tests: Add kms_mmap_write_crc for cache coherency tests

This program can be used to detect when CPU writes in the dma-buf mapped object
don't land in scanout due cache incoherency.

Although this seems a problem inherently of non-LCC machines ("Atom"), this
particular test catches a cache dirt on scanout on LLC machines as well. It's
inspired in Ville's kms_pwrite_crc.c and can be used also to test the
correctness of the driver's begin_cpu_access and end_cpu_access (which requires
i915 implementation.

To see the need for flush, one has to run using '-n' option to not call the
sync ioctls which, via a rather simple CPU hog the system will trashes the
caches, while the test will catch the coherency issue. If you now suppress
'-n', then things should just work like expected.

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

v2: use prime_handle_to_fd_for_mmap instead.
v3: merge end_cpu_access() patch with this and provide options to disable sync.
v4: use library's prime_sync_{start,end} instead.
v7: use CPU hog instead and use testing rounds to catch the sync problems.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>

tests/Makefile.sources

@@ -168,6 +168,7 @@ TESTS_progs = \
 	kms_3d \
 	kms_fence_pin_leak \
 	kms_force_connector_basic \
+	kms_mmap_write_crc \
 	kms_pwrite_crc \
 	kms_sink_crc_basic \
 	prime_udl \

tests/kms_mmap_write_crc.c

@@ -0,0 +1,313 @@
+/*
+ * 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 <tiago.vignatti at intel.com>
+ */
+
+#include <errno.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "drmtest.h"
+#include "igt_debugfs.h"
+#include "igt_kms.h"
+#include "intel_chipset.h"
+#include "ioctl_wrappers.h"
+#include "igt_aux.h"
+
+IGT_TEST_DESCRIPTION(
+   "Use the display CRC support to validate mmap write to an already uncached future scanout buffer.");
+
+#define ROUNDS 10
+
+typedef struct {
+	int drm_fd;
+	igt_display_t display;
+	struct igt_fb fb[2];
+	igt_output_t *output;
+	igt_plane_t *primary;
+	enum pipe pipe;
+	igt_crc_t ref_crc;
+	igt_pipe_crc_t *pipe_crc;
+	uint32_t devid;
+} data_t;
+
+static int ioctl_sync = true;
+int dma_buf_fd;
+
+static char *dmabuf_mmap_framebuffer(int drm_fd, struct igt_fb *fb)
+{
+	char *ptr = NULL;
+
+	dma_buf_fd = prime_handle_to_fd_for_mmap(drm_fd, fb->gem_handle);
+	igt_skip_on(dma_buf_fd == -1 && errno == EINVAL);
+
+	ptr = mmap(NULL, fb->size, PROT_READ | PROT_WRITE, MAP_SHARED, dma_buf_fd, 0);
+	igt_assert(ptr != MAP_FAILED);
+
+	return ptr;
+}
+
+static void test(data_t *data)
+{
+	igt_display_t *display = &data->display;
+	igt_output_t *output = data->output;
+	struct igt_fb *fb = &data->fb[1];
+	drmModeModeInfo *mode;
+	cairo_t *cr;
+	char *ptr;
+	uint32_t caching;
+	void *buf;
+	igt_crc_t crc;
+
+	mode = igt_output_get_mode(output);
+
+	/* create a non-white fb where we can write later */
+	igt_create_fb(data->drm_fd, mode->hdisplay, mode->vdisplay,
+		      DRM_FORMAT_XRGB8888, LOCAL_DRM_FORMAT_MOD_NONE, fb);
+
+	ptr = dmabuf_mmap_framebuffer(data->drm_fd, fb);
+
+	cr = igt_get_cairo_ctx(data->drm_fd, fb);
+	igt_paint_test_pattern(cr, fb->width, fb->height);
+	cairo_destroy(cr);
+
+	/* flip to it to make it UC/WC and fully flushed */
+	igt_plane_set_fb(data->primary, fb);
+	igt_display_commit(display);
+
+	/* flip back the original white buffer */
+	igt_plane_set_fb(data->primary, &data->fb[0]);
+	igt_display_commit(display);
+
+	/* make sure caching mode has become UC/WT */
+	caching = gem_get_caching(data->drm_fd, fb->gem_handle);
+	igt_assert(caching == I915_CACHING_NONE || caching == I915_CACHING_DISPLAY);
+
+	/*
+	 * firstly demonstrate the need for DMA_BUF_SYNC_START ("begin_cpu_access")
+	 */
+	if (ioctl_sync)
+		prime_sync_start(dma_buf_fd);
+
+	/* use dmabuf pointer to make the other fb all white too */
+	buf = malloc(fb->size);
+	igt_assert(buf != NULL);
+	memset(buf, 0xff, fb->size);
+	memcpy(ptr, buf, fb->size);
+	free(buf);
+
+	/* and flip to it */
+	igt_plane_set_fb(data->primary, fb);
+	igt_display_commit(display);
+
+	/* check that the crc is as expected, which requires that caches got flushed */
+	igt_pipe_crc_collect_crc(data->pipe_crc, &crc);
+	igt_assert_crc_equal(&crc, &data->ref_crc);
+
+	/*
+	 * now demonstrates the need for DMA_BUF_SYNC_END ("end_cpu_access")
+	 */
+
+	/* start over, writing non-white to the fb again and flip to it to make it
+	 * fully flushed */
+	cr = igt_get_cairo_ctx(data->drm_fd, fb);
+	igt_paint_test_pattern(cr, fb->width, fb->height);
+	cairo_destroy(cr);
+
+	igt_plane_set_fb(data->primary, fb);
+	igt_display_commit(display);
+
+	/* sync start, to move to CPU domain */
+	if (ioctl_sync)
+		prime_sync_start(dma_buf_fd);
+
+	/* use dmabuf pointer in the same fb to make it all white */
+	buf = malloc(fb->size);
+	igt_assert(buf != NULL);
+	memset(buf, 0xff, fb->size);
+	memcpy(ptr, buf, fb->size);
+	free(buf);
+
+	/* if we don't change to the GTT domain again, the whites won't get flushed
+	 * and therefore we demonstrates the need for sync end here */
+	if (ioctl_sync)
+		prime_sync_end(dma_buf_fd);
+
+	/* check that the crc is as expected, which requires that caches got flushed */
+	igt_pipe_crc_collect_crc(data->pipe_crc, &crc);
+	igt_assert_crc_equal(&crc, &data->ref_crc);
+}
+
+static bool prepare_crtc(data_t *data)
+{
+	igt_display_t *display = &data->display;
+	igt_output_t *output = data->output;
+	drmModeModeInfo *mode;
+
+	/* select the pipe we want to use */
+	igt_output_set_pipe(output, data->pipe);
+	igt_display_commit(display);
+
+	if (!output->valid) {
+		igt_output_set_pipe(output, PIPE_ANY);
+		igt_display_commit(display);
+		return false;
+	}
+
+	mode = igt_output_get_mode(output);
+
+	/* create a white reference fb and flip to it */
+	igt_create_color_fb(data->drm_fd, mode->hdisplay, mode->vdisplay,
+			    DRM_FORMAT_XRGB8888, LOCAL_DRM_FORMAT_MOD_NONE,
+			    1.0, 1.0, 1.0, &data->fb[0]);
+
+	data->primary = igt_output_get_plane(output, IGT_PLANE_PRIMARY);
+
+	igt_plane_set_fb(data->primary, &data->fb[0]);
+	igt_display_commit(display);
+
+	if (data->pipe_crc)
+		igt_pipe_crc_free(data->pipe_crc);
+
+	data->pipe_crc = igt_pipe_crc_new(data->pipe,
+					  INTEL_PIPE_CRC_SOURCE_AUTO);
+
+	/* get reference crc for the white fb */
+	igt_pipe_crc_collect_crc(data->pipe_crc, &data->ref_crc);
+
+	return true;
+}
+
+static void cleanup_crtc(data_t *data)
+{
+	igt_display_t *display = &data->display;
+	igt_output_t *output = data->output;
+
+	igt_pipe_crc_free(data->pipe_crc);
+	data->pipe_crc = NULL;
+
+	igt_plane_set_fb(data->primary, NULL);
+
+	igt_output_set_pipe(output, PIPE_ANY);
+	igt_display_commit(display);
+
+	igt_remove_fb(data->drm_fd, &data->fb[0]);
+	igt_remove_fb(data->drm_fd, &data->fb[1]);
+}
+
+static void run_test(data_t *data)
+{
+	igt_display_t *display = &data->display;
+	igt_output_t *output;
+	enum pipe pipe;
+
+	for_each_connected_output(display, output) {
+		data->output = output;
+		for_each_pipe(display, pipe) {
+			data->pipe = pipe;
+
+			if (!prepare_crtc(data))
+				continue;
+
+			test(data);
+			cleanup_crtc(data);
+
+			/* once is enough */
+			return;
+		}
+	}
+
+	igt_skip("no valid crtc/connector combinations found\n");
+}
+
+/**
+ * fork_cpuhog_helper:
+ *
+ * Fork a child process that loops indefinitely to consume CPU. This is used to
+ * fill the CPU caches with random information so they can get stalled,
+ * provoking incoherency with the GPU most likely.
+ */
+static void fork_cpuhog_helper(void) {
+
+	/* TODO: if the parent is about to die before its child, e.g.
+	 * igt_assert_crc_equal() fails, there will be a boring exit handler
+	 * waiting the child to exit also. A workaround is to simply disable that
+	 * handler, buy this needs to be fixed properly in an elegant way. */
+	igt_disable_exit_handler();
+
+	igt_fork(hog, 1) {
+		while (1) {
+			usleep(10); /* quite ramdom really. */
+
+			if ((int)getppid() == 1) /* Parent has died, so must we. */
+				exit(0);
+		}
+	}
+}
+
+static int opt_handler(int opt, int opt_index, void *data)
+{
+	if (opt == 'n') {
+		ioctl_sync = false;
+		igt_info("set via cmd line to not use sync ioctls\n");
+	}
+
+	return 0;
+}
+
+static data_t data;
+
+int main(int argc, char **argv)
+{
+	int i;
+	igt_simple_init_parse_opts(&argc, argv, "n", NULL, NULL, opt_handler, NULL);
+
+	igt_skip_on_simulation();
+
+	igt_fixture {
+		data.drm_fd = drm_open_driver_master(DRIVER_INTEL);
+
+		data.devid = intel_get_drm_devid(data.drm_fd);
+
+		kmstest_set_vt_graphics_mode();
+
+		igt_require_pipe_crc();
+
+		igt_display_init(&data.display, data.drm_fd);
+	}
+
+	igt_info("Using %d rounds for the test\n", ROUNDS);
+	fork_cpuhog_helper();
+
+	for (i = 0; i < ROUNDS; i++)
+		run_test(&data);
+
+	igt_fixture {
+		igt_display_fini(&data.display);
+	}
+
+	igt_exit();
+}