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
26 MODULE_IMPORT_NS("DMA_BUF");
27
28 struct 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
58 struct gntdev_dmabuf_wait_obj {
59 struct list_head next;
60 struct gntdev_dmabuf *gntdev_dmabuf;
61 struct completion completion;
62 };
63
64 struct gntdev_dmabuf_attachment {
65 struct sg_table *sgt;
66 enum dma_data_direction dir;
67 };
68
69 struct 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
90 static void dmabuf_exp_release(struct kref *kref);
91
92 static struct gntdev_dmabuf_wait_obj *
dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv * priv,struct gntdev_dmabuf * gntdev_dmabuf)93 dmabuf_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_obj(*obj);
99 if (!obj) {
100 kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
101 return ERR_PTR(-ENOMEM);
102 }
103
104 init_completion(&obj->completion);
105 obj->gntdev_dmabuf = gntdev_dmabuf;
106
107 mutex_lock(&priv->lock);
108 list_add(&obj->next, &priv->exp_wait_list);
109 /* Put our reference and wait for gntdev_dmabuf's release to fire. */
110 kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
111 mutex_unlock(&priv->lock);
112 return obj;
113 }
114
dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv * priv,struct gntdev_dmabuf_wait_obj * obj)115 static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv,
116 struct gntdev_dmabuf_wait_obj *obj)
117 {
118 mutex_lock(&priv->lock);
119 list_del(&obj->next);
120 mutex_unlock(&priv->lock);
121 kfree(obj);
122 }
123
dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj * obj,u32 wait_to_ms)124 static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj,
125 u32 wait_to_ms)
126 {
127 if (wait_for_completion_timeout(&obj->completion,
128 msecs_to_jiffies(wait_to_ms)) <= 0)
129 return -ETIMEDOUT;
130
131 return 0;
132 }
133
dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv * priv,struct gntdev_dmabuf * gntdev_dmabuf)134 static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv,
135 struct gntdev_dmabuf *gntdev_dmabuf)
136 {
137 struct gntdev_dmabuf_wait_obj *obj;
138
139 list_for_each_entry(obj, &priv->exp_wait_list, next)
140 if (obj->gntdev_dmabuf == gntdev_dmabuf) {
141 pr_debug("Found gntdev_dmabuf in the wait list, wake\n");
142 complete_all(&obj->completion);
143 break;
144 }
145 }
146
147 static struct gntdev_dmabuf *
dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv * priv,int fd)148 dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv *priv, int fd)
149 {
150 struct gntdev_dmabuf *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
151
152 mutex_lock(&priv->lock);
153 list_for_each_entry(gntdev_dmabuf, &priv->exp_list, next)
154 if (gntdev_dmabuf->fd == fd) {
155 pr_debug("Found gntdev_dmabuf in the wait list\n");
156 kref_get(&gntdev_dmabuf->u.exp.refcount);
157 ret = gntdev_dmabuf;
158 break;
159 }
160 mutex_unlock(&priv->lock);
161 return ret;
162 }
163
dmabuf_exp_wait_released(struct gntdev_dmabuf_priv * priv,int fd,int wait_to_ms)164 static int dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd,
165 int wait_to_ms)
166 {
167 struct gntdev_dmabuf *gntdev_dmabuf;
168 struct gntdev_dmabuf_wait_obj *obj;
169 int ret;
170
171 pr_debug("Will wait for dma-buf with fd %d\n", fd);
172 /*
173 * Try to find the DMA buffer: if not found means that
174 * either the buffer has already been released or file descriptor
175 * provided is wrong.
176 */
177 gntdev_dmabuf = dmabuf_exp_wait_obj_get_dmabuf(priv, fd);
178 if (IS_ERR(gntdev_dmabuf))
179 return PTR_ERR(gntdev_dmabuf);
180
181 /*
182 * gntdev_dmabuf still exists and is reference count locked by us now,
183 * so prepare to wait: allocate wait object and add it to the wait list,
184 * so we can find it on release.
185 */
186 obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf);
187 if (IS_ERR(obj))
188 return PTR_ERR(obj);
189
190 ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms);
191 dmabuf_exp_wait_obj_free(priv, obj);
192 return ret;
193 }
194
195 /* DMA buffer export support. */
196
197 static struct sg_table *
dmabuf_pages_to_sgt(struct page ** pages,unsigned int nr_pages)198 dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
199 {
200 struct sg_table *sgt;
201 int ret;
202
203 sgt = kmalloc_obj(*sgt);
204 if (!sgt) {
205 ret = -ENOMEM;
206 goto out;
207 }
208
209 ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0,
210 nr_pages << PAGE_SHIFT,
211 GFP_KERNEL);
212 if (ret)
213 goto out;
214
215 return sgt;
216
217 out:
218 kfree(sgt);
219 return ERR_PTR(ret);
220 }
221
dmabuf_exp_ops_attach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)222 static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf,
223 struct dma_buf_attachment *attach)
224 {
225 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach;
226
227 gntdev_dmabuf_attach = kzalloc_obj(*gntdev_dmabuf_attach);
228 if (!gntdev_dmabuf_attach)
229 return -ENOMEM;
230
231 gntdev_dmabuf_attach->dir = DMA_NONE;
232 attach->priv = gntdev_dmabuf_attach;
233 return 0;
234 }
235
dmabuf_exp_ops_detach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)236 static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf,
237 struct dma_buf_attachment *attach)
238 {
239 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
240
241 if (gntdev_dmabuf_attach) {
242 struct sg_table *sgt = gntdev_dmabuf_attach->sgt;
243
244 if (sgt) {
245 if (gntdev_dmabuf_attach->dir != DMA_NONE)
246 dma_unmap_sgtable(attach->dev, sgt,
247 gntdev_dmabuf_attach->dir,
248 DMA_ATTR_SKIP_CPU_SYNC);
249 sg_free_table(sgt);
250 }
251
252 kfree(sgt);
253 kfree(gntdev_dmabuf_attach);
254 attach->priv = NULL;
255 }
256 }
257
258 static struct sg_table *
dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment * attach,enum dma_data_direction dir)259 dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach,
260 enum dma_data_direction dir)
261 {
262 struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv;
263 struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv;
264 struct sg_table *sgt;
265
266 pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages,
267 attach->dev);
268
269 if (dir == DMA_NONE || !gntdev_dmabuf_attach)
270 return ERR_PTR(-EINVAL);
271
272 /* Return the cached mapping when possible. */
273 if (gntdev_dmabuf_attach->dir == dir)
274 return gntdev_dmabuf_attach->sgt;
275
276 /*
277 * Two mappings with different directions for the same attachment are
278 * not allowed.
279 */
280 if (gntdev_dmabuf_attach->dir != DMA_NONE)
281 return ERR_PTR(-EBUSY);
282
283 sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages,
284 gntdev_dmabuf->nr_pages);
285 if (!IS_ERR(sgt)) {
286 if (dma_map_sgtable(attach->dev, sgt, dir,
287 DMA_ATTR_SKIP_CPU_SYNC)) {
288 sg_free_table(sgt);
289 kfree(sgt);
290 sgt = ERR_PTR(-ENOMEM);
291 } else {
292 gntdev_dmabuf_attach->sgt = sgt;
293 gntdev_dmabuf_attach->dir = dir;
294 }
295 }
296 if (IS_ERR(sgt))
297 pr_debug("Failed to map sg table for dev %p\n", attach->dev);
298 return sgt;
299 }
300
dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment * attach,struct sg_table * sgt,enum dma_data_direction dir)301 static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach,
302 struct sg_table *sgt,
303 enum dma_data_direction dir)
304 {
305 /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */
306 }
307
dmabuf_exp_release(struct kref * kref)308 static void dmabuf_exp_release(struct kref *kref)
309 {
310 struct gntdev_dmabuf *gntdev_dmabuf =
311 container_of(kref, struct gntdev_dmabuf, u.exp.refcount);
312
313 dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf);
314 list_del(&gntdev_dmabuf->next);
315 fput(gntdev_dmabuf->priv->filp);
316 kfree(gntdev_dmabuf);
317 }
318
dmabuf_exp_remove_map(struct gntdev_priv * priv,struct gntdev_grant_map * map)319 static void dmabuf_exp_remove_map(struct gntdev_priv *priv,
320 struct gntdev_grant_map *map)
321 {
322 mutex_lock(&priv->lock);
323 list_del(&map->next);
324 gntdev_put_map(NULL /* already removed */, map);
325 mutex_unlock(&priv->lock);
326 }
327
dmabuf_exp_ops_release(struct dma_buf * dma_buf)328 static void dmabuf_exp_ops_release(struct dma_buf *dma_buf)
329 {
330 struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv;
331 struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv;
332
333 dmabuf_exp_remove_map(gntdev_dmabuf->u.exp.priv,
334 gntdev_dmabuf->u.exp.map);
335 mutex_lock(&priv->lock);
336 kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release);
337 mutex_unlock(&priv->lock);
338 }
339
340 static const struct dma_buf_ops dmabuf_exp_ops = {
341 .attach = dmabuf_exp_ops_attach,
342 .detach = dmabuf_exp_ops_detach,
343 .map_dma_buf = dmabuf_exp_ops_map_dma_buf,
344 .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf,
345 .release = dmabuf_exp_ops_release,
346 };
347
348 struct gntdev_dmabuf_export_args {
349 struct gntdev_priv *priv;
350 struct gntdev_grant_map *map;
351 struct gntdev_dmabuf_priv *dmabuf_priv;
352 struct device *dev;
353 int count;
354 struct page **pages;
355 u32 fd;
356 };
357
dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args * args)358 static int dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args)
359 {
360 DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
361 struct gntdev_dmabuf *gntdev_dmabuf __free(kfree) = NULL;
362 CLASS(get_unused_fd, ret)(O_CLOEXEC);
363
364 if (ret < 0)
365 return ret;
366
367 gntdev_dmabuf = kzalloc_obj(*gntdev_dmabuf);
368 if (!gntdev_dmabuf)
369 return -ENOMEM;
370
371 kref_init(&gntdev_dmabuf->u.exp.refcount);
372
373 gntdev_dmabuf->priv = args->dmabuf_priv;
374 gntdev_dmabuf->nr_pages = args->count;
375 gntdev_dmabuf->pages = args->pages;
376 gntdev_dmabuf->u.exp.priv = args->priv;
377 gntdev_dmabuf->u.exp.map = args->map;
378
379 exp_info.exp_name = KBUILD_MODNAME;
380 if (args->dev->driver && args->dev->driver->owner)
381 exp_info.owner = args->dev->driver->owner;
382 else
383 exp_info.owner = THIS_MODULE;
384 exp_info.ops = &dmabuf_exp_ops;
385 exp_info.size = args->count << PAGE_SHIFT;
386 exp_info.flags = O_RDWR;
387 exp_info.priv = gntdev_dmabuf;
388
389 gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
390 if (IS_ERR(gntdev_dmabuf->dmabuf))
391 return PTR_ERR(gntdev_dmabuf->dmabuf);
392
393 gntdev_dmabuf->fd = ret;
394 args->fd = ret;
395
396 pr_debug("Exporting DMA buffer with fd %d\n", ret);
397
398 get_file(gntdev_dmabuf->priv->filp);
399 mutex_lock(&args->dmabuf_priv->lock);
400 list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
401 mutex_unlock(&args->dmabuf_priv->lock);
402
403 fd_install(take_fd(ret), no_free_ptr(gntdev_dmabuf)->dmabuf->file);
404 return 0;
405 }
406
407 static struct gntdev_grant_map *
dmabuf_exp_alloc_backing_storage(struct gntdev_priv * priv,int dmabuf_flags,int count)408 dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
409 int count)
410 {
411 struct gntdev_grant_map *map;
412
413 if (unlikely(gntdev_test_page_count(count)))
414 return ERR_PTR(-EINVAL);
415
416 if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
417 (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
418 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
419 return ERR_PTR(-EINVAL);
420 }
421
422 map = gntdev_alloc_map(priv, count, dmabuf_flags);
423 if (!map)
424 return ERR_PTR(-ENOMEM);
425
426 return map;
427 }
428
dmabuf_exp_from_refs(struct gntdev_priv * priv,int flags,int count,u32 domid,u32 * refs,u32 * fd)429 static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
430 int count, u32 domid, u32 *refs, u32 *fd)
431 {
432 struct gntdev_grant_map *map;
433 struct gntdev_dmabuf_export_args args;
434 int i, ret;
435
436 map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
437 if (IS_ERR(map))
438 return PTR_ERR(map);
439
440 for (i = 0; i < count; i++) {
441 map->grants[i].domid = domid;
442 map->grants[i].ref = refs[i];
443 }
444
445 mutex_lock(&priv->lock);
446 gntdev_add_map(priv, map);
447 mutex_unlock(&priv->lock);
448
449 map->flags |= GNTMAP_host_map;
450 #if defined(CONFIG_X86)
451 map->flags |= GNTMAP_device_map;
452 #endif
453
454 ret = gntdev_map_grant_pages(map);
455 if (ret < 0)
456 goto out;
457
458 args.priv = priv;
459 args.map = map;
460 args.dev = priv->dma_dev;
461 args.dmabuf_priv = priv->dmabuf_priv;
462 args.count = map->count;
463 args.pages = map->pages;
464 args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
465
466 ret = dmabuf_exp_from_pages(&args);
467 if (ret < 0)
468 goto out;
469
470 *fd = args.fd;
471 return 0;
472
473 out:
474 dmabuf_exp_remove_map(priv, map);
475 return ret;
476 }
477
478 /* DMA buffer import support. */
479
480 static int
dmabuf_imp_grant_foreign_access(unsigned long * gfns,u32 * refs,int count,int domid)481 dmabuf_imp_grant_foreign_access(unsigned long *gfns, u32 *refs,
482 int count, int domid)
483 {
484 grant_ref_t priv_gref_head;
485 int i, ret;
486
487 ret = gnttab_alloc_grant_references(count, &priv_gref_head);
488 if (ret < 0) {
489 pr_debug("Cannot allocate grant references, ret %d\n", ret);
490 return ret;
491 }
492
493 for (i = 0; i < count; i++) {
494 int cur_ref;
495
496 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
497 if (cur_ref < 0) {
498 ret = cur_ref;
499 pr_debug("Cannot claim grant reference, ret %d\n", ret);
500 goto out;
501 }
502
503 gnttab_grant_foreign_access_ref(cur_ref, domid,
504 gfns[i], 0);
505 refs[i] = cur_ref;
506 }
507
508 return 0;
509
510 out:
511 gnttab_free_grant_references(priv_gref_head);
512 return ret;
513 }
514
dmabuf_imp_end_foreign_access(u32 * refs,int count)515 static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
516 {
517 int i;
518
519 for (i = 0; i < count; i++)
520 if (refs[i] != INVALID_GRANT_REF)
521 gnttab_end_foreign_access(refs[i], NULL);
522 }
523
dmabuf_imp_free_storage(struct gntdev_dmabuf * gntdev_dmabuf)524 static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
525 {
526 kfree(gntdev_dmabuf->u.imp.refs);
527 kfree(gntdev_dmabuf);
528 }
529
dmabuf_imp_alloc_storage(int count)530 static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
531 {
532 struct gntdev_dmabuf *gntdev_dmabuf;
533 int i;
534
535 gntdev_dmabuf = kzalloc_obj(*gntdev_dmabuf);
536 if (!gntdev_dmabuf)
537 goto fail_no_free;
538
539 gntdev_dmabuf->u.imp.refs = kzalloc_objs(gntdev_dmabuf->u.imp.refs[0],
540 count);
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
551 fail:
552 dmabuf_imp_free_storage(gntdev_dmabuf);
553 fail_no_free:
554 return ERR_PTR(-ENOMEM);
555 }
556
557 static struct gntdev_dmabuf *
dmabuf_imp_to_refs(struct gntdev_dmabuf_priv * priv,struct device * dev,int fd,int count,int domid)558 dmabuf_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
650 fail_end_access:
651 dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
652 fail_unmap:
653 dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_BIDIRECTIONAL);
654 fail_detach:
655 dma_buf_detach(dma_buf, attach);
656 fail_free_obj:
657 dmabuf_imp_free_storage(gntdev_dmabuf);
658 fail_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 */
667 static struct gntdev_dmabuf *
dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv * priv,int fd)668 dmabuf_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
dmabuf_imp_release(struct gntdev_dmabuf_priv * priv,u32 fd)685 static 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
dmabuf_imp_release_all(struct gntdev_dmabuf_priv * priv)713 static 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
gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv * priv,struct ioctl_gntdev_dmabuf_exp_from_refs __user * u)723 long 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
758 out:
759 kfree(refs);
760 return ret;
761 }
762
gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv * priv,struct ioctl_gntdev_dmabuf_exp_wait_released __user * u)763 long 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
gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv * priv,struct ioctl_gntdev_dmabuf_imp_to_refs __user * u)775 long 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
801 out_release:
802 dmabuf_imp_release(priv->dmabuf_priv, op.fd);
803 return ret;
804 }
805
gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv * priv,struct ioctl_gntdev_dmabuf_imp_release __user * u)806 long 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
gntdev_dmabuf_init(struct file * filp)817 struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
818 {
819 struct gntdev_dmabuf_priv *priv;
820
821 priv = kzalloc_obj(*priv);
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
gntdev_dmabuf_fini(struct gntdev_dmabuf_priv * priv)835 void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
836 {
837 dmabuf_imp_release_all(priv);
838 kfree(priv);
839 }
840