gpuvm: remove gem.gpuva.lock_dep_map

Since all users of gem.gpuva.lock_dep_map now rely on the mutex directly
in gpuva, we may remove it. Whether the mutex is used is now tracked by
a flag in gpuvm rather than by whether lock_dep_map is null.

Note that a GEM object may not be pushed to multiple gpuvms that
disagree on the value of this new flag. But that's okay because a single
driver should use the same locking scheme everywhere, and a GEM object
is driver specific (when a GEM is exported with prime, a new GEM object
instance is created from the backing dma-buf).

The flag is present even with CONFIG_LOCKDEP=n because the intent is
that the flag will also cause vm_bo cleanup to become deferred. However,
that will happen in a follow-up patch.

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20250827-gpuva-mutex-in-gem-v3-3-bd89f5a82c0d@google.com
[ Use lockdep_is_held() instead of lock_is_held(). - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

3 files changed, 17 insertions, 19 deletions

diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c
index d6bea8a4fffd..78a1a4f09509 100644
--- a/drivers/gpu/drm/drm_gpuvm.c
+++ b/drivers/gpu/drm/drm_gpuvm.c
@@ -497,8 +497,7 @@
  * DRM GPUVM also does not take care of the locking of the backing
  * &drm_gem_object buffers GPU VA lists and &drm_gpuvm_bo abstractions by
  * itself; drivers are responsible to enforce mutual exclusion using either the
- * GEMs dma_resv lock or alternatively a driver specific external lock. For the
- * latter see also drm_gem_gpuva_set_lock().
+ * GEMs dma_resv lock or the GEMs gpuva.lock mutex.
  *
  * However, DRM GPUVM contains lockdep checks to ensure callers of its API hold
  * the corresponding lock whenever the &drm_gem_objects GPU VA list is accessed
@@ -1582,7 +1581,7 @@ drm_gpuvm_bo_destroy(struct kref *kref)
 	drm_gpuvm_bo_list_del(vm_bo, extobj, lock);
 	drm_gpuvm_bo_list_del(vm_bo, evict, lock);
 
-	drm_gem_gpuva_assert_lock_held(obj);
+	drm_gem_gpuva_assert_lock_held(gpuvm, obj);
 	list_del(&vm_bo->list.entry.gem);
 
 	if (ops && ops->vm_bo_free)
@@ -1603,7 +1602,8 @@ drm_gpuvm_bo_destroy(struct kref *kref)
  * If the reference count drops to zero, the &gpuvm_bo is destroyed, which
  * includes removing it from the GEMs gpuva list. Hence, if a call to this
  * function can potentially let the reference count drop to zero the caller must
- * hold the dma-resv or driver specific GEM gpuva lock.
+ * hold the lock that the GEM uses for its gpuva list (either the GEM's
+ * dma-resv or gpuva.lock mutex).
  *
  * This function may only be called from non-atomic context.
  *
@@ -1627,7 +1627,7 @@ __drm_gpuvm_bo_find(struct drm_gpuvm *gpuvm,
 {
 	struct drm_gpuvm_bo *vm_bo;
 
-	drm_gem_gpuva_assert_lock_held(obj);
+	drm_gem_gpuva_assert_lock_held(gpuvm, obj);
 	drm_gem_for_each_gpuvm_bo(vm_bo, obj)
 		if (vm_bo->vm == gpuvm)
 			return vm_bo;
@@ -1686,7 +1686,7 @@ drm_gpuvm_bo_obtain(struct drm_gpuvm *gpuvm,
 	if (!vm_bo)
 		return ERR_PTR(-ENOMEM);
 
-	drm_gem_gpuva_assert_lock_held(obj);
+	drm_gem_gpuva_assert_lock_held(gpuvm, obj);
 	list_add_tail(&vm_bo->list.entry.gem, &obj->gpuva.list);
 
 	return vm_bo;
@@ -1722,7 +1722,7 @@ drm_gpuvm_bo_obtain_prealloc(struct drm_gpuvm_bo *__vm_bo)
 		return vm_bo;
 	}
 
-	drm_gem_gpuva_assert_lock_held(obj);
+	drm_gem_gpuva_assert_lock_held(gpuvm, obj);
 	list_add_tail(&__vm_bo->list.entry.gem, &obj->gpuva.list);
 
 	return __vm_bo;
@@ -1894,8 +1894,7 @@ EXPORT_SYMBOL_GPL(drm_gpuva_remove);
  * reference of the latter is taken.
  *
  * This function expects the caller to protect the GEM's GPUVA list against
- * concurrent access using either the GEMs dma_resv lock or a driver specific
- * lock set through drm_gem_gpuva_set_lock().
+ * concurrent access using either the GEM's dma-resv or gpuva.lock mutex.
  */
 void
 drm_gpuva_link(struct drm_gpuva *va, struct drm_gpuvm_bo *vm_bo)
@@ -1910,7 +1909,7 @@ drm_gpuva_link(struct drm_gpuva *va, struct drm_gpuvm_bo *vm_bo)
 
 	va->vm_bo = drm_gpuvm_bo_get(vm_bo);
 
-	drm_gem_gpuva_assert_lock_held(obj);
+	drm_gem_gpuva_assert_lock_held(gpuvm, obj);
 	list_add_tail(&va->gem.entry, &vm_bo->list.gpuva);
 }
 EXPORT_SYMBOL_GPL(drm_gpuva_link);
@@ -1930,8 +1929,7 @@ EXPORT_SYMBOL_GPL(drm_gpuva_link);
  * the latter is dropped.
  *
  * This function expects the caller to protect the GEM's GPUVA list against
- * concurrent access using either the GEMs dma_resv lock or a driver specific
- * lock set through drm_gem_gpuva_set_lock().
+ * concurrent access using either the GEM's dma-resv or gpuva.lock mutex.
  */
 void
 drm_gpuva_unlink(struct drm_gpuva *va)
@@ -1942,7 +1940,7 @@ drm_gpuva_unlink(struct drm_gpuva *va)
 	if (unlikely(!obj))
 		return;
 
-	drm_gem_gpuva_assert_lock_held(obj);
+	drm_gem_gpuva_assert_lock_held(va->vm, obj);
 	list_del_init(&va->gem.entry);
 
 	va->vm_bo = NULL;
@@ -2943,8 +2941,8 @@ EXPORT_SYMBOL_GPL(drm_gpuvm_prefetch_ops_create);
  * After the caller finished processing the returned &drm_gpuva_ops, they must
  * be freed with &drm_gpuva_ops_free.
  *
- * It is the callers responsibility to protect the GEMs GPUVA list against
- * concurrent access using the GEMs dma_resv lock.
+ * This function expects the caller to protect the GEM's GPUVA list against
+ * concurrent access using either the GEM's dma-resv or gpuva.lock mutex.
  *
  * Returns: a pointer to the &drm_gpuva_ops on success, an ERR_PTR on failure
  */
@@ -2956,7 +2954,7 @@ drm_gpuvm_bo_unmap_ops_create(struct drm_gpuvm_bo *vm_bo)
 	struct drm_gpuva *va;
 	int ret;
 
-	drm_gem_gpuva_assert_lock_held(vm_bo->obj);
+	drm_gem_gpuva_assert_lock_held(vm_bo->vm, vm_bo->obj);
 
 	ops = kzalloc(sizeof(*ops), GFP_KERNEL);
 	if (!ops)
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
index c654a3377903..156c7a0b62a2 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -245,7 +245,6 @@ struct drm_gem_object *panthor_gem_create_object(struct drm_device *ddev, size_t
 
 	obj->base.base.funcs = &panthor_gem_funcs;
 	obj->base.map_wc = !ptdev->coherent;
-	drm_gem_gpuva_set_lock(&obj->base.base, &obj->base.base.gpuva.lock);
 	mutex_init(&obj->label.lock);
 
 	panthor_gem_debugfs_bo_init(obj);
diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 2881942ab511..ee9e94448b76 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -2420,8 +2420,9 @@ panthor_vm_create(struct panthor_device *ptdev, bool for_mcu,
 	 * to be handled the same way user VMAs are.
 	 */
 	drm_gpuvm_init(&vm->base, for_mcu ? "panthor-MCU-VM" : "panthor-GPU-VM",
-		       DRM_GPUVM_RESV_PROTECTED, &ptdev->base, dummy_gem,
-		       min_va, va_range, 0, 0, &panthor_gpuvm_ops);
+		       DRM_GPUVM_RESV_PROTECTED | DRM_GPUVM_IMMEDIATE_MODE,
+		       &ptdev->base, dummy_gem, min_va, va_range, 0, 0,
+		       &panthor_gpuvm_ops);
 	drm_gem_object_put(dummy_gem);
 	return vm;