Re: [PATCH i-g-t v4 02/41] lib/vkms: Add minimal VKMS library and test device default files

["José Expósito" <jose.exposito89@gmail.com>]

Hi Kamil,

On Wed, Aug 13, 2025 at 03:28:26PM +0200, Kamil Konieczny wrote:
> Hi José,
> On 2025-08-07 at 09:45:11 +0200, José Expósito wrote:
> > Create a library containing helpers for creating VKMS devices and
> > configuring them dynamically using configfs.
> > For the moment, add the minimal number of helpers to be able to start
> > testing VKMS's configfs support: Create device, destroy device and
> > destroy all devices.
> > 
> > Also, include the simplest possible test using those helpers (checking
> > the device's default files) and the scaffolding required to generate
> > the documentation.
> > 
> > Co-developed-by: Jim Shargo <jshargo@chromium.org>
> > Signed-off-by: Jim Shargo <jshargo@chromium.org>
> > Co-developed-by: Marius Vlad <marius.vlad@collabora.com>
> > Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
> > Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> > ---
> >  lib/igt_vkms.c             | 206 +++++++++++++++++++++++++++++++++++++
> >  lib/igt_vkms.h             |  27 +++++
> >  lib/meson.build            |   1 +
> >  meson.build                |   8 ++
> >  tests/meson.build          |   2 +
> >  tests/vkms/meson.build     |  13 +++
> >  tests/vkms/vkms_configfs.c | 131 +++++++++++++++++++++++
> 
> I checked changes as they are only minimal, imho you could keep
> Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
> 
> Also, you removed changes from testplan and docs building so
> for build/meson changes
> Reviewed-by: Kamil Konieczny <kamil.konieczny@linux.intel.com>
> 
> Btw checkpatch suggests even one more const 
> static const char * array should probably be static const char * const
> but you could fix that later.

Thanks a lot for your reviews. Almost all patches are reviewed now.
Let's see if the DRM series get merged soon and we can merge this
one as well :)

About the additional const, I noticed it, but then ARRAY_SIZE() would
trigger a warning about that extra const, so I decided to ignore
checkpatch and avoid unnecessary refactors.

Thanks,
Jose

> Regards,
> Kamil
> 
> >  7 files changed, 388 insertions(+)
> >  create mode 100644 lib/igt_vkms.c
> >  create mode 100644 lib/igt_vkms.h
> >  create mode 100644 tests/vkms/meson.build
> >  create mode 100644 tests/vkms/vkms_configfs.c
> > 
> > diff --git a/lib/igt_vkms.c b/lib/igt_vkms.c
> > new file mode 100644
> > index 000000000..03931d2e4
> > --- /dev/null
> > +++ b/lib/igt_vkms.c
> > @@ -0,0 +1,206 @@
> > +// SPDX-License-Identifier: MIT
> > +/*
> > + * Copyright © 2023 Google LLC.
> > + * Copyright © 2023 Collabora, Ltd.
> > + * Copyright © 2024-2025 Red Hat, Inc.
> > + */
> > +
> > +#include <dirent.h>
> > +#include <errno.h>
> > +#include <ftw.h>
> > +#include <limits.h>
> > +#include <string.h>
> > +#include <sys/stat.h>
> > +
> > +#include "igt.h"
> > +#include "igt_vkms.h"
> > +
> > +#define VKMS_ROOT_DIR_NAME		"vkms"
> > +
> > +/**
> > + * SECTION:igt_vkms
> > + * @short_description: Helpers to create and configure VKMS devices
> > + * @title: VKMS
> > + * @include: igt_vkms.h
> > + *
> > + * Helpers for creating VKMS devices and configuring them dynamically.
> > + *
> > + * First, create a VKMS device, next, add pipeline items (planes, CRTCs,
> > + * encoders, CRTCs and connectors) compose the pipeline by attaching each item
> > + * using the _attach_ functions and finally, enable the VKMS device.
> > + */
> > +
> > +static const char *mount_vkms_configfs(void)
> > +{
> > +	static char vkms_root_path[PATH_MAX];
> > +	const char *configfs_path;
> > +	int ret;
> > +
> > +	configfs_path = igt_configfs_mount();
> > +	igt_assert_f(configfs_path, "Error mounting configfs");
> > +
> > +	ret = snprintf(vkms_root_path, sizeof(vkms_root_path), "%s/%s",
> > +		       configfs_path, VKMS_ROOT_DIR_NAME);
> > +	igt_assert(ret >= 0 && ret < sizeof(vkms_root_path));
> > +
> > +	return vkms_root_path;
> > +}
> > +
> > +/**
> > + * igt_require_vkms_configfs:
> > + *
> > + * Require that VKMS supports configfs configuration.
> > + */
> > +void igt_require_vkms_configfs(void)
> > +{
> > +	const char *vkms_root_path;
> > +	DIR *dir;
> > +
> > +	vkms_root_path = mount_vkms_configfs();
> > +
> > +	dir = opendir(vkms_root_path);
> > +	igt_require(dir);
> > +	if (dir)
> > +		closedir(dir);
> > +}
> > +
> > +/**
> > + * igt_vkms_device_create:
> > + * @name: VKMS device name
> > + *
> > + * Create a directory in the ConfigFS VKMS root directory, where the entire
> > + * pipeline will be configured.
> > + */
> > +igt_vkms_t *igt_vkms_device_create(const char *name)
> > +{
> > +	igt_vkms_t *dev;
> > +	const char *vkms_root_path;
> > +	size_t path_len;
> > +	DIR *dir;
> > +	int ret;
> > +
> > +	dev = calloc(1, sizeof(*dev));
> > +
> > +	vkms_root_path = mount_vkms_configfs();
> > +
> > +	path_len = strlen(vkms_root_path) + strlen(name) + 2;
> > +	dev->path = malloc(path_len);
> > +	ret = snprintf(dev->path, path_len, "%s/%s", vkms_root_path, name);
> > +	igt_assert(ret >= 0 && ret < path_len);
> > +
> > +	dir = opendir(dev->path);
> > +	if (dir) {
> > +		igt_debug("Device at path %s already exists\n", dev->path);
> > +		closedir(dir);
> > +	} else {
> > +		ret = mkdir(dev->path, 0777);
> > +		if (ret != 0) {
> > +			free(dev->path);
> > +			free(dev);
> > +			dev = NULL;
> > +		}
> > +	}
> > +
> > +	return dev;
> > +}
> > +
> > +static int detach_pipeline_items(const char *path, const struct stat *info,
> > +				 const int typeflag, struct FTW *pathinfo)
> > +{
> > +	/*
> > +	 * Level 4 are the links in the possible_* directories:
> > +	 * vkms/<dev>/<pipeline items>/<pipeline item>/<possible_*>/<links>
> > +	 */
> > +	if (pathinfo->level == 4 && typeflag == FTW_SL) {
> > +		igt_debug("Detaching pipeline item %s\n", path);
> > +		return unlink(path);
> > +	}
> > +
> > +	/* Ignore the other files, they are removed by remove_pipeline_items */
> > +	return 0;
> > +}
> > +
> > +static int remove_pipeline_items(const char *path, const struct stat *info,
> > +				 const int typeflag, struct FTW *pathinfo)
> > +{
> > +	/* Level 0 is the device root directory: vkms/<dev> */
> > +	if (pathinfo->level == 0) {
> > +		igt_debug("Removing pipeline item %s\n", path);
> > +		return rmdir(path);
> > +	}
> > +
> > +	/*
> > +	 * Level 2 directories are the pipeline items:
> > +	 * vkms/<dev>/<pipeline items>/<pipeline item>
> > +	 */
> > +	if (pathinfo->level == 2 && typeflag == FTW_DP) {
> > +		igt_debug("Removing pipeline item %s\n", path);
> > +		return rmdir(path);
> > +	}
> > +
> > +	/* Ignore the other files, they are removed by VKMS */
> > +	return 0;
> > +}
> > +
> > +static int remove_device_dir(igt_vkms_t *dev)
> > +{
> > +	int ret;
> > +
> > +	ret = nftw(dev->path, detach_pipeline_items, 64, FTW_DEPTH | FTW_PHYS);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = nftw(dev->path, remove_pipeline_items, 64, FTW_DEPTH | FTW_PHYS);
> > +	return ret;
> > +}
> > +
> > +/**
> > + * igt_vkms_device_destroy:
> > + * @dev: Device to destroy
> > + *
> > + * Remove and free the VKMS device.
> > + */
> > +void igt_vkms_device_destroy(igt_vkms_t *dev)
> > +{
> > +	int ret;
> > +
> > +	igt_assert(dev);
> > +
> > +	ret = remove_device_dir(dev);
> > +	igt_assert_f(ret == 0,
> > +		     "Unable to rmdir device directory '%s'. Got errno=%d (%s)\n",
> > +		     dev->path, errno, strerror(errno));
> > +
> > +	free(dev->path);
> > +	free(dev);
> > +}
> > +
> > +/**
> > + * igt_vkms_destroy_all_devices:
> > + *
> > + * Remove all VKMS devices created via configfs.
> > + */
> > +void igt_vkms_destroy_all_devices(void)
> > +{
> > +	igt_vkms_t *dev;
> > +	const char *vkms_root_path;
> > +	DIR *dir;
> > +	struct dirent *ent;
> > +
> > +	vkms_root_path = mount_vkms_configfs();
> > +	dir = opendir(vkms_root_path);
> > +	igt_assert_f(dir, "VKMS configfs directory not available at '%s'. "
> > +		     "Got errno=%d (%s)\n", vkms_root_path, errno,
> > +		     strerror(errno));
> > +
> > +	while ((ent = readdir(dir)) != NULL) {
> > +		if (strcmp(ent->d_name, ".") == 0 ||
> > +		    strcmp(ent->d_name, "..") == 0)
> > +			continue;
> > +
> > +		dev = igt_vkms_device_create(ent->d_name);
> > +		igt_vkms_device_destroy(dev);
> > +	}
> > +
> > +	closedir(dir);
> > +}
> > diff --git a/lib/igt_vkms.h b/lib/igt_vkms.h
> > new file mode 100644
> > index 000000000..95d7a53cd
> > --- /dev/null
> > +++ b/lib/igt_vkms.h
> > @@ -0,0 +1,27 @@
> > +/* SPDX-License-Identifier: MIT */
> > +/*
> > + * Copyright © 2023 Google LLC.
> > + * Copyright © 2023 Collabora, Ltd.
> > + * Copyright © 2024-2025 Red Hat, Inc.
> > + */
> > +
> > +#ifndef __IGT_VKMS_H__
> > +#define __IGT_VKMS_H__
> > +
> > +/**
> > + * igt_vkms_t:
> > + * @path: VKMS root directory inside configfs mounted directory
> > + *
> > + * A struct representing a VKMS device.
> > + */
> > +typedef struct igt_vkms {
> > +	char *path;
> > +} igt_vkms_t;
> > +
> > +void igt_require_vkms_configfs(void);
> > +
> > +igt_vkms_t *igt_vkms_device_create(const char *name);
> > +void igt_vkms_device_destroy(igt_vkms_t *dev);
> > +void igt_vkms_destroy_all_devices(void);
> > +
> > +#endif /* __IGT_VKMS_H__ */
> > diff --git a/lib/meson.build b/lib/meson.build
> > index 2eaca42a4..62ba7f262 100644
> > --- a/lib/meson.build
> > +++ b/lib/meson.build
> > @@ -50,6 +50,7 @@ lib_sources = [
> >  	'igt_types.c',
> >  	'igt_vec.c',
> >  	'igt_vgem.c',
> > +	'igt_vkms.c',
> >  	'igt_x86.c',
> >  	'instdone.c',
> >  	'intel_allocator.c',
> > diff --git a/meson.build b/meson.build
> > index aeed3b1d2..f7ae427b3 100644
> > --- a/meson.build
> > +++ b/meson.build
> > @@ -290,6 +290,7 @@ msmdir = join_paths(libexecdir, 'msm')
> >  panfrostdir = join_paths(libexecdir, 'panfrost')
> >  v3ddir = join_paths(libexecdir, 'v3d')
> >  vc4dir = join_paths(libexecdir, 'vc4')
> > +vkmsdir = join_paths(libexecdir, 'vkms')
> >  vmwgfxdir = join_paths(libexecdir, 'vmwgfx')
> >  mandir = get_option('mandir')
> >  pkgconfigdir = join_paths(libdir, 'pkgconfig')
> > @@ -352,6 +353,12 @@ if get_option('use_rpath')
> >  	endforeach
> >  	vc4_rpathdir = join_paths(vc4_rpathdir, libdir)
> >  
> > +	vkms_rpathdir = '$ORIGIN'
> > +	foreach p : vkmsdir.split('/')
> > +		vkms_rpathdir = join_paths(vkms_rpathdir, '..')
> > +	endforeach
> > +	vkms_rpathdir = join_paths(vkms_rpathdir, libdir)
> > +
> >  	vmwgfx_rpathdir = '$ORIGIN'
> >  	foreach p : vmwgfxdir.split('/')
> >  		vmwgfx_rpathdir = join_paths(vmwgfx_rpathdir, '..')
> > @@ -365,6 +372,7 @@ else
> >  	panfrost_rpathdir = ''
> >  	v3d_rpathdir = ''
> >  	vc4_rpathdir = ''
> > +	vkms_rpathdir = ''
> >  	vmwgfx_rpathdir = ''
> >  endif
> >  
> > diff --git a/tests/meson.build b/tests/meson.build
> > index 5c01c64e9..a7b9375ed 100644
> > --- a/tests/meson.build
> > +++ b/tests/meson.build
> > @@ -490,6 +490,8 @@ subdir('v3d')
> >  
> >  subdir('vc4')
> >  
> > +subdir('vkms')
> > +
> >  subdir('vmwgfx')
> >  
> >  gen_testlist = find_program('generate_testlist.sh')
> > diff --git a/tests/vkms/meson.build b/tests/vkms/meson.build
> > new file mode 100644
> > index 000000000..e55ba32ba
> > --- /dev/null
> > +++ b/tests/vkms/meson.build
> > @@ -0,0 +1,13 @@
> > +vkms_progs = [
> > +	'vkms_configfs',
> > +]
> > +vkms_deps = test_deps
> > +
> > +foreach prog : vkms_progs
> > +	test_executables += executable(prog, prog + '.c',
> > +				       dependencies : vkms_deps,
> > +				       install_dir : vkmsdir,
> > +				       install_rpath : vkms_rpathdir,
> > +				       install : true)
> > +	test_list += join_paths('vkms', prog)
> > +endforeach
> > diff --git a/tests/vkms/vkms_configfs.c b/tests/vkms/vkms_configfs.c
> > new file mode 100644
> > index 000000000..f659a7a22
> > --- /dev/null
> > +++ b/tests/vkms/vkms_configfs.c
> > @@ -0,0 +1,131 @@
> > +// SPDX-License-Identifier: MIT
> > +/*
> > + * Copyright © 2023 Google LLC.
> > + * Copyright © 2023 Collabora, Ltd.
> > + * Copyright © 2024-2025 Red Hat, Inc.
> > + */
> > +
> > +/**
> > + * TEST: Tests for VKMS configfs support.
> > + * Category: Display
> > + * Mega feature: General Display Features
> > + * Sub-category: uapi
> > + * Functionality: vkms,configfs
> > + * Test category: functionality test
> > + */
> > +
> > +#include <dirent.h>
> > +#include <limits.h>
> > +#include <string.h>
> > +#include <sys/stat.h>
> > +
> > +#include "drmtest.h"
> > +#include "igt.h"
> > +#include "igt_vkms.h"
> > +
> > +static void assert_default_files(const char *path,
> > +				 const char **files, size_t n_files,
> > +				 const char **dirs, size_t n_dirs)
> > +{
> > +	DIR *dir;
> > +	struct dirent *ent;
> > +	int total = 0;
> > +	int ret;
> > +
> > +	/* Check that the number of files/directories matches the expected */
> > +	dir = opendir(path);
> > +	igt_assert(dir);
> > +	while ((ent = readdir(dir)) != NULL) {
> > +		if (strcmp(ent->d_name, ".") == 0 ||
> > +		    strcmp(ent->d_name, "..") == 0)
> > +			continue;
> > +
> > +		total++;
> > +	}
> > +	igt_assert_eq(total, n_dirs + n_files);
> > +	closedir(dir);
> > +
> > +	/* Check that the files/directories are present */
> > +	for (int i = 0; i < n_files; i++) {
> > +		char file_path[PATH_MAX];
> > +		struct stat buf;
> > +
> > +		ret = snprintf(file_path, sizeof(file_path), "%s/%s", path,
> > +			       files[i]);
> > +		igt_assert(ret >= 0 && ret < sizeof(file_path));
> > +
> > +		igt_assert_f(stat(file_path, &buf) == 0,
> > +			     "File %s does not exists\n", file_path);
> > +	}
> > +
> > +	for (int i = 0; i < n_dirs; i++) {
> > +		char dir_path[PATH_MAX];
> > +
> > +		ret = snprintf(dir_path, sizeof(dir_path), "%s/%s", path,
> > +			       dirs[i]);
> > +		igt_assert(ret >= 0 && ret < sizeof(dir_path));
> > +
> > +		dir = opendir(dir_path);
> > +		igt_assert_f(dir, "Directory %s does not exists\n", dir_path);
> > +		closedir(dir);
> > +	}
> > +}
> > +
> > +/**
> > + * SUBTEST: device-default-files
> > + * Description: Test that creating a VKMS device creates the default files and
> > + *              directories.
> > + */
> > +
> > +static void test_device_default_files(void)
> > +{
> > +	igt_vkms_t *dev;
> > +
> > +	static const char *files[] = {
> > +		"enabled",
> > +	};
> > +
> > +	static const char *dirs[] = {
> > +		"planes",
> > +		"crtcs",
> > +		"encoders",
> > +		"connectors",
> > +	};
> > +
> > +	dev = igt_vkms_device_create(__func__);
> > +	igt_assert(dev);
> > +
> > +	assert_default_files(dev->path,
> > +			     files, ARRAY_SIZE(files),
> > +			     dirs, ARRAY_SIZE(dirs));
> > +
> > +	igt_vkms_device_destroy(dev);
> > +}
> > +
> > +igt_main
> > +{
> > +	struct {
> > +		const char *name;
> > +		void (*fn)(void);
> > +	} tests[] = {
> > +		{ "device-default-files", test_device_default_files },
> > +	};
> > +
> > +	igt_fixture {
> > +		drm_load_module(DRIVER_VKMS);
> > +		igt_require_vkms();
> > +		igt_require_vkms_configfs();
> > +		igt_vkms_destroy_all_devices();
> > +	}
> > +
> > +	for (int i = 0; i < ARRAY_SIZE(tests); i++) {
> > +		igt_subtest(tests[i].name)
> > +			tests[i].fn();
> > +	}
> > +
> > +	igt_fixture {
> > +		igt_require_vkms();
> > +		igt_require_vkms_configfs();
> > +		igt_vkms_destroy_all_devices();
> > +	}
> > +}
> > -- 
> > 2.50.1
> >