[igt-dev] [PATCH i-g-t] tests/i915: Exercise coherency of mmapped frame buffers

Janusz Krzysztofik janusz.krzysztofik at linux.intel.com
Tue May 16 09:14:43 UTC 2023


Hi Kamil,

Thanks for review.

On Monday, 15 May 2023 22:02:51 CEST Kamil Konieczny wrote:
> Hi Janusz,
> 
> On 2023-05-15 at 10:50:20 +0200, Janusz Krzysztofik wrote:
> > Visible glitches have been observed when running graphics applications on
> > Linux under Xen hypervisor.  Those observations have been confirmed with
> > failures from kms_pwrite_crc IGT test that verifies data coherency of DRM
> > frame buffer objects using hardware CRC checksums calculated by display
> > controllers, exposed to userspace via debugfs.  Since not all applications
> > exhibit the issue, we need to exercise more methods than just pwrite in
> > order to identify all affected processing paths.
> > 
> > Create a new test focused on exercising coherency of future scanout
> > buffers populated over mmap.  Cover all available mmap methods and caching
> > modes expected to be device coherent.
> > 
> 
> +cc kms dev Bhanuprakash Modem

OK.

> 
> > Link: https://gitlab.freedesktop.org/drm/intel/-/issues/7648
> > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
> > ---
> >  tests/i915/kms_fb_coherency.c | 354 ++++++++++++++++++++++++++++++++++
> >  tests/meson.build             |   1 +
> >  2 files changed, 355 insertions(+)
> >  create mode 100644 tests/i915/kms_fb_coherency.c
> > 
> > diff --git a/tests/i915/kms_fb_coherency.c b/tests/i915/kms_fb_coherency.c
> > new file mode 100644
> > index 0000000000..9223f13b05
> > --- /dev/null
> > +++ b/tests/i915/kms_fb_coherency.c
> > @@ -0,0 +1,354 @@
> > +// SPDX-License-Identifier: MIT
> > +/*
> > + * Copyright © 2023 Intel Corporation
> > + *
> > + * Derived from tests/i915/kms_pwrite_crc.c
> > + * Copyright © 2014 Intel Corporation
> 
> imho you do not need above two lines, you already wrote this
> in description.

OK.

> 
> > + */
> > +
> > +/**
> > + * TEST: kms_fb_coherency
> > + * Description: Exercise coherency of future scanout buffer objects
> > + */
> > +
> > +#include "igt.h"
> 
> Put this after sys includes below.

Copy-pasted from kms_pwrite_crc.c.  I'll fix it.

> 
> > +#include <errno.h>
> > +#include <limits.h>
> > +#include <stdbool.h>
> > +#include <stdio.h>
> > +#include <string.h>
> > +
> 
> Here put any igt include(s).

Yes.

> 
> > +
> > +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 void prepare_crtc(data_t *data)
> > +{
> > +	igt_display_t *display = &data->display;
> > +	igt_output_t *output = data->output;
> > +	drmModeModeInfo *mode;
> > +
> > +	igt_display_reset(display);
> > +	/* select the pipe we want to use */
> > +	igt_output_set_pipe(output, data->pipe);
> > +
> > +	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, DRM_FORMAT_MOD_LINEAR,
> > +			    1.0, 1.0, 1.0, &data->fb[0]);
> > +
> > +	data->primary = igt_output_get_plane_type(output, DRM_PLANE_TYPE_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->drm_fd, data->pipe,
> > +					  IGT_PIPE_CRC_SOURCE_AUTO);
> > +
> > +	/* get reference crc for the white fb */
> > +	igt_pipe_crc_collect_crc(data->pipe_crc, &data->ref_crc);
> > +}
> > +
> > +static struct igt_fb *prepare_fb(data_t *data)
> > +{
> > +	igt_output_t *output = data->output;
> > +	struct igt_fb *fb = &data->fb[1];
> > +	drmModeModeInfo *mode;
> > +
> > +	prepare_crtc(data);
> > +
> > +	mode = igt_output_get_mode(output);
> > +
> > +	/* create a non-white fb we can overwrite later */
> > +	igt_create_pattern_fb(data->drm_fd, mode->hdisplay, mode->vdisplay,
> > +			      DRM_FORMAT_XRGB8888, DRM_FORMAT_MOD_LINEAR, fb);
> > +
> > +	/* flip to it to make it UC/WC and fully flushed */
> > +	drmModeSetPlane(data->drm_fd,
> > +			data->primary->drm_plane->plane_id,
> > +			output->config.crtc->crtc_id,
> > +			fb->fb_id, 0,
> > +			0, 0, fb->width, fb->height,
> > +			0, 0, fb->width << 16, fb->height << 16);
> > +
> > +	/* flip back the original white buffer */
> > +	drmModeSetPlane(data->drm_fd,
> > +			data->primary->drm_plane->plane_id,
> > +			output->config.crtc->crtc_id,
> > +			data->fb[0].fb_id, 0,
> > +			0, 0, fb->width, fb->height,
> > +			0, 0, fb->width << 16, fb->height << 16);
> > +
> > +	if (!gem_has_lmem(data->drm_fd)) {
> > +		uint32_t caching;
> > +
> > +		/* 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);
> > +	}
> > +
> > +	return fb;
> > +}
> > +
> > +static igt_crc_t get_buf_crc(data_t *data, void *buf, igt_fb_t *fb)
> > +{
> > +	igt_crc_t crc;
> > +
> > +	/* use memset to make the mmapped fb all white */
> > +	memset(buf, 0xff, fb->size);
> > +	munmap(buf, fb->size);
> > +
> > +	/* and flip to it */
> > +	drmModeSetPlane(data->drm_fd,
> > +			data->primary->drm_plane->plane_id,
> > +			data->output->config.crtc->crtc_id,
> > +			fb->fb_id, 0,
> > +			0, 0, fb->width, fb->height,
> > +			0, 0, fb->width << 16, fb->height << 16);
> > +
> > +	/* check that the crc is as expected, which requires that caches got flushed */
> ---------- ^
> Checks happen later, here you collect it.

Right.

> 
> > +	igt_pipe_crc_collect_crc(data->pipe_crc, &crc);
> 
> Add newline.

OK.

> 
> > +	return crc;
> > +}
> > +
> > +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]);
> > +
> 
> Remove empty line.

OK.

> 
> > +}
> > +
> > +static void test_mmap_gtt(data_t *data)
> > +{
> > +	igt_crc_t crc;
> > +	igt_fb_t *fb;
> > +	void *buf;
> > +
> > +	gem_require_mappable_ggtt(data->drm_fd);
> > +
> > +	fb = prepare_fb(data);
> > +
> > +	buf = gem_mmap__gtt(data->drm_fd, fb->gem_handle, fb->size, PROT_WRITE);
> > +
> > +	crc = get_buf_crc(data, buf, fb);
> > +	igt_assert_crc_equal(&crc, &data->ref_crc);
> > +}
> > +
> > +static void test_mmap_offset_wc(data_t *data)
> > +{
> > +	igt_crc_t crc;
> > +	igt_fb_t *fb;
> > +	void *buf;
> > +
> > +	igt_require(gem_mmap_offset__has_wc(data->drm_fd));
> > +
> > +	fb = prepare_fb(data);
> > +
> > +	buf = gem_mmap_offset__wc(data->drm_fd, fb->gem_handle, 0, fb->size, PROT_WRITE);
> > +
> > +	crc = get_buf_crc(data, buf, fb);
> > +	igt_assert_crc_equal(&crc, &data->ref_crc);
> > +}
> > +
> > +static void test_mmap_offset_wb(data_t *data)
> > +{
> > +	igt_crc_t crc;
> > +	igt_fb_t *fb;
> > +	void *buf;
> > +
> > +	igt_require(gem_has_mmap_offset(data->drm_fd));
> > +	igt_skip_on(gem_has_lmem(data->drm_fd));
> > +
> > +	fb = prepare_fb(data);
> > +
> > +	/* mmap the fb */
> > +	buf = gem_mmap_offset__cpu(data->drm_fd, fb->gem_handle, 0, fb->size, PROT_WRITE);
> > +
> > +	crc = get_buf_crc(data, buf, fb);
> > +	igt_fail_on(igt_check_crc_equal(&crc, &data->ref_crc));
> 
> Why not use igt_assert_crc_equal ?

Because I expected the opposite -- crc not equal with non-coherent caching 
modes in use.  But please note that this function and the similar  
test_legacy_mmap_cpu() below are actually not used and should be dropped.  
I used them on trybot to verify if it is possible to get consistent results  
across different platforms when using non-coherent caching modes and I found 
it's not -- some succeeded, some were failing.  Then, I decided to just drop 
non-coherent dynamic subtests, but forgot to drop the corresponding functions.

Thanks,
Janusz

> 
> > +}
> > +
> > +static void test_mmap_offset_uc(data_t *data)
> > +{
> > +	igt_crc_t crc;
> > +	igt_fb_t *fb;
> > +	void *buf;
> > +
> > +	igt_require(gem_has_mmap_offset(data->drm_fd));
> > +	igt_skip_on(gem_has_lmem(data->drm_fd));
> > +
> > +	fb = prepare_fb(data);
> > +
> > +	/* mmap the fb */
> > +	buf = __gem_mmap_offset(data->drm_fd, fb->gem_handle, 0, fb->size, PROT_WRITE,
> > +				I915_MMAP_OFFSET_UC);
> > +	igt_assert(buf);
> > +
> > +	crc = get_buf_crc(data, buf, fb);
> > +	igt_assert_crc_equal(&crc, &data->ref_crc);
> > +}
> > +
> > +static void test_mmap_offset_fixed(data_t *data)
> > +{
> > +	igt_crc_t crc;
> > +	igt_fb_t *fb;
> > +	void *buf;
> > +
> > +	igt_require(gem_has_lmem(data->drm_fd));
> > +
> > +	fb = prepare_fb(data);
> > +
> > +	/* mmap the fb */
> > +	buf = gem_mmap_offset__fixed(data->drm_fd, fb->gem_handle, 0, fb->size, PROT_WRITE);
> > +
> > +	crc = get_buf_crc(data, buf, fb);
> > +	igt_assert_crc_equal(&crc, &data->ref_crc);
> > +}
> > +
> > +static void test_legacy_mmap_wc(data_t *data)
> > +{
> > +	igt_crc_t crc;
> > +	igt_fb_t *fb;
> > +	void *buf;
> > +
> > +	igt_require(gem_has_legacy_mmap(data->drm_fd));
> > +	igt_require(gem_mmap__has_wc(data->drm_fd));
> > +
> > +	fb = prepare_fb(data);
> > +
> > +	/* mmap the fb */
> > +	buf = gem_mmap__wc(data->drm_fd, fb->gem_handle, 0, fb->size, PROT_WRITE);
> > +
> > +	crc = get_buf_crc(data, buf, fb);
> > +	igt_assert_crc_equal(&crc, &data->ref_crc);
> > +}
> > +
> > +static void test_legacy_mmap_cpu(data_t *data)
> > +{
> > +	igt_crc_t crc;
> > +	igt_fb_t *fb;
> > +	void *buf;
> > +
> > +	igt_require(gem_has_legacy_mmap(data->drm_fd));
> > +
> > +	fb = prepare_fb(data);
> > +
> > +	/* mmap the fb */
> > +	buf = gem_mmap__cpu(data->drm_fd, fb->gem_handle, 0, fb->size, PROT_WRITE);
> > +
> > +	crc = get_buf_crc(data, buf, fb);
> > +	igt_fail_on(igt_check_crc_equal(&crc, &data->ref_crc));
> 
> Same here, use igt_assert_crc_equal ?
> 
> Regards,
> Kamil
> 
> > +}
> > +
> > +static void select_valid_pipe_output_combo(data_t *data)
> > +{
> > +	igt_display_t *display = &data->display;
> > +
> > +	for_each_pipe_with_valid_output(display, data->pipe, data->output) {
> > +		igt_display_reset(display);
> > +
> > +		igt_output_set_pipe(data->output, data->pipe);
> > +		if (!i915_pipe_output_combo_valid(display))
> > +			continue;
> > +
> > +		/* one is enough */
> > +		return;
> > +	}
> > +
> > +	igt_skip("no valid crtc/connector combinations found\n");
> > +}
> > +
> > +igt_main
> > +{
> > +	data_t data;
> > +
> > +	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(data.drm_fd);
> > +
> > +		igt_display_require(&data.display, data.drm_fd);
> > +
> > +		select_valid_pipe_output_combo(&data);
> > +	}
> > +
> > +	/**
> > +	 * SUBTEST: memset-crc
> > +	 * Description: Use display controller CRC hardware to validate (non)coherency
> > +	 *		of memset operations on future scanout buffer objects
> > +	 *		mmapped with different mmap methods and different caching modes.
> > +	 */
> > +	igt_subtest_with_dynamic("memset-crc") {
> > +		if (gem_has_mappable_ggtt(data.drm_fd)) {
> > +			igt_dynamic("mmap-gtt")
> > +				test_mmap_gtt(&data);
> > +
> > +			cleanup_crtc(&data);
> > +		}
> > +
> > +		if (gem_mmap_offset__has_wc(data.drm_fd)) {
> > +			igt_dynamic("mmap-offset-wc")
> > +				test_mmap_offset_wc(&data);
> > +
> > +			cleanup_crtc(&data);
> > +		}
> > +
> > +		if (gem_has_mmap_offset(data.drm_fd)) {
> > +			if (gem_has_lmem(data.drm_fd)) {
> > +				igt_dynamic("mmap-offset-fixed")
> > +					test_mmap_offset_fixed(&data);
> > +
> > +				cleanup_crtc(&data);
> > +
> > +			} else {
> > +				igt_dynamic("mmap-offset-uc")
> > +					test_mmap_offset_uc(&data);
> > +
> > +				cleanup_crtc(&data);
> > +			}
> > +		}
> > +
> > +		if (gem_has_legacy_mmap(data.drm_fd) &&
> > +		    gem_mmap__has_wc(data.drm_fd)) {
> > +			igt_dynamic("mmap-legacy-wc")
> > +				test_legacy_mmap_wc(&data);
> > +
> > +			cleanup_crtc(&data);
> > +		}
> > +	}
> > +
> > +	igt_fixture {
> > +		igt_display_fini(&data.display);
> > +		close(data.drm_fd);
> > +	}
> > +}
> > diff --git a/tests/meson.build b/tests/meson.build
> > index c15eb3a08c..371b501992 100644
> > --- a/tests/meson.build
> > +++ b/tests/meson.build
> > @@ -224,6 +224,7 @@ i915_progs = [
> >  	'kms_ccs',
> >  	'kms_cdclk',
> >  	'kms_draw_crc',
> > +	'kms_fb_coherency',
> >  	'kms_fbcon_fbt',
> >  	'kms_fence_pin_leak',
> >  	'kms_flip_scaled_crc',
> 






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