gntdev-dmabuf.c

  1// SPDX-License-Identifier: GPL-2.0
  2
  3/*
  4 * Xen dma-buf functionality for gntdev.
  5 *
  6 * DMA buffer implementation is based on drivers/gpu/drm/drm_prime.c.
  7 *
  8 * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
  9 */
 10
 11#include <linux/kernel.h>
 12#include <linux/errno.h>
 13#include <linux/dma-buf.h>
 14#include <linux/dma-direct.h>
 15#include <linux/slab.h>
 16#include <linux/types.h>
 17#include <linux/uaccess.h>
 18#include <linux/module.h>
 19
 20#include <xen/xen.h>
 21#include <xen/grant_table.h>
 22
 23#include "gntdev-common.h"
 24#include "gntdev-dmabuf.h"
 25
 26MODULE_IMPORT_NS("DMA_BUF");
 27
 28struct gntdev_dmabuf {
 29	struct gntdev_dmabuf_priv *priv;
 30	struct dma_buf *dmabuf;
 31	struct list_head next;
 32	int fd;
 33
 34	union {
 35		struct {
 36			/* Exported buffers are reference counted. */
 37			struct kref refcount;
 38
 39			struct gntdev_priv *priv;
 40			struct gntdev_grant_map *map;
 41		} exp;
 42		struct {
 43			/* Granted references of the imported buffer. */
 44			grant_ref_t *refs;
 45			/* Scatter-gather table of the imported buffer. */
 46			struct sg_table *sgt;
 47			/* dma-buf attachment of the imported buffer. */
 48			struct dma_buf_attachment *attach;
 49		} imp;
 50	} u;
 51
 52	/* Number of pages this buffer has. */
 53	int nr_pages;
 54	/* Pages of this buffer (only for dma-buf export). */
 55	struct page **pages;
 56};
 57
 58struct gntdev_dmabuf_wait_obj {
 59	struct list_head next;
 60	struct gntdev_dmabuf *gntdev_dmabuf;
 61	struct completion completion;
 62};
 63
 64struct gntdev_dmabuf_attachment {
 65	struct sg_table *sgt;
 66	enum dma_data_direction dir;
 67};
 68
 69struct gntdev_dmabuf_priv {
 70	/* List of exported DMA buffers. */
 71	struct list_head exp_list;
 72	/* List of wait objects. */
 73	struct list_head exp_wait_list;
 74	/* List of imported DMA buffers. */
 75	struct list_head imp_list;
 76	/* This is the lock which protects dma_buf_xxx lists. */
 77	struct mutex lock;
 78	/*
 79	 * We reference this file while exporting dma-bufs, so
 80	 * the grant device context is not destroyed while there are
 81	 * external users alive.
 82	 */
 83	struct file *filp;
 84};
 85
 86/* DMA buffer export support. */
 87
 88/* Implementation of wait for exported DMA buffer to be released. */
 89
 90static void dmabuf_exp_release(struct kref *kref);
 91
 92static struct gntdev_dmabuf_wait_obj *
 93dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv,
 94			struct gntdev_dmabuf *gntdev_dmabuf)
 95{
 96	struct gntdev_dmabuf_wait_obj *obj;
 97
 98	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 99	if (!obj)
100		return ERR_PTR(-ENOMEM);
101
102	init_completion(&obj->completion);
103	obj->gntdev_dmabuf = gntdev_dmabuf;
104
105	mutex_lock(&priv->lock);
106	list_add(&obj->next, &priv->exp_wait_list);
107	/* Put our reference and wait for gntdev_dmabuf's release to fire. */
108	kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
109	mutex_unlock(&priv->lock);
110	return obj;
111}
112
113static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
114				     struct gntdev_dmabuf_wait_obj *obj)
115{
116	mutex_lock(&priv->lock);
117	list_del(&obj->next);
118	mutex_unlock(&priv->lock);
119	kfree(obj);
120}
121
122static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
123				    u32 wait_to_ms)
124{
125	if (wait_for_completion_timeout(&obj->completion,
126			msecs_to_jiffies(wait_to_ms)) <= 0)
127		return -ETIMEDOUT;
128
129	return 0;
130}
131
132static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
133				       struct gntdev_dmabuf *gntdev_dmabuf)
134{
135	struct gntdev_dmabuf_wait_obj *obj;
136
137	list_for_each_entry(obj, &priv->exp_wait_list, next)
138		if (obj->gntdev_dmabuf == gntdev_dmabuf) {
139			pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
140			complete_all(&obj->completion);
141			break;
142		}
143}
144
145static struct gntdev_dmabuf *
146dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
147{
148	struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
149
150	mutex_lock(&priv->lock);
151	list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
152		if (gntdev_dmabuf->fd == fd) {
153			pr_debug("Found gntdev_dmabuf in the wait list\n");
154			kref_get(&gntdev_dmabuf->u.exp.refcount);
155			ret = gntdev_dmabuf;
156			break;
157		}
158	mutex_unlock(&priv->lock);
159	return ret;
160}
161
162static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
163				    int wait_to_ms)
164{
165	struct gntdev_dmabuf *gntdev_dmabuf;
166	struct gntdev_dmabuf_wait_obj *obj;
167	int ret;
168
169	pr_debug("Will wait for dma-buf with fd %d\n", fd);
170	/*
171	 * Try to find the DMA buffer: if not found means that
172	 * either the buffer has already been released or file descriptor
173	 * provided is wrong.
174	 */
175	gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
176	if (IS_ERR(gntdev_dmabuf))
177		return PTR_ERR(gntdev_dmabuf);
178
179	/*
180	 * gntdev_dmabuf still exists and is reference count locked by us now,
181	 * so prepare to wait: allocate wait object and add it to the wait list,
182	 * so we can find it on release.
183	 */
184	obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
185	if (IS_ERR(obj))
186		return PTR_ERR(obj);
187
188	ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
189	dmabuf_exp_wait_obj_free(priv, obj);
190	return ret;
191}
192
193/* DMA buffer export support. */
194
195static struct sg_table *
196dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
197{
198	struct sg_table *sgt;
199	int ret;
200
201	sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
202	if (!sgt) {
203		ret = -ENOMEM;
204		goto out;
205	}
206
207	ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
208					nr_pages << PAGE_SHIFT,
209					GFP_KERNEL);
210	if (ret)
211		goto out;
212
213	return sgt;
214
215out:
216	kfree(sgt);
217	return ERR_PTR(ret);
218}
219
220static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
221				 struct dma_buf_attachment *attach)
222{
223	struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
224
225	gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach),
226				       GFP_KERNEL);
227	if (!gntdev_dmabuf_attach)
228		return -ENOMEM;
229
230	gntdev_dmabuf_attach->dir = DMA_NONE;
231	attach->priv = gntdev_dmabuf_attach;
232	return 0;
233}
234
235static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
236				  struct dma_buf_attachment *attach)
237{
238	struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
239
240	if (gntdev_dmabuf_attach) {
241		struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
242
243		if (sgt) {
244			if (gntdev_dmabuf_attach->dir != DMA_NONE)
245				dma_unmap_sgtable(attach->dev, sgt,
246						  gntdev_dmabuf_attach->dir,
247						  DMA_ATTR_SKIP_CPU_SYNC);
248			sg_free_table(sgt);
249		}
250
251		kfree(sgt);
252		kfree(gntdev_dmabuf_attach);
253		attach->priv = NULL;
254	}
255}
256
257static struct sg_table *
258dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
259			   enum dma_data_direction dir)
260{
261	struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
262	struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
263	struct sg_table *sgt;
264
265	pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
266		 attach->dev);
267
268	if (dir == DMA_NONE || !gntdev_dmabuf_attach)
269		return ERR_PTR(-EINVAL);
270
271	/* Return the cached mapping when possible. */
272	if (gntdev_dmabuf_attach->dir == dir)
273		return gntdev_dmabuf_attach->sgt;
274
275	/*
276	 * Two mappings with different directions for the same attachment are
277	 * not allowed.
278	 */
279	if (gntdev_dmabuf_attach->dir != DMA_NONE)
280		return ERR_PTR(-EBUSY);
281
282	sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
283				  gntdev_dmabuf->nr_pages);
284	if (!IS_ERR(sgt)) {
285		if (dma_map_sgtable(attach->dev, sgt, dir,
286				    DMA_ATTR_SKIP_CPU_SYNC)) {
287			sg_free_table(sgt);
288			kfree(sgt);
289			sgt = ERR_PTR(-ENOMEM);
290		} else {
291			gntdev_dmabuf_attach->sgt = sgt;
292			gntdev_dmabuf_attach->dir = dir;
293		}
294	}
295	if (IS_ERR(sgt))
296		pr_debug("Failed to map sg table for dev %p\n", attach->dev);
297	return sgt;
298}
299
300static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
301					 struct sg_table *sgt,
302					 enum dma_data_direction dir)
303{
304	/* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
305}
306
307static void dmabuf_exp_release(struct kref *kref)
308{
309	struct gntdev_dmabuf *gntdev_dmabuf =
310		container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
311
312	dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
313	list_del(&gntdev_dmabuf->next);
314	fput(gntdev_dmabuf->priv->filp);
315	kfree(gntdev_dmabuf);
316}
317
318static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
319				  struct gntdev_grant_map *map)
320{
321	mutex_lock(&priv->lock);
322	list_del(&map->next);
323	gntdev_put_map(NULL /* already removed */, map);
324	mutex_unlock(&priv->lock);
325}
326
327static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
328{
329	struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
330	struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
331
332	dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
333			      gntdev_dmabuf->u.exp.map);
334	mutex_lock(&priv->lock);
335	kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
336	mutex_unlock(&priv->lock);
337}
338
339static const struct dma_buf_ops dmabuf_exp_ops =  {
340	.attach = dmabuf_exp_ops_attach,
341	.detach = dmabuf_exp_ops_detach,
342	.map_dma_buf = dmabuf_exp_ops_map_dma_buf,
343	.unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
344	.release = dmabuf_exp_ops_release,
345};
346
347struct gntdev_dmabuf_export_args {
348	struct gntdev_priv *priv;
349	struct gntdev_grant_map *map;
350	struct gntdev_dmabuf_priv *dmabuf_priv;
351	struct device *dev;
352	int count;
353	struct page **pages;
354	u32 fd;
355};
356
357static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
358{
359	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
360	struct gntdev_dmabuf *gntdev_dmabuf __free(kfree) = NULL;
361	CLASS(get_unused_fd, ret)(O_CLOEXEC);
362
363	if (ret < 0)
364		return ret;
365
366	gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
367	if (!gntdev_dmabuf)
368		return -ENOMEM;
369
370	kref_init(&gntdev_dmabuf->u.exp.refcount);
371
372	gntdev_dmabuf->priv = args->dmabuf_priv;
373	gntdev_dmabuf->nr_pages = args->count;
374	gntdev_dmabuf->pages = args->pages;
375	gntdev_dmabuf->u.exp.priv = args->priv;
376	gntdev_dmabuf->u.exp.map = args->map;
377
378	exp_info.exp_name = KBUILD_MODNAME;
379	if (args->dev->driver && args->dev->driver->owner)
380		exp_info.owner = args->dev->driver->owner;
381	else
382		exp_info.owner = THIS_MODULE;
383	exp_info.ops = &dmabuf_exp_ops;
384	exp_info.size = args->count << PAGE_SHIFT;
385	exp_info.flags = O_RDWR;
386	exp_info.priv = gntdev_dmabuf;
387
388	gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
389	if (IS_ERR(gntdev_dmabuf->dmabuf))
390		return PTR_ERR(gntdev_dmabuf->dmabuf);
391
392	gntdev_dmabuf->fd = ret;
393	args->fd = ret;
394
395	pr_debug("Exporting DMA buffer with fd %d\n", ret);
396
397	get_file(gntdev_dmabuf->priv->filp);
398	mutex_lock(&args->dmabuf_priv->lock);
399	list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
400	mutex_unlock(&args->dmabuf_priv->lock);
401
402	fd_install(take_fd(ret), no_free_ptr(gntdev_dmabuf)->dmabuf->file);
403	return 0;
404}
405
406static struct gntdev_grant_map *
407dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
408				 int count)
409{
410	struct gntdev_grant_map *map;
411
412	if (unlikely(gntdev_test_page_count(count)))
413		return ERR_PTR(-EINVAL);
414
415	if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
416	    (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
417		pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
418		return ERR_PTR(-EINVAL);
419	}
420
421	map = gntdev_alloc_map(priv, count, dmabuf_flags);
422	if (!map)
423		return ERR_PTR(-ENOMEM);
424
425	return map;
426}
427
428static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
429				int count, u32 domid, u32 *refs, u32 *fd)
430{
431	struct gntdev_grant_map *map;
432	struct gntdev_dmabuf_export_args args;
433	int i, ret;
434
435	map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
436	if (IS_ERR(map))
437		return PTR_ERR(map);
438
439	for (i = 0; i < count; i++) {
440		map->grants[i].domid = domid;
441		map->grants[i].ref = refs[i];
442	}
443
444	mutex_lock(&priv->lock);
445	gntdev_add_map(priv, map);
446	mutex_unlock(&priv->lock);
447
448	map->flags |= GNTMAP_host_map;
449#if defined(CONFIG_X86)
450	map->flags |= GNTMAP_device_map;
451#endif
452
453	ret = gntdev_map_grant_pages(map);
454	if (ret < 0)
455		goto out;
456
457	args.priv = priv;
458	args.map = map;
459	args.dev = priv->dma_dev;
460	args.dmabuf_priv = priv->dmabuf_priv;
461	args.count = map->count;
462	args.pages = map->pages;
463	args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
464
465	ret = dmabuf_exp_from_pages(&args);
466	if (ret < 0)
467		goto out;
468
469	*fd = args.fd;
470	return 0;
471
472out:
473	dmabuf_exp_remove_map(priv, map);
474	return ret;
475}
476
477/* DMA buffer import support. */
478
479static int
480dmabuf_imp_grant_foreign_access(unsigned long *gfns, u32 *refs,
481				int count, int domid)
482{
483	grant_ref_t priv_gref_head;
484	int i, ret;
485
486	ret = gnttab_alloc_grant_references(count, &priv_gref_head);
487	if (ret < 0) {
488		pr_debug("Cannot allocate grant references, ret %d\n", ret);
489		return ret;
490	}
491
492	for (i = 0; i < count; i++) {
493		int cur_ref;
494
495		cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
496		if (cur_ref < 0) {
497			ret = cur_ref;
498			pr_debug("Cannot claim grant reference, ret %d\n", ret);
499			goto out;
500		}
501
502		gnttab_grant_foreign_access_ref(cur_ref, domid,
503						gfns[i], 0);
504		refs[i] = cur_ref;
505	}
506
507	return 0;
508
509out:
510	gnttab_free_grant_references(priv_gref_head);
511	return ret;
512}
513
514static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
515{
516	int i;
517
518	for (i = 0; i < count; i++)
519		if (refs[i] != INVALID_GRANT_REF)
520			gnttab_end_foreign_access(refs[i], NULL);
521}
522
523static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
524{
525	kfree(gntdev_dmabuf->u.imp.refs);
526	kfree(gntdev_dmabuf);
527}
528
529static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
530{
531	struct gntdev_dmabuf *gntdev_dmabuf;
532	int i;
533
534	gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
535	if (!gntdev_dmabuf)
536		goto fail_no_free;
537
538	gntdev_dmabuf->u.imp.refs = kcalloc(count,
539					    sizeof(gntdev_dmabuf->u.imp.refs[0]),
540					    GFP_KERNEL);
541	if (!gntdev_dmabuf->u.imp.refs)
542		goto fail;
543
544	gntdev_dmabuf->nr_pages = count;
545
546	for (i = 0; i < count; i++)
547		gntdev_dmabuf->u.imp.refs[i] = INVALID_GRANT_REF;
548
549	return gntdev_dmabuf;
550
551fail:
552	dmabuf_imp_free_storage(gntdev_dmabuf);
553fail_no_free:
554	return ERR_PTR(-ENOMEM);
555}
556
557static struct gntdev_dmabuf *
558dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
559		   int fd, int count, int domid)
560{
561	struct gntdev_dmabuf *gntdev_dmabuf, *ret;
562	struct dma_buf *dma_buf;
563	struct dma_buf_attachment *attach;
564	struct sg_table *sgt;
565	struct sg_dma_page_iter sg_iter;
566	unsigned long *gfns;
567	int i;
568
569	dma_buf = dma_buf_get(fd);
570	if (IS_ERR(dma_buf))
571		return ERR_CAST(dma_buf);
572
573	gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
574	if (IS_ERR(gntdev_dmabuf)) {
575		ret = gntdev_dmabuf;
576		goto fail_put;
577	}
578
579	gntdev_dmabuf->priv = priv;
580	gntdev_dmabuf->fd = fd;
581
582	attach = dma_buf_attach(dma_buf, dev);
583	if (IS_ERR(attach)) {
584		ret = ERR_CAST(attach);
585		goto fail_free_obj;
586	}
587
588	gntdev_dmabuf->u.imp.attach = attach;
589
590	sgt = dma_buf_map_attachment_unlocked(attach, DMA_BIDIRECTIONAL);
591	if (IS_ERR(sgt)) {
592		ret = ERR_CAST(sgt);
593		goto fail_detach;
594	}
595
596	/* Check that we have zero offset. */
597	if (sgt->sgl->offset) {
598		ret = ERR_PTR(-EINVAL);
599		pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n",
600			 sgt->sgl->offset);
601		goto fail_unmap;
602	}
603
604	/* Check number of pages that imported buffer has. */
605	if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
606		ret = ERR_PTR(-EINVAL);
607		pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
608			 attach->dmabuf->size, gntdev_dmabuf->nr_pages);
609		goto fail_unmap;
610	}
611
612	gntdev_dmabuf->u.imp.sgt = sgt;
613
614	gfns = kcalloc(count, sizeof(*gfns), GFP_KERNEL);
615	if (!gfns) {
616		ret = ERR_PTR(-ENOMEM);
617		goto fail_unmap;
618	}
619
620	/*
621	 * Now convert sgt to array of gfns without accessing underlying pages.
622	 * It is not allowed to access the underlying struct page of an sg table
623	 * exported by DMA-buf, but since we deal with special Xen dma device here
624	 * (not a normal physical one) look at the dma addresses in the sg table
625	 * and then calculate gfns directly from them.
626	 */
627	i = 0;
628	for_each_sgtable_dma_page(sgt, &sg_iter, 0) {
629		dma_addr_t addr = sg_page_iter_dma_address(&sg_iter);
630		unsigned long pfn = bfn_to_pfn(XEN_PFN_DOWN(dma_to_phys(dev, addr)));
631
632		gfns[i++] = pfn_to_gfn(pfn);
633	}
634
635	ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gfns,
636						      gntdev_dmabuf->u.imp.refs,
637						      count, domid));
638	kfree(gfns);
639	if (IS_ERR(ret))
640		goto fail_end_access;
641
642	pr_debug("Imported DMA buffer with fd %d\n", fd);
643
644	mutex_lock(&priv->lock);
645	list_add(&gntdev_dmabuf->next, &priv->imp_list);
646	mutex_unlock(&priv->lock);
647
648	return gntdev_dmabuf;
649
650fail_end_access:
651	dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
652fail_unmap:
653	dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_BIDIRECTIONAL);
654fail_detach:
655	dma_buf_detach(dma_buf, attach);
656fail_free_obj:
657	dmabuf_imp_free_storage(gntdev_dmabuf);
658fail_put:
659	dma_buf_put(dma_buf);
660	return ret;
661}
662
663/*
664 * Find the hyper dma-buf by its file descriptor and remove
665 * it from the buffer's list.
666 */
667static struct gntdev_dmabuf *
668dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
669{
670	struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
671
672	mutex_lock(&priv->lock);
673	list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
674		if (gntdev_dmabuf->fd == fd) {
675			pr_debug("Found gntdev_dmabuf in the import list\n");
676			ret = gntdev_dmabuf;
677			list_del(&gntdev_dmabuf->next);
678			break;
679		}
680	}
681	mutex_unlock(&priv->lock);
682	return ret;
683}
684
685static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
686{
687	struct gntdev_dmabuf *gntdev_dmabuf;
688	struct dma_buf_attachment *attach;
689	struct dma_buf *dma_buf;
690
691	gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
692	if (IS_ERR(gntdev_dmabuf))
693		return PTR_ERR(gntdev_dmabuf);
694
695	pr_debug("Releasing DMA buffer with fd %d\n", fd);
696
697	dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
698				      gntdev_dmabuf->nr_pages);
699
700	attach = gntdev_dmabuf->u.imp.attach;
701
702	if (gntdev_dmabuf->u.imp.sgt)
703		dma_buf_unmap_attachment_unlocked(attach, gntdev_dmabuf->u.imp.sgt,
704						  DMA_BIDIRECTIONAL);
705	dma_buf = attach->dmabuf;
706	dma_buf_detach(attach->dmabuf, attach);
707	dma_buf_put(dma_buf);
708
709	dmabuf_imp_free_storage(gntdev_dmabuf);
710	return 0;
711}
712
713static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
714{
715	struct gntdev_dmabuf *q, *gntdev_dmabuf;
716
717	list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next)
718		dmabuf_imp_release(priv, gntdev_dmabuf->fd);
719}
720
721/* DMA buffer IOCTL support. */
722
723long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv,
724				       struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
725{
726	struct ioctl_gntdev_dmabuf_exp_from_refs op;
727	u32 *refs;
728	long ret;
729
730	if (xen_pv_domain()) {
731		pr_debug("Cannot provide dma-buf in a PV domain\n");
732		return -EINVAL;
733	}
734
735	if (copy_from_user(&op, u, sizeof(op)) != 0)
736		return -EFAULT;
737
738	if (unlikely(gntdev_test_page_count(op.count)))
739		return -EINVAL;
740
741	refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
742	if (!refs)
743		return -ENOMEM;
744
745	if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
746		ret = -EFAULT;
747		goto out;
748	}
749
750	ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
751				   op.domid, refs, &op.fd);
752	if (ret)
753		goto out;
754
755	if (copy_to_user(u, &op, sizeof(op)) != 0)
756		ret = -EFAULT;
757
758out:
759	kfree(refs);
760	return ret;
761}
762
763long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
764					   struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
765{
766	struct ioctl_gntdev_dmabuf_exp_wait_released op;
767
768	if (copy_from_user(&op, u, sizeof(op)) != 0)
769		return -EFAULT;
770
771	return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
772					op.wait_to_ms);
773}
774
775long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
776				     struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
777{
778	struct ioctl_gntdev_dmabuf_imp_to_refs op;
779	struct gntdev_dmabuf *gntdev_dmabuf;
780	long ret;
781
782	if (copy_from_user(&op, u, sizeof(op)) != 0)
783		return -EFAULT;
784
785	if (unlikely(gntdev_test_page_count(op.count)))
786		return -EINVAL;
787
788	gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
789					   priv->dma_dev, op.fd,
790					   op.count, op.domid);
791	if (IS_ERR(gntdev_dmabuf))
792		return PTR_ERR(gntdev_dmabuf);
793
794	if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
795			 sizeof(*u->refs) * op.count) != 0) {
796		ret = -EFAULT;
797		goto out_release;
798	}
799	return 0;
800
801out_release:
802	dmabuf_imp_release(priv->dmabuf_priv, op.fd);
803	return ret;
804}
805
806long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
807				     struct ioctl_gntdev_dmabuf_imp_release __user *u)
808{
809	struct ioctl_gntdev_dmabuf_imp_release op;
810
811	if (copy_from_user(&op, u, sizeof(op)) != 0)
812		return -EFAULT;
813
814	return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
815}
816
817struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
818{
819	struct gntdev_dmabuf_priv *priv;
820
821	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
822	if (!priv)
823		return ERR_PTR(-ENOMEM);
824
825	mutex_init(&priv->lock);
826	INIT_LIST_HEAD(&priv->exp_list);
827	INIT_LIST_HEAD(&priv->exp_wait_list);
828	INIT_LIST_HEAD(&priv->imp_list);
829
830	priv->filp = filp;
831
832	return priv;
833}
834
835void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
836{
837	dmabuf_imp_release_all(priv);
838	kfree(priv);
839}