
+	if (err)
+		return err;
+
+	page = i915_gem_object_get_page(obj, offset >> PAGE_SHIFT);
+	map = kmap_atomic(page);
+	if (needs_clflush & CLFLUSH_BEFORE)
+		clflush(map+offset_in_page(offset) / sizeof(*map));
+	map[offset_in_page(offset) / sizeof(*map)] = v;
+	if (needs_clflush & CLFLUSH_AFTER)
+		clflush(map+offset_in_page(offset) / sizeof(*map));
+	kunmap_atomic(map);
+
+	i915_gem_obj_finish_shmem_access(obj);
+	return 0;
+}
+
+static int cpu_get(struct drm_i915_gem_object *obj,
+		   unsigned long offset,
+		   u32 *v)
+{
+	unsigned int needs_clflush;
+	struct page *page;
+	typeof(v) map;
+	int err;
+
+	err = i915_gem_obj_prepare_shmem_read(obj, &needs_clflush);
+	if (err)
+		return err;
+
+	page = i915_gem_object_get_page(obj, offset >> PAGE_SHIFT);
+	map = kmap_atomic(page);
+	if (needs_clflush & CLFLUSH_BEFORE)
+		clflush(map+offset_in_page(offset) / sizeof(*map));
+	*v = map[offset_in_page(offset) / sizeof(*map)];
+	kunmap_atomic(map);
+
+	i915_gem_obj_finish_shmem_access(obj);
+	return 0;
+}
+
+static int gtt_set(struct drm_i915_gem_object *obj,
+		   unsigned long offset,
+		   u32 v)
+{
+	struct i915_vma *vma;
+	typeof(v) *map;
+	int err;
+
+	err = i915_gem_object_set_to_gtt_domain(obj, true);
+	if (err)
+		return err;
+
+	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, PIN_MAPPABLE);
+	if (IS_ERR(vma))
+		return PTR_ERR(vma);
+
+	map = i915_vma_pin_iomap(vma);
+	i915_vma_unpin(vma);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	map[offset / sizeof(*map)] = v;
+	i915_vma_unpin_iomap(vma);
+
+	return 0;
+}
+
+static int gtt_get(struct drm_i915_gem_object *obj,
+		   unsigned long offset,
+		   u32 *v)
+{
+	struct i915_vma *vma;
+	typeof(v) map;
+	int err;
+
+	err = i915_gem_object_set_to_gtt_domain(obj, false);
+	if (err)
+		return err;
+
+	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, PIN_MAPPABLE);
+	if (IS_ERR(vma))
+		return PTR_ERR(vma);
+
+	map = i915_vma_pin_iomap(vma);
+	i915_vma_unpin(vma);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	*v = map[offset / sizeof(*map)];
+	i915_vma_unpin_iomap(vma);
+
+	return 0;
+}
+
+static int wc_set(struct drm_i915_gem_object *obj,
+		  unsigned long offset,
+		  u32 v)
+{
+	typeof(v) *map;
+	int err;
+
+	/* XXX GTT write followed by WC write go missing */
+	i915_gem_object_flush_gtt_write_domain(obj);
+
+	err = i915_gem_object_set_to_gtt_domain(obj, true);
+	if (err)
+		return err;
+
+	map = i915_gem_object_pin_map(obj, I915_MAP_WC);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	map[offset / sizeof(*map)] = v;
+	i915_gem_object_unpin_map(obj);
+
+	return 0;
+}
+
+static int wc_get(struct drm_i915_gem_object *obj,
+		  unsigned long offset,
+		  u32 *v)
+{
+	typeof(v) map;
+	int err;
+
+	/* XXX WC write followed by GTT write go missing */
+	i915_gem_object_flush_gtt_write_domain(obj);
+
+	err = i915_gem_object_set_to_gtt_domain(obj, false);
+	if (err)
+		return err;
+
+	map = i915_gem_object_pin_map(obj, I915_MAP_WC);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	*v = map[offset / sizeof(*map)];
+	i915_gem_object_unpin_map(obj);
+
+	return 0;
+}
+
+static int gpu_set(struct drm_i915_gem_object *obj,
+		   unsigned long offset,
+		   u32 v)
+{
+	struct drm_i915_private *i915 = to_i915(obj->base.dev);
+	struct drm_i915_gem_request *rq;
+	struct i915_vma *vma;
+	int err;
+
+	err = i915_gem_object_set_to_gtt_domain(obj, true);
+	if (err)
+		return err;
+
+	vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, 0);
+	if (IS_ERR(vma))
+		return PTR_ERR(vma);
+
+	rq = i915_gem_request_alloc(i915->engine[RCS], i915->kernel_context);
+	if (IS_ERR(rq)) {
+		i915_vma_unpin(vma);
+		return PTR_ERR(rq);
+	}
+
+	err = intel_ring_begin(rq, 4);
+	if (err) {
+		__i915_add_request(rq, false);
+		i915_vma_unpin(vma);
+		return err;
+	}
+
+	if (INTEL_GEN(i915) >= 8) {
+		intel_ring_emit(rq->ring, MI_STORE_DWORD_IMM_GEN4 | 1 << 22);
+		intel_ring_emit(rq->ring, lower_32_bits(i915_ggtt_offset(vma) + offset));
+		intel_ring_emit(rq->ring, upper_32_bits(i915_ggtt_offset(vma) + offset));
+		intel_ring_emit(rq->ring, v);
+	} else if (INTEL_GEN(i915) >= 4) {
+		intel_ring_emit(rq->ring, MI_STORE_DWORD_IMM_GEN4 | 1 << 22);
+		intel_ring_emit(rq->ring, 0);
+		intel_ring_emit(rq->ring, i915_ggtt_offset(vma) + offset);
+		intel_ring_emit(rq->ring, v);
+	} else {
+		intel_ring_emit(rq->ring, MI_STORE_DWORD_IMM | 1 << 22);
+		intel_ring_emit(rq->ring, i915_ggtt_offset(vma) + offset);
+		intel_ring_emit(rq->ring, v);
+		intel_ring_emit(rq->ring, MI_NOOP);
+	}
+	intel_ring_advance(rq->ring);
+
+	i915_vma_move_to_active(vma, rq, EXEC_OBJECT_WRITE);
+	i915_vma_unpin(vma);
+
+	reservation_object_lock(obj->resv, NULL);
+	reservation_object_add_excl_fence(obj->resv, &rq->fence);
+	reservation_object_unlock(obj->resv);
+
+	__i915_add_request(rq, true);
+
+	return 0;
+}
+
+static const struct igt_coherency_mode {
+	const char *name;
+	int (*set)(struct drm_i915_gem_object *, unsigned long offset, u32 v);
+	int (*get)(struct drm_i915_gem_object *, unsigned long offset, u32 *v);
+} igt_coherency_mode[] = {
+	{ "cpu", cpu_set, cpu_get },
+	{ "gtt", gtt_set, gtt_get },
+	{ "wc", wc_set, wc_get },
+	{ "gpu", gpu_set, NULL },
+	{ },
+};
+
+static int igt_gem_coherency(void *arg)
+{
+	const unsigned int ncachelines = PAGE_SIZE/64;
+	I915_RND_STATE(prng);
+	struct drm_i915_private *i915 = arg;
+	const struct igt_coherency_mode *read, *write, *over;
+	struct drm_i915_gem_object *obj;
+	unsigned long count, n;
+	u32 *offsets, *values;
+	int err;
+
+	/* We repeatedly write, overwrite and read from a sequence of
+	 * cachelines in order to try and detect incoherency (unflushed writes
+	 * from either the CPU or GPU). Each setter/getter uses our cache
+	 * domain API which should prevent incoherency.
+	 */
+
+	offsets = kmalloc_array(ncachelines, 2*sizeof(u32), GFP_KERNEL);
+	if (!offsets)
+		return -ENOMEM;
+	for (count = 0; count < ncachelines; count++)
+		offsets[count] = count * 64 + 4 * (count % 16);
+
+	values = offsets + ncachelines;
+
+	mutex_lock(&i915->drm.struct_mutex);
+	for (over = igt_coherency_mode; over->name; over++) {
+		if (!over->set)
+			continue;
+
+		for (write = igt_coherency_mode; write->name; write++) {
+			if (!write->set)
+				continue;
+
+			for (read = igt_coherency_mode; read->name; read++) {
+				if (!read->get)
+					continue;
+
+				for_each_prime_number_from(count, 1, ncachelines) {
+					obj = i915_gem_object_create_internal(i915, PAGE_SIZE);
+					if (IS_ERR(obj)) {
+						err = PTR_ERR(obj);
+						goto unlock;
+					}
+
+					i915_random_reorder(offsets, ncachelines, &prng);
+					for (n = 0; n < count; n++)
+						values[n] = prandom_u32_state(&prng);
+
+					for (n = 0; n < count; n++) {
+						err = over->set(obj, offsets[n], ~values[n]);
+						if (err) {
+							pr_err("Failed to set stale value[%ld/%ld] in object using %s, err=%d\n",
+							       n, count, over->name, err);
+							goto unlock;
+						}
+					}
+
+					for (n = 0; n < count; n++) {
+						err = write->set(obj, offsets[n], values[n]);
+						if (err) {
+							pr_err("Failed to set value[%ld/%ld] in object using %s, err=%d\n",
+							       n, count, write->name, err);
+							goto unlock;
+						}
+					}
+
+					for (n = 0; n < count; n++) {
+						u32 found;
+
+						err = read->get(obj, offsets[n], &found);
+						if (err) {
+							pr_err("Failed to get value[%ld/%ld] in object using %s, err=%d\n",
+							       n, count, read->name, err);
+							goto unlock;
+						}
+
+						if (found != values[n]) {
+							pr_err("Value[%ld/%ld] mismatch, (overwrite with %s) wrote [%s] %x read [%s] %x (inverse %x), at offset %x\n",
+							       n, count, over->name,
+							       write->name, values[n],
+							       read->name, found,
+							       ~values[n], offsets[n]);
+							err = -EINVAL;
+							goto unlock;
+						}
+					}
+
+					__i915_gem_object_release_unless_active(obj);
+					obj = NULL;
+				}
+			}
+		}
+	}
+unlock:
+	if (obj)
+		__i915_gem_object_release_unless_active(obj);
+	mutex_unlock(&i915->drm.struct_mutex);
+	kfree(offsets);
+	return err;
+}
+
+int i915_gem_coherency_live_selftests(struct drm_i915_private *i915)
+{
+	static const struct i915_subtest tests[] = {
+		SUBTEST(igt_gem_coherency),
+	};
+
+	return i915_subtests(tests, i915);
+}
diff --git a/drivers/gpu/drm/i915/selftests/i915_live_selftests.h b/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
index 1822ac99d577..fde9ef22cfe8 100644
--- a/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
+++ b/drivers/gpu/drm/i915/selftests/i915_live_selftests.h
@@ -11,3 +11,4 @@
 selftest(sanitycheck, i915_live_sanitycheck) /* keep first (igt selfcheck) */
 selftest(requests, i915_gem_request_live_selftests)
 selftest(object, i915_gem_object_live_selftests)
+selftest(coherency, i915_gem_coherency_live_selftests)
-- 
2.11.0

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