[PATCH] drm/xe/madvise: Skip invalidation for purgeable state updates

[Arvind Yadav <arvind.yadav@intel.com>]

Purgeable state updates only change VMA/BO metadata. They do not zap
PTEs when switching between DONTNEED and WILLNEED. PTEs are zapped
later if the BO is actually purged.

xe_vm_invalidate_madvise_range() waits on the VM dma-resv before checking
vma->skip_invalidation. Since purgeable madvise marks all affected VMAs to
skip invalidation, this wait is unnecessary and can stall on unrelated
in-flight work.

Skip the invalidate path entirely for purgeable state updates.

Suggested-by: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
---
 drivers/gpu/drm/xe/xe_vm_madvise.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_vm_madvise.c b/drivers/gpu/drm/xe/xe_vm_madvise.c
index c4fb29004195..7db3cee73430 100644
--- a/drivers/gpu/drm/xe/xe_vm_madvise.c
+++ b/drivers/gpu/drm/xe/xe_vm_madvise.c
@@ -708,8 +708,13 @@ int xe_vm_madvise_ioctl(struct drm_device *dev, void *data, struct drm_file *fil
 	madvise_funcs[attr_type](xe, vm, madvise_range.vmas, madvise_range.num_vmas, args,
 				 &details);
 
-	err = xe_vm_invalidate_madvise_range(vm, madvise_range.addr,
-					     madvise_range.addr + args->range);
+	/*
+	 * PURGEABLE_STATE updates only change VMA/BO metadata. PTEs remain valid until
+	 * the BO is actually purged, so skip the invalidate path and its dma-resv wait.
+	 */
+	if (args->type != DRM_XE_VMA_ATTR_PURGEABLE_STATE)
+		err = xe_vm_invalidate_madvise_range(vm, madvise_range.addr,
+						     madvise_range.addr + args->range);
 
 	if (madvise_range.has_svm_userptr_vmas)
 		xe_svm_notifier_unlock(vm);
-- 
2.43.0