From: Matthew Brost <matthew.brost@intel.com>
Date: Thu, 9 Oct 2025 13:06:29 +0000 (-0700)
Subject: drm/xe: Handle mixed mappings and existing VRAM on atomic faults
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=75188605c56d10c1bd3b1cd94f4872f349c3a9c8;p=thirdparty%2Fkernel%2Flinux.git

drm/xe: Handle mixed mappings and existing VRAM on atomic faults

Moving to VRAM will fail if mixed mappings are present or if the page is
already located in VRAM. Atomic faults that require a move to VRAM
currently retry without attempting to evict mixed mappings or locate
existing VRAM mappings.

This patch fixes the issue by attempting to evict mixed mappings or find
existing VRAM pages when a move to VRAM fails during atomic fault
handling.

Fixes: a9ac0fa455b0 ("drm/xe: Strict migration policy for atomic SVM faults")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://lore.kernel.org/r/20251009130629.3531962-1-matthew.brost@intel.com
---

diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index 7e2db71ff34ee..b268ee0d22710 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -1073,7 +1073,17 @@ retry:
 				drm_dbg(&vm->xe->drm,
 					"VRAM allocation failed, falling back to retrying fault, asid=%u, errno=%pe\n",
 					vm->usm.asid, ERR_PTR(err));
-				goto retry;
+
+				/*
+				 * In the devmem-only case, mixed mappings may
+				 * be found. The get_pages function will fix
+				 * these up to a single location, allowing the
+				 * page fault handler to make forward progress.
+				 */
+				if (ctx.devmem_only)
+					goto get_pages;
+				else
+					goto retry;
 			} else {
 				drm_err(&vm->xe->drm,
 					"VRAM allocation failed, retry count exceeded, asid=%u, errno=%pe\n",
@@ -1083,6 +1093,7 @@ retry:
 		}
 	}
 
+get_pages:
 	get_pages_start = xe_svm_stats_ktime_get();
 
 	range_debug(range, "GET PAGES");