xref: /openbmc/linux/drivers/gpu/drm/ttm/ttm_bo_util.c (revision 7f9321ff)
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_vma_manager.h>
35 #include <linux/dma-buf-map.h>
36 #include <linux/io.h>
37 #include <linux/highmem.h>
38 #include <linux/wait.h>
39 #include <linux/slab.h>
40 #include <linux/vmalloc.h>
41 #include <linux/module.h>
42 #include <linux/dma-resv.h>
43 
44 struct ttm_transfer_obj {
45 	struct ttm_buffer_object base;
46 	struct ttm_buffer_object *bo;
47 };
48 
49 int ttm_mem_io_reserve(struct ttm_device *bdev,
50 		       struct ttm_resource *mem)
51 {
52 	if (mem->bus.offset || mem->bus.addr)
53 		return 0;
54 
55 	mem->bus.is_iomem = false;
56 	if (!bdev->funcs->io_mem_reserve)
57 		return 0;
58 
59 	return bdev->funcs->io_mem_reserve(bdev, mem);
60 }
61 
62 void ttm_mem_io_free(struct ttm_device *bdev,
63 		     struct ttm_resource *mem)
64 {
65 	if (!mem->bus.offset && !mem->bus.addr)
66 		return;
67 
68 	if (bdev->funcs->io_mem_free)
69 		bdev->funcs->io_mem_free(bdev, mem);
70 
71 	mem->bus.offset = 0;
72 	mem->bus.addr = NULL;
73 }
74 
75 static int ttm_resource_ioremap(struct ttm_device *bdev,
76 			       struct ttm_resource *mem,
77 			       void **virtual)
78 {
79 	int ret;
80 	void *addr;
81 
82 	*virtual = NULL;
83 	ret = ttm_mem_io_reserve(bdev, mem);
84 	if (ret || !mem->bus.is_iomem)
85 		return ret;
86 
87 	if (mem->bus.addr) {
88 		addr = mem->bus.addr;
89 	} else {
90 		size_t bus_size = (size_t)mem->num_pages << PAGE_SHIFT;
91 
92 		if (mem->bus.caching == ttm_write_combined)
93 			addr = ioremap_wc(mem->bus.offset, bus_size);
94 		else
95 			addr = ioremap(mem->bus.offset, bus_size);
96 		if (!addr) {
97 			ttm_mem_io_free(bdev, mem);
98 			return -ENOMEM;
99 		}
100 	}
101 	*virtual = addr;
102 	return 0;
103 }
104 
105 static void ttm_resource_iounmap(struct ttm_device *bdev,
106 				struct ttm_resource *mem,
107 				void *virtual)
108 {
109 	if (virtual && mem->bus.addr == NULL)
110 		iounmap(virtual);
111 	ttm_mem_io_free(bdev, mem);
112 }
113 
114 static int ttm_copy_io_page(void *dst, void *src, unsigned long page)
115 {
116 	uint32_t *dstP =
117 	    (uint32_t *) ((unsigned long)dst + (page << PAGE_SHIFT));
118 	uint32_t *srcP =
119 	    (uint32_t *) ((unsigned long)src + (page << PAGE_SHIFT));
120 
121 	int i;
122 	for (i = 0; i < PAGE_SIZE / sizeof(uint32_t); ++i)
123 		iowrite32(ioread32(srcP++), dstP++);
124 	return 0;
125 }
126 
127 static int ttm_copy_io_ttm_page(struct ttm_tt *ttm, void *src,
128 				unsigned long page,
129 				pgprot_t prot)
130 {
131 	struct page *d = ttm->pages[page];
132 	void *dst;
133 
134 	if (!d)
135 		return -ENOMEM;
136 
137 	src = (void *)((unsigned long)src + (page << PAGE_SHIFT));
138 	dst = kmap_atomic_prot(d, prot);
139 	if (!dst)
140 		return -ENOMEM;
141 
142 	memcpy_fromio(dst, src, PAGE_SIZE);
143 
144 	kunmap_atomic(dst);
145 
146 	return 0;
147 }
148 
149 static int ttm_copy_ttm_io_page(struct ttm_tt *ttm, void *dst,
150 				unsigned long page,
151 				pgprot_t prot)
152 {
153 	struct page *s = ttm->pages[page];
154 	void *src;
155 
156 	if (!s)
157 		return -ENOMEM;
158 
159 	dst = (void *)((unsigned long)dst + (page << PAGE_SHIFT));
160 	src = kmap_atomic_prot(s, prot);
161 	if (!src)
162 		return -ENOMEM;
163 
164 	memcpy_toio(dst, src, PAGE_SIZE);
165 
166 	kunmap_atomic(src);
167 
168 	return 0;
169 }
170 
171 int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
172 		       struct ttm_operation_ctx *ctx,
173 		       struct ttm_resource *new_mem)
174 {
175 	struct ttm_device *bdev = bo->bdev;
176 	struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
177 	struct ttm_tt *ttm = bo->ttm;
178 	struct ttm_resource *old_mem = &bo->mem;
179 	struct ttm_resource old_copy = *old_mem;
180 	void *old_iomap;
181 	void *new_iomap;
182 	int ret;
183 	unsigned long i;
184 
185 	ret = ttm_bo_wait_ctx(bo, ctx);
186 	if (ret)
187 		return ret;
188 
189 	ret = ttm_resource_ioremap(bdev, old_mem, &old_iomap);
190 	if (ret)
191 		return ret;
192 	ret = ttm_resource_ioremap(bdev, new_mem, &new_iomap);
193 	if (ret)
194 		goto out;
195 
196 	/*
197 	 * Single TTM move. NOP.
198 	 */
199 	if (old_iomap == NULL && new_iomap == NULL)
200 		goto out2;
201 
202 	/*
203 	 * Don't move nonexistent data. Clear destination instead.
204 	 */
205 	if (old_iomap == NULL &&
206 	    (ttm == NULL || (!ttm_tt_is_populated(ttm) &&
207 			     !(ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)))) {
208 		memset_io(new_iomap, 0, new_mem->num_pages*PAGE_SIZE);
209 		goto out2;
210 	}
211 
212 	/*
213 	 * TTM might be null for moves within the same region.
214 	 */
215 	if (ttm) {
216 		ret = ttm_tt_populate(bdev, ttm, ctx);
217 		if (ret)
218 			goto out1;
219 	}
220 
221 	for (i = 0; i < new_mem->num_pages; ++i) {
222 		if (old_iomap == NULL) {
223 			pgprot_t prot = ttm_io_prot(bo, old_mem, PAGE_KERNEL);
224 			ret = ttm_copy_ttm_io_page(ttm, new_iomap, i,
225 						   prot);
226 		} else if (new_iomap == NULL) {
227 			pgprot_t prot = ttm_io_prot(bo, new_mem, PAGE_KERNEL);
228 			ret = ttm_copy_io_ttm_page(ttm, old_iomap, i,
229 						   prot);
230 		} else {
231 			ret = ttm_copy_io_page(new_iomap, old_iomap, i);
232 		}
233 		if (ret)
234 			goto out1;
235 	}
236 	mb();
237 out2:
238 	old_copy = *old_mem;
239 
240 	ttm_bo_assign_mem(bo, new_mem);
241 
242 	if (!man->use_tt)
243 		ttm_bo_tt_destroy(bo);
244 
245 out1:
246 	ttm_resource_iounmap(bdev, old_mem, new_iomap);
247 out:
248 	ttm_resource_iounmap(bdev, &old_copy, old_iomap);
249 
250 	/*
251 	 * On error, keep the mm node!
252 	 */
253 	if (!ret)
254 		ttm_resource_free(bo, &old_copy);
255 	return ret;
256 }
257 EXPORT_SYMBOL(ttm_bo_move_memcpy);
258 
259 static void ttm_transfered_destroy(struct ttm_buffer_object *bo)
260 {
261 	struct ttm_transfer_obj *fbo;
262 
263 	fbo = container_of(bo, struct ttm_transfer_obj, base);
264 	ttm_bo_put(fbo->bo);
265 	kfree(fbo);
266 }
267 
268 /**
269  * ttm_buffer_object_transfer
270  *
271  * @bo: A pointer to a struct ttm_buffer_object.
272  * @new_obj: A pointer to a pointer to a newly created ttm_buffer_object,
273  * holding the data of @bo with the old placement.
274  *
275  * This is a utility function that may be called after an accelerated move
276  * has been scheduled. A new buffer object is created as a placeholder for
277  * the old data while it's being copied. When that buffer object is idle,
278  * it can be destroyed, releasing the space of the old placement.
279  * Returns:
280  * !0: Failure.
281  */
282 
283 static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
284 				      struct ttm_buffer_object **new_obj)
285 {
286 	struct ttm_transfer_obj *fbo;
287 	int ret;
288 
289 	fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);
290 	if (!fbo)
291 		return -ENOMEM;
292 
293 	fbo->base = *bo;
294 
295 	ttm_bo_get(bo);
296 	fbo->bo = bo;
297 
298 	/**
299 	 * Fix up members that we shouldn't copy directly:
300 	 * TODO: Explicit member copy would probably be better here.
301 	 */
302 
303 	atomic_inc(&ttm_glob.bo_count);
304 	INIT_LIST_HEAD(&fbo->base.ddestroy);
305 	INIT_LIST_HEAD(&fbo->base.lru);
306 	INIT_LIST_HEAD(&fbo->base.swap);
307 	fbo->base.moving = NULL;
308 	drm_vma_node_reset(&fbo->base.base.vma_node);
309 
310 	kref_init(&fbo->base.kref);
311 	fbo->base.destroy = &ttm_transfered_destroy;
312 	fbo->base.pin_count = 0;
313 	if (bo->type != ttm_bo_type_sg)
314 		fbo->base.base.resv = &fbo->base.base._resv;
315 
316 	dma_resv_init(&fbo->base.base._resv);
317 	fbo->base.base.dev = NULL;
318 	ret = dma_resv_trylock(&fbo->base.base._resv);
319 	WARN_ON(!ret);
320 
321 	ttm_bo_move_to_lru_tail_unlocked(&fbo->base);
322 
323 	*new_obj = &fbo->base;
324 	return 0;
325 }
326 
327 pgprot_t ttm_io_prot(struct ttm_buffer_object *bo, struct ttm_resource *res,
328 		     pgprot_t tmp)
329 {
330 	struct ttm_resource_manager *man;
331 	enum ttm_caching caching;
332 
333 	man = ttm_manager_type(bo->bdev, res->mem_type);
334 	caching = man->use_tt ? bo->ttm->caching : res->bus.caching;
335 
336 	/* Cached mappings need no adjustment */
337 	if (caching == ttm_cached)
338 		return tmp;
339 
340 #if defined(__i386__) || defined(__x86_64__)
341 	if (caching == ttm_write_combined)
342 		tmp = pgprot_writecombine(tmp);
343 	else if (boot_cpu_data.x86 > 3)
344 		tmp = pgprot_noncached(tmp);
345 #endif
346 #if defined(__ia64__) || defined(__arm__) || defined(__aarch64__) || \
347     defined(__powerpc__) || defined(__mips__)
348 	if (caching == ttm_write_combined)
349 		tmp = pgprot_writecombine(tmp);
350 	else
351 		tmp = pgprot_noncached(tmp);
352 #endif
353 #if defined(__sparc__)
354 	tmp = pgprot_noncached(tmp);
355 #endif
356 	return tmp;
357 }
358 EXPORT_SYMBOL(ttm_io_prot);
359 
360 static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
361 			  unsigned long offset,
362 			  unsigned long size,
363 			  struct ttm_bo_kmap_obj *map)
364 {
365 	struct ttm_resource *mem = &bo->mem;
366 
367 	if (bo->mem.bus.addr) {
368 		map->bo_kmap_type = ttm_bo_map_premapped;
369 		map->virtual = (void *)(((u8 *)bo->mem.bus.addr) + offset);
370 	} else {
371 		map->bo_kmap_type = ttm_bo_map_iomap;
372 		if (mem->bus.caching == ttm_write_combined)
373 			map->virtual = ioremap_wc(bo->mem.bus.offset + offset,
374 						  size);
375 		else
376 			map->virtual = ioremap(bo->mem.bus.offset + offset,
377 					       size);
378 	}
379 	return (!map->virtual) ? -ENOMEM : 0;
380 }
381 
382 static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
383 			   unsigned long start_page,
384 			   unsigned long num_pages,
385 			   struct ttm_bo_kmap_obj *map)
386 {
387 	struct ttm_resource *mem = &bo->mem;
388 	struct ttm_operation_ctx ctx = {
389 		.interruptible = false,
390 		.no_wait_gpu = false
391 	};
392 	struct ttm_tt *ttm = bo->ttm;
393 	pgprot_t prot;
394 	int ret;
395 
396 	BUG_ON(!ttm);
397 
398 	ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
399 	if (ret)
400 		return ret;
401 
402 	if (num_pages == 1 && ttm->caching == ttm_cached) {
403 		/*
404 		 * We're mapping a single page, and the desired
405 		 * page protection is consistent with the bo.
406 		 */
407 
408 		map->bo_kmap_type = ttm_bo_map_kmap;
409 		map->page = ttm->pages[start_page];
410 		map->virtual = kmap(map->page);
411 	} else {
412 		/*
413 		 * We need to use vmap to get the desired page protection
414 		 * or to make the buffer object look contiguous.
415 		 */
416 		prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
417 		map->bo_kmap_type = ttm_bo_map_vmap;
418 		map->virtual = vmap(ttm->pages + start_page, num_pages,
419 				    0, prot);
420 	}
421 	return (!map->virtual) ? -ENOMEM : 0;
422 }
423 
424 int ttm_bo_kmap(struct ttm_buffer_object *bo,
425 		unsigned long start_page, unsigned long num_pages,
426 		struct ttm_bo_kmap_obj *map)
427 {
428 	unsigned long offset, size;
429 	int ret;
430 
431 	map->virtual = NULL;
432 	map->bo = bo;
433 	if (num_pages > bo->mem.num_pages)
434 		return -EINVAL;
435 	if ((start_page + num_pages) > bo->mem.num_pages)
436 		return -EINVAL;
437 
438 	ret = ttm_mem_io_reserve(bo->bdev, &bo->mem);
439 	if (ret)
440 		return ret;
441 	if (!bo->mem.bus.is_iomem) {
442 		return ttm_bo_kmap_ttm(bo, start_page, num_pages, map);
443 	} else {
444 		offset = start_page << PAGE_SHIFT;
445 		size = num_pages << PAGE_SHIFT;
446 		return ttm_bo_ioremap(bo, offset, size, map);
447 	}
448 }
449 EXPORT_SYMBOL(ttm_bo_kmap);
450 
451 void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
452 {
453 	if (!map->virtual)
454 		return;
455 	switch (map->bo_kmap_type) {
456 	case ttm_bo_map_iomap:
457 		iounmap(map->virtual);
458 		break;
459 	case ttm_bo_map_vmap:
460 		vunmap(map->virtual);
461 		break;
462 	case ttm_bo_map_kmap:
463 		kunmap(map->page);
464 		break;
465 	case ttm_bo_map_premapped:
466 		break;
467 	default:
468 		BUG();
469 	}
470 	ttm_mem_io_free(map->bo->bdev, &map->bo->mem);
471 	map->virtual = NULL;
472 	map->page = NULL;
473 }
474 EXPORT_SYMBOL(ttm_bo_kunmap);
475 
476 int ttm_bo_vmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
477 {
478 	struct ttm_resource *mem = &bo->mem;
479 	int ret;
480 
481 	ret = ttm_mem_io_reserve(bo->bdev, mem);
482 	if (ret)
483 		return ret;
484 
485 	if (mem->bus.is_iomem) {
486 		void __iomem *vaddr_iomem;
487 
488 		if (mem->bus.addr)
489 			vaddr_iomem = (void __iomem *)mem->bus.addr;
490 		else if (mem->bus.caching == ttm_write_combined)
491 			vaddr_iomem = ioremap_wc(mem->bus.offset,
492 						 bo->base.size);
493 		else
494 			vaddr_iomem = ioremap(mem->bus.offset, bo->base.size);
495 
496 		if (!vaddr_iomem)
497 			return -ENOMEM;
498 
499 		dma_buf_map_set_vaddr_iomem(map, vaddr_iomem);
500 
501 	} else {
502 		struct ttm_operation_ctx ctx = {
503 			.interruptible = false,
504 			.no_wait_gpu = false
505 		};
506 		struct ttm_tt *ttm = bo->ttm;
507 		pgprot_t prot;
508 		void *vaddr;
509 
510 		ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
511 		if (ret)
512 			return ret;
513 
514 		/*
515 		 * We need to use vmap to get the desired page protection
516 		 * or to make the buffer object look contiguous.
517 		 */
518 		prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
519 		vaddr = vmap(ttm->pages, ttm->num_pages, 0, prot);
520 		if (!vaddr)
521 			return -ENOMEM;
522 
523 		dma_buf_map_set_vaddr(map, vaddr);
524 	}
525 
526 	return 0;
527 }
528 EXPORT_SYMBOL(ttm_bo_vmap);
529 
530 void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
531 {
532 	struct ttm_resource *mem = &bo->mem;
533 
534 	if (dma_buf_map_is_null(map))
535 		return;
536 
537 	if (!map->is_iomem)
538 		vunmap(map->vaddr);
539 	else if (!mem->bus.addr)
540 		iounmap(map->vaddr_iomem);
541 	dma_buf_map_clear(map);
542 
543 	ttm_mem_io_free(bo->bdev, &bo->mem);
544 }
545 EXPORT_SYMBOL(ttm_bo_vunmap);
546 
547 static int ttm_bo_wait_free_node(struct ttm_buffer_object *bo,
548 				 bool dst_use_tt)
549 {
550 	int ret;
551 	ret = ttm_bo_wait(bo, false, false);
552 	if (ret)
553 		return ret;
554 
555 	if (!dst_use_tt)
556 		ttm_bo_tt_destroy(bo);
557 	ttm_resource_free(bo, &bo->mem);
558 	return 0;
559 }
560 
561 static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
562 				struct dma_fence *fence,
563 				bool dst_use_tt)
564 {
565 	struct ttm_buffer_object *ghost_obj;
566 	int ret;
567 
568 	/**
569 	 * This should help pipeline ordinary buffer moves.
570 	 *
571 	 * Hang old buffer memory on a new buffer object,
572 	 * and leave it to be released when the GPU
573 	 * operation has completed.
574 	 */
575 
576 	dma_fence_put(bo->moving);
577 	bo->moving = dma_fence_get(fence);
578 
579 	ret = ttm_buffer_object_transfer(bo, &ghost_obj);
580 	if (ret)
581 		return ret;
582 
583 	dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);
584 
585 	/**
586 	 * If we're not moving to fixed memory, the TTM object
587 	 * needs to stay alive. Otherwhise hang it on the ghost
588 	 * bo to be unbound and destroyed.
589 	 */
590 
591 	if (dst_use_tt)
592 		ghost_obj->ttm = NULL;
593 	else
594 		bo->ttm = NULL;
595 
596 	dma_resv_unlock(&ghost_obj->base._resv);
597 	ttm_bo_put(ghost_obj);
598 	return 0;
599 }
600 
601 static void ttm_bo_move_pipeline_evict(struct ttm_buffer_object *bo,
602 				       struct dma_fence *fence)
603 {
604 	struct ttm_device *bdev = bo->bdev;
605 	struct ttm_resource_manager *from = ttm_manager_type(bdev, bo->mem.mem_type);
606 
607 	/**
608 	 * BO doesn't have a TTM we need to bind/unbind. Just remember
609 	 * this eviction and free up the allocation
610 	 */
611 	spin_lock(&from->move_lock);
612 	if (!from->move || dma_fence_is_later(fence, from->move)) {
613 		dma_fence_put(from->move);
614 		from->move = dma_fence_get(fence);
615 	}
616 	spin_unlock(&from->move_lock);
617 
618 	ttm_resource_free(bo, &bo->mem);
619 
620 	dma_fence_put(bo->moving);
621 	bo->moving = dma_fence_get(fence);
622 }
623 
624 int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
625 			      struct dma_fence *fence,
626 			      bool evict,
627 			      bool pipeline,
628 			      struct ttm_resource *new_mem)
629 {
630 	struct ttm_device *bdev = bo->bdev;
631 	struct ttm_resource_manager *from = ttm_manager_type(bdev, bo->mem.mem_type);
632 	struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
633 	int ret = 0;
634 
635 	dma_resv_add_excl_fence(bo->base.resv, fence);
636 	if (!evict)
637 		ret = ttm_bo_move_to_ghost(bo, fence, man->use_tt);
638 	else if (!from->use_tt && pipeline)
639 		ttm_bo_move_pipeline_evict(bo, fence);
640 	else
641 		ret = ttm_bo_wait_free_node(bo, man->use_tt);
642 
643 	if (ret)
644 		return ret;
645 
646 	ttm_bo_assign_mem(bo, new_mem);
647 
648 	return 0;
649 }
650 EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);
651 
652 int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
653 {
654 	struct ttm_buffer_object *ghost;
655 	int ret;
656 
657 	ret = ttm_buffer_object_transfer(bo, &ghost);
658 	if (ret)
659 		return ret;
660 
661 	ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
662 	/* Last resort, wait for the BO to be idle when we are OOM */
663 	if (ret)
664 		ttm_bo_wait(bo, false, false);
665 
666 	memset(&bo->mem, 0, sizeof(bo->mem));
667 	bo->mem.mem_type = TTM_PL_SYSTEM;
668 	bo->ttm = NULL;
669 
670 	dma_resv_unlock(&ghost->base._resv);
671 	ttm_bo_put(ghost);
672 
673 	return 0;
674 }
675