1 /******************************************************************************
2 * gntdev.c
3 *
4 * Device for accessing (in user-space) pages that have been granted by other
5 * domains.
6 *
7 * Copyright (c) 2006-2007, D G Murray.
8 * (c) 2009 Gerd Hoffmann <kraxel@redhat.com>
9 * (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 #undef DEBUG
22
23 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
24
25 #include <linux/dma-mapping.h>
26 #include <linux/module.h>
27 #include <linux/kernel.h>
28 #include <linux/init.h>
29 #include <linux/miscdevice.h>
30 #include <linux/fs.h>
31 #include <linux/uaccess.h>
32 #include <linux/sched.h>
33 #include <linux/sched/mm.h>
34 #include <linux/spinlock.h>
35 #include <linux/slab.h>
36 #include <linux/highmem.h>
37 #include <linux/refcount.h>
38 #include <linux/workqueue.h>
39
40 #include <xen/xen.h>
41 #include <xen/grant_table.h>
42 #include <xen/balloon.h>
43 #include <xen/gntdev.h>
44 #include <xen/events.h>
45 #include <xen/page.h>
46 #include <asm/xen/hypervisor.h>
47 #include <asm/xen/hypercall.h>
48
49 #include "gntdev-common.h"
50 #ifdef CONFIG_XEN_GNTDEV_DMABUF
51 #include "gntdev-dmabuf.h"
52 #endif
53
54 MODULE_LICENSE("GPL");
55 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
56 "Gerd Hoffmann <kraxel@redhat.com>");
57 MODULE_DESCRIPTION("User-space granted page access driver");
58
59 static unsigned int limit = 64*1024;
60 module_param(limit, uint, 0644);
61 MODULE_PARM_DESC(limit,
62 "Maximum number of grants that may be mapped by one mapping request");
63
64 /* True in PV mode, false otherwise */
65 static int use_ptemod;
66
67 static void unmap_grant_pages(struct gntdev_grant_map *map,
68 int offset, int pages);
69
70 static struct miscdevice gntdev_miscdev;
71
72 /* ------------------------------------------------------------------ */
73
gntdev_test_page_count(unsigned int count)74 bool gntdev_test_page_count(unsigned int count)
75 {
76 return !count || count > limit;
77 }
78
gntdev_print_maps(struct gntdev_priv * priv,char * text,int text_index)79 static void gntdev_print_maps(struct gntdev_priv *priv,
80 char *text, int text_index)
81 {
82 #ifdef DEBUG
83 struct gntdev_grant_map *map;
84
85 pr_debug("%s: maps list (priv %p)\n", __func__, priv);
86 list_for_each_entry(map, &priv->maps, next)
87 pr_debug(" index %2d, count %2d %s\n",
88 map->index, map->count,
89 map->index == text_index && text ? text : "");
90 #endif
91 }
92
gntdev_free_map(struct gntdev_grant_map * map)93 static void gntdev_free_map(struct gntdev_grant_map *map)
94 {
95 if (map == NULL)
96 return;
97
98 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
99 if (map->dma_vaddr) {
100 struct gnttab_dma_alloc_args args;
101
102 args.dev = map->dma_dev;
103 args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);
104 args.nr_pages = map->count;
105 args.pages = map->pages;
106 args.frames = map->frames;
107 args.vaddr = map->dma_vaddr;
108 args.dev_bus_addr = map->dma_bus_addr;
109
110 gnttab_dma_free_pages(&args);
111 } else
112 #endif
113 if (map->pages)
114 gnttab_free_pages(map->count, map->pages);
115
116 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
117 kvfree(map->frames);
118 #endif
119 kvfree(map->pages);
120 kvfree(map->grants);
121 kvfree(map->map_ops);
122 kvfree(map->unmap_ops);
123 kvfree(map->kmap_ops);
124 kvfree(map->kunmap_ops);
125 kvfree(map->being_removed);
126 kfree(map);
127 }
128
gntdev_alloc_map(struct gntdev_priv * priv,int count,int dma_flags)129 struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
130 int dma_flags)
131 {
132 struct gntdev_grant_map *add;
133 int i;
134
135 add = kzalloc(sizeof(*add), GFP_KERNEL);
136 if (NULL == add)
137 return NULL;
138
139 add->grants = kvmalloc_array(count, sizeof(add->grants[0]),
140 GFP_KERNEL);
141 add->map_ops = kvmalloc_array(count, sizeof(add->map_ops[0]),
142 GFP_KERNEL);
143 add->unmap_ops = kvmalloc_array(count, sizeof(add->unmap_ops[0]),
144 GFP_KERNEL);
145 add->pages = kvcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
146 add->being_removed =
147 kvcalloc(count, sizeof(add->being_removed[0]), GFP_KERNEL);
148 if (NULL == add->grants ||
149 NULL == add->map_ops ||
150 NULL == add->unmap_ops ||
151 NULL == add->pages ||
152 NULL == add->being_removed)
153 goto err;
154 if (use_ptemod) {
155 add->kmap_ops = kvmalloc_array(count, sizeof(add->kmap_ops[0]),
156 GFP_KERNEL);
157 add->kunmap_ops = kvmalloc_array(count, sizeof(add->kunmap_ops[0]),
158 GFP_KERNEL);
159 if (NULL == add->kmap_ops || NULL == add->kunmap_ops)
160 goto err;
161 }
162
163 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
164 add->dma_flags = dma_flags;
165
166 /*
167 * Check if this mapping is requested to be backed
168 * by a DMA buffer.
169 */
170 if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) {
171 struct gnttab_dma_alloc_args args;
172
173 add->frames = kvcalloc(count, sizeof(add->frames[0]),
174 GFP_KERNEL);
175 if (!add->frames)
176 goto err;
177
178 /* Remember the device, so we can free DMA memory. */
179 add->dma_dev = priv->dma_dev;
180
181 args.dev = priv->dma_dev;
182 args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT);
183 args.nr_pages = count;
184 args.pages = add->pages;
185 args.frames = add->frames;
186
187 if (gnttab_dma_alloc_pages(&args))
188 goto err;
189
190 add->dma_vaddr = args.vaddr;
191 add->dma_bus_addr = args.dev_bus_addr;
192 } else
193 #endif
194 if (gnttab_alloc_pages(count, add->pages))
195 goto err;
196
197 for (i = 0; i < count; i++) {
198 add->grants[i].domid = DOMID_INVALID;
199 add->grants[i].ref = INVALID_GRANT_REF;
200 add->map_ops[i].handle = INVALID_GRANT_HANDLE;
201 add->unmap_ops[i].handle = INVALID_GRANT_HANDLE;
202 if (use_ptemod) {
203 add->kmap_ops[i].handle = INVALID_GRANT_HANDLE;
204 add->kunmap_ops[i].handle = INVALID_GRANT_HANDLE;
205 }
206 }
207
208 add->index = 0;
209 add->count = count;
210 refcount_set(&add->users, 1);
211
212 return add;
213
214 err:
215 gntdev_free_map(add);
216 return NULL;
217 }
218
gntdev_add_map(struct gntdev_priv * priv,struct gntdev_grant_map * add)219 void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add)
220 {
221 struct gntdev_grant_map *map;
222
223 list_for_each_entry(map, &priv->maps, next) {
224 if (add->index + add->count < map->index) {
225 list_add_tail(&add->next, &map->next);
226 goto done;
227 }
228 add->index = map->index + map->count;
229 }
230 list_add_tail(&add->next, &priv->maps);
231
232 done:
233 gntdev_print_maps(priv, "[new]", add->index);
234 }
235
gntdev_find_map_index(struct gntdev_priv * priv,int index,int count)236 static struct gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
237 int index, int count)
238 {
239 struct gntdev_grant_map *map;
240
241 list_for_each_entry(map, &priv->maps, next) {
242 if (map->index != index)
243 continue;
244 if (count && map->count != count)
245 continue;
246 return map;
247 }
248 return NULL;
249 }
250
gntdev_put_map(struct gntdev_priv * priv,struct gntdev_grant_map * map)251 void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map)
252 {
253 if (!map)
254 return;
255
256 if (!refcount_dec_and_test(&map->users))
257 return;
258
259 if (map->pages && !use_ptemod) {
260 /*
261 * Increment the reference count. This ensures that the
262 * subsequent call to unmap_grant_pages() will not wind up
263 * re-entering itself. It *can* wind up calling
264 * gntdev_put_map() recursively, but such calls will be with a
265 * reference count greater than 1, so they will return before
266 * this code is reached. The recursion depth is thus limited to
267 * 1. Do NOT use refcount_inc() here, as it will detect that
268 * the reference count is zero and WARN().
269 */
270 refcount_set(&map->users, 1);
271
272 /*
273 * Unmap the grants. This may or may not be asynchronous, so it
274 * is possible that the reference count is 1 on return, but it
275 * could also be greater than 1.
276 */
277 unmap_grant_pages(map, 0, map->count);
278
279 /* Check if the memory now needs to be freed */
280 if (!refcount_dec_and_test(&map->users))
281 return;
282
283 /*
284 * All pages have been returned to the hypervisor, so free the
285 * map.
286 */
287 }
288
289 if (use_ptemod && map->notifier_init)
290 mmu_interval_notifier_remove(&map->notifier);
291
292 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
293 notify_remote_via_evtchn(map->notify.event);
294 evtchn_put(map->notify.event);
295 }
296 gntdev_free_map(map);
297 }
298
299 /* ------------------------------------------------------------------ */
300
find_grant_ptes(pte_t * pte,unsigned long addr,void * data)301 static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data)
302 {
303 struct gntdev_grant_map *map = data;
304 unsigned int pgnr = (addr - map->pages_vm_start) >> PAGE_SHIFT;
305 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte |
306 (1 << _GNTMAP_guest_avail0);
307 u64 pte_maddr;
308
309 BUG_ON(pgnr >= map->count);
310 pte_maddr = arbitrary_virt_to_machine(pte).maddr;
311
312 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
313 map->grants[pgnr].ref,
314 map->grants[pgnr].domid);
315 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
316 INVALID_GRANT_HANDLE);
317 return 0;
318 }
319
gntdev_map_grant_pages(struct gntdev_grant_map * map)320 int gntdev_map_grant_pages(struct gntdev_grant_map *map)
321 {
322 size_t alloced = 0;
323 int i, err = 0;
324
325 if (!use_ptemod) {
326 /* Note: it could already be mapped */
327 if (map->map_ops[0].handle != INVALID_GRANT_HANDLE)
328 return 0;
329 for (i = 0; i < map->count; i++) {
330 unsigned long addr = (unsigned long)
331 pfn_to_kaddr(page_to_pfn(map->pages[i]));
332 gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
333 map->grants[i].ref,
334 map->grants[i].domid);
335 gnttab_set_unmap_op(&map->unmap_ops[i], addr,
336 map->flags, INVALID_GRANT_HANDLE);
337 }
338 } else {
339 /*
340 * Setup the map_ops corresponding to the pte entries pointing
341 * to the kernel linear addresses of the struct pages.
342 * These ptes are completely different from the user ptes dealt
343 * with find_grant_ptes.
344 * Note that GNTMAP_device_map isn't needed here: The
345 * dev_bus_addr output field gets consumed only from ->map_ops,
346 * and by not requesting it when mapping we also avoid needing
347 * to mirror dev_bus_addr into ->unmap_ops (and holding an extra
348 * reference to the page in the hypervisor).
349 */
350 unsigned int flags = (map->flags & ~GNTMAP_device_map) |
351 GNTMAP_host_map;
352
353 for (i = 0; i < map->count; i++) {
354 unsigned long address = (unsigned long)
355 pfn_to_kaddr(page_to_pfn(map->pages[i]));
356 BUG_ON(PageHighMem(map->pages[i]));
357
358 gnttab_set_map_op(&map->kmap_ops[i], address, flags,
359 map->grants[i].ref,
360 map->grants[i].domid);
361 gnttab_set_unmap_op(&map->kunmap_ops[i], address,
362 flags, INVALID_GRANT_HANDLE);
363 }
364 }
365
366 pr_debug("map %d+%d\n", map->index, map->count);
367 err = gnttab_map_refs(map->map_ops, map->kmap_ops, map->pages,
368 map->count);
369
370 for (i = 0; i < map->count; i++) {
371 if (map->map_ops[i].status == GNTST_okay) {
372 map->unmap_ops[i].handle = map->map_ops[i].handle;
373 alloced++;
374 } else if (!err)
375 err = -EINVAL;
376
377 if (map->flags & GNTMAP_device_map)
378 map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr;
379
380 if (use_ptemod) {
381 if (map->kmap_ops[i].status == GNTST_okay) {
382 alloced++;
383 map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
384 } else if (!err)
385 err = -EINVAL;
386 }
387 }
388 atomic_add(alloced, &map->live_grants);
389 return err;
390 }
391
__unmap_grant_pages_done(int result,struct gntab_unmap_queue_data * data)392 static void __unmap_grant_pages_done(int result,
393 struct gntab_unmap_queue_data *data)
394 {
395 unsigned int i;
396 struct gntdev_grant_map *map = data->data;
397 unsigned int offset = data->unmap_ops - map->unmap_ops;
398 int successful_unmaps = 0;
399 int live_grants;
400
401 for (i = 0; i < data->count; i++) {
402 if (map->unmap_ops[offset + i].status == GNTST_okay &&
403 map->unmap_ops[offset + i].handle != INVALID_GRANT_HANDLE)
404 successful_unmaps++;
405
406 WARN_ON(map->unmap_ops[offset + i].status != GNTST_okay &&
407 map->unmap_ops[offset + i].handle != INVALID_GRANT_HANDLE);
408 pr_debug("unmap handle=%d st=%d\n",
409 map->unmap_ops[offset+i].handle,
410 map->unmap_ops[offset+i].status);
411 map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
412 if (use_ptemod) {
413 if (map->kunmap_ops[offset + i].status == GNTST_okay &&
414 map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE)
415 successful_unmaps++;
416
417 WARN_ON(map->kunmap_ops[offset + i].status != GNTST_okay &&
418 map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE);
419 pr_debug("kunmap handle=%u st=%d\n",
420 map->kunmap_ops[offset+i].handle,
421 map->kunmap_ops[offset+i].status);
422 map->kunmap_ops[offset+i].handle = INVALID_GRANT_HANDLE;
423 }
424 }
425
426 /*
427 * Decrease the live-grant counter. This must happen after the loop to
428 * prevent premature reuse of the grants by gnttab_mmap().
429 */
430 live_grants = atomic_sub_return(successful_unmaps, &map->live_grants);
431 if (WARN_ON(live_grants < 0))
432 pr_err("%s: live_grants became negative (%d) after unmapping %d pages!\n",
433 __func__, live_grants, successful_unmaps);
434
435 /* Release reference taken by __unmap_grant_pages */
436 gntdev_put_map(NULL, map);
437 }
438
__unmap_grant_pages(struct gntdev_grant_map * map,int offset,int pages)439 static void __unmap_grant_pages(struct gntdev_grant_map *map, int offset,
440 int pages)
441 {
442 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
443 int pgno = (map->notify.addr >> PAGE_SHIFT);
444
445 if (pgno >= offset && pgno < offset + pages) {
446 /* No need for kmap, pages are in lowmem */
447 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
448
449 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
450 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
451 }
452 }
453
454 map->unmap_data.unmap_ops = map->unmap_ops + offset;
455 map->unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
456 map->unmap_data.pages = map->pages + offset;
457 map->unmap_data.count = pages;
458 map->unmap_data.done = __unmap_grant_pages_done;
459 map->unmap_data.data = map;
460 refcount_inc(&map->users); /* to keep map alive during async call below */
461
462 gnttab_unmap_refs_async(&map->unmap_data);
463 }
464
unmap_grant_pages(struct gntdev_grant_map * map,int offset,int pages)465 static void unmap_grant_pages(struct gntdev_grant_map *map, int offset,
466 int pages)
467 {
468 int range;
469
470 if (atomic_read(&map->live_grants) == 0)
471 return; /* Nothing to do */
472
473 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
474
475 /* It is possible the requested range will have a "hole" where we
476 * already unmapped some of the grants. Only unmap valid ranges.
477 */
478 while (pages) {
479 while (pages && map->being_removed[offset]) {
480 offset++;
481 pages--;
482 }
483 range = 0;
484 while (range < pages) {
485 if (map->being_removed[offset + range])
486 break;
487 map->being_removed[offset + range] = true;
488 range++;
489 }
490 if (range)
491 __unmap_grant_pages(map, offset, range);
492 offset += range;
493 pages -= range;
494 }
495 }
496
497 /* ------------------------------------------------------------------ */
498
gntdev_vma_open(struct vm_area_struct * vma)499 static void gntdev_vma_open(struct vm_area_struct *vma)
500 {
501 struct gntdev_grant_map *map = vma->vm_private_data;
502
503 pr_debug("gntdev_vma_open %p\n", vma);
504 refcount_inc(&map->users);
505 }
506
gntdev_vma_close(struct vm_area_struct * vma)507 static void gntdev_vma_close(struct vm_area_struct *vma)
508 {
509 struct gntdev_grant_map *map = vma->vm_private_data;
510 struct file *file = vma->vm_file;
511 struct gntdev_priv *priv = file->private_data;
512
513 pr_debug("gntdev_vma_close %p\n", vma);
514
515 vma->vm_private_data = NULL;
516 gntdev_put_map(priv, map);
517 }
518
gntdev_vma_find_special_page(struct vm_area_struct * vma,unsigned long addr)519 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma,
520 unsigned long addr)
521 {
522 struct gntdev_grant_map *map = vma->vm_private_data;
523
524 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
525 }
526
527 static const struct vm_operations_struct gntdev_vmops = {
528 .open = gntdev_vma_open,
529 .close = gntdev_vma_close,
530 .find_special_page = gntdev_vma_find_special_page,
531 };
532
533 /* ------------------------------------------------------------------ */
534
gntdev_invalidate(struct mmu_interval_notifier * mn,const struct mmu_notifier_range * range,unsigned long cur_seq)535 static bool gntdev_invalidate(struct mmu_interval_notifier *mn,
536 const struct mmu_notifier_range *range,
537 unsigned long cur_seq)
538 {
539 struct gntdev_grant_map *map =
540 container_of(mn, struct gntdev_grant_map, notifier);
541 unsigned long mstart, mend;
542 unsigned long map_start, map_end;
543
544 if (!mmu_notifier_range_blockable(range))
545 return false;
546
547 map_start = map->pages_vm_start;
548 map_end = map->pages_vm_start + (map->count << PAGE_SHIFT);
549
550 /*
551 * If the VMA is split or otherwise changed the notifier is not
552 * updated, but we don't want to process VA's outside the modified
553 * VMA. FIXME: It would be much more understandable to just prevent
554 * modifying the VMA in the first place.
555 */
556 if (map_start >= range->end || map_end <= range->start)
557 return true;
558
559 mstart = max(range->start, map_start);
560 mend = min(range->end, map_end);
561 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
562 map->index, map->count, map_start, map_end,
563 range->start, range->end, mstart, mend);
564 unmap_grant_pages(map, (mstart - map_start) >> PAGE_SHIFT,
565 (mend - mstart) >> PAGE_SHIFT);
566
567 return true;
568 }
569
570 static const struct mmu_interval_notifier_ops gntdev_mmu_ops = {
571 .invalidate = gntdev_invalidate,
572 };
573
574 /* ------------------------------------------------------------------ */
575
gntdev_open(struct inode * inode,struct file * flip)576 static int gntdev_open(struct inode *inode, struct file *flip)
577 {
578 struct gntdev_priv *priv;
579
580 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
581 if (!priv)
582 return -ENOMEM;
583
584 INIT_LIST_HEAD(&priv->maps);
585 mutex_init(&priv->lock);
586
587 #ifdef CONFIG_XEN_GNTDEV_DMABUF
588 priv->dmabuf_priv = gntdev_dmabuf_init(flip);
589 if (IS_ERR(priv->dmabuf_priv)) {
590 int ret = PTR_ERR(priv->dmabuf_priv);
591
592 kfree(priv);
593 return ret;
594 }
595 #endif
596
597 flip->private_data = priv;
598 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
599 priv->dma_dev = gntdev_miscdev.this_device;
600 dma_coerce_mask_and_coherent(priv->dma_dev, DMA_BIT_MASK(64));
601 #endif
602 pr_debug("priv %p\n", priv);
603
604 return 0;
605 }
606
gntdev_release(struct inode * inode,struct file * flip)607 static int gntdev_release(struct inode *inode, struct file *flip)
608 {
609 struct gntdev_priv *priv = flip->private_data;
610 struct gntdev_grant_map *map;
611
612 pr_debug("priv %p\n", priv);
613
614 mutex_lock(&priv->lock);
615 while (!list_empty(&priv->maps)) {
616 map = list_entry(priv->maps.next,
617 struct gntdev_grant_map, next);
618 list_del(&map->next);
619 gntdev_put_map(NULL /* already removed */, map);
620 }
621 mutex_unlock(&priv->lock);
622
623 #ifdef CONFIG_XEN_GNTDEV_DMABUF
624 gntdev_dmabuf_fini(priv->dmabuf_priv);
625 #endif
626
627 kfree(priv);
628 return 0;
629 }
630
gntdev_ioctl_map_grant_ref(struct gntdev_priv * priv,struct ioctl_gntdev_map_grant_ref __user * u)631 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
632 struct ioctl_gntdev_map_grant_ref __user *u)
633 {
634 struct ioctl_gntdev_map_grant_ref op;
635 struct gntdev_grant_map *map;
636 int err;
637
638 if (copy_from_user(&op, u, sizeof(op)) != 0)
639 return -EFAULT;
640 pr_debug("priv %p, add %d\n", priv, op.count);
641 if (unlikely(gntdev_test_page_count(op.count)))
642 return -EINVAL;
643
644 err = -ENOMEM;
645 map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */);
646 if (!map)
647 return err;
648
649 if (copy_from_user(map->grants, &u->refs,
650 sizeof(map->grants[0]) * op.count) != 0) {
651 gntdev_put_map(NULL, map);
652 return -EFAULT;
653 }
654
655 mutex_lock(&priv->lock);
656 gntdev_add_map(priv, map);
657 op.index = map->index << PAGE_SHIFT;
658 mutex_unlock(&priv->lock);
659
660 if (copy_to_user(u, &op, sizeof(op)) != 0)
661 return -EFAULT;
662
663 return 0;
664 }
665
gntdev_ioctl_unmap_grant_ref(struct gntdev_priv * priv,struct ioctl_gntdev_unmap_grant_ref __user * u)666 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
667 struct ioctl_gntdev_unmap_grant_ref __user *u)
668 {
669 struct ioctl_gntdev_unmap_grant_ref op;
670 struct gntdev_grant_map *map;
671 int err = -ENOENT;
672
673 if (copy_from_user(&op, u, sizeof(op)) != 0)
674 return -EFAULT;
675 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
676
677 mutex_lock(&priv->lock);
678 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
679 if (map) {
680 list_del(&map->next);
681 err = 0;
682 }
683 mutex_unlock(&priv->lock);
684 if (map)
685 gntdev_put_map(priv, map);
686 return err;
687 }
688
gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv * priv,struct ioctl_gntdev_get_offset_for_vaddr __user * u)689 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
690 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
691 {
692 struct ioctl_gntdev_get_offset_for_vaddr op;
693 struct vm_area_struct *vma;
694 struct gntdev_grant_map *map;
695 int rv = -EINVAL;
696
697 if (copy_from_user(&op, u, sizeof(op)) != 0)
698 return -EFAULT;
699 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
700
701 mmap_read_lock(current->mm);
702 vma = find_vma(current->mm, op.vaddr);
703 if (!vma || vma->vm_ops != &gntdev_vmops)
704 goto out_unlock;
705
706 map = vma->vm_private_data;
707 if (!map)
708 goto out_unlock;
709
710 op.offset = map->index << PAGE_SHIFT;
711 op.count = map->count;
712 rv = 0;
713
714 out_unlock:
715 mmap_read_unlock(current->mm);
716
717 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
718 return -EFAULT;
719 return rv;
720 }
721
gntdev_ioctl_notify(struct gntdev_priv * priv,void __user * u)722 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
723 {
724 struct ioctl_gntdev_unmap_notify op;
725 struct gntdev_grant_map *map;
726 int rc;
727 int out_flags;
728 evtchn_port_t out_event;
729
730 if (copy_from_user(&op, u, sizeof(op)))
731 return -EFAULT;
732
733 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
734 return -EINVAL;
735
736 /* We need to grab a reference to the event channel we are going to use
737 * to send the notify before releasing the reference we may already have
738 * (if someone has called this ioctl twice). This is required so that
739 * it is possible to change the clear_byte part of the notification
740 * without disturbing the event channel part, which may now be the last
741 * reference to that event channel.
742 */
743 if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
744 if (evtchn_get(op.event_channel_port))
745 return -EINVAL;
746 }
747
748 out_flags = op.action;
749 out_event = op.event_channel_port;
750
751 mutex_lock(&priv->lock);
752
753 list_for_each_entry(map, &priv->maps, next) {
754 uint64_t begin = map->index << PAGE_SHIFT;
755 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
756 if (op.index >= begin && op.index < end)
757 goto found;
758 }
759 rc = -ENOENT;
760 goto unlock_out;
761
762 found:
763 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
764 (map->flags & GNTMAP_readonly)) {
765 rc = -EINVAL;
766 goto unlock_out;
767 }
768
769 out_flags = map->notify.flags;
770 out_event = map->notify.event;
771
772 map->notify.flags = op.action;
773 map->notify.addr = op.index - (map->index << PAGE_SHIFT);
774 map->notify.event = op.event_channel_port;
775
776 rc = 0;
777
778 unlock_out:
779 mutex_unlock(&priv->lock);
780
781 /* Drop the reference to the event channel we did not save in the map */
782 if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
783 evtchn_put(out_event);
784
785 return rc;
786 }
787
788 #define GNTDEV_COPY_BATCH 16
789
790 struct gntdev_copy_batch {
791 struct gnttab_copy ops[GNTDEV_COPY_BATCH];
792 struct page *pages[GNTDEV_COPY_BATCH];
793 s16 __user *status[GNTDEV_COPY_BATCH];
794 unsigned int nr_ops;
795 unsigned int nr_pages;
796 bool writeable;
797 };
798
gntdev_get_page(struct gntdev_copy_batch * batch,void __user * virt,unsigned long * gfn)799 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
800 unsigned long *gfn)
801 {
802 unsigned long addr = (unsigned long)virt;
803 struct page *page;
804 unsigned long xen_pfn;
805 int ret;
806
807 ret = pin_user_pages_fast(addr, 1, batch->writeable ? FOLL_WRITE : 0, &page);
808 if (ret < 0)
809 return ret;
810
811 batch->pages[batch->nr_pages++] = page;
812
813 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK);
814 *gfn = pfn_to_gfn(xen_pfn);
815
816 return 0;
817 }
818
gntdev_put_pages(struct gntdev_copy_batch * batch)819 static void gntdev_put_pages(struct gntdev_copy_batch *batch)
820 {
821 unpin_user_pages_dirty_lock(batch->pages, batch->nr_pages, batch->writeable);
822 batch->nr_pages = 0;
823 batch->writeable = false;
824 }
825
gntdev_copy(struct gntdev_copy_batch * batch)826 static int gntdev_copy(struct gntdev_copy_batch *batch)
827 {
828 unsigned int i;
829
830 gnttab_batch_copy(batch->ops, batch->nr_ops);
831 gntdev_put_pages(batch);
832
833 /*
834 * For each completed op, update the status if the op failed
835 * and all previous ops for the segment were successful.
836 */
837 for (i = 0; i < batch->nr_ops; i++) {
838 s16 status = batch->ops[i].status;
839 s16 old_status;
840
841 if (status == GNTST_okay)
842 continue;
843
844 if (__get_user(old_status, batch->status[i]))
845 return -EFAULT;
846
847 if (old_status != GNTST_okay)
848 continue;
849
850 if (__put_user(status, batch->status[i]))
851 return -EFAULT;
852 }
853
854 batch->nr_ops = 0;
855 return 0;
856 }
857
gntdev_grant_copy_seg(struct gntdev_copy_batch * batch,struct gntdev_grant_copy_segment * seg,s16 __user * status)858 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
859 struct gntdev_grant_copy_segment *seg,
860 s16 __user *status)
861 {
862 uint16_t copied = 0;
863
864 /*
865 * Disallow local -> local copies since there is only space in
866 * batch->pages for one page per-op and this would be a very
867 * expensive memcpy().
868 */
869 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref)))
870 return -EINVAL;
871
872 /* Can't cross page if source/dest is a grant ref. */
873 if (seg->flags & GNTCOPY_source_gref) {
874 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE)
875 return -EINVAL;
876 }
877 if (seg->flags & GNTCOPY_dest_gref) {
878 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE)
879 return -EINVAL;
880 }
881
882 if (put_user(GNTST_okay, status))
883 return -EFAULT;
884
885 while (copied < seg->len) {
886 struct gnttab_copy *op;
887 void __user *virt;
888 size_t len, off;
889 unsigned long gfn;
890 int ret;
891
892 if (batch->nr_ops >= GNTDEV_COPY_BATCH) {
893 ret = gntdev_copy(batch);
894 if (ret < 0)
895 return ret;
896 }
897
898 len = seg->len - copied;
899
900 op = &batch->ops[batch->nr_ops];
901 op->flags = 0;
902
903 if (seg->flags & GNTCOPY_source_gref) {
904 op->source.u.ref = seg->source.foreign.ref;
905 op->source.domid = seg->source.foreign.domid;
906 op->source.offset = seg->source.foreign.offset + copied;
907 op->flags |= GNTCOPY_source_gref;
908 } else {
909 virt = seg->source.virt + copied;
910 off = (unsigned long)virt & ~XEN_PAGE_MASK;
911 len = min(len, (size_t)XEN_PAGE_SIZE - off);
912 batch->writeable = false;
913
914 ret = gntdev_get_page(batch, virt, &gfn);
915 if (ret < 0)
916 return ret;
917
918 op->source.u.gmfn = gfn;
919 op->source.domid = DOMID_SELF;
920 op->source.offset = off;
921 }
922
923 if (seg->flags & GNTCOPY_dest_gref) {
924 op->dest.u.ref = seg->dest.foreign.ref;
925 op->dest.domid = seg->dest.foreign.domid;
926 op->dest.offset = seg->dest.foreign.offset + copied;
927 op->flags |= GNTCOPY_dest_gref;
928 } else {
929 virt = seg->dest.virt + copied;
930 off = (unsigned long)virt & ~XEN_PAGE_MASK;
931 len = min(len, (size_t)XEN_PAGE_SIZE - off);
932 batch->writeable = true;
933
934 ret = gntdev_get_page(batch, virt, &gfn);
935 if (ret < 0)
936 return ret;
937
938 op->dest.u.gmfn = gfn;
939 op->dest.domid = DOMID_SELF;
940 op->dest.offset = off;
941 }
942
943 op->len = len;
944 copied += len;
945
946 batch->status[batch->nr_ops] = status;
947 batch->nr_ops++;
948 }
949
950 return 0;
951 }
952
gntdev_ioctl_grant_copy(struct gntdev_priv * priv,void __user * u)953 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
954 {
955 struct ioctl_gntdev_grant_copy copy;
956 struct gntdev_copy_batch batch;
957 unsigned int i;
958 int ret = 0;
959
960 if (copy_from_user(©, u, sizeof(copy)))
961 return -EFAULT;
962
963 batch.nr_ops = 0;
964 batch.nr_pages = 0;
965
966 for (i = 0; i < copy.count; i++) {
967 struct gntdev_grant_copy_segment seg;
968
969 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) {
970 ret = -EFAULT;
971 goto out;
972 }
973
974 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status);
975 if (ret < 0)
976 goto out;
977
978 cond_resched();
979 }
980 if (batch.nr_ops)
981 ret = gntdev_copy(&batch);
982 return ret;
983
984 out:
985 gntdev_put_pages(&batch);
986 return ret;
987 }
988
gntdev_ioctl(struct file * flip,unsigned int cmd,unsigned long arg)989 static long gntdev_ioctl(struct file *flip,
990 unsigned int cmd, unsigned long arg)
991 {
992 struct gntdev_priv *priv = flip->private_data;
993 void __user *ptr = (void __user *)arg;
994
995 switch (cmd) {
996 case IOCTL_GNTDEV_MAP_GRANT_REF:
997 return gntdev_ioctl_map_grant_ref(priv, ptr);
998
999 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
1000 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
1001
1002 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
1003 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
1004
1005 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
1006 return gntdev_ioctl_notify(priv, ptr);
1007
1008 case IOCTL_GNTDEV_GRANT_COPY:
1009 return gntdev_ioctl_grant_copy(priv, ptr);
1010
1011 #ifdef CONFIG_XEN_GNTDEV_DMABUF
1012 case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS:
1013 return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr);
1014
1015 case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED:
1016 return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr);
1017
1018 case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS:
1019 return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr);
1020
1021 case IOCTL_GNTDEV_DMABUF_IMP_RELEASE:
1022 return gntdev_ioctl_dmabuf_imp_release(priv, ptr);
1023 #endif
1024
1025 default:
1026 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
1027 return -ENOIOCTLCMD;
1028 }
1029
1030 return 0;
1031 }
1032
gntdev_mmap(struct file * flip,struct vm_area_struct * vma)1033 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
1034 {
1035 struct gntdev_priv *priv = flip->private_data;
1036 int index = vma->vm_pgoff;
1037 int count = vma_pages(vma);
1038 struct gntdev_grant_map *map;
1039 int err = -EINVAL;
1040
1041 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
1042 return -EINVAL;
1043
1044 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
1045 index, count, vma->vm_start, vma->vm_pgoff);
1046
1047 mutex_lock(&priv->lock);
1048 map = gntdev_find_map_index(priv, index, count);
1049 if (!map)
1050 goto unlock_out;
1051 if (!atomic_add_unless(&map->in_use, 1, 1))
1052 goto unlock_out;
1053
1054 refcount_inc(&map->users);
1055
1056 vma->vm_ops = &gntdev_vmops;
1057
1058 vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP);
1059
1060 if (use_ptemod)
1061 vm_flags_set(vma, VM_DONTCOPY);
1062
1063 vma->vm_private_data = map;
1064 if (map->flags) {
1065 if ((vma->vm_flags & VM_WRITE) &&
1066 (map->flags & GNTMAP_readonly))
1067 goto out_unlock_put;
1068 } else {
1069 map->flags = GNTMAP_host_map;
1070 if (!(vma->vm_flags & VM_WRITE))
1071 map->flags |= GNTMAP_readonly;
1072 }
1073
1074 map->pages_vm_start = vma->vm_start;
1075
1076 if (use_ptemod) {
1077 err = mmu_interval_notifier_insert_locked(
1078 &map->notifier, vma->vm_mm, vma->vm_start,
1079 vma->vm_end - vma->vm_start, &gntdev_mmu_ops);
1080 if (err)
1081 goto out_unlock_put;
1082
1083 map->notifier_init = true;
1084 }
1085 mutex_unlock(&priv->lock);
1086
1087 if (use_ptemod) {
1088 /*
1089 * gntdev takes the address of the PTE in find_grant_ptes() and
1090 * passes it to the hypervisor in gntdev_map_grant_pages(). The
1091 * purpose of the notifier is to prevent the hypervisor pointer
1092 * to the PTE from going stale.
1093 *
1094 * Since this vma's mappings can't be touched without the
1095 * mmap_lock, and we are holding it now, there is no need for
1096 * the notifier_range locking pattern.
1097 */
1098 mmu_interval_read_begin(&map->notifier);
1099
1100 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
1101 vma->vm_end - vma->vm_start,
1102 find_grant_ptes, map);
1103 if (err) {
1104 pr_warn("find_grant_ptes() failure.\n");
1105 goto out_put_map;
1106 }
1107 }
1108
1109 err = gntdev_map_grant_pages(map);
1110 if (err)
1111 goto out_put_map;
1112
1113 if (!use_ptemod) {
1114 err = vm_map_pages_zero(vma, map->pages, map->count);
1115 if (err)
1116 goto out_put_map;
1117 }
1118
1119 return 0;
1120
1121 unlock_out:
1122 mutex_unlock(&priv->lock);
1123 return err;
1124
1125 out_unlock_put:
1126 mutex_unlock(&priv->lock);
1127 out_put_map:
1128 if (use_ptemod)
1129 unmap_grant_pages(map, 0, map->count);
1130 gntdev_put_map(priv, map);
1131 return err;
1132 }
1133
1134 static const struct file_operations gntdev_fops = {
1135 .owner = THIS_MODULE,
1136 .open = gntdev_open,
1137 .release = gntdev_release,
1138 .mmap = gntdev_mmap,
1139 .unlocked_ioctl = gntdev_ioctl
1140 };
1141
1142 static struct miscdevice gntdev_miscdev = {
1143 .minor = MISC_DYNAMIC_MINOR,
1144 .name = "xen/gntdev",
1145 .fops = &gntdev_fops,
1146 };
1147
1148 /* ------------------------------------------------------------------ */
1149
gntdev_init(void)1150 static int __init gntdev_init(void)
1151 {
1152 int err;
1153
1154 if (!xen_domain())
1155 return -ENODEV;
1156
1157 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
1158
1159 err = misc_register(&gntdev_miscdev);
1160 if (err != 0) {
1161 pr_err("Could not register gntdev device\n");
1162 return err;
1163 }
1164 return 0;
1165 }
1166
gntdev_exit(void)1167 static void __exit gntdev_exit(void)
1168 {
1169 misc_deregister(&gntdev_miscdev);
1170 }
1171
1172 module_init(gntdev_init);
1173 module_exit(gntdev_exit);
1174
1175 /* ------------------------------------------------------------------ */
1176