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

[Anna Karas <anna.karas@intel.com>]

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);
+}
+
+/**
+ * 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 */
+
-- 
2.25.1

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