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

[Karas, Anna]

Hi Christoph,

On 15.05.2023 11:51, Manszewski, Christoph wrote:
> 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 at 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 at 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?
> 
> ChristophYou're right, I did something similar with gem_reopen_driver.

During the review process (no record on ML, unfortunately. See more: 
VLK-47609, VLK-46133) it turned out that there is no need for resetting 
the defaults anyway.

Anna

> 
> 
>> +
>> +/**
>> + * 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 at 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 */
>> +