[PATCH 05/10] drm/gem: Use dynamic allocation for GEM object dma_resv

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Remove the embedded dma_resv (_resv) from struct drm_gem_object and use
dynamically allocated reservations instead. This change aligns with the
new reference counted dma_resv infrastructure and reduces the size of
drm_gem_object.

In drm_gem_private_object_init(), when no external resv is provided,
allocate a new dma_resv using dma_resv_alloc() instead of initializing
the embedded _resv field. This allows proper error handling if the
allocation fails, returning -ENOMEM to the caller.

The corresponding cleanup in drm_gem_private_object_fini() is simplified
to only put the resv pointer, removing the redundant put on _resv.

For TTM buffer objects, add an individual_resv field to track the
dynamically allocated reservation object for proper cleanup during
destruction. This ensures we can distinguish between shared and
individual reservations when freeing resources.

This change builds on the previous work to make drm_gem_private_object_init()
return an error code, now utilizing that capability to handle allocation
failures properly.

Signed-off-by: Christian König <christian.koenig@amd.com>
Assisted-by: Claude:Sonnet 4
---
 .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  |  2 +-
 drivers/gpu/drm/amd/amdgpu/amdgpu_object.c    | 12 ++---
 drivers/gpu/drm/drm_gem.c                     |  9 ++--
 drivers/gpu/drm/i915/gem/i915_gem_object.c    |  1 -
 drivers/gpu/drm/nouveau/nouveau_bo.c          |  3 --
 .../gpu/drm/ttm/tests/ttm_bo_validate_test.c  |  2 +-
 drivers/gpu/drm/ttm/ttm_bo.c                  | 26 ++++++-----
 drivers/gpu/drm/ttm/ttm_bo_util.c             | 44 +++++++++++++------
 drivers/gpu/drm/xe/xe_bo.c                    |  8 ++--
 include/drm/drm_gem.h                         |  9 ----
 include/drm/ttm/ttm_bo.h                      |  2 +
 11 files changed, 65 insertions(+), 53 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
index 20831dbebc31..a168083edab2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
@@ -397,7 +397,7 @@ static int amdgpu_amdkfd_remove_eviction_fence(struct amdgpu_bo *bo,
  */
 void amdgpu_amdkfd_remove_all_eviction_fences(struct amdgpu_bo *bo)
 {
-	struct dma_resv *resv = &bo->tbo.base._resv;
+	struct dma_resv *resv = bo->tbo.individual_resv;
 	struct dma_fence *fence, *stub;
 	struct dma_resv_iter cursor;
 
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 6c5182d54f7d..026821f6da7c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -1319,7 +1319,7 @@ void amdgpu_bo_release_notify(struct ttm_buffer_object *bo)
 	 * So when this locking here fails something is wrong with the reference
 	 * counting.
 	 */
-	if (WARN_ON_ONCE(!dma_resv_trylock(&bo->base._resv)))
+	if (WARN_ON_ONCE(!dma_resv_trylock(bo->individual_resv)))
 		return;
 
 	amdgpu_amdkfd_remove_all_eviction_fences(abo);
@@ -1329,22 +1329,22 @@ void amdgpu_bo_release_notify(struct ttm_buffer_object *bo)
 	    adev->in_suspend || drm_dev_is_unplugged(adev_to_drm(adev)))
 		goto out;
 
-	r = dma_resv_reserve_fences(&bo->base._resv, 1);
+	r = dma_resv_reserve_fences(bo->individual_resv, 1);
 	if (r)
 		goto out;
 
 	r = amdgpu_ttm_clear_buffer(amdgpu_ttm_next_clear_entity(adev),
-				    abo, &bo->base._resv, &fence,
-				    false, AMDGPU_KERNEL_JOB_ID_CLEAR_ON_RELEASE);
+				    abo, bo->individual_resv, &fence, false,
+				    AMDGPU_KERNEL_JOB_ID_CLEAR_ON_RELEASE);
 	if (WARN_ON(r))
 		goto out;
 
 	amdgpu_vram_mgr_set_cleared(bo->resource);
-	dma_resv_add_fence(&bo->base._resv, fence, DMA_RESV_USAGE_KERNEL);
+	dma_resv_add_fence(bo->individual_resv, fence, DMA_RESV_USAGE_KERNEL);
 	dma_fence_put(fence);
 
 out:
-	dma_resv_unlock(&bo->base._resv);
+	dma_resv_unlock(bo->individual_resv);
 }
 
 /**
diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index d2ce18bbddea..480391df556d 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -235,9 +235,11 @@ int drm_gem_private_object_init(struct drm_device *dev,
 	obj->handle_count = 0;
 	obj->size = size;
 	mutex_init(&obj->gpuva.lock);
-	dma_resv_init(&obj->_resv);
-	if (!obj->resv)
-		obj->resv = dma_resv_get(&obj->_resv);
+	if (!obj->resv) {
+		obj->resv = dma_resv_alloc();
+		if (!obj->resv)
+			return -ENOMEM;
+	}
 
 	drm_gem_gpuva_init(obj);
 
@@ -259,7 +261,6 @@ void drm_gem_private_object_fini(struct drm_gem_object *obj)
 	WARN_ON(obj->dma_buf);
 
 	dma_resv_put(obj->resv);
-	dma_resv_put(&obj->_resv);
 	mutex_destroy(&obj->gpuva.lock);
 }
 EXPORT_SYMBOL(drm_gem_private_object_fini);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 384c74794fdc..5e48e169f2de 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -144,7 +144,6 @@ void __i915_gem_object_fini(struct drm_i915_gem_object *obj)
 {
 	mutex_destroy(&obj->mm.get_page.lock);
 	mutex_destroy(&obj->mm.get_dma_page.lock);
-	dma_resv_put(&obj->base._resv);
 }
 
 /**
diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index 67c9d32f4f27..65e1f0c2f984 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -159,8 +159,6 @@ nouveau_bo_del_ttm(struct ttm_buffer_object *bo)
 			drm_gem_object_put(nvbo->r_obj);
 
 		drm_gem_object_release(&bo->base);
-	} else {
-		dma_resv_put(&bo->base._resv);
 	}
 
 	kfree(nvbo);
@@ -385,7 +383,6 @@ nouveau_bo_new(struct nouveau_cli *cli, u64 size, int align,
 		return PTR_ERR(nvbo);
 
 	nvbo->bo.base.size = size;
-	dma_resv_init(&nvbo->bo.base._resv);
 	drm_vma_node_reset(&nvbo->bo.base.vma_node);
 
 	/* This must be called before ttm_bo_init_reserved(). Subsequent
diff --git a/drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c b/drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c
index bb430763e7a5..6fc381a9d2da 100644
--- a/drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c
+++ b/drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c
@@ -637,7 +637,7 @@ static void ttm_bo_validate_no_placement_not_signaled(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, ctx.bytes_moved, 0);
 
 	if (bo->type != ttm_bo_type_sg)
-		KUNIT_ASSERT_PTR_EQ(test, bo->base.resv, &bo->base._resv);
+		KUNIT_ASSERT_PTR_EQ(test, bo->base.resv, &bo->individual_resv);
 
 	/* Make sure we have an idle object at this point */
 	dma_resv_wait_timeout(bo->base.resv, usage, false, MAX_SCHEDULE_TIMEOUT);
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 999c24251fb7..ecb5f55a0dd1 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -193,13 +193,13 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
 {
 	int r;
 
-	if (bo->base.resv == &bo->base._resv)
+	if (bo->base.resv == bo->individual_resv)
 		return 0;
 
-	BUG_ON(!dma_resv_trylock(&bo->base._resv));
+	BUG_ON(!dma_resv_trylock(bo->individual_resv));
 
-	r = dma_resv_copy_fences(&bo->base._resv, bo->base.resv);
-	dma_resv_unlock(&bo->base._resv);
+	r = dma_resv_copy_fences(bo->individual_resv, bo->base.resv);
+	dma_resv_unlock(bo->individual_resv);
 	if (r)
 		return r;
 
@@ -209,7 +209,7 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
 		 * the resv object while holding the lru_lock.
 		 */
 		spin_lock(&bo->bdev->lru_lock);
-		drm_gem_object_set_resv(&bo->base, &bo->base._resv);
+		drm_gem_object_set_resv(&bo->base, bo->individual_resv);
 		spin_unlock(&bo->bdev->lru_lock);
 	}
 
@@ -218,7 +218,7 @@ static int ttm_bo_individualize_resv(struct ttm_buffer_object *bo)
 
 static void ttm_bo_flush_all_fences(struct ttm_buffer_object *bo)
 {
-	struct dma_resv *resv = &bo->base._resv;
+	struct dma_resv *resv = bo->individual_resv;
 	struct dma_resv_iter cursor;
 	struct dma_fence *fence;
 
@@ -238,8 +238,8 @@ static void ttm_bo_delayed_delete(struct work_struct *work)
 
 	bo = container_of(work, typeof(*bo), delayed_delete);
 
-	dma_resv_wait_timeout(&bo->base._resv, DMA_RESV_USAGE_BOOKKEEP, false,
-			      MAX_SCHEDULE_TIMEOUT);
+	dma_resv_wait_timeout(bo->individual_resv, DMA_RESV_USAGE_BOOKKEEP,
+			      false, MAX_SCHEDULE_TIMEOUT);
 	dma_resv_lock(bo->base.resv, NULL);
 	ttm_bo_cleanup_memtype_use(bo);
 	dma_resv_unlock(bo->base.resv);
@@ -273,7 +273,7 @@ static void ttm_bo_release(struct kref *kref)
 		drm_vma_offset_remove(bdev->vma_manager, &bo->base.vma_node);
 		ttm_mem_io_free(bdev, bo->resource);
 
-		if (!dma_resv_test_signaled(&bo->base._resv,
+		if (!dma_resv_test_signaled(bo->individual_resv,
 					    DMA_RESV_USAGE_BOOKKEEP) ||
 		    (want_init_on_free() && (bo->ttm != NULL)) ||
 		    bo->type == ttm_bo_type_sg ||
@@ -316,6 +316,8 @@ static void ttm_bo_release(struct kref *kref)
 	}
 
 	atomic_dec(&ttm_glob.bo_count);
+	dma_resv_put(bo->individual_resv);
+	bo->individual_resv = NULL;
 	bo->destroy(bo);
 }
 
@@ -1197,7 +1199,11 @@ int ttm_bo_init_reserved(struct ttm_device *bdev, struct ttm_buffer_object *bo,
 	bo->pin_count = 0;
 	bo->sg = sg;
 	bo->bulk_move = NULL;
-	drm_gem_object_set_resv(&bo->base, resv ?: &bo->base._resv);
+
+	/* Save the original resv object before overwriting it */
+	bo->individual_resv = dma_resv_get(bo->base.resv);
+	if (resv)
+		drm_gem_object_set_resv(&bo->base, resv);
 	atomic_inc(&ttm_glob.bo_count);
 
 	/*
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index af5732f9e489..7457a16b744f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -207,7 +207,7 @@ static void ttm_transfered_destroy(struct ttm_buffer_object *bo)
 	struct ttm_transfer_obj *fbo;
 
 	fbo = container_of(bo, struct ttm_transfer_obj, base);
-	dma_resv_put(&fbo->base.base._resv);
+	dma_resv_put(fbo->base.individual_resv);
 	ttm_bo_put(fbo->bo);
 	kfree(fbo);
 }
@@ -237,12 +237,23 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 	if (!fbo)
 		return -ENOMEM;
 
-	fbo->base = *bo;
 
 	/**
 	 * Fix up members that we shouldn't copy directly:
 	 * TODO: Explicit member copy would probably be better here.
 	 */
+	fbo->base = *bo;
+
+	fbo->base.individual_resv = dma_resv_alloc();
+	if (!fbo->base.individual_resv) {
+		ret = -ENOMEM;
+		goto error_free;
+	}
+
+	if (bo->type != ttm_bo_type_sg)
+		fbo->base.base.resv = dma_resv_get(fbo->base.individual_resv);
+	else
+		dma_resv_get(fbo->base.base.resv);
 
 	atomic_inc(&ttm_glob.bo_count);
 	drm_vma_node_reset(&fbo->base.base.vma_node);
@@ -250,19 +261,16 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 	kref_init(&fbo->base.kref);
 	fbo->base.destroy = &ttm_transfered_destroy;
 	fbo->base.pin_count = 0;
-	if (bo->type != ttm_bo_type_sg)
-		fbo->base.base.resv = &fbo->base.base._resv;
 
-	dma_resv_init(&fbo->base.base._resv);
 	fbo->base.base.dev = NULL;
-	ret = dma_resv_trylock(&fbo->base.base._resv);
+	ret = dma_resv_trylock(fbo->base.individual_resv);
 	WARN_ON(!ret);
 
-	ret = dma_resv_reserve_fences(&fbo->base.base._resv, TTM_NUM_MOVE_FENCES);
+	ret = dma_resv_reserve_fences(fbo->base.individual_resv,
+				      TTM_NUM_MOVE_FENCES);
 	if (ret) {
-		dma_resv_unlock(&fbo->base.base._resv);
-		kfree(fbo);
-		return ret;
+		dma_resv_unlock(fbo->base.individual_resv);
+		goto error_unref;
 	}
 
 	if (fbo->base.resource) {
@@ -280,6 +288,14 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 
 	*new_obj = &fbo->base;
 	return 0;
+
+error_unref:
+	dma_resv_put(fbo->base.individual_resv);
+	dma_resv_put(fbo->base.base.resv);
+
+error_free:
+	kfree(fbo);
+	return ret;
 }
 
 /**
@@ -617,7 +633,7 @@ static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
 	if (ret)
 		return ret;
 
-	dma_resv_add_fence(&ghost_obj->base._resv, fence,
+	dma_resv_add_fence(ghost_obj->individual_resv, fence,
 			   DMA_RESV_USAGE_KERNEL);
 
 	/**
@@ -631,7 +647,7 @@ static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
 	else
 		bo->ttm = NULL;
 
-	dma_resv_unlock(&ghost_obj->base._resv);
+	dma_resv_unlock(ghost_obj->individual_resv);
 	ttm_bo_put(ghost_obj);
 	return 0;
 }
@@ -801,14 +817,14 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 	if (ret)
 		goto error_destroy_tt;
 
-	ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
+	ret = dma_resv_copy_fences(ghost->individual_resv, bo->base.resv);
 	/* Last resort, wait for the BO to be idle when we are OOM */
 	if (ret) {
 		dma_resv_wait_timeout(bo->base.resv, DMA_RESV_USAGE_BOOKKEEP,
 				      false, MAX_SCHEDULE_TIMEOUT);
 	}
 
-	dma_resv_unlock(&ghost->base._resv);
+	dma_resv_unlock(ghost->individual_resv);
 	ttm_bo_put(ghost);
 	bo->ttm = ttm;
 	return 0;
diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index 41b404cdd680..37e9e7ce6574 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -1660,7 +1660,7 @@ static bool xe_ttm_bo_lock_in_destructor(struct ttm_buffer_object *ttm_bo)
 	 * always succeed here, as long as we hold the lru lock.
 	 */
 	spin_lock(&ttm_bo->bdev->lru_lock);
-	locked = dma_resv_trylock(&ttm_bo->base._resv);
+	locked = dma_resv_trylock(ttm_bo->individual_resv);
 	spin_unlock(&ttm_bo->bdev->lru_lock);
 	xe_assert(xe, locked);
 
@@ -1689,14 +1689,14 @@ static void xe_ttm_bo_release_notify(struct ttm_buffer_object *ttm_bo)
 	 * TODO: Don't do this for external bos once we scrub them after
 	 * unbind.
 	 */
-	dma_resv_for_each_fence(&cursor, &ttm_bo->base._resv,
+	dma_resv_for_each_fence(&cursor, ttm_bo->individual_resv,
 				DMA_RESV_USAGE_BOOKKEEP, fence) {
 		if (xe_fence_is_xe_preempt(fence) &&
 		    !dma_fence_is_signaled(fence)) {
 			if (!replacement)
 				replacement = dma_fence_get_stub();
 
-			dma_resv_replace_fences(&ttm_bo->base._resv,
+			dma_resv_replace_fences(ttm_bo->individual_resv,
 						fence->context,
 						replacement,
 						DMA_RESV_USAGE_BOOKKEEP);
@@ -1704,7 +1704,7 @@ static void xe_ttm_bo_release_notify(struct ttm_buffer_object *ttm_bo)
 	}
 	dma_fence_put(replacement);
 
-	dma_resv_unlock(&ttm_bo->base._resv);
+	dma_resv_unlock(ttm_bo->individual_resv);
 }
 
 static void xe_ttm_bo_delete_mem_notify(struct ttm_buffer_object *ttm_bo)
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index f889232e8525..8aed680bfca2 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -385,15 +385,6 @@ struct drm_gem_object {
 	 */
 	struct dma_resv *resv;
 
-	/**
-	 * @_resv:
-	 *
-	 * A reservation object for this GEM object.
-	 *
-	 * This is unused for imported GEM objects.
-	 */
-	struct dma_resv _resv;
-
 	/**
 	 * @gpuva: Fields used by GPUVM to manage mappings pointing to this GEM object.
 	 *
diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
index 32791c4db2a9..f132caa9647f 100644
--- a/include/drm/ttm/ttm_bo.h
+++ b/include/drm/ttm/ttm_bo.h
@@ -77,6 +77,7 @@ enum ttm_bo_type {
  * @bdev: Pointer to the buffer object device structure.
  * @type: The bo type.
  * @page_alignment: Page alignment.
+ * @individual_resv: Individual resv for destruction
  * @destroy: Destruction function. If NULL, kfree is used.
  * @kref: Reference count of this buffer object. When this refcount reaches
  * zero, the object is destroyed or put on the delayed delete list.
@@ -107,6 +108,7 @@ struct ttm_buffer_object {
 	struct ttm_device *bdev;
 	enum ttm_bo_type type;
 	uint32_t page_alignment;
+	struct dma_resv *individual_resv;
 	void (*destroy) (struct ttm_buffer_object *);
 
 	/*
-- 
2.43.0