[RFC PATCH v3 19/21] drm/xe: Use drm_exec for fault locking

[Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>]

Similar to how TTM vm does this, convert the drm/xe fault
handler to use drm_exec locking.

Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Somalapuram Amaranath <Amaranath.Somalapuram@xxxxxxx>
Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
Cc: <dri-devel@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/xe/xe_bo.c | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 3c56858e0751..27d7d36401b5 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -1217,29 +1217,37 @@ static vm_fault_t xe_gem_fault(struct vm_fault *vmf)
 	struct xe_device *xe = to_xe_device(ddev);
 	struct xe_bo *bo = ttm_to_xe_bo(tbo);
 	bool needs_rpm = bo->flags & XE_BO_FLAG_VRAM_MASK;
+	struct drm_exec exec;
 	vm_fault_t ret;
-	int idx;
+	int idx, err;
 
 	if (needs_rpm)
 		xe_pm_runtime_get(xe);
 
-	ret = ttm_bo_vm_reserve(tbo, vmf, NULL);
-	if (ret)
-		goto out;
+	drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 16);
+	drm_exec_until_all_locked(&exec) {
+		ret = ttm_bo_vm_reserve(tbo, vmf, &exec);
+		err = drm_exec_retry_on_contention(&exec, 0);
+		if (err)
+			ret = VM_FAULT_NOPAGE;
+		if (ret)
+			goto out;
 
-	if (drm_dev_enter(ddev, &idx)) {
-		trace_xe_bo_cpu_fault(bo);
+		if (drm_dev_enter(ddev, &idx)) {
+			trace_xe_bo_cpu_fault(bo);
 
-		ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
-					       TTM_BO_VM_NUM_PREFAULT,
-					       NULL);
-		drm_dev_exit(idx);
-	} else {
-		ret = ttm_bo_vm_dummy_page(vmf, vmf->vma->vm_page_prot);
+			ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
+						       TTM_BO_VM_NUM_PREFAULT,
+						       &exec);
+			drm_dev_exit(idx);
+			err = drm_exec_retry_on_contention(&exec, 0);
+			if (err)
+				ret = VM_FAULT_NOPAGE;
+		} else {
+			ret = ttm_bo_vm_dummy_page(vmf, vmf->vma->vm_page_prot);
+		}
 	}
 
-	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
-		goto out;
 	/*
 	 * ttm_bo_vm_reserve() already has dma_resv_lock.
 	 */
@@ -1250,8 +1258,8 @@ static vm_fault_t xe_gem_fault(struct vm_fault *vmf)
 		mutex_unlock(&xe->mem_access.vram_userfault.lock);
 	}
 
-	dma_resv_unlock(tbo->base.resv);
 out:
+	drm_exec_fini(&exec);
 	if (needs_rpm)
 		xe_pm_runtime_put(xe);
 
-- 
2.44.0