[PATCH i-g-t v3] Do not require QUERY_OA_UNITS for all Xe tests

[Peter Senna Tschudin <peter.senna@linux.intel.com>]

Changes xe_query_oa_units_new() to return NULL instead of aborting
due to assertion failure when querying for DRM_XE_DEVICE_QUERY_OA_UNITS.

It adds a skip to xe_oa.c to make sure it will not try to run the tests if the
query has failed before.

The motivation is as follows:
 - The only test that requires oa_units is tests/intel/xe_oa.c, however current
   code will prevent all Xe tests from running if OA_UNITS is not supported
 - Before this patch, trying to run IGT on the Xe module from Fedora 40
   (6.9.9-200.fc40.x86_64) fails
 - After this patch, we can run some tests, such as xe_exec_basic
   successfully

Here is an example of the impact of this patch:
 1. Use Fedora 40 with the following kernel command line arguments:
    "xe.force_probe=* i915.force_probe=!* modprobe.blacklist=i915,ast,snd_hda_intel,xe"

 2. Running IGT without this patch will fail:
     $ sudo ./build/tests/xe_exec_basic
     $ echo $?
     98

 3. Running after fix applied will succeed:
    sudo ./build/tests/xe_exec_basic
     $ sudo ./build/tests/xe_exec_basic
     $ echo $?
     0

V3:
 - Update comment syntax and shorten comments
 - Update comment content to describe from kernel version perspective only
 - Update test to make '!= 0' implicit

V2:
 - Cleanup headers from message body
 - Add 'lib/xe/xe_query:' to subject line

Signed-off-by: Peter Senna Tschudin <peter.senna@intel.com>
---
 lib/xe/xe_query.c   | 4 +++-
 tests/intel/xe_oa.c | 6 +++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/lib/xe/xe_query.c b/lib/xe/xe_query.c
index 84eaaac96..8694fa3f9 100644
--- a/lib/xe/xe_query.c
+++ b/lib/xe/xe_query.c
@@ -124,7 +124,9 @@ static struct drm_xe_query_oa_units *xe_query_oa_units_new(int fd)
 		.data = 0,
 	};
 
-	igt_assert_eq(igt_ioctl(fd, DRM_IOCTL_XE_DEVICE_QUERY, &query), 0);
+	/* Support older kernels where this uapi is not yet available */
+	if (igt_ioctl(fd, DRM_IOCTL_XE_DEVICE_QUERY, &query))
+		return NULL;
 
 	oa_units = malloc(query.size);
 	igt_assert(oa_units);
diff --git a/tests/intel/xe_oa.c b/tests/intel/xe_oa.c
index ff2218300..1f82dce06 100644
--- a/tests/intel/xe_oa.c
+++ b/tests/intel/xe_oa.c
@@ -4503,6 +4503,7 @@ static const char *xe_engine_class_name(uint32_t engine_class)
 igt_main
 {
 	struct drm_xe_engine_class_instance *hwe = NULL;
+	struct xe_device *xe_dev;
 
 	igt_fixture {
 		struct stat sb;
@@ -4527,7 +4528,10 @@ igt_main
 		igt_assert_eq(drm_fd, -1);
 
 		drm_fd = drm_open_driver(DRIVER_XE);
-		xe_device_get(drm_fd);
+		xe_dev = xe_device_get(drm_fd);
+
+		/* See xe_query_oa_units_new() */
+		igt_require(xe_dev->oa_units);
 
 		devid = intel_get_drm_devid(drm_fd);
 		sysfs = igt_sysfs_open(drm_fd);
-- 
2.34.1