[PATCH igt v7 6/6] tests: Add prime_mmap_coherency for cache coherency tests

[Tiago Vignatti <tiago.vignatti@intel.com>]

Different than kms_mmap_write_crc that captures the coherency issues within the
scanout mapped buffer, this one is meant for test dma-buf mmap on !llc
platforms mostly and provoke coherency bugs so we know where we need the sync
ioctls.

I tested this with !llc and llc platforms, BTY and IVY respectively.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
---
 tests/Makefile.sources       |   1 +
 tests/prime_mmap_coherency.c | 246 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 247 insertions(+)
 create mode 100644 tests/prime_mmap_coherency.c

diff --git a/tests/Makefile.sources b/tests/Makefile.sources
index ad2dd6a..78605c6 100644
--- a/tests/Makefile.sources
+++ b/tests/Makefile.sources
@@ -97,6 +97,7 @@ TESTS_progs_M = \
 	pm_rc6_residency \
 	pm_sseu \
 	prime_mmap \
+	prime_mmap_coherency \
 	prime_self_import \
 	template \
 	$(NULL)
diff --git a/tests/prime_mmap_coherency.c b/tests/prime_mmap_coherency.c
new file mode 100644
index 0000000..a9a2664
--- /dev/null
+++ b/tests/prime_mmap_coherency.c
@@ -0,0 +1,246 @@
+/*
+ * Copyright © 2015 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.
+ *
+ * Authors:
+ *    Tiago Vignatti
+ */
+
+/** @file prime_mmap_coherency.c
+ *
+ * TODO: need to show the need for prime_sync_end().
+ */
+
+#include "igt.h"
+
+IGT_TEST_DESCRIPTION("Test dma-buf mmap on !llc platforms mostly and provoke"
+		" coherency bugs so we know for sure where we need the sync ioctls.");
+
+#define ROUNDS 20
+
+int fd;
+int stale = 0;
+static drm_intel_bufmgr *bufmgr;
+struct intel_batchbuffer *batch;
+static int width = 1024, height = 1024;
+
+/*
+ * Exercises the need for read flush:
+ *   1. create a BO and write '0's, in GTT domain.
+ *   2. read BO using the dma-buf CPU mmap.
+ *   3. write '1's, in GTT domain.
+ *   4. read again through the mapped dma-buf.
+ */
+static void test_read_flush(bool expect_stale_cache)
+{
+	drm_intel_bo *bo_1;
+	drm_intel_bo *bo_2;
+	uint32_t *ptr_cpu;
+	uint32_t *ptr_gtt;
+	int dma_buf_fd, i;
+
+	if (expect_stale_cache)
+		igt_require(!gem_has_llc(fd));
+
+	bo_1 = drm_intel_bo_alloc(bufmgr, "BO 1", width * height * 4, 4096);
+
+	/* STEP #1: put the BO 1 in GTT domain. We use the blitter to copy and fill
+	 * zeros to BO 1, so commands will be submitted and likely to place BO 1 in
+	 * the GTT domain. */
+	bo_2 = drm_intel_bo_alloc(bufmgr, "BO 2", width * height * 4, 4096);
+	intel_copy_bo(batch, bo_1, bo_2, width * height);
+	gem_sync(fd, bo_1->handle);
+	drm_intel_bo_unreference(bo_2);
+
+	/* STEP #2: read BO 1 using the dma-buf CPU mmap. This dirties the CPU caches. */
+	dma_buf_fd = prime_handle_to_fd_for_mmap(fd, bo_1->handle);
+	igt_skip_on(errno == EINVAL);
+
+	ptr_cpu = mmap(NULL, width * height, PROT_READ | PROT_WRITE,
+		       MAP_SHARED, dma_buf_fd, 0);
+	igt_assert(ptr_cpu != MAP_FAILED);
+
+	for (i = 0; i < (width * height) / 4; i++)
+		igt_assert_eq(ptr_cpu[i], 0);
+
+	/* STEP #3: write 0x11 into BO 1. */
+	bo_2 = drm_intel_bo_alloc(bufmgr, "BO 2", width * height * 4, 4096);
+	ptr_gtt = gem_mmap__gtt(fd, bo_2->handle, width * height, PROT_READ | PROT_WRITE);
+	memset(ptr_gtt, 0x11, width * height);
+	munmap(ptr_gtt, width * height);
+
+	intel_copy_bo(batch, bo_1, bo_2, width * height);
+	gem_sync(fd, bo_1->handle);
+	drm_intel_bo_unreference(bo_2);
+
+	/* STEP #4: read again using the CPU mmap. Doing #1 before #3 makes sure we
+	 * don't do a full CPU cache flush in step #3 again. That makes sure all the
+	 * stale cachelines from step #2 survive (mostly, a few will be evicted)
+	 * until we try to read them again in step #4. This behavior could be fixed
+	 * by flush CPU read right before accessing the CPU pointer */
+	if (!expect_stale_cache)
+		prime_sync_start(dma_buf_fd);
+
+	for (i = 0; i < (width * height) / 4; i++)
+		if (ptr_cpu[i] != 0x11111111) {
+			igt_warn_on_f(!expect_stale_cache,
+				    "Found 0x%08x at offset 0x%08x\n", ptr_cpu[i], i);
+			stale++;
+		}
+
+	drm_intel_bo_unreference(bo_1);
+	munmap(ptr_cpu, width * height);
+}
+
+/*
+ * Exercises the need for write flush:
+ *   1. create BO 1 and write '0's, in GTT domain.
+ *   2. write '1's into BO 1 using the dma-buf CPU mmap.
+ *   3. copy BO 1 to new BO 2, in GTT domain.
+ *   4. read via dma-buf mmap BO 2.
+ */
+static void test_write_flush(bool expect_stale_cache)
+{
+	drm_intel_bo *bo_1;
+	drm_intel_bo *bo_2;
+	uint32_t *ptr_cpu;
+	uint32_t *ptr2_cpu;
+	int dma_buf_fd, dma_buf2_fd, i;
+
+	if (expect_stale_cache)
+		igt_require(!gem_has_llc(fd));
+
+	bo_1 = drm_intel_bo_alloc(bufmgr, "BO 1", width * height * 4, 4096);
+
+	/* STEP #1: Put the BO 1 in GTT domain. We use the blitter to copy and fill
+	 * zeros to BO 1, so commands will be submitted and likely to place BO 1 in
+	 * the GTT domain. */
+	bo_2 = drm_intel_bo_alloc(bufmgr, "BO 2", width * height * 4, 4096);
+	intel_copy_bo(batch, bo_1, bo_2, width * height);
+	gem_sync(fd, bo_1->handle);
+	drm_intel_bo_unreference(bo_2);
+
+	/* STEP #2: Write '1's into BO 1 using the dma-buf CPU mmap. */
+	dma_buf_fd = prime_handle_to_fd_for_mmap(fd, bo_1->handle);
+	igt_skip_on(errno == EINVAL);
+
+	ptr_cpu = mmap(NULL, width * height, PROT_READ | PROT_WRITE,
+		       MAP_SHARED, dma_buf_fd, 0);
+	igt_assert(ptr_cpu != MAP_FAILED);
+
+	/* This is the main point of this test: !llc hw requires a cache write
+	 * flush right here (explained in step #4). */
+	if (!expect_stale_cache)
+		prime_sync_start(dma_buf_fd);
+
+	memset(ptr_cpu, 0x11, width * height);
+
+	/* STEP #3: Copy BO 1 into BO 2, using blitter. */
+	bo_2 = drm_intel_bo_alloc(bufmgr, "BO 2", width * height * 4, 4096);
+	intel_copy_bo(batch, bo_2, bo_1, width * height);
+	gem_sync(fd, bo_2->handle);
+
+	/* STEP #4: compare BO 2 against written BO 1. In !llc hardware, there
+	 * should be some cache lines that didn't get flushed out and are still 0,
+	 * requiring cache flush before the write in step 2. */
+	dma_buf2_fd = prime_handle_to_fd_for_mmap(fd, bo_2->handle);
+	igt_skip_on(errno == EINVAL);
+
+	ptr2_cpu = mmap(NULL, width * height, PROT_READ | PROT_WRITE,
+		        MAP_SHARED, dma_buf2_fd, 0);
+	igt_assert(ptr2_cpu != MAP_FAILED);
+
+	for (i = 0; i < (width * height) / 4; i++)
+		if (ptr2_cpu[i] != 0x11111111) {
+			igt_warn_on_f(!expect_stale_cache,
+				      "Found 0x%08x at offset 0x%08x\n", ptr2_cpu[i], i);
+			stale++;
+		}
+
+	drm_intel_bo_unreference(bo_1);
+	drm_intel_bo_unreference(bo_2);
+	munmap(ptr_cpu, width * height);
+}
+
+int main(int argc, char **argv)
+{
+	int i;
+	bool expect_stale_cache;
+	igt_subtest_init(argc, argv);
+
+	igt_fixture {
+		fd = drm_open_driver(DRIVER_INTEL);
+
+		bufmgr = drm_intel_bufmgr_gem_init(fd, 4096);
+		batch = intel_batchbuffer_alloc(bufmgr, intel_get_drm_devid(fd));
+	}
+
+	/* Cache coherency and the eviction are pretty much unpredictable, so
+	 * reproducing boils down to trial and error to hit different scenarios.
+	 * TODO: We may want to improve tests a bit by picking random subranges. */
+	igt_info("%d rounds for each test\n", ROUNDS);
+	igt_subtest("read") {
+		stale = 0;
+		expect_stale_cache = false;
+		igt_info("exercising read flush\n");
+		for (i = 0; i < ROUNDS; i++)
+			test_read_flush(expect_stale_cache);
+		igt_fail_on_f(stale, "num of stale cache lines %d\n", stale);
+	}
+
+	/* Only for !llc platforms */
+	igt_subtest("read-and-fail") {
+		stale = 0;
+		expect_stale_cache = true;
+		igt_info("exercising read flush and expect to fail on !llc\n");
+		for (i = 0; i < ROUNDS; i++)
+			test_read_flush(expect_stale_cache);
+		igt_fail_on_f(!stale, "couldn't find any stale cache lines\n");
+	}
+
+	igt_subtest("write") {
+		stale = 0;
+		expect_stale_cache = false;
+		igt_info("exercising write flush\n");
+		for (i = 0; i < ROUNDS; i++)
+			test_write_flush(expect_stale_cache);
+		igt_fail_on_f(stale, "num of stale cache lines %d\n", stale);
+	}
+
+	/* Only for !llc platforms */
+	igt_subtest("write-and-fail") {
+		stale = 0;
+		expect_stale_cache = true;
+		igt_info("exercising write flush and expect to fail on !llc\n");
+		for (i = 0; i < ROUNDS; i++)
+			test_write_flush(expect_stale_cache);
+		igt_fail_on_f(!stale, "couldn't find any stale cache lines\n");
+	}
+
+	igt_fixture {
+		intel_batchbuffer_free(batch);
+		drm_intel_bufmgr_destroy(bufmgr);
+
+		close(fd);
+	}
+
+	igt_exit();
+}
-- 
2.1.4

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