[PATCH 6.18 382/396] drm/xe/vm: Prevent binding of purged buffer objects

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Arvind Yadav <[email protected]>

[ Upstream commit 4f44961eab8474a47de419113e1d46095f9b44e0 ]

Add purge checking to vma_lock_and_validate() to block new mapping
operations on purged BOs while allowing cleanup operations to proceed.

Purged BOs have their backing pages freed by the kernel. New
mapping operations (MAP, PREFETCH, REMAP) must be rejected with
-EINVAL to prevent GPU access to invalid memory. Cleanup
operations (UNMAP) must be allowed so applications can release
resources after detecting purge via the retained field.

REMAP operations require mixed handling - reject new prev/next
VMAs if the BO is purged, but allow the unmap portion to proceed
for cleanup.

The check_purged flag in struct xe_vma_lock_and_validate_flags
distinguishes between these cases: true for new mappings (must reject),
false for cleanup (allow).

Cc: Himal Prasad Ghimiray <[email protected]>
Cc: Matthew Brost <[email protected]>
Reviewed-by: Thomas Hellström <[email protected]>
Signed-off-by: Arvind Yadav <[email protected]>
Signed-off-by: Matthew Brost <[email protected]>
Link: https://patch.msgid.link/[email protected]
Stable-dep-of: 7bc597ce74ba ("drm/xe/vm: Fix BO prefetch with CONSULT_MEM_ADVISE_PREF_LOC")
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
 drivers/gpu/drm/xe/xe_vm.c |   79 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 68 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/xe/xe_vm.c
+++ b/drivers/gpu/drm/xe/xe_vm.c
@@ -2834,8 +2834,22 @@ static void vm_bind_ioctl_ops_unwind(str
 	}
 }
 
+/**
+ * struct xe_vma_lock_and_validate_flags - Flags for vma_lock_and_validate()
+ * @res_evict: Allow evicting resources during validation
+ * @validate: Perform BO validation
+ * @request_decompress: Request BO decompression
+ * @check_purged: Reject operation if BO is purged
+ */
+struct xe_vma_lock_and_validate_flags {
+	u32 res_evict : 1;
+	u32 validate : 1;
+	u32 request_decompress : 1;
+	u32 check_purged : 1;
+};
+
 static int vma_lock_and_validate(struct drm_exec *exec, struct xe_vma *vma,
-				 bool res_evict, bool validate)
+				 struct xe_vma_lock_and_validate_flags flags)
 {
 	struct xe_bo *bo = xe_vma_bo(vma);
 	struct xe_vm *vm = xe_vma_vm(vma);
@@ -2844,10 +2858,19 @@ static int vma_lock_and_validate(struct
 	if (bo) {
 		if (!bo->vm)
 			err = drm_exec_lock_obj(exec, &bo->ttm.base);
-		if (!err && validate)
+
+		/* Reject new mappings to DONTNEED/purged BOs; allow cleanup operations */
+		if (!err && flags.check_purged) {
+			if (xe_bo_madv_is_dontneed(bo))
+				err = -EBUSY;  /* BO marked purgeable */
+			else if (xe_bo_is_purged(bo))
+				err = -EINVAL; /* BO already purged */
+		}
+
+		if (!err && flags.validate)
 			err = xe_bo_validate(bo, vm,
 					     !xe_vm_in_preempt_fence_mode(vm) &&
-					     res_evict, exec);
+					     flags.res_evict, exec);
 	}
 
 	return err;
@@ -2933,9 +2956,13 @@ static int op_lock_and_prep(struct drm_e
 	case DRM_GPUVA_OP_MAP:
 		if (!op->map.invalidate_on_bind)
 			err = vma_lock_and_validate(exec, op->map.vma,
-						    res_evict,
-						    !xe_vm_in_fault_mode(vm) ||
-						    op->map.immediate);
+						    (struct xe_vma_lock_and_validate_flags) {
+							.res_evict = res_evict,
+							.validate = !xe_vm_in_fault_mode(vm) ||
+								    op->map.immediate,
+							.request_decompress = false,
+							.check_purged = true,
+						    });
 		break;
 	case DRM_GPUVA_OP_REMAP:
 		err = check_ufence(gpuva_to_vma(op->base.remap.unmap->va));
@@ -2944,13 +2971,28 @@ static int op_lock_and_prep(struct drm_e
 
 		err = vma_lock_and_validate(exec,
 					    gpuva_to_vma(op->base.remap.unmap->va),
-					    res_evict, false);
+					    (struct xe_vma_lock_and_validate_flags) {
+						    .res_evict = res_evict,
+						    .validate = false,
+						    .request_decompress = false,
+						    .check_purged = false,
+					    });
 		if (!err && op->remap.prev)
 			err = vma_lock_and_validate(exec, op->remap.prev,
-						    res_evict, true);
+						    (struct xe_vma_lock_and_validate_flags) {
+							    .res_evict = res_evict,
+							    .validate = true,
+							    .request_decompress = false,
+							    .check_purged = true,
+						    });
 		if (!err && op->remap.next)
 			err = vma_lock_and_validate(exec, op->remap.next,
-						    res_evict, true);
+						    (struct xe_vma_lock_and_validate_flags) {
+							    .res_evict = res_evict,
+							    .validate = true,
+							    .request_decompress = false,
+							    .check_purged = true,
+						    });
 		break;
 	case DRM_GPUVA_OP_UNMAP:
 		err = check_ufence(gpuva_to_vma(op->base.unmap.va));
@@ -2959,7 +3001,12 @@ static int op_lock_and_prep(struct drm_e
 
 		err = vma_lock_and_validate(exec,
 					    gpuva_to_vma(op->base.unmap.va),
-					    res_evict, false);
+					    (struct xe_vma_lock_and_validate_flags) {
+						    .res_evict = res_evict,
+						    .validate = false,
+						    .request_decompress = false,
+						    .check_purged = false,
+					    });
 		break;
 	case DRM_GPUVA_OP_PREFETCH:
 	{
@@ -2972,9 +3019,19 @@ static int op_lock_and_prep(struct drm_e
 				  region <= ARRAY_SIZE(region_to_mem_type));
 		}
 
+		/*
+		 * Prefetch attempts to migrate BO's backing store without
+		 * repopulating it first. Purged BOs have no backing store
+		 * to migrate, so reject the operation.
+		 */
 		err = vma_lock_and_validate(exec,
 					    gpuva_to_vma(op->base.prefetch.va),
-					    res_evict, false);
+					    (struct xe_vma_lock_and_validate_flags) {
+						    .res_evict = res_evict,
+						    .validate = false,
+						    .request_decompress = false,
+						    .check_purged = true,
+					    });
 		if (!err && !xe_vma_has_no_bo(vma))
 			err = xe_bo_migrate(xe_vma_bo(vma),
 					    region_to_mem_type[region],