drm/xe/madvise: Enable purgeable buffer object IOCTL support

Hook the madvise_purgeable() handler into the madvise IOCTL now that all
supporting infrastructure is complete:

 - Core purge implementation (patch 3)
 - BO state tracking and helpers (patches 1-2)
 - Per-VMA purgeable state tracking (patch 6)
 - Shrinker integration for memory reclamation (patch 10)

This final patch enables userspace to use the
DRM_XE_VMA_ATTR_PURGEABLE_STATE madvise type to mark buffers as
WILLNEED/DONTNEED and receive the retained status indicating whether
buffers were purged.

The feature was kept disabled in earlier patches to maintain
bisectability and ensure all components are in place before exposing to
userspace.

Userspace can detect kernel support for purgeable BOs by checking the
DRM_XE_QUERY_CONFIG_FLAG_HAS_PURGING_SUPPORT flag in the query_config
response.

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260326130843.3545241-12-arvind.yadav@intel.com

2 files changed, 7 insertions, 17 deletions

diff --git a/drivers/gpu/drm/xe/xe_query.c b/drivers/gpu/drm/xe/xe_query.c
index 4852fdcb4b95..d84d6a422c45 100644
--- a/drivers/gpu/drm/xe/xe_query.c
+++ b/drivers/gpu/drm/xe/xe_query.c
@@ -342,6 +342,8 @@ static int query_config(struct xe_device *xe, struct drm_xe_device_query *query)
 			DRM_XE_QUERY_CONFIG_FLAG_HAS_LOW_LATENCY;
 	config->info[DRM_XE_QUERY_CONFIG_FLAGS] |=
 		DRM_XE_QUERY_CONFIG_FLAG_HAS_DISABLE_STATE_CACHE_PERF_FIX;
+	config->info[DRM_XE_QUERY_CONFIG_FLAGS] |=
+		DRM_XE_QUERY_CONFIG_FLAG_HAS_PURGING_SUPPORT;
 	config->info[DRM_XE_QUERY_CONFIG_MIN_ALIGNMENT] =
 		xe->info.vram_flags & XE_VRAM_FLAGS_NEED64K ? SZ_64K : SZ_4K;
 	config->info[DRM_XE_QUERY_CONFIG_VA_BITS] = xe->info.va_bits;
diff --git a/drivers/gpu/drm/xe/xe_vm_madvise.c b/drivers/gpu/drm/xe/xe_vm_madvise.c
index b7c1c1c525b2..a169cb3f3591 100644
--- a/drivers/gpu/drm/xe/xe_vm_madvise.c
+++ b/drivers/gpu/drm/xe/xe_vm_madvise.c
@@ -337,18 +337,11 @@ void xe_bo_recompute_purgeable_state(struct xe_bo *bo)
  *
  * Handles DONTNEED/WILLNEED/PURGED states. Tracks if any BO was purged
  * in details->has_purged_bo for later copy to userspace.
- *
- * Note: Marked __maybe_unused until hooked into madvise_funcs[] in the
- * final patch to maintain bisectability. The NULL placeholder in the
- * array ensures proper -EINVAL return for userspace until all supporting
- * infrastructure (shrinker, per-VMA tracking) is complete.
  */
-static void __maybe_unused madvise_purgeable(struct xe_device *xe,
-					     struct xe_vm *vm,
-					     struct xe_vma **vmas,
-					     int num_vmas,
-					     struct drm_xe_madvise *op,
-					     struct xe_madvise_details *details)
+static void madvise_purgeable(struct xe_device *xe, struct xe_vm *vm,
+			      struct xe_vma **vmas, int num_vmas,
+			      struct drm_xe_madvise *op,
+			      struct xe_madvise_details *details)
 {
 	int i;
 
@@ -417,12 +410,7 @@ static const madvise_func madvise_funcs[] = {
 	[DRM_XE_MEM_RANGE_ATTR_PREFERRED_LOC] = madvise_preferred_mem_loc,
 	[DRM_XE_MEM_RANGE_ATTR_ATOMIC] = madvise_atomic,
 	[DRM_XE_MEM_RANGE_ATTR_PAT] = madvise_pat_index,
-	/*
-	 * Purgeable support implemented but not enabled yet to maintain
-	 * bisectability. Will be set to madvise_purgeable() in final patch
-	 * when all infrastructure (shrinker, VMA tracking) is complete.
-	 */
-	[DRM_XE_VMA_ATTR_PURGEABLE_STATE] = NULL,
+	[DRM_XE_VMA_ATTR_PURGEABLE_STATE] = madvise_purgeable,
 };
 
 static u8 xe_zap_ptes_in_madvise_range(struct xe_vm *vm, u64 start, u64 end)