drm/xe: Don't use drm exec locking in SVM pagefaults

Only the VM dma-resv lock is needed in SVM pagefaults so
xe_vm_lock/unlock can be used instead of drm exec. Micro optimization
but should save some CPU cycles in a critical path.

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Stuart Summers <stuart.summers@intel.com>
Link: https://lore.kernel.org/r/20250603174012.2195759-1-matthew.brost@intel.com

diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index 83c63fd7b4819ffede292c8b487dc483bf488a43..5f5477d81688f637c34ca21f064e3e89d94aaeec 100644 (file)
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -858,7 +858,6 @@ int xe_svm_handle_pagefault(struct xe_vm *vm, struct xe_vma *vma,
                        vm->xe->atomic_svm_timeslice_ms : 0,
        };
        struct xe_svm_range *range;
-       struct drm_exec exec;
        struct dma_fence *fence;
        struct xe_tile *tile = gt_to_tile(gt);
        int migrate_try_count = ctx.devmem_only ? 3 : 1;
@@ -933,30 +932,21 @@ retry:
        range_debug(range, "PAGE FAULT - BIND");
 
 retry_bind:
-       drm_exec_init(&exec, 0, 0);
-       drm_exec_until_all_locked(&exec) {
-               err = drm_exec_lock_obj(&exec, vm->gpuvm.r_obj);
-               drm_exec_retry_on_contention(&exec);
-               if (err) {
-                       drm_exec_fini(&exec);
-                       goto err_out;
-               }
-
-               fence = xe_vm_range_rebind(vm, vma, range, BIT(tile->id));
-               if (IS_ERR(fence)) {
-                       drm_exec_fini(&exec);
-                       err = PTR_ERR(fence);
-                       if (err == -EAGAIN) {
-                               ctx.timeslice_ms <<= 1; /* Double timeslice if we have to retry */
-                               range_debug(range, "PAGE FAULT - RETRY BIND");
-                               goto retry;
-                       }
-                       if (xe_vm_validate_should_retry(&exec, err, &end))
-                               goto retry_bind;
-                       goto err_out;
+       xe_vm_lock(vm, false);
+       fence = xe_vm_range_rebind(vm, vma, range, BIT(tile->id));
+       if (IS_ERR(fence)) {
+               xe_vm_unlock(vm);
+               err = PTR_ERR(fence);
+               if (err == -EAGAIN) {
+                       ctx.timeslice_ms <<= 1; /* Double timeslice if we have to retry */
+                       range_debug(range, "PAGE FAULT - RETRY BIND");
+                       goto retry;
                }
+               if (xe_vm_validate_should_retry(NULL, err, &end))
+                       goto retry_bind;
+               goto err_out;
        }
-       drm_exec_fini(&exec);
+       xe_vm_unlock(vm);
 
        dma_fence_wait(fence, false);
        dma_fence_put(fence);