drm/vmwgfx: Switch to exclusively using GEM references

Currently we use a combination of TTM and GEM reference counting which is
cumbersome. TTM references are used for kernel internal BOs and operations
like validation. Simply switching the ttm_bo_(get|put) calls to their
GEM equivalents is insufficient as not all BOs are GEM BOs so we must set
the GEM vtable for all BOs even if they are not exposed to userspace.

Suggested-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Ian Forbes <ian.forbes@broadcom.com>
Reviewed-by: Zack Rusin <zack.rusin@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250131200321.193939-1-ian.forbes@broadcom.com

drivers/gpu/drm/vmwgfx/vmwgfx_bo.c

@@ -36,8 +36,7 @@ static void vmw_bo_release(struct vmw_bo *vbo)
 {
 	struct vmw_resource *res;
 
-	WARN_ON(vbo->tbo.base.funcs &&
-		kref_read(&vbo->tbo.base.refcount) != 0);
+	WARN_ON(kref_read(&vbo->tbo.base.refcount) != 0);
 	vmw_bo_unmap(vbo);
 
 	xa_destroy(&vbo->detached_resources);
@@ -469,6 +468,7 @@ int vmw_bo_create(struct vmw_private *vmw,
 	if (unlikely(ret != 0))
 		goto out_error;
 
+	(*p_bo)->tbo.base.funcs = &vmw_gem_object_funcs;
 	return ret;
 out_error:
 	*p_bo = NULL;

drivers/gpu/drm/vmwgfx/vmwgfx_bo.h

@@ -204,12 +204,12 @@ static inline void vmw_bo_unreference(struct vmw_bo **buf)
 
 	*buf = NULL;
 	if (tmp_buf)
-		ttm_bo_put(&tmp_buf->tbo);
+		drm_gem_object_put(&tmp_buf->tbo.base);
 }
 
 static inline struct vmw_bo *vmw_bo_reference(struct vmw_bo *buf)
 {
-	ttm_bo_get(&buf->tbo);
+	drm_gem_object_get(&buf->tbo.base);
 	return buf;
 }
 

drivers/gpu/drm/vmwgfx/vmwgfx_cotable.c

@@ -432,7 +432,7 @@ static int vmw_cotable_resize(struct vmw_resource *res, size_t new_size)
 	 * for the new COTable. Initially pin the buffer object to make sure
 	 * we can use tryreserve without failure.
 	 */
-	ret = vmw_gem_object_create(dev_priv, &bo_params, &buf);
+	ret = vmw_bo_create(dev_priv, &bo_params, &buf);
 	if (ret) {
 		DRM_ERROR("Failed initializing new cotable MOB.\n");
 		goto out_done;

drivers/gpu/drm/vmwgfx/vmwgfx_drv.h

@@ -822,9 +822,7 @@ static inline bool vmw_resource_mob_attached(const struct vmw_resource *res)
  * GEM related functionality - vmwgfx_gem.c
  */
 struct vmw_bo_params;
-int vmw_gem_object_create(struct vmw_private *vmw,
-			  struct vmw_bo_params *params,
-			  struct vmw_bo **p_vbo);
+extern const struct drm_gem_object_funcs vmw_gem_object_funcs;
 extern int vmw_gem_object_create_with_handle(struct vmw_private *dev_priv,
 					     struct drm_file *filp,
 					     uint32_t size,

drivers/gpu/drm/vmwgfx/vmwgfx_gem.c

@@ -140,7 +140,7 @@ static const struct vm_operations_struct vmw_vm_ops = {
 	.close = ttm_bo_vm_close,
 };
 
-static const struct drm_gem_object_funcs vmw_gem_object_funcs = {
+const struct drm_gem_object_funcs vmw_gem_object_funcs = {
 	.free = vmw_gem_object_free,
 	.open = vmw_gem_object_open,
 	.close = vmw_gem_object_close,
@@ -154,20 +154,6 @@ static const struct drm_gem_object_funcs vmw_gem_object_funcs = {
 	.vm_ops = &vmw_vm_ops,
 };
 
-int vmw_gem_object_create(struct vmw_private *vmw,
-			  struct vmw_bo_params *params,
-			  struct vmw_bo **p_vbo)
-{
-	int ret = vmw_bo_create(vmw, params, p_vbo);
-
-	if (ret != 0)
-		goto out_no_bo;
-
-	(*p_vbo)->tbo.base.funcs = &vmw_gem_object_funcs;
-out_no_bo:
-	return ret;
-}
-
 int vmw_gem_object_create_with_handle(struct vmw_private *dev_priv,
 				      struct drm_file *filp,
 				      uint32_t size,
@@ -183,7 +169,7 @@ int vmw_gem_object_create_with_handle(struct vmw_private *dev_priv,
 		.pin = false
 	};
 
-	ret = vmw_gem_object_create(dev_priv, &params, p_vbo);
+	ret = vmw_bo_create(dev_priv, &params, p_vbo);
 	if (ret != 0)
 		goto out_no_bo;
 

drivers/gpu/drm/vmwgfx/vmwgfx_mob.c

@@ -282,8 +282,7 @@ out_no_setup:
 	}
 
 	vmw_bo_unpin_unlocked(&batch->otable_bo->tbo);
-	ttm_bo_put(&batch->otable_bo->tbo);
-	batch->otable_bo = NULL;
+	vmw_bo_unreference(&batch->otable_bo);
 	return ret;
 }
 

drivers/gpu/drm/vmwgfx/vmwgfx_resource.c

@@ -347,7 +347,7 @@ static int vmw_resource_buf_alloc(struct vmw_resource *res,
 		return 0;
 	}
 
-	ret = vmw_gem_object_create(res->dev_priv, &bo_params, &gbo);
+	ret = vmw_bo_create(res->dev_priv, &bo_params, &gbo);
 	if (unlikely(ret != 0))
 		goto out_no_bo;
 
@@ -531,9 +531,9 @@ vmw_resource_check_buffer(struct ww_acquire_ctx *ticket,
 	}
 
 	INIT_LIST_HEAD(&val_list);
-	ttm_bo_get(&res->guest_memory_bo->tbo);
 	val_buf->bo = &res->guest_memory_bo->tbo;
 	val_buf->num_shared = 0;
+	drm_gem_object_get(&val_buf->bo->base);
 	list_add_tail(&val_buf->head, &val_list);
 	ret = ttm_eu_reserve_buffers(ticket, &val_list, interruptible, NULL);
 	if (unlikely(ret != 0))
@@ -557,7 +557,7 @@ vmw_resource_check_buffer(struct ww_acquire_ctx *ticket,
 out_no_validate:
 	ttm_eu_backoff_reservation(ticket, &val_list);
 out_no_reserve:
-	ttm_bo_put(val_buf->bo);
+	drm_gem_object_put(&val_buf->bo->base);
 	val_buf->bo = NULL;
 	if (guest_memory_dirty)
 		vmw_user_bo_unref(&res->guest_memory_bo);
@@ -619,7 +619,7 @@ vmw_resource_backoff_reservation(struct ww_acquire_ctx *ticket,
 	INIT_LIST_HEAD(&val_list);
 	list_add_tail(&val_buf->head, &val_list);
 	ttm_eu_backoff_reservation(ticket, &val_list);
-	ttm_bo_put(val_buf->bo);
+	drm_gem_object_put(&val_buf->bo->base);
 	val_buf->bo = NULL;
 }
 

drivers/gpu/drm/vmwgfx/vmwgfx_scrn.c

@@ -445,7 +445,7 @@ vmw_sou_primary_plane_prepare_fb(struct drm_plane *plane,
 	 * resume the overlays, this is preferred to failing to alloc.
 	 */
 	vmw_overlay_pause_all(dev_priv);
-	ret = vmw_gem_object_create(dev_priv, &bo_params, &vps->uo.buffer);
+	ret = vmw_bo_create(dev_priv, &bo_params, &vps->uo.buffer);
 	vmw_overlay_resume_all(dev_priv);
 	if (ret)
 		return ret;

drivers/gpu/drm/vmwgfx/vmwgfx_surface.c

@@ -830,9 +830,7 @@ int vmw_surface_define_ioctl(struct drm_device *dev, void *data,
 			.pin = false
 		};
 
-		ret = vmw_gem_object_create(dev_priv,
-					    &params,
-					    &res->guest_memory_bo);
+		ret = vmw_bo_create(dev_priv, &params, &res->guest_memory_bo);
 		if (unlikely(ret != 0)) {
 			vmw_resource_unreference(&res);
 			goto out_unlock;

drivers/gpu/drm/vmwgfx/vmwgfx_validation.c

@@ -262,9 +262,8 @@ int vmw_validation_add_bo(struct vmw_validation_context *ctx,
 				bo_node->hash.key);
 		}
 		val_buf = &bo_node->base;
-		val_buf->bo = ttm_bo_get_unless_zero(&vbo->tbo);
-		if (!val_buf->bo)
-			return -ESRCH;
+		vmw_bo_reference(vbo);
+		val_buf->bo = &vbo->tbo;
 		val_buf->num_shared = 0;
 		list_add_tail(&val_buf->head, &ctx->bo_list);
 	}
@@ -656,7 +655,7 @@ void vmw_validation_unref_lists(struct vmw_validation_context *ctx)
 	struct vmw_validation_res_node *val;
 
 	list_for_each_entry(entry, &ctx->bo_list, base.head) {
-		ttm_bo_put(entry->base.bo);
+		drm_gem_object_put(&entry->base.bo->base);
 		entry->base.bo = NULL;
 	}