Re: [igt-dev] [RFC 1/2] lib/xe_gpu: Introduce xe_gpu library

["Manszewski, Christoph" <christoph.manszewski@intel.com>]

Hi Anna,

On 20.04.2023 21:14, Anna Karas wrote:
> Add helpers for requiring the XE driver, reopening drm fd and restoring
> engine properties between tests.
> This lib is a direct port of gem.c from i915.
> 
> Reference: Jira VLK-46235
> Signed-off-by: Anna Karas <anna.karas@intel.com>
> ---
>   lib/meson.build |   1 +
>   lib/xe/xe_gpu.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++++
>   lib/xe/xe_gpu.h |  19 +++++++
>   3 files changed, 156 insertions(+)
>   create mode 100644 lib/xe/xe_gpu.c
>   create mode 100644 lib/xe/xe_gpu.h
> 
> diff --git a/lib/meson.build b/lib/meson.build
> index b21c252b..b33f8ae6 100644
> --- a/lib/meson.build
> +++ b/lib/meson.build
> @@ -100,6 +100,7 @@ lib_sources = [
>   	'igt_msm.c',
>   	'igt_dsc.c',
>   	'xe/xe_compute.c',
> +	'xe/xe_gpu.c',
>   	'xe/xe_compute_square_kernels.c',
>   	'xe/xe_ioctl.c',
>   	'xe/xe_query.c',
> diff --git a/lib/xe/xe_gpu.c b/lib/xe/xe_gpu.c
> new file mode 100644
> index 00000000..7abd8057
> --- /dev/null
> +++ b/lib/xe/xe_gpu.c
> @@ -0,0 +1,136 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2023 Intel Corporation
> + *
> + * Authors:
> + *    Anna Karas <anna.karas@intel.com>
> + */
> +
> +#include <dirent.h>
> +#include <fcntl.h>
> +#include <sys/ioctl.h>
> +
> +#include "xe/xe_gpu.h"
> +#include "igt_sysfs.h"
> +#include "igt.h"
> +
> +
> +/*
> + * Resets all engine properties to defaults prior to the start of a test.
> + */
> +static void __restore_defaults(int engine)
> +{
> +	struct dirent *de;
> +	int defaults;
> +	DIR *dir;
> +
> +	defaults = openat(engine, ".defaults", O_RDONLY);
> +	if (defaults < 0)
> +		return;
> +
> +	dir = fdopendir(defaults);
> +	if (!dir) {
> +		close(defaults);
> +		return;
> +	}
> +
> +	while ((de = readdir(dir))) {
> +		char buf[256];
> +		int fd, len;
> +
> +		if (*de->d_name == '.')
> +			continue;
> +
> +		fd = openat(defaults, de->d_name, O_RDONLY);
> +		if (fd < 0)
> +			continue;
> +
> +		len = read(fd, buf, sizeof(buf));
> +		close(fd);
> +		if (len < 0)
> +			continue;
> +
> +		fd = openat(engine, de->d_name, O_WRONLY);
> +		if (fd < 0)
> +			continue;
> +
> +		write(fd, buf, len);
> +		close(fd);
> +	}
> +
> +	closedir(dir);
> +}
> +
> +static void restore_defaults(int fd)
> +{
> +	struct dirent *de;
> +	int engines;
> +	DIR *dir;
> +	int sys;
> +
> +	sys = igt_sysfs_open(fd);
> +	if (sys < 0)
> +		return;
> +
> +	engines = openat(sys, "engine", O_RDONLY);
> +	if (engines < 0)
> +		goto close_sys;
> +
> +	dir = fdopendir(engines);
> +	if (!dir) {
> +		close(engines);
> +		goto close_sys;
> +	}
> +
> +	while ((de = readdir(dir))) {
> +		int engine;
> +
> +		if (*de->d_name == '.')
> +			continue;
> +
> +		engine = openat(engines, de->d_name, O_RDONLY);
> +		if (engine < 0)
> +			continue;
> +
> +		__restore_defaults(engine);
> +		close(engine);
> +	}
> +
> +	closedir(dir);
> +
> +close_sys:
> +	close(sys);
> +}

Looks like this duplicates 'restore_defaults' and '__restore_defaults' 
from lib/i915/gem.c. Maybe better just move the existing code higher up 
and reuse it?

Christoph


> +
> +/**
> + * xe_reopen_driver:
> + * @fd: re-open the xe drm file descriptor
> + *
> + * Re-opens the drm fd which is useful in instances where a clean default
> + * context is needed.
> + */
> +int xe_reopen_driver(int fd)
> +{
> +	char path[256];
> +
> +	snprintf(path, sizeof(path), "/proc/self/fd/%d", fd);
> +	fd = open(path, O_RDWR);
> +	igt_assert_fd(fd);
> +
> +	return fd;
> +}
> +
> +/**
> + * xe_require_gpu:
> + * @fd: the xe drm file descriptor
> + *
> + * Helper to be used prior to the start of a tests, useful in instances
> + * where a clean default context is needed.
> + */
> +void xe_require_gpu(int fd)
> +{
> +	igt_require_xe(fd);
> +	fd = xe_reopen_driver(fd);
> +	restore_defaults(fd);
> +	close(fd);
> +}
> diff --git a/lib/xe/xe_gpu.h b/lib/xe/xe_gpu.h
> new file mode 100644
> index 00000000..020040ac
> --- /dev/null
> +++ b/lib/xe/xe_gpu.h
> @@ -0,0 +1,19 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2023 Intel Corporation
> + *
> + * Authors:
> + *    Anna Karas <anna.karas@intel.com>
> + */
> +
> +#ifndef XE_GPU_H
> +#define XE_GPU_H
> +
> +#include <stdint.h>
> +#include <xe_drm.h>
> +
> +int xe_reopen_driver(int fd);
> +void xe_require_gpu(int fd);
> +
> +#endif	/* XE_GPU_H */
> +