[PATCH] tests/intel/xe_debugfs: add GT-level debugfs coverage

Extend xe_debugfs with subtests exercising the GT-level debugfs
attributes exposed by the Xe driver.

Subtests:
 - gt-dir: presence and content check for unconditional GT attrs
 - gt-default-lrc: reads per-engine-class default LRC attrs; skips
   engine classes absent on the GT, fails if none are found
 - gt-dir-pf-only: presence and content check for PF-only attrs;
   skipped entirely on VF
 - gt-stats-write: writes an invalid key to stats and verifies the
   kernel rejects it with an error; confirms stats remains readable
   after the rejected write

Signed-off-by: Smitha Balasubramanyam <[email protected]>
---
 tests/intel/xe_debugfs.c | 150 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 147 insertions(+), 3 deletions(-)

diff --git a/tests/intel/xe_debugfs.c b/tests/intel/xe_debugfs.c
index da482157e..74c9d7b0b 100644
--- a/tests/intel/xe_debugfs.c
+++ b/tests/intel/xe_debugfs.c
@@ -9,6 +9,7 @@
 #include "igt.h"
 #include "igt_debugfs.h"
 #include "igt_dir.h"
+#include "igt_sriov_device.h"
 #include "igt_sysfs.h"
 #include "xe/xe_query.h"
 
@@ -16,6 +17,8 @@ struct {
 	bool warn_on_not_hit;
 } opt = { 0 };
 
+static int *gt_dirs;
+
 /**
  * TEST: Xe debugfs test
  * Description: Xe-specific debugfs tests. These are complementary to the
@@ -30,6 +33,20 @@ struct {
  *
  * SUBTEST: check-gt-reg-sr
  * Description: Check the reg_sr list associated with GTs for missing reg values
+ *
+ * SUBTEST: gt-dir
+ * Description: Check GT debugfs attrs present on all contexts for each GT.
+ *
+ * SUBTEST: gt-default-lrc
+ * Description: Validate default LRC content for each engine class present on
+ * each GT. Engine classes absent on the GT are skipped.
+ *
+ * SUBTEST: gt-dir-pf-only
+ * Description: Check that PF-only GT debugfs attrs are present for each GT on PF.
+ *
+ * SUBTEST: gt-stats-write
+ * Description: Write an invalid payload to the stats debugfs attribute for
+ * each GT to verify the kernel rejects malformed input with an error.
  */
 
 IGT_TEST_DESCRIPTION("Validate Xe debugfs devnodes and their contents");
@@ -166,10 +183,12 @@ static bool validate_string(int dirfd, const char *file_name, const char *expect
 		return false;
 	}
 
-	if (expected_str)
+	if (expected_str) {
 		igt_info("Successfully read %s: found '%s'\n", file_name, expected_str);
-	else
-		igt_info("Successfully read %s: %zd bytes\n%s\n", file_name, strlen(buf), buf);
+	} else {
+		igt_info("Successfully read %s: %zd bytes\n", file_name, strlen(buf));
+		igt_debug("%s\n", buf);
+	}
 
 	return true;
 }
@@ -595,6 +614,84 @@ static void check_gt_reg_sr(int fd, int gt)
 	igt_assert_eq(problems, 0);
 }
 
+static void test_gt_dir(struct xe_device *xe_dev, int gt)
+{
+	const struct check_entry expected_files[] = {
+		{ "register-save-restore", O_RDONLY, .validate = VALIDATE_NON_EMPTY },
+		{ "hwconfig",              O_RDONLY, .validate = VALIDATE_NON_EMPTY },
+		{ "stats",                 O_RDONLY, .validate = VALIDATE_NON_EMPTY },
+		{ "force_reset",           O_WRONLY },
+		{ "force_reset_sync",      O_WRONLY },
+	};
+	int missing_count = debugfs_validate_entries(xe_dev, gt_dirs[gt], expected_files,
+						     ARRAY_SIZE(expected_files));
+
+	igt_fail_on_f(missing_count > 0,
+		      "GT%d: %d GT debugfs attrs missing (see warnings above)\n",
+		      gt, missing_count);
+}
+
+static void test_gt_default_lrc(int gt)
+{
+	static const char * const lrc_attrs[] = {
+		"default_lrc_rcs",
+		"default_lrc_ccs",
+		"default_lrc_bcs",
+		"default_lrc_vcs",
+		"default_lrc_vecs",
+	};
+	int engines_present = 0;
+
+	for (size_t i = 0; i < ARRAY_SIZE(lrc_attrs); i++) {
+		if (!file_in_dir_exists(gt_dirs[gt], lrc_attrs[i], O_RDONLY)) {
+			igt_info("GT%d: %s absent\n", gt, lrc_attrs[i]);
+			continue;
+		}
+
+		engines_present++;
+		igt_assert_f(validate_debugfs_file(gt_dirs[gt], lrc_attrs[i],
+						   O_RDONLY, VALIDATE_NON_EMPTY, NULL),
+			     "GT%d: %s is empty or unreadable\n", gt, lrc_attrs[i]);
+	}
+
+	igt_assert_f(engines_present > 0,
+		     "GT%d: no default_lrc_* attrs found; expected at least one engine\n",
+		     gt);
+}
+
+static void test_gt_dir_pf_only(struct xe_device *xe_dev, int gt)
+{
+	const struct check_entry expected_files[] = {
+		{ "hw_engines", O_RDONLY, .validate = VALIDATE_NON_EMPTY },
+		{ "steering",   O_RDONLY, .validate = VALIDATE_NON_EMPTY },
+	};
+	int missing_count = debugfs_validate_entries(xe_dev, gt_dirs[gt], expected_files,
+						     ARRAY_SIZE(expected_files));
+
+	igt_fail_on_f(missing_count > 0,
+		      "GT%d: %d PF-only GT debugfs attrs missing (see warnings above)\n",
+		      gt, missing_count);
+}
+
+static void test_gt_stats_write(int gt)
+{
+	char buf[4096];
+	int len, wret;
+
+	len = igt_sysfs_read(gt_dirs[gt], "stats", buf, sizeof(buf) - 1);
+	igt_assert_f(len > 0,
+		     "GT%d: pre-write stats read failed or empty (%d)\n", gt, len);
+
+	wret = igt_sysfs_write(gt_dirs[gt], "stats", "invalid_key 0\n", strlen("invalid_key 0\n"));
+	igt_assert_f(wret < 0,
+		     "GT%d: stats write accepted invalid key (returned %d, expected error)\n",
+		     gt, wret);
+
+	len = igt_sysfs_read(gt_dirs[gt], "stats", buf, sizeof(buf) - 1);
+	igt_assert_f(len > 0,
+		     "GT%d: stats still readable after rejected write (%d)\n", gt, len);
+}
+
 const char *help_str =
 	"  --warn-not-hit|--w\tWarn about devfs nodes that have no tests";
 
@@ -620,13 +717,28 @@ int igt_main_args("", long_options, help_str, opt_handler, NULL)
 {
 	struct xe_device *xe_dev;
 	unsigned int t;
+	bool is_vf = false;
 	int fd = -1, gt;
+	int max_gt;
 
 	igt_fixture() {
 		fd = drm_open_driver_master(DRIVER_XE);
 		xe_dev = xe_device_get(fd);
 		igt_assert_f(xe_dev, "Failed to get xe device\n");
 		kmstest_set_vt_graphics_mode();
+		is_vf = intel_is_vf_device(fd);
+		max_gt = xe_dev_max_gt(fd);
+
+		gt_dirs = malloc((max_gt + 1) * sizeof(*gt_dirs));
+		igt_assert(gt_dirs);
+		for (int i = 0; i <= max_gt; i++)
+			gt_dirs[i] = -1;
+		xe_for_each_gt(fd, gt) {
+			gt_dirs[gt] = igt_debugfs_gt_dir(fd, gt);
+			igt_assert_f(gt_dirs[gt] >= 0,
+				     "GT%d: failed to open GT debugfs directory\n",
+				     gt);
+		}
 	}
 
 	igt_describe("Check required debugfs devnodes exist in the root debugfs directory.");
@@ -643,12 +755,44 @@ int igt_main_args("", long_options, help_str, opt_handler, NULL)
 	igt_subtest("info-read")
 		test_info_read(xe_dev);
 
+	igt_describe("Check GT debugfs attrs present on all contexts for each GT.");
+	igt_subtest_with_dynamic("gt-dir")
+		xe_for_each_gt(fd, gt)
+			igt_dynamic_f("gt-%d", gt)
+				test_gt_dir(xe_dev, gt);
+
+	igt_describe("Validate default LRC content for each engine class present on each GT.");
+	igt_subtest_with_dynamic("gt-default-lrc")
+		xe_for_each_gt(fd, gt)
+			igt_dynamic_f("gt-%d", gt)
+				test_gt_default_lrc(gt);
+
+	igt_describe("Check that PF-only GT debugfs attrs are present for each GT on PF.");
+	igt_subtest_with_dynamic("gt-dir-pf-only") {
+		igt_skip_on_f(is_vf, "PF-only attributes not present on VF\n");
+		xe_for_each_gt(fd, gt)
+			igt_dynamic_f("gt-%d", gt)
+				test_gt_dir_pf_only(xe_dev, gt);
+	}
+
+	igt_describe("Write an invalid payload to the stats debugfs attribute for each GT.");
+	igt_subtest_with_dynamic("gt-stats-write") {
+		igt_require(geteuid() == 0);
+		xe_for_each_gt(fd, gt)
+			igt_dynamic_f("gt-%d", gt)
+				test_gt_stats_write(gt);
+	}
+
 	igt_subtest_with_dynamic("check-gt-reg-sr")
 		xe_for_each_gt(fd, gt)
 			igt_dynamic_f("gt%d", gt)
 				check_gt_reg_sr(fd, gt);
 
 	igt_fixture() {
+		xe_for_each_gt(fd, gt)
+			if (gt_dirs[gt] >= 0)
+				close(gt_dirs[gt]);
+		free(gt_dirs);
 		drm_close_driver(fd);
 	}
 
-- 
2.43.0