drm/xe: Use helper for ASID -> VM in GPU faults and access counters

Normalize both code paths with a helper. Fixes a possible leak access
counter path too.
Suggested-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240918160503.2021315-1-matthew.brost@intel.com
(cherry picked from commit dc0dce6d63d22e8319e27b6a41be7368376f9471)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>

drivers/gpu/drm/xe/xe_gt_pagefault.c

@@ -185,6 +185,21 @@ static int handle_vma_pagefault(struct xe_tile *tile, struct pagefault *pf,
 	return err;
 }
 
+static struct xe_vm *asid_to_vm(struct xe_device *xe, u32 asid)
+{
+	struct xe_vm *vm;
+
+	down_read(&xe->usm.lock);
+	vm = xa_load(&xe->usm.asid_to_vm, asid);
+	if (vm && xe_vm_in_fault_mode(vm))
+		xe_vm_get(vm);
+	else
+		vm = ERR_PTR(-EINVAL);
+	up_read(&xe->usm.lock);
+
+	return vm;
+}
+
 static int handle_pagefault(struct xe_gt *gt, struct pagefault *pf)
 {
 	struct xe_device *xe = gt_to_xe(gt);
@@ -197,16 +212,9 @@ static int handle_pagefault(struct xe_gt *gt, struct pagefault *pf)
 	if (pf->trva_fault)
 		return -EFAULT;
 
-	/* ASID to VM */
-	down_read(&xe->usm.lock);
-	vm = xa_load(&xe->usm.asid_to_vm, pf->asid);
-	if (vm && xe_vm_in_fault_mode(vm))
-		xe_vm_get(vm);
-	else
-		vm = NULL;
-	up_read(&xe->usm.lock);
-	if (!vm)
-		return -EINVAL;
+	vm = asid_to_vm(xe, pf->asid);
+	if (IS_ERR(vm))
+		return PTR_ERR(vm);
 
 	/*
 	 * TODO: Change to read lock? Using write lock for simplicity.
@@ -548,14 +556,9 @@ static int handle_acc(struct xe_gt *gt, struct acc *acc)
 	if (acc->access_type != ACC_TRIGGER)
 		return -EINVAL;
 
-	/* ASID to VM */
-	down_read(&xe->usm.lock);
-	vm = xa_load(&xe->usm.asid_to_vm, acc->asid);
-	if (vm)
-		xe_vm_get(vm);
-	up_read(&xe->usm.lock);
-	if (!vm || !xe_vm_in_fault_mode(vm))
-		return -EINVAL;
+	vm = asid_to_vm(xe, acc->asid);
+	if (IS_ERR(vm))
+		return PTR_ERR(vm);
 
 	down_read(&vm->lock);