drm/buddy: Integrate lockdep annotations for gpu buddy manager

gpu_buddy APIs are expected to be called with the driver-provided lock
held, but there is no runtime enforcement of this contract. Add lockdep
annotations to catch locking violations early.

Introduce gpu_buddy_driver_set_lock() for the driver to register the
lock that protects the buddy manager. Add gpu_buddy_driver_lock_held()
assertions to all exported gpu_buddy and drm_buddy APIs that
access/modify the manager state. The lock_dep_map field is only compiled
in when CONFIG_LOCKDEP is enabled, adding zero overhead to production
builds.

Wire up xe_ttm_vram_mgr to register its mutex with the buddy manager
after initialization.

Assisted-by: Copilot:claude-opus-4.6
Suggested-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Link: https://patch.msgid.link/20260508065544.4049240-2-tejas.upadhyay@intel.com

3 files changed, 13 insertions, 0 deletions

diff --git a/drivers/gpu/buddy.c b/drivers/gpu/buddy.c
index 52686672e99f..eb1457376307 100644
--- a/drivers/gpu/buddy.c
+++ b/drivers/gpu/buddy.c
@@ -437,6 +437,9 @@ int gpu_buddy_init(struct gpu_buddy *mm, u64 size, u64 chunk_size)
 		root_count++;
 	} while (size);
 
+#ifdef CONFIG_LOCKDEP
+	mm->lock_dep_map = NULL;
+#endif
 	return 0;
 
 out_free_roots:
@@ -538,6 +541,7 @@ void gpu_buddy_reset_clear(struct gpu_buddy *mm, bool is_clear)
 	unsigned int order;
 	int i;
 
+	gpu_buddy_driver_lock_held(mm);
 	size = mm->size;
 	for (i = 0; i < mm->n_roots; ++i) {
 		order = ilog2(size) - ilog2(mm->chunk_size);
@@ -580,6 +584,7 @@ EXPORT_SYMBOL(gpu_buddy_reset_clear);
 void gpu_buddy_free_block(struct gpu_buddy *mm,
 			  struct gpu_buddy_block *block)
 {
+	gpu_buddy_driver_lock_held(mm);
 	BUG_ON(!gpu_buddy_block_is_allocated(block));
 	mm->avail += gpu_buddy_block_size(mm, block);
 	if (gpu_buddy_block_is_clear(block))
@@ -633,6 +638,7 @@ void gpu_buddy_free_list(struct gpu_buddy *mm,
 {
 	bool mark_clear = flags & GPU_BUDDY_CLEARED;
 
+	gpu_buddy_driver_lock_held(mm);
 	__gpu_buddy_free_list(mm, objects, mark_clear, !mark_clear);
 }
 EXPORT_SYMBOL(gpu_buddy_free_list);
@@ -1172,6 +1178,8 @@ int gpu_buddy_block_trim(struct gpu_buddy *mm,
 	u64 new_start;
 	int err;
 
+	gpu_buddy_driver_lock_held(mm);
+
 	if (!list_is_singular(blocks))
 		return -EINVAL;
 
@@ -1287,6 +1295,8 @@ int gpu_buddy_alloc_blocks(struct gpu_buddy *mm,
 	unsigned long pages;
 	int err;
 
+	gpu_buddy_driver_lock_held(mm);
+
 	if (size < mm->chunk_size)
 		return -EINVAL;
 
@@ -1475,6 +1485,7 @@ void gpu_buddy_print(struct gpu_buddy *mm)
 {
 	int order;
 
+	gpu_buddy_driver_lock_held(mm);
 	pr_info("chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB, clear_free: %lluMiB\n",
 		mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20);
 
diff --git a/drivers/gpu/drm/drm_buddy.c b/drivers/gpu/drm/drm_buddy.c
index 841f3de5f307..faa025498de4 100644
--- a/drivers/gpu/drm/drm_buddy.c
+++ b/drivers/gpu/drm/drm_buddy.c
@@ -42,6 +42,7 @@ void drm_buddy_print(struct gpu_buddy *mm, struct drm_printer *p)
 {
 	int order;
 
+	gpu_buddy_driver_lock_held(mm);
 	drm_printf(p, "chunk_size: %lluKiB, total: %lluMiB, free: %lluMiB, clear_free: %lluMiB\n",
 		   mm->chunk_size >> 10, mm->size >> 20, mm->avail >> 20, mm->clear_avail >> 20);
 
diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
index 6ba47996bc7c..9f67df646955 100644
--- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
+++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
@@ -322,6 +322,7 @@ int __xe_ttm_vram_mgr_init(struct xe_device *xe, struct xe_ttm_vram_mgr *mgr,
 	if (err)
 		return err;
 
+	gpu_buddy_driver_set_lock(&mgr->mm, &mgr->lock);
 	ttm_set_driver_manager(&xe->ttm, mem_type, &mgr->manager);
 	ttm_resource_manager_set_used(&mgr->manager, true);