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1 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
2 /**************************************************************************
3  *
4  * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
5  * All Rights Reserved.
6  *
7  * Permission is hereby granted, free of charge, to any person obtaining a
8  * copy of this software and associated documentation files (the
9  * "Software"), to deal in the Software without restriction, including
10  * without limitation the rights to use, copy, modify, merge, publish,
11  * distribute, sub license, and/or sell copies of the Software, and to
12  * permit persons to whom the Software is furnished to do so, subject to
13  * the following conditions:
14  *
15  * The above copyright notice and this permission notice (including the
16  * next paragraph) shall be included in all copies or substantial portions
17  * of the Software.
18  *
19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
22  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
23  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
24  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
25  * USE OR OTHER DEALINGS IN THE SOFTWARE.
26  *
27  **************************************************************************/
28 /*
29  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
30  */
31 
32 #include <drm/ttm/ttm_bo_driver.h>
33 #include <drm/ttm/ttm_placement.h>
34 #include <drm/drm_cache.h>
35 #include <drm/drm_vma_manager.h>
36 #include <linux/dma-buf-map.h>
37 #include <linux/io.h>
38 #include <linux/highmem.h>
39 #include <linux/wait.h>
40 #include <linux/slab.h>
41 #include <linux/vmalloc.h>
42 #include <linux/module.h>
43 #include <linux/dma-resv.h>
44 
45 struct ttm_transfer_obj {
46 	struct ttm_buffer_object base;
47 	struct ttm_buffer_object *bo;
48 };
49 
ttm_mem_io_reserve(struct ttm_device * bdev,struct ttm_resource * mem)50 int ttm_mem_io_reserve(struct ttm_device *bdev,
51 		       struct ttm_resource *mem)
52 {
53 	if (mem->bus.offset || mem->bus.addr)
54 		return 0;
55 
56 	mem->bus.is_iomem = false;
57 	if (!bdev->funcs->io_mem_reserve)
58 		return 0;
59 
60 	return bdev->funcs->io_mem_reserve(bdev, mem);
61 }
62 
ttm_mem_io_free(struct ttm_device * bdev,struct ttm_resource * mem)63 void ttm_mem_io_free(struct ttm_device *bdev,
64 		     struct ttm_resource *mem)
65 {
66 	if (!mem)
67 		return;
68 
69 	if (!mem->bus.offset && !mem->bus.addr)
70 		return;
71 
72 	if (bdev->funcs->io_mem_free)
73 		bdev->funcs->io_mem_free(bdev, mem);
74 
75 	mem->bus.offset = 0;
76 	mem->bus.addr = NULL;
77 }
78 
79 /**
80  * ttm_move_memcpy - Helper to perform a memcpy ttm move operation.
81  * @bo: The struct ttm_buffer_object.
82  * @new_mem: The struct ttm_resource we're moving to (copy destination).
83  * @new_iter: A struct ttm_kmap_iter representing the destination resource.
84  * @src_iter: A struct ttm_kmap_iter representing the source resource.
85  *
86  * This function is intended to be able to move out async under a
87  * dma-fence if desired.
88  */
ttm_move_memcpy(struct ttm_buffer_object * bo,u32 num_pages,struct ttm_kmap_iter * dst_iter,struct ttm_kmap_iter * src_iter)89 void ttm_move_memcpy(struct ttm_buffer_object *bo,
90 		     u32 num_pages,
91 		     struct ttm_kmap_iter *dst_iter,
92 		     struct ttm_kmap_iter *src_iter)
93 {
94 	const struct ttm_kmap_iter_ops *dst_ops = dst_iter->ops;
95 	const struct ttm_kmap_iter_ops *src_ops = src_iter->ops;
96 	struct ttm_tt *ttm = bo->ttm;
97 	struct dma_buf_map src_map, dst_map;
98 	pgoff_t i;
99 
100 	/* Single TTM move. NOP */
101 	if (dst_ops->maps_tt && src_ops->maps_tt)
102 		return;
103 
104 	/* Don't move nonexistent data. Clear destination instead. */
105 	if (src_ops->maps_tt && (!ttm || !ttm_tt_is_populated(ttm))) {
106 		if (ttm && !(ttm->page_flags & TTM_PAGE_FLAG_ZERO_ALLOC))
107 			return;
108 
109 		for (i = 0; i < num_pages; ++i) {
110 			dst_ops->map_local(dst_iter, &dst_map, i);
111 			if (dst_map.is_iomem)
112 				memset_io(dst_map.vaddr_iomem, 0, PAGE_SIZE);
113 			else
114 				memset(dst_map.vaddr, 0, PAGE_SIZE);
115 			if (dst_ops->unmap_local)
116 				dst_ops->unmap_local(dst_iter, &dst_map);
117 		}
118 		return;
119 	}
120 
121 	for (i = 0; i < num_pages; ++i) {
122 		dst_ops->map_local(dst_iter, &dst_map, i);
123 		src_ops->map_local(src_iter, &src_map, i);
124 
125 		drm_memcpy_from_wc(&dst_map, &src_map, PAGE_SIZE);
126 
127 		if (src_ops->unmap_local)
128 			src_ops->unmap_local(src_iter, &src_map);
129 		if (dst_ops->unmap_local)
130 			dst_ops->unmap_local(dst_iter, &dst_map);
131 	}
132 }
133 EXPORT_SYMBOL(ttm_move_memcpy);
134 
ttm_bo_move_memcpy(struct ttm_buffer_object * bo,struct ttm_operation_ctx * ctx,struct ttm_resource * dst_mem)135 int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
136 		       struct ttm_operation_ctx *ctx,
137 		       struct ttm_resource *dst_mem)
138 {
139 	struct ttm_device *bdev = bo->bdev;
140 	struct ttm_resource_manager *dst_man =
141 		ttm_manager_type(bo->bdev, dst_mem->mem_type);
142 	struct ttm_tt *ttm = bo->ttm;
143 	struct ttm_resource *src_mem = bo->resource;
144 	struct ttm_resource_manager *src_man =
145 		ttm_manager_type(bdev, src_mem->mem_type);
146 	union {
147 		struct ttm_kmap_iter_tt tt;
148 		struct ttm_kmap_iter_linear_io io;
149 	} _dst_iter, _src_iter;
150 	struct ttm_kmap_iter *dst_iter, *src_iter;
151 	int ret = 0;
152 
153 	if (ttm && ((ttm->page_flags & TTM_PAGE_FLAG_SWAPPED) ||
154 		    dst_man->use_tt)) {
155 		ret = ttm_tt_populate(bdev, ttm, ctx);
156 		if (ret)
157 			return ret;
158 	}
159 
160 	dst_iter = ttm_kmap_iter_linear_io_init(&_dst_iter.io, bdev, dst_mem);
161 	if (PTR_ERR(dst_iter) == -EINVAL && dst_man->use_tt)
162 		dst_iter = ttm_kmap_iter_tt_init(&_dst_iter.tt, bo->ttm);
163 	if (IS_ERR(dst_iter))
164 		return PTR_ERR(dst_iter);
165 
166 	src_iter = ttm_kmap_iter_linear_io_init(&_src_iter.io, bdev, src_mem);
167 	if (PTR_ERR(src_iter) == -EINVAL && src_man->use_tt)
168 		src_iter = ttm_kmap_iter_tt_init(&_src_iter.tt, bo->ttm);
169 	if (IS_ERR(src_iter)) {
170 		ret = PTR_ERR(src_iter);
171 		goto out_src_iter;
172 	}
173 
174 	ttm_move_memcpy(bo, dst_mem->num_pages, dst_iter, src_iter);
175 
176 	if (!src_iter->ops->maps_tt)
177 		ttm_kmap_iter_linear_io_fini(&_src_iter.io, bdev, src_mem);
178 	ttm_bo_move_sync_cleanup(bo, dst_mem);
179 
180 out_src_iter:
181 	if (!dst_iter->ops->maps_tt)
182 		ttm_kmap_iter_linear_io_fini(&_dst_iter.io, bdev, dst_mem);
183 
184 	return ret;
185 }
186 EXPORT_SYMBOL(ttm_bo_move_memcpy);
187 
ttm_transfered_destroy(struct ttm_buffer_object * bo)188 static void ttm_transfered_destroy(struct ttm_buffer_object *bo)
189 {
190 	struct ttm_transfer_obj *fbo;
191 
192 	fbo = container_of(bo, struct ttm_transfer_obj, base);
193 	dma_resv_fini(&fbo->base.base._resv);
194 	ttm_bo_put(fbo->bo);
195 	kfree(fbo);
196 }
197 
198 /**
199  * ttm_buffer_object_transfer
200  *
201  * @bo: A pointer to a struct ttm_buffer_object.
202  * @new_obj: A pointer to a pointer to a newly created ttm_buffer_object,
203  * holding the data of @bo with the old placement.
204  *
205  * This is a utility function that may be called after an accelerated move
206  * has been scheduled. A new buffer object is created as a placeholder for
207  * the old data while it's being copied. When that buffer object is idle,
208  * it can be destroyed, releasing the space of the old placement.
209  * Returns:
210  * !0: Failure.
211  */
212 
ttm_buffer_object_transfer(struct ttm_buffer_object * bo,struct ttm_buffer_object ** new_obj)213 static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
214 				      struct ttm_buffer_object **new_obj)
215 {
216 	struct ttm_transfer_obj *fbo;
217 	int ret;
218 
219 	fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);
220 	if (!fbo)
221 		return -ENOMEM;
222 
223 	fbo->base = *bo;
224 
225 	ttm_bo_get(bo);
226 	fbo->bo = bo;
227 
228 	/**
229 	 * Fix up members that we shouldn't copy directly:
230 	 * TODO: Explicit member copy would probably be better here.
231 	 */
232 
233 	atomic_inc(&ttm_glob.bo_count);
234 	INIT_LIST_HEAD(&fbo->base.ddestroy);
235 	INIT_LIST_HEAD(&fbo->base.lru);
236 	fbo->base.moving = NULL;
237 	drm_vma_node_reset(&fbo->base.base.vma_node);
238 
239 	kref_init(&fbo->base.kref);
240 	fbo->base.destroy = &ttm_transfered_destroy;
241 	fbo->base.pin_count = 0;
242 	if (bo->type != ttm_bo_type_sg)
243 		fbo->base.base.resv = &fbo->base.base._resv;
244 
245 	dma_resv_init(&fbo->base.base._resv);
246 	fbo->base.base.dev = NULL;
247 	ret = dma_resv_trylock(&fbo->base.base._resv);
248 	WARN_ON(!ret);
249 
250 	ttm_bo_move_to_lru_tail_unlocked(&fbo->base);
251 
252 	*new_obj = &fbo->base;
253 	return 0;
254 }
255 
ttm_io_prot(struct ttm_buffer_object * bo,struct ttm_resource * res,pgprot_t tmp)256 pgprot_t ttm_io_prot(struct ttm_buffer_object *bo, struct ttm_resource *res,
257 		     pgprot_t tmp)
258 {
259 	struct ttm_resource_manager *man;
260 	enum ttm_caching caching;
261 
262 	man = ttm_manager_type(bo->bdev, res->mem_type);
263 	caching = man->use_tt ? bo->ttm->caching : res->bus.caching;
264 
265 	return ttm_prot_from_caching(caching, tmp);
266 }
267 EXPORT_SYMBOL(ttm_io_prot);
268 
ttm_bo_ioremap(struct ttm_buffer_object * bo,unsigned long offset,unsigned long size,struct ttm_bo_kmap_obj * map)269 static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
270 			  unsigned long offset,
271 			  unsigned long size,
272 			  struct ttm_bo_kmap_obj *map)
273 {
274 	struct ttm_resource *mem = bo->resource;
275 
276 	if (bo->resource->bus.addr) {
277 		map->bo_kmap_type = ttm_bo_map_premapped;
278 		map->virtual = ((u8 *)bo->resource->bus.addr) + offset;
279 	} else {
280 		resource_size_t res = bo->resource->bus.offset + offset;
281 
282 		map->bo_kmap_type = ttm_bo_map_iomap;
283 		if (mem->bus.caching == ttm_write_combined)
284 			map->virtual = ioremap_wc(res, size);
285 #ifdef CONFIG_X86
286 		else if (mem->bus.caching == ttm_cached)
287 			map->virtual = ioremap_cache(res, size);
288 #endif
289 		else
290 			map->virtual = ioremap(res, size);
291 	}
292 	return (!map->virtual) ? -ENOMEM : 0;
293 }
294 
ttm_bo_kmap_ttm(struct ttm_buffer_object * bo,unsigned long start_page,unsigned long num_pages,struct ttm_bo_kmap_obj * map)295 static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
296 			   unsigned long start_page,
297 			   unsigned long num_pages,
298 			   struct ttm_bo_kmap_obj *map)
299 {
300 	struct ttm_resource *mem = bo->resource;
301 	struct ttm_operation_ctx ctx = {
302 		.interruptible = false,
303 		.no_wait_gpu = false
304 	};
305 	struct ttm_tt *ttm = bo->ttm;
306 	pgprot_t prot;
307 	int ret;
308 
309 	BUG_ON(!ttm);
310 
311 	ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
312 	if (ret)
313 		return ret;
314 
315 	if (num_pages == 1 && ttm->caching == ttm_cached) {
316 		/*
317 		 * We're mapping a single page, and the desired
318 		 * page protection is consistent with the bo.
319 		 */
320 
321 		map->bo_kmap_type = ttm_bo_map_kmap;
322 		map->page = ttm->pages[start_page];
323 		map->virtual = kmap(map->page);
324 	} else {
325 		/*
326 		 * We need to use vmap to get the desired page protection
327 		 * or to make the buffer object look contiguous.
328 		 */
329 		prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
330 		map->bo_kmap_type = ttm_bo_map_vmap;
331 		map->virtual = vmap(ttm->pages + start_page, num_pages,
332 				    0, prot);
333 	}
334 	return (!map->virtual) ? -ENOMEM : 0;
335 }
336 
ttm_bo_kmap(struct ttm_buffer_object * bo,unsigned long start_page,unsigned long num_pages,struct ttm_bo_kmap_obj * map)337 int ttm_bo_kmap(struct ttm_buffer_object *bo,
338 		unsigned long start_page, unsigned long num_pages,
339 		struct ttm_bo_kmap_obj *map)
340 {
341 	unsigned long offset, size;
342 	int ret;
343 
344 	map->virtual = NULL;
345 	map->bo = bo;
346 	if (num_pages > bo->resource->num_pages)
347 		return -EINVAL;
348 	if ((start_page + num_pages) > bo->resource->num_pages)
349 		return -EINVAL;
350 
351 	ret = ttm_mem_io_reserve(bo->bdev, bo->resource);
352 	if (ret)
353 		return ret;
354 	if (!bo->resource->bus.is_iomem) {
355 		return ttm_bo_kmap_ttm(bo, start_page, num_pages, map);
356 	} else {
357 		offset = start_page << PAGE_SHIFT;
358 		size = num_pages << PAGE_SHIFT;
359 		return ttm_bo_ioremap(bo, offset, size, map);
360 	}
361 }
362 EXPORT_SYMBOL(ttm_bo_kmap);
363 
ttm_bo_kunmap(struct ttm_bo_kmap_obj * map)364 void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
365 {
366 	if (!map->virtual)
367 		return;
368 	switch (map->bo_kmap_type) {
369 	case ttm_bo_map_iomap:
370 		iounmap(map->virtual);
371 		break;
372 	case ttm_bo_map_vmap:
373 		vunmap(map->virtual);
374 		break;
375 	case ttm_bo_map_kmap:
376 		kunmap(map->page);
377 		break;
378 	case ttm_bo_map_premapped:
379 		break;
380 	default:
381 		BUG();
382 	}
383 	ttm_mem_io_free(map->bo->bdev, map->bo->resource);
384 	map->virtual = NULL;
385 	map->page = NULL;
386 }
387 EXPORT_SYMBOL(ttm_bo_kunmap);
388 
ttm_bo_vmap(struct ttm_buffer_object * bo,struct dma_buf_map * map)389 int ttm_bo_vmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
390 {
391 	struct ttm_resource *mem = bo->resource;
392 	int ret;
393 
394 	ret = ttm_mem_io_reserve(bo->bdev, mem);
395 	if (ret)
396 		return ret;
397 
398 	if (mem->bus.is_iomem) {
399 		void __iomem *vaddr_iomem;
400 
401 		if (mem->bus.addr)
402 			vaddr_iomem = (void __iomem *)mem->bus.addr;
403 		else if (mem->bus.caching == ttm_write_combined)
404 			vaddr_iomem = ioremap_wc(mem->bus.offset,
405 						 bo->base.size);
406 #ifdef CONFIG_X86
407 		else if (mem->bus.caching == ttm_cached)
408 			vaddr_iomem = ioremap_cache(mem->bus.offset,
409 						  bo->base.size);
410 #endif
411 		else
412 			vaddr_iomem = ioremap(mem->bus.offset, bo->base.size);
413 
414 		if (!vaddr_iomem)
415 			return -ENOMEM;
416 
417 		dma_buf_map_set_vaddr_iomem(map, vaddr_iomem);
418 
419 	} else {
420 		struct ttm_operation_ctx ctx = {
421 			.interruptible = false,
422 			.no_wait_gpu = false
423 		};
424 		struct ttm_tt *ttm = bo->ttm;
425 		pgprot_t prot;
426 		void *vaddr;
427 
428 		ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
429 		if (ret)
430 			return ret;
431 
432 		/*
433 		 * We need to use vmap to get the desired page protection
434 		 * or to make the buffer object look contiguous.
435 		 */
436 		prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
437 		vaddr = vmap(ttm->pages, ttm->num_pages, 0, prot);
438 		if (!vaddr)
439 			return -ENOMEM;
440 
441 		dma_buf_map_set_vaddr(map, vaddr);
442 	}
443 
444 	return 0;
445 }
446 EXPORT_SYMBOL(ttm_bo_vmap);
447 
ttm_bo_vunmap(struct ttm_buffer_object * bo,struct dma_buf_map * map)448 void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
449 {
450 	struct ttm_resource *mem = bo->resource;
451 
452 	if (dma_buf_map_is_null(map))
453 		return;
454 
455 	if (!map->is_iomem)
456 		vunmap(map->vaddr);
457 	else if (!mem->bus.addr)
458 		iounmap(map->vaddr_iomem);
459 	dma_buf_map_clear(map);
460 
461 	ttm_mem_io_free(bo->bdev, bo->resource);
462 }
463 EXPORT_SYMBOL(ttm_bo_vunmap);
464 
ttm_bo_wait_free_node(struct ttm_buffer_object * bo,bool dst_use_tt)465 static int ttm_bo_wait_free_node(struct ttm_buffer_object *bo,
466 				 bool dst_use_tt)
467 {
468 	int ret;
469 	ret = ttm_bo_wait(bo, false, false);
470 	if (ret)
471 		return ret;
472 
473 	if (!dst_use_tt)
474 		ttm_bo_tt_destroy(bo);
475 	ttm_resource_free(bo, &bo->resource);
476 	return 0;
477 }
478 
ttm_bo_move_to_ghost(struct ttm_buffer_object * bo,struct dma_fence * fence,bool dst_use_tt)479 static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
480 				struct dma_fence *fence,
481 				bool dst_use_tt)
482 {
483 	struct ttm_buffer_object *ghost_obj;
484 	int ret;
485 
486 	/**
487 	 * This should help pipeline ordinary buffer moves.
488 	 *
489 	 * Hang old buffer memory on a new buffer object,
490 	 * and leave it to be released when the GPU
491 	 * operation has completed.
492 	 */
493 
494 	dma_fence_put(bo->moving);
495 	bo->moving = dma_fence_get(fence);
496 
497 	ret = ttm_buffer_object_transfer(bo, &ghost_obj);
498 	if (ret)
499 		return ret;
500 
501 	dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);
502 
503 	/**
504 	 * If we're not moving to fixed memory, the TTM object
505 	 * needs to stay alive. Otherwhise hang it on the ghost
506 	 * bo to be unbound and destroyed.
507 	 */
508 
509 	if (dst_use_tt)
510 		ghost_obj->ttm = NULL;
511 	else
512 		bo->ttm = NULL;
513 	bo->resource = NULL;
514 
515 	dma_resv_unlock(&ghost_obj->base._resv);
516 	ttm_bo_put(ghost_obj);
517 	return 0;
518 }
519 
ttm_bo_move_pipeline_evict(struct ttm_buffer_object * bo,struct dma_fence * fence)520 static void ttm_bo_move_pipeline_evict(struct ttm_buffer_object *bo,
521 				       struct dma_fence *fence)
522 {
523 	struct ttm_device *bdev = bo->bdev;
524 	struct ttm_resource_manager *from;
525 
526 	from = ttm_manager_type(bdev, bo->resource->mem_type);
527 
528 	/**
529 	 * BO doesn't have a TTM we need to bind/unbind. Just remember
530 	 * this eviction and free up the allocation
531 	 */
532 	spin_lock(&from->move_lock);
533 	if (!from->move || dma_fence_is_later(fence, from->move)) {
534 		dma_fence_put(from->move);
535 		from->move = dma_fence_get(fence);
536 	}
537 	spin_unlock(&from->move_lock);
538 
539 	ttm_resource_free(bo, &bo->resource);
540 
541 	dma_fence_put(bo->moving);
542 	bo->moving = dma_fence_get(fence);
543 }
544 
ttm_bo_move_accel_cleanup(struct ttm_buffer_object * bo,struct dma_fence * fence,bool evict,bool pipeline,struct ttm_resource * new_mem)545 int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
546 			      struct dma_fence *fence,
547 			      bool evict,
548 			      bool pipeline,
549 			      struct ttm_resource *new_mem)
550 {
551 	struct ttm_device *bdev = bo->bdev;
552 	struct ttm_resource_manager *from = ttm_manager_type(bdev, bo->resource->mem_type);
553 	struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
554 	int ret = 0;
555 
556 	dma_resv_add_excl_fence(bo->base.resv, fence);
557 	if (!evict)
558 		ret = ttm_bo_move_to_ghost(bo, fence, man->use_tt);
559 	else if (!from->use_tt && pipeline)
560 		ttm_bo_move_pipeline_evict(bo, fence);
561 	else
562 		ret = ttm_bo_wait_free_node(bo, man->use_tt);
563 
564 	if (ret)
565 		return ret;
566 
567 	ttm_bo_assign_mem(bo, new_mem);
568 
569 	return 0;
570 }
571 EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);
572 
573 /**
574  * ttm_bo_pipeline_gutting - purge the contents of a bo
575  * @bo: The buffer object
576  *
577  * Purge the contents of a bo, async if the bo is not idle.
578  * After a successful call, the bo is left unpopulated in
579  * system placement. The function may wait uninterruptible
580  * for idle on OOM.
581  *
582  * Return: 0 if successful, negative error code on failure.
583  */
ttm_bo_pipeline_gutting(struct ttm_buffer_object * bo)584 int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
585 {
586 	static const struct ttm_place sys_mem = { .mem_type = TTM_PL_SYSTEM };
587 	struct ttm_buffer_object *ghost;
588 	struct ttm_resource *sys_res;
589 	struct ttm_tt *ttm;
590 	int ret;
591 
592 	ret = ttm_resource_alloc(bo, &sys_mem, &sys_res);
593 	if (ret)
594 		return ret;
595 
596 	/* If already idle, no need for ghost object dance. */
597 	ret = ttm_bo_wait(bo, false, true);
598 	if (ret != -EBUSY) {
599 		if (!bo->ttm) {
600 			/* See comment below about clearing. */
601 			ret = ttm_tt_create(bo, true);
602 			if (ret)
603 				goto error_free_sys_mem;
604 		} else {
605 			ttm_tt_unpopulate(bo->bdev, bo->ttm);
606 			if (bo->type == ttm_bo_type_device)
607 				ttm_tt_mark_for_clear(bo->ttm);
608 		}
609 		ttm_resource_free(bo, &bo->resource);
610 		ttm_bo_assign_mem(bo, sys_res);
611 		return 0;
612 	}
613 
614 	/*
615 	 * We need an unpopulated ttm_tt after giving our current one,
616 	 * if any, to the ghost object. And we can't afford to fail
617 	 * creating one *after* the operation. If the bo subsequently gets
618 	 * resurrected, make sure it's cleared (if ttm_bo_type_device)
619 	 * to avoid leaking sensitive information to user-space.
620 	 */
621 
622 	ttm = bo->ttm;
623 	bo->ttm = NULL;
624 	ret = ttm_tt_create(bo, true);
625 	swap(bo->ttm, ttm);
626 	if (ret)
627 		goto error_free_sys_mem;
628 
629 	ret = ttm_buffer_object_transfer(bo, &ghost);
630 	if (ret)
631 		goto error_destroy_tt;
632 
633 	ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
634 	/* Last resort, wait for the BO to be idle when we are OOM */
635 	if (ret)
636 		ttm_bo_wait(bo, false, false);
637 
638 	dma_resv_unlock(&ghost->base._resv);
639 	ttm_bo_put(ghost);
640 	bo->ttm = ttm;
641 	bo->resource = NULL;
642 	ttm_bo_assign_mem(bo, sys_res);
643 	return 0;
644 
645 error_destroy_tt:
646 	ttm_tt_destroy(bo->bdev, ttm);
647 
648 error_free_sys_mem:
649 	ttm_resource_free(bo, &sys_res);
650 	return ret;
651 }
652