[igt-dev] [RFC, i-g-t, v2] tests/device_reset: Test device sysfs reset

[Marcin Bernatowicz]

Device reset is initiated by writing "1" to reset sysfs file,
which should initiate device FLR if supported by device.

Test scenarios:
1. unbind driver from device, initiate sysfs reset, rebind driver to
device
2. device reset with bound driver

v2: removed unbind-rebind (duplicates core_hotunplug at unbind-rebind)
    added healthcheck to each test (Janusz)

Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz at intel.com>
---
 tests/device_reset.c | 263 +++++++++++++++++++++++++++++++++++++++++++
 tests/meson.build    |   1 +
 2 files changed, 264 insertions(+)
 create mode 100644 tests/device_reset.c

diff --git a/tests/device_reset.c b/tests/device_reset.c
new file mode 100644
index 000000000..0e1e9e3aa
--- /dev/null
+++ b/tests/device_reset.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright(c) 2020 Intel Corporation. All rights reserved.
+ */
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include "igt.h"
+#include "igt_device_scan.h"
+#include "igt_sysfs.h"
+
+IGT_TEST_DESCRIPTION("Examine behavior of a driver on device sysfs reset");
+
+
+#define DEV_PATH_LEN 80
+#define DEV_BUS_ADDR_LEN 13 /* addr has form 0000:00:00.0 */
+
+/**
+ * Helper structure containing sysfs file descriptors
+ * and path related to tested device
+ */
+struct sysfs_fds {
+	struct {
+		int dev;
+		int dev_dir;
+		int drv_dir;
+	} fds;
+	char dev_bus_addr[DEV_BUS_ADDR_LEN];
+};
+
+static int __open_sysfs_dir(int fd, const char* path)
+{
+	int sysfs;
+
+	sysfs = igt_sysfs_open(fd);
+	if (sysfs < 0) {
+		return -1;
+	}
+
+	return openat(sysfs, path, O_DIRECTORY);
+}
+
+static int open_device_sysfs_dir(int fd)
+{
+	return __open_sysfs_dir(fd, "device");
+}
+
+static int open_driver_sysfs_dir(int fd)
+{
+	return __open_sysfs_dir(fd, "device/driver");
+}
+
+/**
+ * device_sysfs_path:
+ * @fd: opened device file descriptor
+ * @path: buffer to store sysfs path to device directory
+ *
+ * Returns:
+ * On successfull path resolution sysfs path to device directory,
+ * NULL otherwise
+ */
+static char *device_sysfs_path(int fd, char *path)
+{
+	char sysfs[DEV_PATH_LEN];
+
+	if (!igt_sysfs_path(fd, sysfs, sizeof(sysfs)))
+		return NULL;
+
+	if (DEV_PATH_LEN <= (strlen(sysfs) + strlen("/device")))
+		return NULL;
+
+	strcat(sysfs, "/device");
+
+	return realpath(sysfs, path);
+}
+
+static void init_sysfs_fds(struct sysfs_fds *sysfs)
+{
+	char dev_path[PATH_MAX];
+	char *addr_pos;
+
+	igt_debug("open device\n");
+	/**
+	 * As subtests must be able to close examined devices
+	 * completely, don't use drm_open_driver() as it keeps
+	 * a device file descriptor open for exit handler use.
+	 */
+	sysfs->fds.dev = __drm_open_driver(DRIVER_ANY);
+	igt_assert_fd(sysfs->fds.dev);
+
+	igt_assert(device_sysfs_path(sysfs->fds.dev, dev_path));
+	addr_pos = strrchr(dev_path, '/');
+	snprintf(sysfs->dev_bus_addr, sizeof(sysfs->dev_bus_addr),
+		 "%s", (addr_pos ? addr_pos + 1 : ""));
+	igt_assert(sysfs->dev_bus_addr[0]);
+
+	sysfs->fds.dev_dir = open_device_sysfs_dir(sysfs->fds.dev);
+	igt_assert_fd(sysfs->fds.dev_dir);
+
+	sysfs->fds.drv_dir = open_driver_sysfs_dir(sysfs->fds.dev);
+	igt_assert_fd(sysfs->fds.drv_dir);
+}
+
+static int close_if_opened(int *fd)
+{
+	int rc = 0;
+	if (fd && *fd != -1) {
+		rc = close(*fd);
+		*fd = -1;
+	}
+	return rc;
+}
+
+static void cleanup_sysfs_fds(struct sysfs_fds *sysfs)
+{
+	close_if_opened(&sysfs->fds.dev);
+	close_if_opened(&sysfs->fds.dev_dir);
+	close_if_opened(&sysfs->fds.drv_dir);
+	sysfs->dev_bus_addr[0] = '\0';
+}
+
+/**
+ * is_sysfs_reset_supported:
+ * @fd: opened device file descriptor
+ *
+ * Check if device supports reset based on sysfs file presence.
+ *
+ * Returns:
+ * True if device supports reset, false otherwise.
+ */
+static bool is_sysfs_reset_supported(int fd)
+{
+	struct stat st;
+	int rc;
+	int sysfs;
+	int reset_fd = -1;
+
+	sysfs = igt_sysfs_open(fd);
+
+	if (sysfs >= 0) {
+		reset_fd = openat(sysfs, "device/reset", O_WRONLY);
+		close(sysfs);
+	}
+
+	if (reset_fd < 0)
+		return false;
+
+	rc = fstat(reset_fd, &st);
+	close(reset_fd);
+
+	if (rc || !S_ISREG(st.st_mode))
+		return false;
+
+	return true;
+}
+
+/* Unbind the driver from the device */
+static void driver_unbind(struct sysfs_fds *sysfs)
+{
+	igt_debug("unbind the driver from the device\n");
+	igt_assert(igt_sysfs_set(sysfs->fds.drv_dir, "unbind",
+		   sysfs->dev_bus_addr));
+}
+
+/* Re-bind the driver to the device */
+static void driver_bind(struct sysfs_fds *sysfs)
+{
+	igt_debug("rebind the driver to the device\n");
+	igt_abort_on_f(!igt_sysfs_set(sysfs->fds.drv_dir, "bind",
+		       sysfs->dev_bus_addr), "driver rebind failed");
+}
+
+/* Initiate device reset */
+static void initiate_device_reset(struct sysfs_fds *sysfs)
+{
+	igt_debug("reset device\n");
+	igt_assert(igt_sysfs_set(sysfs->fds.dev_dir, "reset", "1"));
+}
+
+/**
+ * healthcheck:
+ * @sysfs: structure with device descriptor, if descriptor equals -1
+ * 	   the device is reopened
+ */
+static void healthcheck(struct sysfs_fds *sysfs)
+{
+	if (sysfs->fds.dev == -1) {
+		/* refresh device list */
+		igt_devices_scan(true);
+		igt_debug("reopen the device\n");
+		sysfs->fds.dev = __drm_open_driver(DRIVER_ANY);
+	}
+	igt_assert_fd(sysfs->fds.dev);
+
+	if (is_i915_device(sysfs->fds.dev))
+		gem_test_engine(sysfs->fds.dev, ALL_ENGINES);
+}
+
+/**
+ * set_device_filter:
+ *
+ * Sets device filter to ensure subtests always reopen the same device
+ *
+ * @dev_path: path to device under tests
+ */
+static void set_device_filter(const char* dev_path)
+{
+	char filter[strlen("sys:") + strlen(dev_path) + 1];
+
+	snprintf(filter, sizeof(filter), "sys:%s", dev_path);
+	igt_device_filter_free_all();
+	igt_assert_eq(igt_device_filter_add(filter), 1);
+}
+
+static void unbind_reset_rebind(struct sysfs_fds *sysfs)
+{
+	igt_debug("close the device\n");
+	close_if_opened(&sysfs->fds.dev);
+
+	driver_unbind(sysfs);
+
+	initiate_device_reset(sysfs);
+
+	driver_bind(sysfs);
+}
+
+igt_main
+{
+	struct sysfs_fds sysfs;
+
+	igt_fixture {
+		char dev_path[PATH_MAX];
+
+		igt_debug("opening device\n");
+		init_sysfs_fds(&sysfs);
+
+		/* Make sure subtests always reopen the same device */
+		igt_assert(device_sysfs_path(sysfs.fds.dev, dev_path));
+		set_device_filter(dev_path);
+
+		igt_skip_on(!is_sysfs_reset_supported(sysfs.fds.dev));
+
+		igt_set_timeout(60, "device reset tests timed out after 60s");
+	}
+
+	igt_describe("Unbinds driver from device, initiates reset"
+		     " then rebinds driver to device");
+	igt_subtest("unbind-reset-rebind") {
+		unbind_reset_rebind(&sysfs);
+		healthcheck(&sysfs);
+	}
+
+	igt_describe("Resets device with bound driver");
+	igt_subtest("reset-bound") {
+		initiate_device_reset(&sysfs);
+		healthcheck(&sysfs);
+	}
+
+	igt_fixture {
+		igt_reset_timeout();
+		cleanup_sysfs_fds(&sysfs);
+	}
+}
diff --git a/tests/meson.build b/tests/meson.build
index 28091794f..b0acdf7c0 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -8,6 +8,7 @@ test_progs = [
 	'core_setmaster_vs_auth',
 	'debugfs_test',
 	'dmabuf',
+	'device_reset',
 	'drm_import_export',
 	'drm_mm',
 	'drm_read',
-- 
2.25.1

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