Re: [PATCH i-g-t v7 3/9] lib/xe: add xe_cgroup_region_name() helper

[Tvrtko Ursulin]

On 23/09/2026 21:44, Thadeu Lima de Souza Cascardo wrote:

From: Thomas Hellström <thomas.hellst...@linux.intel.com>

Add xe_cgroup_region_name(fd, region) which constructs the dmem cgroup
region path for a given xe memory region.  The returned string has the
form "drm/<pci-slot>/<region>" (e.g. "drm/0000:03:00.0/vram0"),
matching the name registered by the kernel via drmm_cgroup_register_region().

Only VRAM regions are tracked by the dmem controller; system and stolen
memory regions return NULL.

Assisted-by: GitHub Copilot:claude-sonnet-4.6
Signed-off-by: Thomas Hellström <thomas.hellst...@linux.intel.com>
---
  lib/xe/xe_query.c | 32 ++++++++++++++++++++++++++++++++
  lib/xe/xe_query.h |  2 ++
  2 files changed, 34 insertions(+)

diff --git a/lib/xe/xe_query.c b/lib/xe/xe_query.c
index 91ffc36e6425..058f95ed1484 100644
--- a/lib/xe/xe_query.c
+++ b/lib/xe/xe_query.c
@@ -7,6 +7,7 @@
   */

#include <fcntl.h>

+#include <limits.h>
  #include <stdlib.h>
  #include <pthread.h>

@@ -21,6 +22,7 @@ #include "drmtest.h"

  #include "igt_debugfs.h"
+#include "igt_device.h"
  #include "ioctl_wrappers.h"
  #include "igt_map.h"
  #include "intel_common.h"
@@ -1302,6 +1304,36 @@ int xe_query_eu_thread_count(int fd, int gt)
                xe_hwconfig_lookup_value_u32(fd, 
INTEL_HWCONFIG_NUM_THREADS_PER_EU);
  }

+/**

+ * xe_cgroup_region_name() - Build the dmem cgroup region name for an xe 
memory region.
+ * @fd: xe device fd.
+ * @region: Region mask (as used by xe_mem_region(), xe_region_name(), etc.).
+ *
+ * Constructs the full dmem cgroup region path for @region on the device
+ * identified by @fd.  The returned string has the form
+ * ``drm/<pci-slot>/<region>`` (e.g. ``drm/0000:03:00.0/vram0``), matching
+ * the name registered by the kernel driver via drmm_cgroup_register_region().
+ *
+ * Only VRAM regions are registered with the dmem controller; passing a
+ * system-memory region returns %NULL.
+ *
+ * Return: A newly allocated string that the caller must free(), or %NULL if
+ * @region is not tracked by the dmem cgroup controller.
+ */
+char *xe_cgroup_region_name(int fd, uint64_t region)
+{
+       char pci_slot[NAME_MAX];
+       char *name;
+
+       if (xe_region_class(fd, region) != DRM_XE_MEM_REGION_CLASS_VRAM)
+               return NULL;
+
+       igt_device_get_pci_slot_name(fd, pci_slot);
+
+       igt_assert(asprintf(&name, "drm/%s/%s", pci_slot, xe_region_name(region)) 
> 0);
+       return name;
+}
+
  igt_constructor
  {
        xe_device_cache_init();
diff --git a/lib/xe/xe_query.h b/lib/xe/xe_query.h
index 59330d80fd1b..a6ef9cab9aa1 100644
--- a/lib/xe/xe_query.h
+++ b/lib/xe/xe_query.h
@@ -206,4 +206,6 @@ void xe_device_put(int fd);
  int xe_query_eu_count(int fd, int gt);
  int xe_query_eu_thread_count(int fd, int gt);

+char *xe_cgroup_region_name(int fd, uint64_t region);

+
  #endif        /* XE_QUERY_H */

Reviewed-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com>

Regards,

Tvrtko