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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/slab.h>
15#include <linux/types.h>
16#include <linux/uaccess.h>
17
18#include <xen/xen.h>
19#include <xen/grant_table.h>
20
21#include "gntdev-common.h"
22#include "gntdev-dmabuf.h"
23
24#ifndef GRANT_INVALID_REF
25/*
26 * Note on usage of grant reference 0 as invalid grant reference:
27 * grant reference 0 is valid, but never exposed to a driver,
28 * because of the fact it is already in use/reserved by the PV console.
29 */
30#define GRANT_INVALID_REF 0
31#endif
32
33struct gntdev_dmabuf {
34 struct gntdev_dmabuf_priv *priv;
35 struct dma_buf *dmabuf;
36 struct list_head next;
37 int fd;
38
39 union {
40 struct {
41 /* Exported buffers are reference counted. */
42 struct kref refcount;
43
44 struct gntdev_priv *priv;
45 struct gntdev_grant_map *map;
46 } exp;
47 struct {
48 /* Granted references of the imported buffer. */
49 grant_ref_t *refs;
50 /* Scatter-gather table of the imported buffer. */
51 struct sg_table *sgt;
52 /* dma-buf attachment of the imported buffer. */
53 struct dma_buf_attachment *attach;
54 } imp;
55 } u;
56
57 /* Number of pages this buffer has. */
58 int nr_pages;
59 /* Pages of this buffer. */
60 struct page **pages;
61};
62
63struct gntdev_dmabuf_wait_obj {
64 struct list_head next;
65 struct gntdev_dmabuf *gntdev_dmabuf;
66 struct completion completion;
67};
68
69struct gntdev_dmabuf_attachment {
70 struct sg_table *sgt;
71 enum dma_data_direction dir;
72};
73
74struct gntdev_dmabuf_priv {
75 /* List of exported DMA buffers. */
76 struct list_head exp_list;
77 /* List of wait objects. */
78 struct list_head exp_wait_list;
79 /* List of imported DMA buffers. */
80 struct list_head imp_list;
81 /* This is the lock which protects dma_buf_xxx lists. */
82 struct mutex lock;
83 /*
84 * We reference this file while exporting dma-bufs, so
85 * the grant device context is not destroyed while there are
86 * external users alive.
87 */
88 struct file *filp;
89};
90
91/* DMA buffer export support. */
92
93/* Implementation of wait for exported DMA buffer to be released. */
94
95static void dmabuf_exp_release(struct kref *kref);
96
97static struct gntdev_dmabuf_wait_obj *
98dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv,
99 struct gntdev_dmabuf *gntdev_dmabuf)
100{
101 struct gntdev_dmabuf_wait_obj *obj;
102
103 obj = kzalloc(sizeof(*obj), GFP_KERNEL);
104 if (!obj)
105 return ERR_PTR(-ENOMEM);
106
107 init_completion(&obj->completion);
108 obj->gntdev_dmabuf = gntdev_dmabuf;
109
110 mutex_lock(&priv->lock);
111 list_add(&obj->next, &priv->exp_wait_list);
112 /* Put our reference and wait for gntdev_dmabuf's release to fire. */
113 kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
114 mutex_unlock(&priv->lock);
115 return obj;
116}
117
118static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
119 struct gntdev_dmabuf_wait_obj *obj)
120{
121 mutex_lock(&priv->lock);
122 list_del(&obj->next);
123 mutex_unlock(&priv->lock);
124 kfree(obj);
125}
126
127static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
128 u32 wait_to_ms)
129{
130 if (wait_for_completion_timeout(&obj->completion,
131 msecs_to_jiffies(wait_to_ms)) <= 0)
132 return -ETIMEDOUT;
133
134 return 0;
135}
136
137static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
138 struct gntdev_dmabuf *gntdev_dmabuf)
139{
140 struct gntdev_dmabuf_wait_obj *obj;
141
142 list_for_each_entry(obj, &priv->exp_wait_list, next)
143 if (obj->gntdev_dmabuf == gntdev_dmabuf) {
144 pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
145 complete_all(&obj->completion);
146 break;
147 }
148}
149
150static struct gntdev_dmabuf *
151dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
152{
153 struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
154
155 mutex_lock(&priv->lock);
156 list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
157 if (gntdev_dmabuf->fd == fd) {
158 pr_debug("Found gntdev_dmabuf in the wait list\n");
159 kref_get(&gntdev_dmabuf->u.exp.refcount);
160 ret = gntdev_dmabuf;
161 break;
162 }
163 mutex_unlock(&priv->lock);
164 return ret;
165}
166
167static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
168 int wait_to_ms)
169{
170 struct gntdev_dmabuf *gntdev_dmabuf;
171 struct gntdev_dmabuf_wait_obj *obj;
172 int ret;
173
174 pr_debug("Will wait for dma-buf with fd %d\n", fd);
175 /*
176 * Try to find the DMA buffer: if not found means that
177 * either the buffer has already been released or file descriptor
178 * provided is wrong.
179 */
180 gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
181 if (IS_ERR(gntdev_dmabuf))
182 return PTR_ERR(gntdev_dmabuf);
183
184 /*
185 * gntdev_dmabuf still exists and is reference count locked by us now,
186 * so prepare to wait: allocate wait object and add it to the wait list,
187 * so we can find it on release.
188 */
189 obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
190 if (IS_ERR(obj))
191 return PTR_ERR(obj);
192
193 ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
194 dmabuf_exp_wait_obj_free(priv, obj);
195 return ret;
196}
197
198/* DMA buffer export support. */
199
200static struct sg_table *
201dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
202{
203 struct sg_table *sgt;
204 int ret;
205
206 sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
207 if (!sgt) {
208 ret = -ENOMEM;
209 goto out;
210 }
211
212 ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
213 nr_pages << PAGE_SHIFT,
214 GFP_KERNEL);
215 if (ret)
216 goto out;
217
218 return sgt;
219
220out:
221 kfree(sgt);
222 return ERR_PTR(ret);
223}
224
225static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
226 struct dma_buf_attachment *attach)
227{
228 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
229
230 gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach),
231 GFP_KERNEL);
232 if (!gntdev_dmabuf_attach)
233 return -ENOMEM;
234
235 gntdev_dmabuf_attach->dir = DMA_NONE;
236 attach->priv = gntdev_dmabuf_attach;
237 return 0;
238}
239
240static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
241 struct dma_buf_attachment *attach)
242{
243 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
244
245 if (gntdev_dmabuf_attach) {
246 struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
247
248 if (sgt) {
249 if (gntdev_dmabuf_attach->dir != DMA_NONE)
250 dma_unmap_sg_attrs(attach->dev, sgt->sgl,
251 sgt->nents,
252 gntdev_dmabuf_attach->dir,
253 DMA_ATTR_SKIP_CPU_SYNC);
254 sg_free_table(sgt);
255 }
256
257 kfree(sgt);
258 kfree(gntdev_dmabuf_attach);
259 attach->priv = NULL;
260 }
261}
262
263static struct sg_table *
264dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
265 enum dma_data_direction dir)
266{
267 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
268 struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
269 struct sg_table *sgt;
270
271 pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
272 attach->dev);
273
274 if (dir == DMA_NONE || !gntdev_dmabuf_attach)
275 return ERR_PTR(-EINVAL);
276
277 /* Return the cached mapping when possible. */
278 if (gntdev_dmabuf_attach->dir == dir)
279 return gntdev_dmabuf_attach->sgt;
280
281 /*
282 * Two mappings with different directions for the same attachment are
283 * not allowed.
284 */
285 if (gntdev_dmabuf_attach->dir != DMA_NONE)
286 return ERR_PTR(-EBUSY);
287
288 sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
289 gntdev_dmabuf->nr_pages);
290 if (!IS_ERR(sgt)) {
291 if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
292 DMA_ATTR_SKIP_CPU_SYNC)) {
293 sg_free_table(sgt);
294 kfree(sgt);
295 sgt = ERR_PTR(-ENOMEM);
296 } else {
297 gntdev_dmabuf_attach->sgt = sgt;
298 gntdev_dmabuf_attach->dir = dir;
299 }
300 }
301 if (IS_ERR(sgt))
302 pr_debug("Failed to map sg table for dev %p\n", attach->dev);
303 return sgt;
304}
305
306static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
307 struct sg_table *sgt,
308 enum dma_data_direction dir)
309{
310 /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
311}
312
313static void dmabuf_exp_release(struct kref *kref)
314{
315 struct gntdev_dmabuf *gntdev_dmabuf =
316 container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
317
318 dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
319 list_del(&gntdev_dmabuf->next);
320 fput(gntdev_dmabuf->priv->filp);
321 kfree(gntdev_dmabuf);
322}
323
324static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
325 struct gntdev_grant_map *map)
326{
327 mutex_lock(&priv->lock);
328 list_del(&map->next);
329 gntdev_put_map(NULL /* already removed */, map);
330 mutex_unlock(&priv->lock);
331}
332
333static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
334{
335 struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
336 struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
337
338 dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
339 gntdev_dmabuf->u.exp.map);
340 mutex_lock(&priv->lock);
341 kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
342 mutex_unlock(&priv->lock);
343}
344
345static const struct dma_buf_ops dmabuf_exp_ops = {
346 .attach = dmabuf_exp_ops_attach,
347 .detach = dmabuf_exp_ops_detach,
348 .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
349 .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
350 .release = dmabuf_exp_ops_release,
351};
352
353struct gntdev_dmabuf_export_args {
354 struct gntdev_priv *priv;
355 struct gntdev_grant_map *map;
356 struct gntdev_dmabuf_priv *dmabuf_priv;
357 struct device *dev;
358 int count;
359 struct page **pages;
360 u32 fd;
361};
362
363static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
364{
365 DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
366 struct gntdev_dmabuf *gntdev_dmabuf;
367 int ret;
368
369 gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
370 if (!gntdev_dmabuf)
371 return -ENOMEM;
372
373 kref_init(&gntdev_dmabuf->u.exp.refcount);
374
375 gntdev_dmabuf->priv = args->dmabuf_priv;
376 gntdev_dmabuf->nr_pages = args->count;
377 gntdev_dmabuf->pages = args->pages;
378 gntdev_dmabuf->u.exp.priv = args->priv;
379 gntdev_dmabuf->u.exp.map = args->map;
380
381 exp_info.exp_name = KBUILD_MODNAME;
382 if (args->dev->driver && args->dev->driver->owner)
383 exp_info.owner = args->dev->driver->owner;
384 else
385 exp_info.owner = THIS_MODULE;
386 exp_info.ops = &dmabuf_exp_ops;
387 exp_info.size = args->count << PAGE_SHIFT;
388 exp_info.flags = O_RDWR;
389 exp_info.priv = gntdev_dmabuf;
390
391 gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
392 if (IS_ERR(gntdev_dmabuf->dmabuf)) {
393 ret = PTR_ERR(gntdev_dmabuf->dmabuf);
394 gntdev_dmabuf->dmabuf = NULL;
395 goto fail;
396 }
397
398 ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
399 if (ret < 0)
400 goto fail;
401
402 gntdev_dmabuf->fd = ret;
403 args->fd = ret;
404
405 pr_debug("Exporting DMA buffer with fd %d\n", ret);
406
407 mutex_lock(&args->dmabuf_priv->lock);
408 list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
409 mutex_unlock(&args->dmabuf_priv->lock);
410 get_file(gntdev_dmabuf->priv->filp);
411 return 0;
412
413fail:
414 if (gntdev_dmabuf->dmabuf)
415 dma_buf_put(gntdev_dmabuf->dmabuf);
416 kfree(gntdev_dmabuf);
417 return ret;
418}
419
420static struct gntdev_grant_map *
421dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
422 int count)
423{
424 struct gntdev_grant_map *map;
425
426 if (unlikely(gntdev_test_page_count(count)))
427 return ERR_PTR(-EINVAL);
428
429 if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
430 (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
431 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
432 return ERR_PTR(-EINVAL);
433 }
434
435 map = gntdev_alloc_map(priv, count, dmabuf_flags);
436 if (!map)
437 return ERR_PTR(-ENOMEM);
438
439 return map;
440}
441
442static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
443 int count, u32 domid, u32 *refs, u32 *fd)
444{
445 struct gntdev_grant_map *map;
446 struct gntdev_dmabuf_export_args args;
447 int i, ret;
448
449 map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
450 if (IS_ERR(map))
451 return PTR_ERR(map);
452
453 for (i = 0; i < count; i++) {
454 map->grants[i].domid = domid;
455 map->grants[i].ref = refs[i];
456 }
457
458 mutex_lock(&priv->lock);
459 gntdev_add_map(priv, map);
460 mutex_unlock(&priv->lock);
461
462 map->flags |= GNTMAP_host_map;
463#if defined(CONFIG_X86)
464 map->flags |= GNTMAP_device_map;
465#endif
466
467 ret = gntdev_map_grant_pages(map);
468 if (ret < 0)
469 goto out;
470
471 args.priv = priv;
472 args.map = map;
473 args.dev = priv->dma_dev;
474 args.dmabuf_priv = priv->dmabuf_priv;
475 args.count = map->count;
476 args.pages = map->pages;
477 args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
478
479 ret = dmabuf_exp_from_pages(&args);
480 if (ret < 0)
481 goto out;
482
483 *fd = args.fd;
484 return 0;
485
486out:
487 dmabuf_exp_remove_map(priv, map);
488 return ret;
489}
490
491/* DMA buffer import support. */
492
493static int
494dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
495 int count, int domid)
496{
497 grant_ref_t priv_gref_head;
498 int i, ret;
499
500 ret = gnttab_alloc_grant_references(count, &priv_gref_head);
501 if (ret < 0) {
502 pr_debug("Cannot allocate grant references, ret %d\n", ret);
503 return ret;
504 }
505
506 for (i = 0; i < count; i++) {
507 int cur_ref;
508
509 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
510 if (cur_ref < 0) {
511 ret = cur_ref;
512 pr_debug("Cannot claim grant reference, ret %d\n", ret);
513 goto out;
514 }
515
516 gnttab_grant_foreign_access_ref(cur_ref, domid,
517 xen_page_to_gfn(pages[i]), 0);
518 refs[i] = cur_ref;
519 }
520
521 return 0;
522
523out:
524 gnttab_free_grant_references(priv_gref_head);
525 return ret;
526}
527
528static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
529{
530 int i;
531
532 for (i = 0; i < count; i++)
533 if (refs[i] != GRANT_INVALID_REF)
534 gnttab_end_foreign_access(refs[i], 0, 0UL);
535}
536
537static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
538{
539 kfree(gntdev_dmabuf->pages);
540 kfree(gntdev_dmabuf->u.imp.refs);
541 kfree(gntdev_dmabuf);
542}
543
544static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
545{
546 struct gntdev_dmabuf *gntdev_dmabuf;
547 int i;
548
549 gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
550 if (!gntdev_dmabuf)
551 goto fail_no_free;
552
553 gntdev_dmabuf->u.imp.refs = kcalloc(count,
554 sizeof(gntdev_dmabuf->u.imp.refs[0]),
555 GFP_KERNEL);
556 if (!gntdev_dmabuf->u.imp.refs)
557 goto fail;
558
559 gntdev_dmabuf->pages = kcalloc(count,
560 sizeof(gntdev_dmabuf->pages[0]),
561 GFP_KERNEL);
562 if (!gntdev_dmabuf->pages)
563 goto fail;
564
565 gntdev_dmabuf->nr_pages = count;
566
567 for (i = 0; i < count; i++)
568 gntdev_dmabuf->u.imp.refs[i] = GRANT_INVALID_REF;
569
570 return gntdev_dmabuf;
571
572fail:
573 dmabuf_imp_free_storage(gntdev_dmabuf);
574fail_no_free:
575 return ERR_PTR(-ENOMEM);
576}
577
578static struct gntdev_dmabuf *
579dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
580 int fd, int count, int domid)
581{
582 struct gntdev_dmabuf *gntdev_dmabuf, *ret;
583 struct dma_buf *dma_buf;
584 struct dma_buf_attachment *attach;
585 struct sg_table *sgt;
586 struct sg_page_iter sg_iter;
587 int i;
588
589 dma_buf = dma_buf_get(fd);
590 if (IS_ERR(dma_buf))
591 return ERR_CAST(dma_buf);
592
593 gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
594 if (IS_ERR(gntdev_dmabuf)) {
595 ret = gntdev_dmabuf;
596 goto fail_put;
597 }
598
599 gntdev_dmabuf->priv = priv;
600 gntdev_dmabuf->fd = fd;
601
602 attach = dma_buf_attach(dma_buf, dev);
603 if (IS_ERR(attach)) {
604 ret = ERR_CAST(attach);
605 goto fail_free_obj;
606 }
607
608 gntdev_dmabuf->u.imp.attach = attach;
609
610 sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
611 if (IS_ERR(sgt)) {
612 ret = ERR_CAST(sgt);
613 goto fail_detach;
614 }
615
616 /* Check that we have zero offset. */
617 if (sgt->sgl->offset) {
618 ret = ERR_PTR(-EINVAL);
619 pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n",
620 sgt->sgl->offset);
621 goto fail_unmap;
622 }
623
624 /* Check number of pages that imported buffer has. */
625 if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
626 ret = ERR_PTR(-EINVAL);
627 pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
628 attach->dmabuf->size, gntdev_dmabuf->nr_pages);
629 goto fail_unmap;
630 }
631
632 gntdev_dmabuf->u.imp.sgt = sgt;
633
634 /* Now convert sgt to array of pages and check for page validity. */
635 i = 0;
636 for_each_sg_page(sgt->sgl, &sg_iter, sgt->nents, 0) {
637 struct page *page = sg_page_iter_page(&sg_iter);
638 /*
639 * Check if page is valid: this can happen if we are given
640 * a page from VRAM or other resources which are not backed
641 * by a struct page.
642 */
643 if (!pfn_valid(page_to_pfn(page))) {
644 ret = ERR_PTR(-EINVAL);
645 goto fail_unmap;
646 }
647
648 gntdev_dmabuf->pages[i++] = page;
649 }
650
651 ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
652 gntdev_dmabuf->u.imp.refs,
653 count, domid));
654 if (IS_ERR(ret))
655 goto fail_end_access;
656
657 pr_debug("Imported DMA buffer with fd %d\n", fd);
658
659 mutex_lock(&priv->lock);
660 list_add(&gntdev_dmabuf->next, &priv->imp_list);
661 mutex_unlock(&priv->lock);
662
663 return gntdev_dmabuf;
664
665fail_end_access:
666 dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
667fail_unmap:
668 dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
669fail_detach:
670 dma_buf_detach(dma_buf, attach);
671fail_free_obj:
672 dmabuf_imp_free_storage(gntdev_dmabuf);
673fail_put:
674 dma_buf_put(dma_buf);
675 return ret;
676}
677
678/*
679 * Find the hyper dma-buf by its file descriptor and remove
680 * it from the buffer's list.
681 */
682static struct gntdev_dmabuf *
683dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
684{
685 struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
686
687 mutex_lock(&priv->lock);
688 list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
689 if (gntdev_dmabuf->fd == fd) {
690 pr_debug("Found gntdev_dmabuf in the import list\n");
691 ret = gntdev_dmabuf;
692 list_del(&gntdev_dmabuf->next);
693 break;
694 }
695 }
696 mutex_unlock(&priv->lock);
697 return ret;
698}
699
700static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
701{
702 struct gntdev_dmabuf *gntdev_dmabuf;
703 struct dma_buf_attachment *attach;
704 struct dma_buf *dma_buf;
705
706 gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
707 if (IS_ERR(gntdev_dmabuf))
708 return PTR_ERR(gntdev_dmabuf);
709
710 pr_debug("Releasing DMA buffer with fd %d\n", fd);
711
712 dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
713 gntdev_dmabuf->nr_pages);
714
715 attach = gntdev_dmabuf->u.imp.attach;
716
717 if (gntdev_dmabuf->u.imp.sgt)
718 dma_buf_unmap_attachment(attach, gntdev_dmabuf->u.imp.sgt,
719 DMA_BIDIRECTIONAL);
720 dma_buf = attach->dmabuf;
721 dma_buf_detach(attach->dmabuf, attach);
722 dma_buf_put(dma_buf);
723
724 dmabuf_imp_free_storage(gntdev_dmabuf);
725 return 0;
726}
727
728static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
729{
730 struct gntdev_dmabuf *q, *gntdev_dmabuf;
731
732 list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next)
733 dmabuf_imp_release(priv, gntdev_dmabuf->fd);
734}
735
736/* DMA buffer IOCTL support. */
737
738long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
739 struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
740{
741 struct ioctl_gntdev_dmabuf_exp_from_refs op;
742 u32 *refs;
743 long ret;
744
745 if (use_ptemod) {
746 pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
747 use_ptemod);
748 return -EINVAL;
749 }
750
751 if (copy_from_user(&op, u, sizeof(op)) != 0)
752 return -EFAULT;
753
754 if (unlikely(gntdev_test_page_count(op.count)))
755 return -EINVAL;
756
757 refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
758 if (!refs)
759 return -ENOMEM;
760
761 if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
762 ret = -EFAULT;
763 goto out;
764 }
765
766 ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
767 op.domid, refs, &op.fd);
768 if (ret)
769 goto out;
770
771 if (copy_to_user(u, &op, sizeof(op)) != 0)
772 ret = -EFAULT;
773
774out:
775 kfree(refs);
776 return ret;
777}
778
779long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
780 struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
781{
782 struct ioctl_gntdev_dmabuf_exp_wait_released op;
783
784 if (copy_from_user(&op, u, sizeof(op)) != 0)
785 return -EFAULT;
786
787 return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
788 op.wait_to_ms);
789}
790
791long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
792 struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
793{
794 struct ioctl_gntdev_dmabuf_imp_to_refs op;
795 struct gntdev_dmabuf *gntdev_dmabuf;
796 long ret;
797
798 if (copy_from_user(&op, u, sizeof(op)) != 0)
799 return -EFAULT;
800
801 if (unlikely(gntdev_test_page_count(op.count)))
802 return -EINVAL;
803
804 gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
805 priv->dma_dev, op.fd,
806 op.count, op.domid);
807 if (IS_ERR(gntdev_dmabuf))
808 return PTR_ERR(gntdev_dmabuf);
809
810 if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
811 sizeof(*u->refs) * op.count) != 0) {
812 ret = -EFAULT;
813 goto out_release;
814 }
815 return 0;
816
817out_release:
818 dmabuf_imp_release(priv->dmabuf_priv, op.fd);
819 return ret;
820}
821
822long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
823 struct ioctl_gntdev_dmabuf_imp_release __user *u)
824{
825 struct ioctl_gntdev_dmabuf_imp_release op;
826
827 if (copy_from_user(&op, u, sizeof(op)) != 0)
828 return -EFAULT;
829
830 return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
831}
832
833struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
834{
835 struct gntdev_dmabuf_priv *priv;
836
837 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
838 if (!priv)
839 return ERR_PTR(-ENOMEM);
840
841 mutex_init(&priv->lock);
842 INIT_LIST_HEAD(&priv->exp_list);
843 INIT_LIST_HEAD(&priv->exp_wait_list);
844 INIT_LIST_HEAD(&priv->imp_list);
845
846 priv->filp = filp;
847
848 return priv;
849}
850
851void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
852{
853 dmabuf_imp_release_all(priv);
854 kfree(priv);
855}
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/slab.h>
15#include <linux/types.h>
16#include <linux/uaccess.h>
17#include <linux/module.h>
18
19#include <xen/xen.h>
20#include <xen/grant_table.h>
21
22#include "gntdev-common.h"
23#include "gntdev-dmabuf.h"
24
25MODULE_IMPORT_NS(DMA_BUF);
26
27struct gntdev_dmabuf {
28 struct gntdev_dmabuf_priv *priv;
29 struct dma_buf *dmabuf;
30 struct list_head next;
31 int fd;
32
33 union {
34 struct {
35 /* Exported buffers are reference counted. */
36 struct kref refcount;
37
38 struct gntdev_priv *priv;
39 struct gntdev_grant_map *map;
40 } exp;
41 struct {
42 /* Granted references of the imported buffer. */
43 grant_ref_t *refs;
44 /* Scatter-gather table of the imported buffer. */
45 struct sg_table *sgt;
46 /* dma-buf attachment of the imported buffer. */
47 struct dma_buf_attachment *attach;
48 } imp;
49 } u;
50
51 /* Number of pages this buffer has. */
52 int nr_pages;
53 /* Pages of this buffer. */
54 struct page **pages;
55};
56
57struct gntdev_dmabuf_wait_obj {
58 struct list_head next;
59 struct gntdev_dmabuf *gntdev_dmabuf;
60 struct completion completion;
61};
62
63struct gntdev_dmabuf_attachment {
64 struct sg_table *sgt;
65 enum dma_data_direction dir;
66};
67
68struct gntdev_dmabuf_priv {
69 /* List of exported DMA buffers. */
70 struct list_head exp_list;
71 /* List of wait objects. */
72 struct list_head exp_wait_list;
73 /* List of imported DMA buffers. */
74 struct list_head imp_list;
75 /* This is the lock which protects dma_buf_xxx lists. */
76 struct mutex lock;
77 /*
78 * We reference this file while exporting dma-bufs, so
79 * the grant device context is not destroyed while there are
80 * external users alive.
81 */
82 struct file *filp;
83};
84
85/* DMA buffer export support. */
86
87/* Implementation of wait for exported DMA buffer to be released. */
88
89static void dmabuf_exp_release(struct kref *kref);
90
91static struct gntdev_dmabuf_wait_obj *
92dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv,
93 struct gntdev_dmabuf *gntdev_dmabuf)
94{
95 struct gntdev_dmabuf_wait_obj *obj;
96
97 obj = kzalloc(sizeof(*obj), GFP_KERNEL);
98 if (!obj)
99 return ERR_PTR(-ENOMEM);
100
101 init_completion(&obj->completion);
102 obj->gntdev_dmabuf = gntdev_dmabuf;
103
104 mutex_lock(&priv->lock);
105 list_add(&obj->next, &priv->exp_wait_list);
106 /* Put our reference and wait for gntdev_dmabuf's release to fire. */
107 kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
108 mutex_unlock(&priv->lock);
109 return obj;
110}
111
112static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
113 struct gntdev_dmabuf_wait_obj *obj)
114{
115 mutex_lock(&priv->lock);
116 list_del(&obj->next);
117 mutex_unlock(&priv->lock);
118 kfree(obj);
119}
120
121static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
122 u32 wait_to_ms)
123{
124 if (wait_for_completion_timeout(&obj->completion,
125 msecs_to_jiffies(wait_to_ms)) <= 0)
126 return -ETIMEDOUT;
127
128 return 0;
129}
130
131static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
132 struct gntdev_dmabuf *gntdev_dmabuf)
133{
134 struct gntdev_dmabuf_wait_obj *obj;
135
136 list_for_each_entry(obj, &priv->exp_wait_list, next)
137 if (obj->gntdev_dmabuf == gntdev_dmabuf) {
138 pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
139 complete_all(&obj->completion);
140 break;
141 }
142}
143
144static struct gntdev_dmabuf *
145dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
146{
147 struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
148
149 mutex_lock(&priv->lock);
150 list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
151 if (gntdev_dmabuf->fd == fd) {
152 pr_debug("Found gntdev_dmabuf in the wait list\n");
153 kref_get(&gntdev_dmabuf->u.exp.refcount);
154 ret = gntdev_dmabuf;
155 break;
156 }
157 mutex_unlock(&priv->lock);
158 return ret;
159}
160
161static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
162 int wait_to_ms)
163{
164 struct gntdev_dmabuf *gntdev_dmabuf;
165 struct gntdev_dmabuf_wait_obj *obj;
166 int ret;
167
168 pr_debug("Will wait for dma-buf with fd %d\n", fd);
169 /*
170 * Try to find the DMA buffer: if not found means that
171 * either the buffer has already been released or file descriptor
172 * provided is wrong.
173 */
174 gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
175 if (IS_ERR(gntdev_dmabuf))
176 return PTR_ERR(gntdev_dmabuf);
177
178 /*
179 * gntdev_dmabuf still exists and is reference count locked by us now,
180 * so prepare to wait: allocate wait object and add it to the wait list,
181 * so we can find it on release.
182 */
183 obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
184 if (IS_ERR(obj))
185 return PTR_ERR(obj);
186
187 ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
188 dmabuf_exp_wait_obj_free(priv, obj);
189 return ret;
190}
191
192/* DMA buffer export support. */
193
194static struct sg_table *
195dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
196{
197 struct sg_table *sgt;
198 int ret;
199
200 sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
201 if (!sgt) {
202 ret = -ENOMEM;
203 goto out;
204 }
205
206 ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
207 nr_pages << PAGE_SHIFT,
208 GFP_KERNEL);
209 if (ret)
210 goto out;
211
212 return sgt;
213
214out:
215 kfree(sgt);
216 return ERR_PTR(ret);
217}
218
219static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
220 struct dma_buf_attachment *attach)
221{
222 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
223
224 gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach),
225 GFP_KERNEL);
226 if (!gntdev_dmabuf_attach)
227 return -ENOMEM;
228
229 gntdev_dmabuf_attach->dir = DMA_NONE;
230 attach->priv = gntdev_dmabuf_attach;
231 return 0;
232}
233
234static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
235 struct dma_buf_attachment *attach)
236{
237 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
238
239 if (gntdev_dmabuf_attach) {
240 struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
241
242 if (sgt) {
243 if (gntdev_dmabuf_attach->dir != DMA_NONE)
244 dma_unmap_sgtable(attach->dev, sgt,
245 gntdev_dmabuf_attach->dir,
246 DMA_ATTR_SKIP_CPU_SYNC);
247 sg_free_table(sgt);
248 }
249
250 kfree(sgt);
251 kfree(gntdev_dmabuf_attach);
252 attach->priv = NULL;
253 }
254}
255
256static struct sg_table *
257dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
258 enum dma_data_direction dir)
259{
260 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
261 struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
262 struct sg_table *sgt;
263
264 pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
265 attach->dev);
266
267 if (dir == DMA_NONE || !gntdev_dmabuf_attach)
268 return ERR_PTR(-EINVAL);
269
270 /* Return the cached mapping when possible. */
271 if (gntdev_dmabuf_attach->dir == dir)
272 return gntdev_dmabuf_attach->sgt;
273
274 /*
275 * Two mappings with different directions for the same attachment are
276 * not allowed.
277 */
278 if (gntdev_dmabuf_attach->dir != DMA_NONE)
279 return ERR_PTR(-EBUSY);
280
281 sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
282 gntdev_dmabuf->nr_pages);
283 if (!IS_ERR(sgt)) {
284 if (dma_map_sgtable(attach->dev, sgt, dir,
285 DMA_ATTR_SKIP_CPU_SYNC)) {
286 sg_free_table(sgt);
287 kfree(sgt);
288 sgt = ERR_PTR(-ENOMEM);
289 } else {
290 gntdev_dmabuf_attach->sgt = sgt;
291 gntdev_dmabuf_attach->dir = dir;
292 }
293 }
294 if (IS_ERR(sgt))
295 pr_debug("Failed to map sg table for dev %p\n", attach->dev);
296 return sgt;
297}
298
299static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
300 struct sg_table *sgt,
301 enum dma_data_direction dir)
302{
303 /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
304}
305
306static void dmabuf_exp_release(struct kref *kref)
307{
308 struct gntdev_dmabuf *gntdev_dmabuf =
309 container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
310
311 dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
312 list_del(&gntdev_dmabuf->next);
313 fput(gntdev_dmabuf->priv->filp);
314 kfree(gntdev_dmabuf);
315}
316
317static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
318 struct gntdev_grant_map *map)
319{
320 mutex_lock(&priv->lock);
321 list_del(&map->next);
322 gntdev_put_map(NULL /* already removed */, map);
323 mutex_unlock(&priv->lock);
324}
325
326static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
327{
328 struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
329 struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
330
331 dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
332 gntdev_dmabuf->u.exp.map);
333 mutex_lock(&priv->lock);
334 kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
335 mutex_unlock(&priv->lock);
336}
337
338static const struct dma_buf_ops dmabuf_exp_ops = {
339 .attach = dmabuf_exp_ops_attach,
340 .detach = dmabuf_exp_ops_detach,
341 .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
342 .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
343 .release = dmabuf_exp_ops_release,
344};
345
346struct gntdev_dmabuf_export_args {
347 struct gntdev_priv *priv;
348 struct gntdev_grant_map *map;
349 struct gntdev_dmabuf_priv *dmabuf_priv;
350 struct device *dev;
351 int count;
352 struct page **pages;
353 u32 fd;
354};
355
356static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
357{
358 DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
359 struct gntdev_dmabuf *gntdev_dmabuf;
360 int ret;
361
362 gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
363 if (!gntdev_dmabuf)
364 return -ENOMEM;
365
366 kref_init(&gntdev_dmabuf->u.exp.refcount);
367
368 gntdev_dmabuf->priv = args->dmabuf_priv;
369 gntdev_dmabuf->nr_pages = args->count;
370 gntdev_dmabuf->pages = args->pages;
371 gntdev_dmabuf->u.exp.priv = args->priv;
372 gntdev_dmabuf->u.exp.map = args->map;
373
374 exp_info.exp_name = KBUILD_MODNAME;
375 if (args->dev->driver && args->dev->driver->owner)
376 exp_info.owner = args->dev->driver->owner;
377 else
378 exp_info.owner = THIS_MODULE;
379 exp_info.ops = &dmabuf_exp_ops;
380 exp_info.size = args->count << PAGE_SHIFT;
381 exp_info.flags = O_RDWR;
382 exp_info.priv = gntdev_dmabuf;
383
384 gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
385 if (IS_ERR(gntdev_dmabuf->dmabuf)) {
386 ret = PTR_ERR(gntdev_dmabuf->dmabuf);
387 gntdev_dmabuf->dmabuf = NULL;
388 goto fail;
389 }
390
391 ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC);
392 if (ret < 0)
393 goto fail;
394
395 gntdev_dmabuf->fd = ret;
396 args->fd = ret;
397
398 pr_debug("Exporting DMA buffer with fd %d\n", ret);
399
400 mutex_lock(&args->dmabuf_priv->lock);
401 list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
402 mutex_unlock(&args->dmabuf_priv->lock);
403 get_file(gntdev_dmabuf->priv->filp);
404 return 0;
405
406fail:
407 if (gntdev_dmabuf->dmabuf)
408 dma_buf_put(gntdev_dmabuf->dmabuf);
409 kfree(gntdev_dmabuf);
410 return ret;
411}
412
413static struct gntdev_grant_map *
414dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
415 int count)
416{
417 struct gntdev_grant_map *map;
418
419 if (unlikely(gntdev_test_page_count(count)))
420 return ERR_PTR(-EINVAL);
421
422 if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
423 (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
424 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
425 return ERR_PTR(-EINVAL);
426 }
427
428 map = gntdev_alloc_map(priv, count, dmabuf_flags);
429 if (!map)
430 return ERR_PTR(-ENOMEM);
431
432 return map;
433}
434
435static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
436 int count, u32 domid, u32 *refs, u32 *fd)
437{
438 struct gntdev_grant_map *map;
439 struct gntdev_dmabuf_export_args args;
440 int i, ret;
441
442 map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
443 if (IS_ERR(map))
444 return PTR_ERR(map);
445
446 for (i = 0; i < count; i++) {
447 map->grants[i].domid = domid;
448 map->grants[i].ref = refs[i];
449 }
450
451 mutex_lock(&priv->lock);
452 gntdev_add_map(priv, map);
453 mutex_unlock(&priv->lock);
454
455 map->flags |= GNTMAP_host_map;
456#if defined(CONFIG_X86)
457 map->flags |= GNTMAP_device_map;
458#endif
459
460 ret = gntdev_map_grant_pages(map);
461 if (ret < 0)
462 goto out;
463
464 args.priv = priv;
465 args.map = map;
466 args.dev = priv->dma_dev;
467 args.dmabuf_priv = priv->dmabuf_priv;
468 args.count = map->count;
469 args.pages = map->pages;
470 args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
471
472 ret = dmabuf_exp_from_pages(&args);
473 if (ret < 0)
474 goto out;
475
476 *fd = args.fd;
477 return 0;
478
479out:
480 dmabuf_exp_remove_map(priv, map);
481 return ret;
482}
483
484/* DMA buffer import support. */
485
486static int
487dmabuf_imp_grant_foreign_access(struct page **pages, u32 *refs,
488 int count, int domid)
489{
490 grant_ref_t priv_gref_head;
491 int i, ret;
492
493 ret = gnttab_alloc_grant_references(count, &priv_gref_head);
494 if (ret < 0) {
495 pr_debug("Cannot allocate grant references, ret %d\n", ret);
496 return ret;
497 }
498
499 for (i = 0; i < count; i++) {
500 int cur_ref;
501
502 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
503 if (cur_ref < 0) {
504 ret = cur_ref;
505 pr_debug("Cannot claim grant reference, ret %d\n", ret);
506 goto out;
507 }
508
509 gnttab_grant_foreign_access_ref(cur_ref, domid,
510 xen_page_to_gfn(pages[i]), 0);
511 refs[i] = cur_ref;
512 }
513
514 return 0;
515
516out:
517 gnttab_free_grant_references(priv_gref_head);
518 return ret;
519}
520
521static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
522{
523 int i;
524
525 for (i = 0; i < count; i++)
526 if (refs[i] != INVALID_GRANT_REF)
527 gnttab_end_foreign_access(refs[i], NULL);
528}
529
530static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
531{
532 kfree(gntdev_dmabuf->pages);
533 kfree(gntdev_dmabuf->u.imp.refs);
534 kfree(gntdev_dmabuf);
535}
536
537static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
538{
539 struct gntdev_dmabuf *gntdev_dmabuf;
540 int i;
541
542 gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL);
543 if (!gntdev_dmabuf)
544 goto fail_no_free;
545
546 gntdev_dmabuf->u.imp.refs = kcalloc(count,
547 sizeof(gntdev_dmabuf->u.imp.refs[0]),
548 GFP_KERNEL);
549 if (!gntdev_dmabuf->u.imp.refs)
550 goto fail;
551
552 gntdev_dmabuf->pages = kcalloc(count,
553 sizeof(gntdev_dmabuf->pages[0]),
554 GFP_KERNEL);
555 if (!gntdev_dmabuf->pages)
556 goto fail;
557
558 gntdev_dmabuf->nr_pages = count;
559
560 for (i = 0; i < count; i++)
561 gntdev_dmabuf->u.imp.refs[i] = INVALID_GRANT_REF;
562
563 return gntdev_dmabuf;
564
565fail:
566 dmabuf_imp_free_storage(gntdev_dmabuf);
567fail_no_free:
568 return ERR_PTR(-ENOMEM);
569}
570
571static struct gntdev_dmabuf *
572dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
573 int fd, int count, int domid)
574{
575 struct gntdev_dmabuf *gntdev_dmabuf, *ret;
576 struct dma_buf *dma_buf;
577 struct dma_buf_attachment *attach;
578 struct sg_table *sgt;
579 struct sg_page_iter sg_iter;
580 int i;
581
582 dma_buf = dma_buf_get(fd);
583 if (IS_ERR(dma_buf))
584 return ERR_CAST(dma_buf);
585
586 gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
587 if (IS_ERR(gntdev_dmabuf)) {
588 ret = gntdev_dmabuf;
589 goto fail_put;
590 }
591
592 gntdev_dmabuf->priv = priv;
593 gntdev_dmabuf->fd = fd;
594
595 attach = dma_buf_attach(dma_buf, dev);
596 if (IS_ERR(attach)) {
597 ret = ERR_CAST(attach);
598 goto fail_free_obj;
599 }
600
601 gntdev_dmabuf->u.imp.attach = attach;
602
603 sgt = dma_buf_map_attachment_unlocked(attach, DMA_BIDIRECTIONAL);
604 if (IS_ERR(sgt)) {
605 ret = ERR_CAST(sgt);
606 goto fail_detach;
607 }
608
609 /* Check that we have zero offset. */
610 if (sgt->sgl->offset) {
611 ret = ERR_PTR(-EINVAL);
612 pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n",
613 sgt->sgl->offset);
614 goto fail_unmap;
615 }
616
617 /* Check number of pages that imported buffer has. */
618 if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
619 ret = ERR_PTR(-EINVAL);
620 pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
621 attach->dmabuf->size, gntdev_dmabuf->nr_pages);
622 goto fail_unmap;
623 }
624
625 gntdev_dmabuf->u.imp.sgt = sgt;
626
627 /* Now convert sgt to array of pages and check for page validity. */
628 i = 0;
629 for_each_sgtable_page(sgt, &sg_iter, 0) {
630 struct page *page = sg_page_iter_page(&sg_iter);
631 /*
632 * Check if page is valid: this can happen if we are given
633 * a page from VRAM or other resources which are not backed
634 * by a struct page.
635 */
636 if (!pfn_valid(page_to_pfn(page))) {
637 ret = ERR_PTR(-EINVAL);
638 goto fail_unmap;
639 }
640
641 gntdev_dmabuf->pages[i++] = page;
642 }
643
644 ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gntdev_dmabuf->pages,
645 gntdev_dmabuf->u.imp.refs,
646 count, domid));
647 if (IS_ERR(ret))
648 goto fail_end_access;
649
650 pr_debug("Imported DMA buffer with fd %d\n", fd);
651
652 mutex_lock(&priv->lock);
653 list_add(&gntdev_dmabuf->next, &priv->imp_list);
654 mutex_unlock(&priv->lock);
655
656 return gntdev_dmabuf;
657
658fail_end_access:
659 dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
660fail_unmap:
661 dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_BIDIRECTIONAL);
662fail_detach:
663 dma_buf_detach(dma_buf, attach);
664fail_free_obj:
665 dmabuf_imp_free_storage(gntdev_dmabuf);
666fail_put:
667 dma_buf_put(dma_buf);
668 return ret;
669}
670
671/*
672 * Find the hyper dma-buf by its file descriptor and remove
673 * it from the buffer's list.
674 */
675static struct gntdev_dmabuf *
676dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
677{
678 struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
679
680 mutex_lock(&priv->lock);
681 list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
682 if (gntdev_dmabuf->fd == fd) {
683 pr_debug("Found gntdev_dmabuf in the import list\n");
684 ret = gntdev_dmabuf;
685 list_del(&gntdev_dmabuf->next);
686 break;
687 }
688 }
689 mutex_unlock(&priv->lock);
690 return ret;
691}
692
693static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
694{
695 struct gntdev_dmabuf *gntdev_dmabuf;
696 struct dma_buf_attachment *attach;
697 struct dma_buf *dma_buf;
698
699 gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
700 if (IS_ERR(gntdev_dmabuf))
701 return PTR_ERR(gntdev_dmabuf);
702
703 pr_debug("Releasing DMA buffer with fd %d\n", fd);
704
705 dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
706 gntdev_dmabuf->nr_pages);
707
708 attach = gntdev_dmabuf->u.imp.attach;
709
710 if (gntdev_dmabuf->u.imp.sgt)
711 dma_buf_unmap_attachment_unlocked(attach, gntdev_dmabuf->u.imp.sgt,
712 DMA_BIDIRECTIONAL);
713 dma_buf = attach->dmabuf;
714 dma_buf_detach(attach->dmabuf, attach);
715 dma_buf_put(dma_buf);
716
717 dmabuf_imp_free_storage(gntdev_dmabuf);
718 return 0;
719}
720
721static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
722{
723 struct gntdev_dmabuf *q, *gntdev_dmabuf;
724
725 list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next)
726 dmabuf_imp_release(priv, gntdev_dmabuf->fd);
727}
728
729/* DMA buffer IOCTL support. */
730
731long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv, int use_ptemod,
732 struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
733{
734 struct ioctl_gntdev_dmabuf_exp_from_refs op;
735 u32 *refs;
736 long ret;
737
738 if (use_ptemod) {
739 pr_debug("Cannot provide dma-buf: use_ptemode %d\n",
740 use_ptemod);
741 return -EINVAL;
742 }
743
744 if (copy_from_user(&op, u, sizeof(op)) != 0)
745 return -EFAULT;
746
747 if (unlikely(gntdev_test_page_count(op.count)))
748 return -EINVAL;
749
750 refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
751 if (!refs)
752 return -ENOMEM;
753
754 if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
755 ret = -EFAULT;
756 goto out;
757 }
758
759 ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
760 op.domid, refs, &op.fd);
761 if (ret)
762 goto out;
763
764 if (copy_to_user(u, &op, sizeof(op)) != 0)
765 ret = -EFAULT;
766
767out:
768 kfree(refs);
769 return ret;
770}
771
772long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
773 struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
774{
775 struct ioctl_gntdev_dmabuf_exp_wait_released op;
776
777 if (copy_from_user(&op, u, sizeof(op)) != 0)
778 return -EFAULT;
779
780 return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
781 op.wait_to_ms);
782}
783
784long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
785 struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
786{
787 struct ioctl_gntdev_dmabuf_imp_to_refs op;
788 struct gntdev_dmabuf *gntdev_dmabuf;
789 long ret;
790
791 if (copy_from_user(&op, u, sizeof(op)) != 0)
792 return -EFAULT;
793
794 if (unlikely(gntdev_test_page_count(op.count)))
795 return -EINVAL;
796
797 gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
798 priv->dma_dev, op.fd,
799 op.count, op.domid);
800 if (IS_ERR(gntdev_dmabuf))
801 return PTR_ERR(gntdev_dmabuf);
802
803 if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
804 sizeof(*u->refs) * op.count) != 0) {
805 ret = -EFAULT;
806 goto out_release;
807 }
808 return 0;
809
810out_release:
811 dmabuf_imp_release(priv->dmabuf_priv, op.fd);
812 return ret;
813}
814
815long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
816 struct ioctl_gntdev_dmabuf_imp_release __user *u)
817{
818 struct ioctl_gntdev_dmabuf_imp_release op;
819
820 if (copy_from_user(&op, u, sizeof(op)) != 0)
821 return -EFAULT;
822
823 return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
824}
825
826struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
827{
828 struct gntdev_dmabuf_priv *priv;
829
830 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
831 if (!priv)
832 return ERR_PTR(-ENOMEM);
833
834 mutex_init(&priv->lock);
835 INIT_LIST_HEAD(&priv->exp_list);
836 INIT_LIST_HEAD(&priv->exp_wait_list);
837 INIT_LIST_HEAD(&priv->imp_list);
838
839 priv->filp = filp;
840
841 return priv;
842}
843
844void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
845{
846 dmabuf_imp_release_all(priv);
847 kfree(priv);
848}