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 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
dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv * priv,struct gntdev_dmabuf_wait_obj * obj)113 static 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
dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj * obj,u32 wait_to_ms)122 static 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
dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv * priv,struct gntdev_dmabuf * gntdev_dmabuf)132 static 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
145 static struct gntdev_dmabuf *
dmabuf_exp_wait_obj_get_dmabuf(struct gntdev_dmabuf_priv * priv,int fd)146 dmabuf_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
dmabuf_exp_wait_released(struct gntdev_dmabuf_priv * priv,int fd,int wait_to_ms)162 static 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
195 static struct sg_table *
dmabuf_pages_to_sgt(struct page ** pages,unsigned int nr_pages)196 dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages)
197 {
198 struct sg_table *sgt;
199 int ret;
200
201 sgt = kmalloc_obj(*sgt);
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
215 out:
216 kfree(sgt);
217 return ERR_PTR(ret);
218 }
219
dmabuf_exp_ops_attach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)220 static 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_obj(*gntdev_dmabuf_attach);
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
dmabuf_exp_ops_detach(struct dma_buf * dma_buf,struct dma_buf_attachment * attach)234 static 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
256 static struct sg_table *
dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment * attach,enum dma_data_direction dir)257 dmabuf_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
dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment * attach,struct sg_table * sgt,enum dma_data_direction dir)299 static 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
dmabuf_exp_release(struct kref * kref)306 static 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
dmabuf_exp_remove_map(struct gntdev_priv * priv,struct gntdev_grant_map * map)317 static 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
dmabuf_exp_ops_release(struct dma_buf * dma_buf)326 static 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
338 static 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
346 struct 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
dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args * args)356 static 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 __free(kfree) = NULL;
360 CLASS(get_unused_fd, ret)(O_CLOEXEC);
361
362 if (ret < 0)
363 return ret;
364
365 gntdev_dmabuf = kzalloc_obj(*gntdev_dmabuf);
366 if (!gntdev_dmabuf)
367 return -ENOMEM;
368
369 kref_init(&gntdev_dmabuf->u.exp.refcount);
370
371 gntdev_dmabuf->priv = args->dmabuf_priv;
372 gntdev_dmabuf->nr_pages = args->count;
373 gntdev_dmabuf->pages = args->pages;
374 gntdev_dmabuf->u.exp.priv = args->priv;
375 gntdev_dmabuf->u.exp.map = args->map;
376
377 exp_info.exp_name = KBUILD_MODNAME;
378 if (args->dev->driver && args->dev->driver->owner)
379 exp_info.owner = args->dev->driver->owner;
380 else
381 exp_info.owner = THIS_MODULE;
382 exp_info.ops = &dmabuf_exp_ops;
383 exp_info.size = args->count << PAGE_SHIFT;
384 exp_info.flags = O_RDWR;
385 exp_info.priv = gntdev_dmabuf;
386
387 gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info);
388 if (IS_ERR(gntdev_dmabuf->dmabuf))
389 return PTR_ERR(gntdev_dmabuf->dmabuf);
390
391 gntdev_dmabuf->fd = ret;
392 args->fd = ret;
393
394 pr_debug("Exporting DMA buffer with fd %d\n", ret);
395
396 get_file(gntdev_dmabuf->priv->filp);
397 mutex_lock(&args->dmabuf_priv->lock);
398 list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list);
399 mutex_unlock(&args->dmabuf_priv->lock);
400
401 fd_install(take_fd(ret), no_free_ptr(gntdev_dmabuf)->dmabuf->file);
402 return 0;
403 }
404
405 static struct gntdev_grant_map *
dmabuf_exp_alloc_backing_storage(struct gntdev_priv * priv,int dmabuf_flags,int count)406 dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags,
407 int count)
408 {
409 struct gntdev_grant_map *map;
410
411 if (unlikely(gntdev_test_page_count(count)))
412 return ERR_PTR(-EINVAL);
413
414 if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) &&
415 (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) {
416 pr_debug("Wrong dma-buf flags: 0x%x\n", dmabuf_flags);
417 return ERR_PTR(-EINVAL);
418 }
419
420 map = gntdev_alloc_map(priv, count, dmabuf_flags);
421 if (!map)
422 return ERR_PTR(-ENOMEM);
423
424 return map;
425 }
426
dmabuf_exp_from_refs(struct gntdev_priv * priv,int flags,int count,u32 domid,u32 * refs,u32 * fd)427 static int dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags,
428 int count, u32 domid, u32 *refs, u32 *fd)
429 {
430 struct gntdev_grant_map *map;
431 struct gntdev_dmabuf_export_args args;
432 int i, ret;
433
434 map = dmabuf_exp_alloc_backing_storage(priv, flags, count);
435 if (IS_ERR(map))
436 return PTR_ERR(map);
437
438 for (i = 0; i < count; i++) {
439 map->grants[i].domid = domid;
440 map->grants[i].ref = refs[i];
441 }
442
443 mutex_lock(&priv->lock);
444 gntdev_add_map(priv, map);
445 mutex_unlock(&priv->lock);
446
447 map->flags |= GNTMAP_host_map;
448 #if defined(CONFIG_X86)
449 map->flags |= GNTMAP_device_map;
450 #endif
451
452 ret = gntdev_map_grant_pages(map);
453 if (ret < 0)
454 goto out;
455
456 args.priv = priv;
457 args.map = map;
458 args.dev = priv->dma_dev;
459 args.dmabuf_priv = priv->dmabuf_priv;
460 args.count = map->count;
461 args.pages = map->pages;
462 args.fd = -1; /* Shut up unnecessary gcc warning for i386 */
463
464 ret = dmabuf_exp_from_pages(&args);
465 if (ret < 0)
466 goto out;
467
468 *fd = args.fd;
469 return 0;
470
471 out:
472 dmabuf_exp_remove_map(priv, map);
473 return ret;
474 }
475
476 /* DMA buffer import support. */
477
478 static int
dmabuf_imp_grant_foreign_access(unsigned long * gfns,u32 * refs,int count,int domid)479 dmabuf_imp_grant_foreign_access(unsigned long *gfns, u32 *refs,
480 int count, int domid)
481 {
482 grant_ref_t priv_gref_head;
483 int i, ret;
484
485 ret = gnttab_alloc_grant_references(count, &priv_gref_head);
486 if (ret < 0) {
487 pr_debug("Cannot allocate grant references, ret %d\n", ret);
488 return ret;
489 }
490
491 for (i = 0; i < count; i++) {
492 int cur_ref;
493
494 cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
495 if (cur_ref < 0) {
496 ret = cur_ref;
497 pr_debug("Cannot claim grant reference, ret %d\n", ret);
498 goto out;
499 }
500
501 gnttab_grant_foreign_access_ref(cur_ref, domid,
502 gfns[i], 0);
503 refs[i] = cur_ref;
504 }
505
506 return 0;
507
508 out:
509 gnttab_free_grant_references(priv_gref_head);
510 return ret;
511 }
512
dmabuf_imp_end_foreign_access(u32 * refs,int count)513 static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
514 {
515 int i;
516
517 for (i = 0; i < count; i++)
518 if (refs[i] != INVALID_GRANT_REF)
519 gnttab_end_foreign_access(refs[i], NULL);
520 }
521
dmabuf_imp_free_storage(struct gntdev_dmabuf * gntdev_dmabuf)522 static void dmabuf_imp_free_storage(struct gntdev_dmabuf *gntdev_dmabuf)
523 {
524 kfree(gntdev_dmabuf->u.imp.refs);
525 kfree(gntdev_dmabuf);
526 }
527
dmabuf_imp_alloc_storage(int count)528 static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
529 {
530 struct gntdev_dmabuf *gntdev_dmabuf;
531 int i;
532
533 gntdev_dmabuf = kzalloc_obj(*gntdev_dmabuf);
534 if (!gntdev_dmabuf)
535 goto fail_no_free;
536
537 gntdev_dmabuf->u.imp.refs = kzalloc_objs(gntdev_dmabuf->u.imp.refs[0],
538 count);
539 if (!gntdev_dmabuf->u.imp.refs)
540 goto fail;
541
542 gntdev_dmabuf->nr_pages = count;
543
544 for (i = 0; i < count; i++)
545 gntdev_dmabuf->u.imp.refs[i] = INVALID_GRANT_REF;
546
547 return gntdev_dmabuf;
548
549 fail:
550 dmabuf_imp_free_storage(gntdev_dmabuf);
551 fail_no_free:
552 return ERR_PTR(-ENOMEM);
553 }
554
555 static struct gntdev_dmabuf *
dmabuf_imp_to_refs(struct gntdev_dmabuf_priv * priv,struct device * dev,int fd,int count,int domid)556 dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev,
557 int fd, int count, int domid)
558 {
559 struct gntdev_dmabuf *gntdev_dmabuf, *ret;
560 struct dma_buf *dma_buf;
561 struct dma_buf_attachment *attach;
562 struct sg_table *sgt;
563 struct sg_dma_page_iter sg_iter;
564 unsigned long *gfns;
565 int i;
566
567 dma_buf = dma_buf_get(fd);
568 if (IS_ERR(dma_buf))
569 return ERR_CAST(dma_buf);
570
571 gntdev_dmabuf = dmabuf_imp_alloc_storage(count);
572 if (IS_ERR(gntdev_dmabuf)) {
573 ret = gntdev_dmabuf;
574 goto fail_put;
575 }
576
577 gntdev_dmabuf->priv = priv;
578 gntdev_dmabuf->fd = fd;
579
580 attach = dma_buf_attach(dma_buf, dev);
581 if (IS_ERR(attach)) {
582 ret = ERR_CAST(attach);
583 goto fail_free_obj;
584 }
585
586 gntdev_dmabuf->u.imp.attach = attach;
587
588 sgt = dma_buf_map_attachment_unlocked(attach, DMA_BIDIRECTIONAL);
589 if (IS_ERR(sgt)) {
590 ret = ERR_CAST(sgt);
591 goto fail_detach;
592 }
593
594 /* Check that we have zero offset. */
595 if (sgt->sgl->offset) {
596 ret = ERR_PTR(-EINVAL);
597 pr_debug("DMA buffer has %d bytes offset, user-space expects 0\n",
598 sgt->sgl->offset);
599 goto fail_unmap;
600 }
601
602 /* Check number of pages that imported buffer has. */
603 if (attach->dmabuf->size != gntdev_dmabuf->nr_pages << PAGE_SHIFT) {
604 ret = ERR_PTR(-EINVAL);
605 pr_debug("DMA buffer has %zu pages, user-space expects %d\n",
606 attach->dmabuf->size, gntdev_dmabuf->nr_pages);
607 goto fail_unmap;
608 }
609
610 gntdev_dmabuf->u.imp.sgt = sgt;
611
612 gfns = kcalloc(count, sizeof(*gfns), GFP_KERNEL);
613 if (!gfns) {
614 ret = ERR_PTR(-ENOMEM);
615 goto fail_unmap;
616 }
617
618 /*
619 * Now convert sgt to array of gfns without accessing underlying pages.
620 * It is not allowed to access the underlying struct page of an sg table
621 * exported by DMA-buf, but since we deal with special Xen dma device here
622 * (not a normal physical one) look at the dma addresses in the sg table
623 * and then calculate gfns directly from them.
624 */
625 i = 0;
626 for_each_sgtable_dma_page(sgt, &sg_iter, 0) {
627 dma_addr_t addr = sg_page_iter_dma_address(&sg_iter);
628 unsigned long pfn = bfn_to_pfn(XEN_PFN_DOWN(dma_to_phys(dev, addr)));
629
630 gfns[i++] = pfn_to_gfn(pfn);
631 }
632
633 ret = ERR_PTR(dmabuf_imp_grant_foreign_access(gfns,
634 gntdev_dmabuf->u.imp.refs,
635 count, domid));
636 kfree(gfns);
637 if (IS_ERR(ret))
638 goto fail_end_access;
639
640 pr_debug("Imported DMA buffer with fd %d\n", fd);
641
642 mutex_lock(&priv->lock);
643 list_add(&gntdev_dmabuf->next, &priv->imp_list);
644 mutex_unlock(&priv->lock);
645
646 return gntdev_dmabuf;
647
648 fail_end_access:
649 dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs, count);
650 fail_unmap:
651 dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_BIDIRECTIONAL);
652 fail_detach:
653 dma_buf_detach(dma_buf, attach);
654 fail_free_obj:
655 dmabuf_imp_free_storage(gntdev_dmabuf);
656 fail_put:
657 dma_buf_put(dma_buf);
658 return ret;
659 }
660
661 /*
662 * Find the hyper dma-buf by its file descriptor and remove
663 * it from the buffer's list.
664 */
665 static struct gntdev_dmabuf *
dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv * priv,int fd)666 dmabuf_imp_find_unlink(struct gntdev_dmabuf_priv *priv, int fd)
667 {
668 struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT);
669
670 mutex_lock(&priv->lock);
671 list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next) {
672 if (gntdev_dmabuf->fd == fd) {
673 pr_debug("Found gntdev_dmabuf in the import list\n");
674 ret = gntdev_dmabuf;
675 list_del(&gntdev_dmabuf->next);
676 break;
677 }
678 }
679 mutex_unlock(&priv->lock);
680 return ret;
681 }
682
dmabuf_imp_release(struct gntdev_dmabuf_priv * priv,u32 fd)683 static int dmabuf_imp_release(struct gntdev_dmabuf_priv *priv, u32 fd)
684 {
685 struct gntdev_dmabuf *gntdev_dmabuf;
686 struct dma_buf_attachment *attach;
687 struct dma_buf *dma_buf;
688
689 gntdev_dmabuf = dmabuf_imp_find_unlink(priv, fd);
690 if (IS_ERR(gntdev_dmabuf))
691 return PTR_ERR(gntdev_dmabuf);
692
693 pr_debug("Releasing DMA buffer with fd %d\n", fd);
694
695 dmabuf_imp_end_foreign_access(gntdev_dmabuf->u.imp.refs,
696 gntdev_dmabuf->nr_pages);
697
698 attach = gntdev_dmabuf->u.imp.attach;
699
700 if (gntdev_dmabuf->u.imp.sgt)
701 dma_buf_unmap_attachment_unlocked(attach, gntdev_dmabuf->u.imp.sgt,
702 DMA_BIDIRECTIONAL);
703 dma_buf = attach->dmabuf;
704 dma_buf_detach(attach->dmabuf, attach);
705 dma_buf_put(dma_buf);
706
707 dmabuf_imp_free_storage(gntdev_dmabuf);
708 return 0;
709 }
710
dmabuf_imp_release_all(struct gntdev_dmabuf_priv * priv)711 static void dmabuf_imp_release_all(struct gntdev_dmabuf_priv *priv)
712 {
713 struct gntdev_dmabuf *q, *gntdev_dmabuf;
714
715 list_for_each_entry_safe(gntdev_dmabuf, q, &priv->imp_list, next)
716 dmabuf_imp_release(priv, gntdev_dmabuf->fd);
717 }
718
719 /* DMA buffer IOCTL support. */
720
gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv * priv,struct ioctl_gntdev_dmabuf_exp_from_refs __user * u)721 long gntdev_ioctl_dmabuf_exp_from_refs(struct gntdev_priv *priv,
722 struct ioctl_gntdev_dmabuf_exp_from_refs __user *u)
723 {
724 struct ioctl_gntdev_dmabuf_exp_from_refs op;
725 u32 *refs;
726 long ret;
727
728 if (xen_pv_domain()) {
729 pr_debug("Cannot provide dma-buf in a PV domain\n");
730 return -EINVAL;
731 }
732
733 if (copy_from_user(&op, u, sizeof(op)) != 0)
734 return -EFAULT;
735
736 if (unlikely(gntdev_test_page_count(op.count)))
737 return -EINVAL;
738
739 refs = kcalloc(op.count, sizeof(*refs), GFP_KERNEL);
740 if (!refs)
741 return -ENOMEM;
742
743 if (copy_from_user(refs, u->refs, sizeof(*refs) * op.count) != 0) {
744 ret = -EFAULT;
745 goto out;
746 }
747
748 ret = dmabuf_exp_from_refs(priv, op.flags, op.count,
749 op.domid, refs, &op.fd);
750 if (ret)
751 goto out;
752
753 if (copy_to_user(u, &op, sizeof(op)) != 0)
754 ret = -EFAULT;
755
756 out:
757 kfree(refs);
758 return ret;
759 }
760
gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv * priv,struct ioctl_gntdev_dmabuf_exp_wait_released __user * u)761 long gntdev_ioctl_dmabuf_exp_wait_released(struct gntdev_priv *priv,
762 struct ioctl_gntdev_dmabuf_exp_wait_released __user *u)
763 {
764 struct ioctl_gntdev_dmabuf_exp_wait_released op;
765
766 if (copy_from_user(&op, u, sizeof(op)) != 0)
767 return -EFAULT;
768
769 return dmabuf_exp_wait_released(priv->dmabuf_priv, op.fd,
770 op.wait_to_ms);
771 }
772
gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv * priv,struct ioctl_gntdev_dmabuf_imp_to_refs __user * u)773 long gntdev_ioctl_dmabuf_imp_to_refs(struct gntdev_priv *priv,
774 struct ioctl_gntdev_dmabuf_imp_to_refs __user *u)
775 {
776 struct ioctl_gntdev_dmabuf_imp_to_refs op;
777 struct gntdev_dmabuf *gntdev_dmabuf;
778 long ret;
779
780 if (copy_from_user(&op, u, sizeof(op)) != 0)
781 return -EFAULT;
782
783 if (unlikely(gntdev_test_page_count(op.count)))
784 return -EINVAL;
785
786 gntdev_dmabuf = dmabuf_imp_to_refs(priv->dmabuf_priv,
787 priv->dma_dev, op.fd,
788 op.count, op.domid);
789 if (IS_ERR(gntdev_dmabuf))
790 return PTR_ERR(gntdev_dmabuf);
791
792 if (copy_to_user(u->refs, gntdev_dmabuf->u.imp.refs,
793 sizeof(*u->refs) * op.count) != 0) {
794 ret = -EFAULT;
795 goto out_release;
796 }
797 return 0;
798
799 out_release:
800 dmabuf_imp_release(priv->dmabuf_priv, op.fd);
801 return ret;
802 }
803
gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv * priv,struct ioctl_gntdev_dmabuf_imp_release __user * u)804 long gntdev_ioctl_dmabuf_imp_release(struct gntdev_priv *priv,
805 struct ioctl_gntdev_dmabuf_imp_release __user *u)
806 {
807 struct ioctl_gntdev_dmabuf_imp_release op;
808
809 if (copy_from_user(&op, u, sizeof(op)) != 0)
810 return -EFAULT;
811
812 return dmabuf_imp_release(priv->dmabuf_priv, op.fd);
813 }
814
gntdev_dmabuf_init(struct file * filp)815 struct gntdev_dmabuf_priv *gntdev_dmabuf_init(struct file *filp)
816 {
817 struct gntdev_dmabuf_priv *priv;
818
819 priv = kzalloc_obj(*priv);
820 if (!priv)
821 return ERR_PTR(-ENOMEM);
822
823 mutex_init(&priv->lock);
824 INIT_LIST_HEAD(&priv->exp_list);
825 INIT_LIST_HEAD(&priv->exp_wait_list);
826 INIT_LIST_HEAD(&priv->imp_list);
827
828 priv->filp = filp;
829
830 return priv;
831 }
832
gntdev_dmabuf_fini(struct gntdev_dmabuf_priv * priv)833 void gntdev_dmabuf_fini(struct gntdev_dmabuf_priv *priv)
834 {
835 dmabuf_imp_release_all(priv);
836 kfree(priv);
837 }
838