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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 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20#undef DEBUG
21
22#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
23
24#include <linux/module.h>
25#include <linux/kernel.h>
26#include <linux/init.h>
27#include <linux/miscdevice.h>
28#include <linux/fs.h>
29#include <linux/mm.h>
30#include <linux/mman.h>
31#include <linux/mmu_notifier.h>
32#include <linux/types.h>
33#include <linux/uaccess.h>
34#include <linux/sched.h>
35#include <linux/sched/mm.h>
36#include <linux/spinlock.h>
37#include <linux/slab.h>
38#include <linux/highmem.h>
39#include <linux/refcount.h>
40
41#include <xen/xen.h>
42#include <xen/grant_table.h>
43#include <xen/balloon.h>
44#include <xen/gntdev.h>
45#include <xen/events.h>
46#include <xen/page.h>
47#include <asm/xen/hypervisor.h>
48#include <asm/xen/hypercall.h>
49
50MODULE_LICENSE("GPL");
51MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
52 "Gerd Hoffmann <kraxel@redhat.com>");
53MODULE_DESCRIPTION("User-space granted page access driver");
54
55static int limit = 1024*1024;
56module_param(limit, int, 0644);
57MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
58 "the gntdev device");
59
60static atomic_t pages_mapped = ATOMIC_INIT(0);
61
62static int use_ptemod;
63#define populate_freeable_maps use_ptemod
64
65struct gntdev_priv {
66 /* maps with visible offsets in the file descriptor */
67 struct list_head maps;
68 /* maps that are not visible; will be freed on munmap.
69 * Only populated if populate_freeable_maps == 1 */
70 struct list_head freeable_maps;
71 /* lock protects maps and freeable_maps */
72 struct mutex lock;
73 struct mm_struct *mm;
74 struct mmu_notifier mn;
75};
76
77struct unmap_notify {
78 int flags;
79 /* Address relative to the start of the grant_map */
80 int addr;
81 int event;
82};
83
84struct grant_map {
85 struct list_head next;
86 struct vm_area_struct *vma;
87 int index;
88 int count;
89 int flags;
90 refcount_t users;
91 struct unmap_notify notify;
92 struct ioctl_gntdev_grant_ref *grants;
93 struct gnttab_map_grant_ref *map_ops;
94 struct gnttab_unmap_grant_ref *unmap_ops;
95 struct gnttab_map_grant_ref *kmap_ops;
96 struct gnttab_unmap_grant_ref *kunmap_ops;
97 struct page **pages;
98 unsigned long pages_vm_start;
99};
100
101static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
102
103/* ------------------------------------------------------------------ */
104
105static void gntdev_print_maps(struct gntdev_priv *priv,
106 char *text, int text_index)
107{
108#ifdef DEBUG
109 struct grant_map *map;
110
111 pr_debug("%s: maps list (priv %p)\n", __func__, priv);
112 list_for_each_entry(map, &priv->maps, next)
113 pr_debug(" index %2d, count %2d %s\n",
114 map->index, map->count,
115 map->index == text_index && text ? text : "");
116#endif
117}
118
119static void gntdev_free_map(struct grant_map *map)
120{
121 if (map == NULL)
122 return;
123
124 if (map->pages)
125 gnttab_free_pages(map->count, map->pages);
126 kfree(map->pages);
127 kfree(map->grants);
128 kfree(map->map_ops);
129 kfree(map->unmap_ops);
130 kfree(map->kmap_ops);
131 kfree(map->kunmap_ops);
132 kfree(map);
133}
134
135static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
136{
137 struct grant_map *add;
138 int i;
139
140 add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
141 if (NULL == add)
142 return NULL;
143
144 add->grants = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
145 add->map_ops = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
146 add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
147 add->kmap_ops = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
148 add->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]), GFP_KERNEL);
149 add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
150 if (NULL == add->grants ||
151 NULL == add->map_ops ||
152 NULL == add->unmap_ops ||
153 NULL == add->kmap_ops ||
154 NULL == add->kunmap_ops ||
155 NULL == add->pages)
156 goto err;
157
158 if (gnttab_alloc_pages(count, add->pages))
159 goto err;
160
161 for (i = 0; i < count; i++) {
162 add->map_ops[i].handle = -1;
163 add->unmap_ops[i].handle = -1;
164 add->kmap_ops[i].handle = -1;
165 add->kunmap_ops[i].handle = -1;
166 }
167
168 add->index = 0;
169 add->count = count;
170 refcount_set(&add->users, 1);
171
172 return add;
173
174err:
175 gntdev_free_map(add);
176 return NULL;
177}
178
179static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
180{
181 struct grant_map *map;
182
183 list_for_each_entry(map, &priv->maps, next) {
184 if (add->index + add->count < map->index) {
185 list_add_tail(&add->next, &map->next);
186 goto done;
187 }
188 add->index = map->index + map->count;
189 }
190 list_add_tail(&add->next, &priv->maps);
191
192done:
193 gntdev_print_maps(priv, "[new]", add->index);
194}
195
196static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
197 int index, int count)
198{
199 struct grant_map *map;
200
201 list_for_each_entry(map, &priv->maps, next) {
202 if (map->index != index)
203 continue;
204 if (count && map->count != count)
205 continue;
206 return map;
207 }
208 return NULL;
209}
210
211static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
212{
213 if (!map)
214 return;
215
216 if (!refcount_dec_and_test(&map->users))
217 return;
218
219 atomic_sub(map->count, &pages_mapped);
220
221 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
222 notify_remote_via_evtchn(map->notify.event);
223 evtchn_put(map->notify.event);
224 }
225
226 if (populate_freeable_maps && priv) {
227 mutex_lock(&priv->lock);
228 list_del(&map->next);
229 mutex_unlock(&priv->lock);
230 }
231
232 if (map->pages && !use_ptemod)
233 unmap_grant_pages(map, 0, map->count);
234 gntdev_free_map(map);
235}
236
237/* ------------------------------------------------------------------ */
238
239static int find_grant_ptes(pte_t *pte, pgtable_t token,
240 unsigned long addr, void *data)
241{
242 struct grant_map *map = data;
243 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
244 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
245 u64 pte_maddr;
246
247 BUG_ON(pgnr >= map->count);
248 pte_maddr = arbitrary_virt_to_machine(pte).maddr;
249
250 /*
251 * Set the PTE as special to force get_user_pages_fast() fall
252 * back to the slow path. If this is not supported as part of
253 * the grant map, it will be done afterwards.
254 */
255 if (xen_feature(XENFEAT_gnttab_map_avail_bits))
256 flags |= (1 << _GNTMAP_guest_avail0);
257
258 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
259 map->grants[pgnr].ref,
260 map->grants[pgnr].domid);
261 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
262 -1 /* handle */);
263 return 0;
264}
265
266#ifdef CONFIG_X86
267static int set_grant_ptes_as_special(pte_t *pte, pgtable_t token,
268 unsigned long addr, void *data)
269{
270 set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte));
271 return 0;
272}
273#endif
274
275static int map_grant_pages(struct grant_map *map)
276{
277 int i, err = 0;
278
279 if (!use_ptemod) {
280 /* Note: it could already be mapped */
281 if (map->map_ops[0].handle != -1)
282 return 0;
283 for (i = 0; i < map->count; i++) {
284 unsigned long addr = (unsigned long)
285 pfn_to_kaddr(page_to_pfn(map->pages[i]));
286 gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
287 map->grants[i].ref,
288 map->grants[i].domid);
289 gnttab_set_unmap_op(&map->unmap_ops[i], addr,
290 map->flags, -1 /* handle */);
291 }
292 } else {
293 /*
294 * Setup the map_ops corresponding to the pte entries pointing
295 * to the kernel linear addresses of the struct pages.
296 * These ptes are completely different from the user ptes dealt
297 * with find_grant_ptes.
298 */
299 for (i = 0; i < map->count; i++) {
300 unsigned long address = (unsigned long)
301 pfn_to_kaddr(page_to_pfn(map->pages[i]));
302 BUG_ON(PageHighMem(map->pages[i]));
303
304 gnttab_set_map_op(&map->kmap_ops[i], address,
305 map->flags | GNTMAP_host_map,
306 map->grants[i].ref,
307 map->grants[i].domid);
308 gnttab_set_unmap_op(&map->kunmap_ops[i], address,
309 map->flags | GNTMAP_host_map, -1);
310 }
311 }
312
313 pr_debug("map %d+%d\n", map->index, map->count);
314 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
315 map->pages, map->count);
316 if (err)
317 return err;
318
319 for (i = 0; i < map->count; i++) {
320 if (map->map_ops[i].status) {
321 err = -EINVAL;
322 continue;
323 }
324
325 map->unmap_ops[i].handle = map->map_ops[i].handle;
326 if (use_ptemod)
327 map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
328 }
329 return err;
330}
331
332static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
333{
334 int i, err = 0;
335 struct gntab_unmap_queue_data unmap_data;
336
337 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
338 int pgno = (map->notify.addr >> PAGE_SHIFT);
339 if (pgno >= offset && pgno < offset + pages) {
340 /* No need for kmap, pages are in lowmem */
341 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
342 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
343 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
344 }
345 }
346
347 unmap_data.unmap_ops = map->unmap_ops + offset;
348 unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
349 unmap_data.pages = map->pages + offset;
350 unmap_data.count = pages;
351
352 err = gnttab_unmap_refs_sync(&unmap_data);
353 if (err)
354 return err;
355
356 for (i = 0; i < pages; i++) {
357 if (map->unmap_ops[offset+i].status)
358 err = -EINVAL;
359 pr_debug("unmap handle=%d st=%d\n",
360 map->unmap_ops[offset+i].handle,
361 map->unmap_ops[offset+i].status);
362 map->unmap_ops[offset+i].handle = -1;
363 }
364 return err;
365}
366
367static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
368{
369 int range, err = 0;
370
371 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
372
373 /* It is possible the requested range will have a "hole" where we
374 * already unmapped some of the grants. Only unmap valid ranges.
375 */
376 while (pages && !err) {
377 while (pages && map->unmap_ops[offset].handle == -1) {
378 offset++;
379 pages--;
380 }
381 range = 0;
382 while (range < pages) {
383 if (map->unmap_ops[offset+range].handle == -1)
384 break;
385 range++;
386 }
387 err = __unmap_grant_pages(map, offset, range);
388 offset += range;
389 pages -= range;
390 }
391
392 return err;
393}
394
395/* ------------------------------------------------------------------ */
396
397static void gntdev_vma_open(struct vm_area_struct *vma)
398{
399 struct grant_map *map = vma->vm_private_data;
400
401 pr_debug("gntdev_vma_open %p\n", vma);
402 refcount_inc(&map->users);
403}
404
405static void gntdev_vma_close(struct vm_area_struct *vma)
406{
407 struct grant_map *map = vma->vm_private_data;
408 struct file *file = vma->vm_file;
409 struct gntdev_priv *priv = file->private_data;
410
411 pr_debug("gntdev_vma_close %p\n", vma);
412 if (use_ptemod) {
413 /* It is possible that an mmu notifier could be running
414 * concurrently, so take priv->lock to ensure that the vma won't
415 * vanishing during the unmap_grant_pages call, since we will
416 * spin here until that completes. Such a concurrent call will
417 * not do any unmapping, since that has been done prior to
418 * closing the vma, but it may still iterate the unmap_ops list.
419 */
420 mutex_lock(&priv->lock);
421 map->vma = NULL;
422 mutex_unlock(&priv->lock);
423 }
424 vma->vm_private_data = NULL;
425 gntdev_put_map(priv, map);
426}
427
428static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma,
429 unsigned long addr)
430{
431 struct grant_map *map = vma->vm_private_data;
432
433 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
434}
435
436static const struct vm_operations_struct gntdev_vmops = {
437 .open = gntdev_vma_open,
438 .close = gntdev_vma_close,
439 .find_special_page = gntdev_vma_find_special_page,
440};
441
442/* ------------------------------------------------------------------ */
443
444static void unmap_if_in_range(struct grant_map *map,
445 unsigned long start, unsigned long end)
446{
447 unsigned long mstart, mend;
448 int err;
449
450 if (!map->vma)
451 return;
452 if (map->vma->vm_start >= end)
453 return;
454 if (map->vma->vm_end <= start)
455 return;
456 mstart = max(start, map->vma->vm_start);
457 mend = min(end, map->vma->vm_end);
458 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
459 map->index, map->count,
460 map->vma->vm_start, map->vma->vm_end,
461 start, end, mstart, mend);
462 err = unmap_grant_pages(map,
463 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
464 (mend - mstart) >> PAGE_SHIFT);
465 WARN_ON(err);
466}
467
468static void mn_invl_range_start(struct mmu_notifier *mn,
469 struct mm_struct *mm,
470 unsigned long start, unsigned long end)
471{
472 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
473 struct grant_map *map;
474
475 mutex_lock(&priv->lock);
476 list_for_each_entry(map, &priv->maps, next) {
477 unmap_if_in_range(map, start, end);
478 }
479 list_for_each_entry(map, &priv->freeable_maps, next) {
480 unmap_if_in_range(map, start, end);
481 }
482 mutex_unlock(&priv->lock);
483}
484
485static void mn_release(struct mmu_notifier *mn,
486 struct mm_struct *mm)
487{
488 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
489 struct grant_map *map;
490 int err;
491
492 mutex_lock(&priv->lock);
493 list_for_each_entry(map, &priv->maps, next) {
494 if (!map->vma)
495 continue;
496 pr_debug("map %d+%d (%lx %lx)\n",
497 map->index, map->count,
498 map->vma->vm_start, map->vma->vm_end);
499 err = unmap_grant_pages(map, /* offset */ 0, map->count);
500 WARN_ON(err);
501 }
502 list_for_each_entry(map, &priv->freeable_maps, next) {
503 if (!map->vma)
504 continue;
505 pr_debug("map %d+%d (%lx %lx)\n",
506 map->index, map->count,
507 map->vma->vm_start, map->vma->vm_end);
508 err = unmap_grant_pages(map, /* offset */ 0, map->count);
509 WARN_ON(err);
510 }
511 mutex_unlock(&priv->lock);
512}
513
514static const struct mmu_notifier_ops gntdev_mmu_ops = {
515 .release = mn_release,
516 .invalidate_range_start = mn_invl_range_start,
517};
518
519/* ------------------------------------------------------------------ */
520
521static int gntdev_open(struct inode *inode, struct file *flip)
522{
523 struct gntdev_priv *priv;
524 int ret = 0;
525
526 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
527 if (!priv)
528 return -ENOMEM;
529
530 INIT_LIST_HEAD(&priv->maps);
531 INIT_LIST_HEAD(&priv->freeable_maps);
532 mutex_init(&priv->lock);
533
534 if (use_ptemod) {
535 priv->mm = get_task_mm(current);
536 if (!priv->mm) {
537 kfree(priv);
538 return -ENOMEM;
539 }
540 priv->mn.ops = &gntdev_mmu_ops;
541 ret = mmu_notifier_register(&priv->mn, priv->mm);
542 mmput(priv->mm);
543 }
544
545 if (ret) {
546 kfree(priv);
547 return ret;
548 }
549
550 flip->private_data = priv;
551 pr_debug("priv %p\n", priv);
552
553 return 0;
554}
555
556static int gntdev_release(struct inode *inode, struct file *flip)
557{
558 struct gntdev_priv *priv = flip->private_data;
559 struct grant_map *map;
560
561 pr_debug("priv %p\n", priv);
562
563 mutex_lock(&priv->lock);
564 while (!list_empty(&priv->maps)) {
565 map = list_entry(priv->maps.next, struct grant_map, next);
566 list_del(&map->next);
567 gntdev_put_map(NULL /* already removed */, map);
568 }
569 WARN_ON(!list_empty(&priv->freeable_maps));
570 mutex_unlock(&priv->lock);
571
572 if (use_ptemod)
573 mmu_notifier_unregister(&priv->mn, priv->mm);
574 kfree(priv);
575 return 0;
576}
577
578static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
579 struct ioctl_gntdev_map_grant_ref __user *u)
580{
581 struct ioctl_gntdev_map_grant_ref op;
582 struct grant_map *map;
583 int err;
584
585 if (copy_from_user(&op, u, sizeof(op)) != 0)
586 return -EFAULT;
587 pr_debug("priv %p, add %d\n", priv, op.count);
588 if (unlikely(op.count <= 0))
589 return -EINVAL;
590
591 err = -ENOMEM;
592 map = gntdev_alloc_map(priv, op.count);
593 if (!map)
594 return err;
595
596 if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
597 pr_debug("can't map: over limit\n");
598 gntdev_put_map(NULL, map);
599 return err;
600 }
601
602 if (copy_from_user(map->grants, &u->refs,
603 sizeof(map->grants[0]) * op.count) != 0) {
604 gntdev_put_map(NULL, map);
605 return -EFAULT;
606 }
607
608 mutex_lock(&priv->lock);
609 gntdev_add_map(priv, map);
610 op.index = map->index << PAGE_SHIFT;
611 mutex_unlock(&priv->lock);
612
613 if (copy_to_user(u, &op, sizeof(op)) != 0)
614 return -EFAULT;
615
616 return 0;
617}
618
619static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
620 struct ioctl_gntdev_unmap_grant_ref __user *u)
621{
622 struct ioctl_gntdev_unmap_grant_ref op;
623 struct grant_map *map;
624 int err = -ENOENT;
625
626 if (copy_from_user(&op, u, sizeof(op)) != 0)
627 return -EFAULT;
628 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
629
630 mutex_lock(&priv->lock);
631 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
632 if (map) {
633 list_del(&map->next);
634 if (populate_freeable_maps)
635 list_add_tail(&map->next, &priv->freeable_maps);
636 err = 0;
637 }
638 mutex_unlock(&priv->lock);
639 if (map)
640 gntdev_put_map(priv, map);
641 return err;
642}
643
644static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
645 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
646{
647 struct ioctl_gntdev_get_offset_for_vaddr op;
648 struct vm_area_struct *vma;
649 struct grant_map *map;
650 int rv = -EINVAL;
651
652 if (copy_from_user(&op, u, sizeof(op)) != 0)
653 return -EFAULT;
654 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
655
656 down_read(¤t->mm->mmap_sem);
657 vma = find_vma(current->mm, op.vaddr);
658 if (!vma || vma->vm_ops != &gntdev_vmops)
659 goto out_unlock;
660
661 map = vma->vm_private_data;
662 if (!map)
663 goto out_unlock;
664
665 op.offset = map->index << PAGE_SHIFT;
666 op.count = map->count;
667 rv = 0;
668
669 out_unlock:
670 up_read(¤t->mm->mmap_sem);
671
672 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
673 return -EFAULT;
674 return rv;
675}
676
677static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
678{
679 struct ioctl_gntdev_unmap_notify op;
680 struct grant_map *map;
681 int rc;
682 int out_flags;
683 unsigned int out_event;
684
685 if (copy_from_user(&op, u, sizeof(op)))
686 return -EFAULT;
687
688 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
689 return -EINVAL;
690
691 /* We need to grab a reference to the event channel we are going to use
692 * to send the notify before releasing the reference we may already have
693 * (if someone has called this ioctl twice). This is required so that
694 * it is possible to change the clear_byte part of the notification
695 * without disturbing the event channel part, which may now be the last
696 * reference to that event channel.
697 */
698 if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
699 if (evtchn_get(op.event_channel_port))
700 return -EINVAL;
701 }
702
703 out_flags = op.action;
704 out_event = op.event_channel_port;
705
706 mutex_lock(&priv->lock);
707
708 list_for_each_entry(map, &priv->maps, next) {
709 uint64_t begin = map->index << PAGE_SHIFT;
710 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
711 if (op.index >= begin && op.index < end)
712 goto found;
713 }
714 rc = -ENOENT;
715 goto unlock_out;
716
717 found:
718 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
719 (map->flags & GNTMAP_readonly)) {
720 rc = -EINVAL;
721 goto unlock_out;
722 }
723
724 out_flags = map->notify.flags;
725 out_event = map->notify.event;
726
727 map->notify.flags = op.action;
728 map->notify.addr = op.index - (map->index << PAGE_SHIFT);
729 map->notify.event = op.event_channel_port;
730
731 rc = 0;
732
733 unlock_out:
734 mutex_unlock(&priv->lock);
735
736 /* Drop the reference to the event channel we did not save in the map */
737 if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
738 evtchn_put(out_event);
739
740 return rc;
741}
742
743#define GNTDEV_COPY_BATCH 16
744
745struct gntdev_copy_batch {
746 struct gnttab_copy ops[GNTDEV_COPY_BATCH];
747 struct page *pages[GNTDEV_COPY_BATCH];
748 s16 __user *status[GNTDEV_COPY_BATCH];
749 unsigned int nr_ops;
750 unsigned int nr_pages;
751};
752
753static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
754 bool writeable, unsigned long *gfn)
755{
756 unsigned long addr = (unsigned long)virt;
757 struct page *page;
758 unsigned long xen_pfn;
759 int ret;
760
761 ret = get_user_pages_fast(addr, 1, writeable, &page);
762 if (ret < 0)
763 return ret;
764
765 batch->pages[batch->nr_pages++] = page;
766
767 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK);
768 *gfn = pfn_to_gfn(xen_pfn);
769
770 return 0;
771}
772
773static void gntdev_put_pages(struct gntdev_copy_batch *batch)
774{
775 unsigned int i;
776
777 for (i = 0; i < batch->nr_pages; i++)
778 put_page(batch->pages[i]);
779 batch->nr_pages = 0;
780}
781
782static int gntdev_copy(struct gntdev_copy_batch *batch)
783{
784 unsigned int i;
785
786 gnttab_batch_copy(batch->ops, batch->nr_ops);
787 gntdev_put_pages(batch);
788
789 /*
790 * For each completed op, update the status if the op failed
791 * and all previous ops for the segment were successful.
792 */
793 for (i = 0; i < batch->nr_ops; i++) {
794 s16 status = batch->ops[i].status;
795 s16 old_status;
796
797 if (status == GNTST_okay)
798 continue;
799
800 if (__get_user(old_status, batch->status[i]))
801 return -EFAULT;
802
803 if (old_status != GNTST_okay)
804 continue;
805
806 if (__put_user(status, batch->status[i]))
807 return -EFAULT;
808 }
809
810 batch->nr_ops = 0;
811 return 0;
812}
813
814static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
815 struct gntdev_grant_copy_segment *seg,
816 s16 __user *status)
817{
818 uint16_t copied = 0;
819
820 /*
821 * Disallow local -> local copies since there is only space in
822 * batch->pages for one page per-op and this would be a very
823 * expensive memcpy().
824 */
825 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref)))
826 return -EINVAL;
827
828 /* Can't cross page if source/dest is a grant ref. */
829 if (seg->flags & GNTCOPY_source_gref) {
830 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE)
831 return -EINVAL;
832 }
833 if (seg->flags & GNTCOPY_dest_gref) {
834 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE)
835 return -EINVAL;
836 }
837
838 if (put_user(GNTST_okay, status))
839 return -EFAULT;
840
841 while (copied < seg->len) {
842 struct gnttab_copy *op;
843 void __user *virt;
844 size_t len, off;
845 unsigned long gfn;
846 int ret;
847
848 if (batch->nr_ops >= GNTDEV_COPY_BATCH) {
849 ret = gntdev_copy(batch);
850 if (ret < 0)
851 return ret;
852 }
853
854 len = seg->len - copied;
855
856 op = &batch->ops[batch->nr_ops];
857 op->flags = 0;
858
859 if (seg->flags & GNTCOPY_source_gref) {
860 op->source.u.ref = seg->source.foreign.ref;
861 op->source.domid = seg->source.foreign.domid;
862 op->source.offset = seg->source.foreign.offset + copied;
863 op->flags |= GNTCOPY_source_gref;
864 } else {
865 virt = seg->source.virt + copied;
866 off = (unsigned long)virt & ~XEN_PAGE_MASK;
867 len = min(len, (size_t)XEN_PAGE_SIZE - off);
868
869 ret = gntdev_get_page(batch, virt, false, &gfn);
870 if (ret < 0)
871 return ret;
872
873 op->source.u.gmfn = gfn;
874 op->source.domid = DOMID_SELF;
875 op->source.offset = off;
876 }
877
878 if (seg->flags & GNTCOPY_dest_gref) {
879 op->dest.u.ref = seg->dest.foreign.ref;
880 op->dest.domid = seg->dest.foreign.domid;
881 op->dest.offset = seg->dest.foreign.offset + copied;
882 op->flags |= GNTCOPY_dest_gref;
883 } else {
884 virt = seg->dest.virt + copied;
885 off = (unsigned long)virt & ~XEN_PAGE_MASK;
886 len = min(len, (size_t)XEN_PAGE_SIZE - off);
887
888 ret = gntdev_get_page(batch, virt, true, &gfn);
889 if (ret < 0)
890 return ret;
891
892 op->dest.u.gmfn = gfn;
893 op->dest.domid = DOMID_SELF;
894 op->dest.offset = off;
895 }
896
897 op->len = len;
898 copied += len;
899
900 batch->status[batch->nr_ops] = status;
901 batch->nr_ops++;
902 }
903
904 return 0;
905}
906
907static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
908{
909 struct ioctl_gntdev_grant_copy copy;
910 struct gntdev_copy_batch batch;
911 unsigned int i;
912 int ret = 0;
913
914 if (copy_from_user(©, u, sizeof(copy)))
915 return -EFAULT;
916
917 batch.nr_ops = 0;
918 batch.nr_pages = 0;
919
920 for (i = 0; i < copy.count; i++) {
921 struct gntdev_grant_copy_segment seg;
922
923 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) {
924 ret = -EFAULT;
925 goto out;
926 }
927
928 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status);
929 if (ret < 0)
930 goto out;
931
932 cond_resched();
933 }
934 if (batch.nr_ops)
935 ret = gntdev_copy(&batch);
936 return ret;
937
938 out:
939 gntdev_put_pages(&batch);
940 return ret;
941}
942
943static long gntdev_ioctl(struct file *flip,
944 unsigned int cmd, unsigned long arg)
945{
946 struct gntdev_priv *priv = flip->private_data;
947 void __user *ptr = (void __user *)arg;
948
949 switch (cmd) {
950 case IOCTL_GNTDEV_MAP_GRANT_REF:
951 return gntdev_ioctl_map_grant_ref(priv, ptr);
952
953 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
954 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
955
956 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
957 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
958
959 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
960 return gntdev_ioctl_notify(priv, ptr);
961
962 case IOCTL_GNTDEV_GRANT_COPY:
963 return gntdev_ioctl_grant_copy(priv, ptr);
964
965 default:
966 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
967 return -ENOIOCTLCMD;
968 }
969
970 return 0;
971}
972
973static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
974{
975 struct gntdev_priv *priv = flip->private_data;
976 int index = vma->vm_pgoff;
977 int count = vma_pages(vma);
978 struct grant_map *map;
979 int i, err = -EINVAL;
980
981 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
982 return -EINVAL;
983
984 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
985 index, count, vma->vm_start, vma->vm_pgoff);
986
987 mutex_lock(&priv->lock);
988 map = gntdev_find_map_index(priv, index, count);
989 if (!map)
990 goto unlock_out;
991 if (use_ptemod && map->vma)
992 goto unlock_out;
993 if (use_ptemod && priv->mm != vma->vm_mm) {
994 pr_warn("Huh? Other mm?\n");
995 goto unlock_out;
996 }
997
998 refcount_inc(&map->users);
999
1000 vma->vm_ops = &gntdev_vmops;
1001
1002 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP;
1003
1004 if (use_ptemod)
1005 vma->vm_flags |= VM_DONTCOPY;
1006
1007 vma->vm_private_data = map;
1008
1009 if (use_ptemod)
1010 map->vma = vma;
1011
1012 if (map->flags) {
1013 if ((vma->vm_flags & VM_WRITE) &&
1014 (map->flags & GNTMAP_readonly))
1015 goto out_unlock_put;
1016 } else {
1017 map->flags = GNTMAP_host_map;
1018 if (!(vma->vm_flags & VM_WRITE))
1019 map->flags |= GNTMAP_readonly;
1020 }
1021
1022 mutex_unlock(&priv->lock);
1023
1024 if (use_ptemod) {
1025 map->pages_vm_start = vma->vm_start;
1026 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
1027 vma->vm_end - vma->vm_start,
1028 find_grant_ptes, map);
1029 if (err) {
1030 pr_warn("find_grant_ptes() failure.\n");
1031 goto out_put_map;
1032 }
1033 }
1034
1035 err = map_grant_pages(map);
1036 if (err)
1037 goto out_put_map;
1038
1039 if (!use_ptemod) {
1040 for (i = 0; i < count; i++) {
1041 err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
1042 map->pages[i]);
1043 if (err)
1044 goto out_put_map;
1045 }
1046 } else {
1047#ifdef CONFIG_X86
1048 /*
1049 * If the PTEs were not made special by the grant map
1050 * hypercall, do so here.
1051 *
1052 * This is racy since the mapping is already visible
1053 * to userspace but userspace should be well-behaved
1054 * enough to not touch it until the mmap() call
1055 * returns.
1056 */
1057 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) {
1058 apply_to_page_range(vma->vm_mm, vma->vm_start,
1059 vma->vm_end - vma->vm_start,
1060 set_grant_ptes_as_special, NULL);
1061 }
1062#endif
1063 }
1064
1065 return 0;
1066
1067unlock_out:
1068 mutex_unlock(&priv->lock);
1069 return err;
1070
1071out_unlock_put:
1072 mutex_unlock(&priv->lock);
1073out_put_map:
1074 if (use_ptemod) {
1075 map->vma = NULL;
1076 unmap_grant_pages(map, 0, map->count);
1077 }
1078 gntdev_put_map(priv, map);
1079 return err;
1080}
1081
1082static const struct file_operations gntdev_fops = {
1083 .owner = THIS_MODULE,
1084 .open = gntdev_open,
1085 .release = gntdev_release,
1086 .mmap = gntdev_mmap,
1087 .unlocked_ioctl = gntdev_ioctl
1088};
1089
1090static struct miscdevice gntdev_miscdev = {
1091 .minor = MISC_DYNAMIC_MINOR,
1092 .name = "xen/gntdev",
1093 .fops = &gntdev_fops,
1094};
1095
1096/* ------------------------------------------------------------------ */
1097
1098static int __init gntdev_init(void)
1099{
1100 int err;
1101
1102 if (!xen_domain())
1103 return -ENODEV;
1104
1105 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
1106
1107 err = misc_register(&gntdev_miscdev);
1108 if (err != 0) {
1109 pr_err("Could not register gntdev device\n");
1110 return err;
1111 }
1112 return 0;
1113}
1114
1115static void __exit gntdev_exit(void)
1116{
1117 misc_deregister(&gntdev_miscdev);
1118}
1119
1120module_init(gntdev_init);
1121module_exit(gntdev_exit);
1122
1123/* ------------------------------------------------------------------ */
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 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 */
19
20#undef DEBUG
21
22#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
23
24#include <linux/module.h>
25#include <linux/kernel.h>
26#include <linux/init.h>
27#include <linux/miscdevice.h>
28#include <linux/fs.h>
29#include <linux/mm.h>
30#include <linux/mman.h>
31#include <linux/mmu_notifier.h>
32#include <linux/types.h>
33#include <linux/uaccess.h>
34#include <linux/sched.h>
35#include <linux/spinlock.h>
36#include <linux/slab.h>
37#include <linux/highmem.h>
38
39#include <xen/xen.h>
40#include <xen/grant_table.h>
41#include <xen/balloon.h>
42#include <xen/gntdev.h>
43#include <xen/events.h>
44#include <xen/page.h>
45#include <asm/xen/hypervisor.h>
46#include <asm/xen/hypercall.h>
47
48MODULE_LICENSE("GPL");
49MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
50 "Gerd Hoffmann <kraxel@redhat.com>");
51MODULE_DESCRIPTION("User-space granted page access driver");
52
53static int limit = 1024*1024;
54module_param(limit, int, 0644);
55MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
56 "the gntdev device");
57
58static atomic_t pages_mapped = ATOMIC_INIT(0);
59
60static int use_ptemod;
61#define populate_freeable_maps use_ptemod
62
63struct gntdev_priv {
64 /* maps with visible offsets in the file descriptor */
65 struct list_head maps;
66 /* maps that are not visible; will be freed on munmap.
67 * Only populated if populate_freeable_maps == 1 */
68 struct list_head freeable_maps;
69 /* lock protects maps and freeable_maps */
70 struct mutex lock;
71 struct mm_struct *mm;
72 struct mmu_notifier mn;
73};
74
75struct unmap_notify {
76 int flags;
77 /* Address relative to the start of the grant_map */
78 int addr;
79 int event;
80};
81
82struct grant_map {
83 struct list_head next;
84 struct vm_area_struct *vma;
85 int index;
86 int count;
87 int flags;
88 atomic_t users;
89 struct unmap_notify notify;
90 struct ioctl_gntdev_grant_ref *grants;
91 struct gnttab_map_grant_ref *map_ops;
92 struct gnttab_unmap_grant_ref *unmap_ops;
93 struct gnttab_map_grant_ref *kmap_ops;
94 struct gnttab_unmap_grant_ref *kunmap_ops;
95 struct page **pages;
96 unsigned long pages_vm_start;
97};
98
99static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
100
101/* ------------------------------------------------------------------ */
102
103static void gntdev_print_maps(struct gntdev_priv *priv,
104 char *text, int text_index)
105{
106#ifdef DEBUG
107 struct grant_map *map;
108
109 pr_debug("%s: maps list (priv %p)\n", __func__, priv);
110 list_for_each_entry(map, &priv->maps, next)
111 pr_debug(" index %2d, count %2d %s\n",
112 map->index, map->count,
113 map->index == text_index && text ? text : "");
114#endif
115}
116
117static void gntdev_free_map(struct grant_map *map)
118{
119 if (map == NULL)
120 return;
121
122 if (map->pages)
123 gnttab_free_pages(map->count, map->pages);
124 kfree(map->pages);
125 kfree(map->grants);
126 kfree(map->map_ops);
127 kfree(map->unmap_ops);
128 kfree(map->kmap_ops);
129 kfree(map->kunmap_ops);
130 kfree(map);
131}
132
133static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
134{
135 struct grant_map *add;
136 int i;
137
138 add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
139 if (NULL == add)
140 return NULL;
141
142 add->grants = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
143 add->map_ops = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
144 add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
145 add->kmap_ops = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
146 add->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]), GFP_KERNEL);
147 add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
148 if (NULL == add->grants ||
149 NULL == add->map_ops ||
150 NULL == add->unmap_ops ||
151 NULL == add->kmap_ops ||
152 NULL == add->kunmap_ops ||
153 NULL == add->pages)
154 goto err;
155
156 if (gnttab_alloc_pages(count, add->pages))
157 goto err;
158
159 for (i = 0; i < count; i++) {
160 add->map_ops[i].handle = -1;
161 add->unmap_ops[i].handle = -1;
162 add->kmap_ops[i].handle = -1;
163 add->kunmap_ops[i].handle = -1;
164 }
165
166 add->index = 0;
167 add->count = count;
168 atomic_set(&add->users, 1);
169
170 return add;
171
172err:
173 gntdev_free_map(add);
174 return NULL;
175}
176
177static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
178{
179 struct grant_map *map;
180
181 list_for_each_entry(map, &priv->maps, next) {
182 if (add->index + add->count < map->index) {
183 list_add_tail(&add->next, &map->next);
184 goto done;
185 }
186 add->index = map->index + map->count;
187 }
188 list_add_tail(&add->next, &priv->maps);
189
190done:
191 gntdev_print_maps(priv, "[new]", add->index);
192}
193
194static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
195 int index, int count)
196{
197 struct grant_map *map;
198
199 list_for_each_entry(map, &priv->maps, next) {
200 if (map->index != index)
201 continue;
202 if (count && map->count != count)
203 continue;
204 return map;
205 }
206 return NULL;
207}
208
209static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
210{
211 if (!map)
212 return;
213
214 if (!atomic_dec_and_test(&map->users))
215 return;
216
217 atomic_sub(map->count, &pages_mapped);
218
219 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
220 notify_remote_via_evtchn(map->notify.event);
221 evtchn_put(map->notify.event);
222 }
223
224 if (populate_freeable_maps && priv) {
225 mutex_lock(&priv->lock);
226 list_del(&map->next);
227 mutex_unlock(&priv->lock);
228 }
229
230 if (map->pages && !use_ptemod)
231 unmap_grant_pages(map, 0, map->count);
232 gntdev_free_map(map);
233}
234
235/* ------------------------------------------------------------------ */
236
237static int find_grant_ptes(pte_t *pte, pgtable_t token,
238 unsigned long addr, void *data)
239{
240 struct grant_map *map = data;
241 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
242 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
243 u64 pte_maddr;
244
245 BUG_ON(pgnr >= map->count);
246 pte_maddr = arbitrary_virt_to_machine(pte).maddr;
247
248 /*
249 * Set the PTE as special to force get_user_pages_fast() fall
250 * back to the slow path. If this is not supported as part of
251 * the grant map, it will be done afterwards.
252 */
253 if (xen_feature(XENFEAT_gnttab_map_avail_bits))
254 flags |= (1 << _GNTMAP_guest_avail0);
255
256 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
257 map->grants[pgnr].ref,
258 map->grants[pgnr].domid);
259 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
260 -1 /* handle */);
261 return 0;
262}
263
264#ifdef CONFIG_X86
265static int set_grant_ptes_as_special(pte_t *pte, pgtable_t token,
266 unsigned long addr, void *data)
267{
268 set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte));
269 return 0;
270}
271#endif
272
273static int map_grant_pages(struct grant_map *map)
274{
275 int i, err = 0;
276
277 if (!use_ptemod) {
278 /* Note: it could already be mapped */
279 if (map->map_ops[0].handle != -1)
280 return 0;
281 for (i = 0; i < map->count; i++) {
282 unsigned long addr = (unsigned long)
283 pfn_to_kaddr(page_to_pfn(map->pages[i]));
284 gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
285 map->grants[i].ref,
286 map->grants[i].domid);
287 gnttab_set_unmap_op(&map->unmap_ops[i], addr,
288 map->flags, -1 /* handle */);
289 }
290 } else {
291 /*
292 * Setup the map_ops corresponding to the pte entries pointing
293 * to the kernel linear addresses of the struct pages.
294 * These ptes are completely different from the user ptes dealt
295 * with find_grant_ptes.
296 */
297 for (i = 0; i < map->count; i++) {
298 unsigned long address = (unsigned long)
299 pfn_to_kaddr(page_to_pfn(map->pages[i]));
300 BUG_ON(PageHighMem(map->pages[i]));
301
302 gnttab_set_map_op(&map->kmap_ops[i], address,
303 map->flags | GNTMAP_host_map,
304 map->grants[i].ref,
305 map->grants[i].domid);
306 gnttab_set_unmap_op(&map->kunmap_ops[i], address,
307 map->flags | GNTMAP_host_map, -1);
308 }
309 }
310
311 pr_debug("map %d+%d\n", map->index, map->count);
312 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
313 map->pages, map->count);
314 if (err)
315 return err;
316
317 for (i = 0; i < map->count; i++) {
318 if (map->map_ops[i].status) {
319 err = -EINVAL;
320 continue;
321 }
322
323 map->unmap_ops[i].handle = map->map_ops[i].handle;
324 if (use_ptemod)
325 map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
326 }
327 return err;
328}
329
330static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
331{
332 int i, err = 0;
333 struct gntab_unmap_queue_data unmap_data;
334
335 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
336 int pgno = (map->notify.addr >> PAGE_SHIFT);
337 if (pgno >= offset && pgno < offset + pages) {
338 /* No need for kmap, pages are in lowmem */
339 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
340 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
341 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
342 }
343 }
344
345 unmap_data.unmap_ops = map->unmap_ops + offset;
346 unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
347 unmap_data.pages = map->pages + offset;
348 unmap_data.count = pages;
349
350 err = gnttab_unmap_refs_sync(&unmap_data);
351 if (err)
352 return err;
353
354 for (i = 0; i < pages; i++) {
355 if (map->unmap_ops[offset+i].status)
356 err = -EINVAL;
357 pr_debug("unmap handle=%d st=%d\n",
358 map->unmap_ops[offset+i].handle,
359 map->unmap_ops[offset+i].status);
360 map->unmap_ops[offset+i].handle = -1;
361 }
362 return err;
363}
364
365static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
366{
367 int range, err = 0;
368
369 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
370
371 /* It is possible the requested range will have a "hole" where we
372 * already unmapped some of the grants. Only unmap valid ranges.
373 */
374 while (pages && !err) {
375 while (pages && map->unmap_ops[offset].handle == -1) {
376 offset++;
377 pages--;
378 }
379 range = 0;
380 while (range < pages) {
381 if (map->unmap_ops[offset+range].handle == -1) {
382 range--;
383 break;
384 }
385 range++;
386 }
387 err = __unmap_grant_pages(map, offset, range);
388 offset += range;
389 pages -= range;
390 }
391
392 return err;
393}
394
395/* ------------------------------------------------------------------ */
396
397static void gntdev_vma_open(struct vm_area_struct *vma)
398{
399 struct grant_map *map = vma->vm_private_data;
400
401 pr_debug("gntdev_vma_open %p\n", vma);
402 atomic_inc(&map->users);
403}
404
405static void gntdev_vma_close(struct vm_area_struct *vma)
406{
407 struct grant_map *map = vma->vm_private_data;
408 struct file *file = vma->vm_file;
409 struct gntdev_priv *priv = file->private_data;
410
411 pr_debug("gntdev_vma_close %p\n", vma);
412 if (use_ptemod) {
413 /* It is possible that an mmu notifier could be running
414 * concurrently, so take priv->lock to ensure that the vma won't
415 * vanishing during the unmap_grant_pages call, since we will
416 * spin here until that completes. Such a concurrent call will
417 * not do any unmapping, since that has been done prior to
418 * closing the vma, but it may still iterate the unmap_ops list.
419 */
420 mutex_lock(&priv->lock);
421 map->vma = NULL;
422 mutex_unlock(&priv->lock);
423 }
424 vma->vm_private_data = NULL;
425 gntdev_put_map(priv, map);
426}
427
428static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma,
429 unsigned long addr)
430{
431 struct grant_map *map = vma->vm_private_data;
432
433 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
434}
435
436static const struct vm_operations_struct gntdev_vmops = {
437 .open = gntdev_vma_open,
438 .close = gntdev_vma_close,
439 .find_special_page = gntdev_vma_find_special_page,
440};
441
442/* ------------------------------------------------------------------ */
443
444static void unmap_if_in_range(struct grant_map *map,
445 unsigned long start, unsigned long end)
446{
447 unsigned long mstart, mend;
448 int err;
449
450 if (!map->vma)
451 return;
452 if (map->vma->vm_start >= end)
453 return;
454 if (map->vma->vm_end <= start)
455 return;
456 mstart = max(start, map->vma->vm_start);
457 mend = min(end, map->vma->vm_end);
458 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
459 map->index, map->count,
460 map->vma->vm_start, map->vma->vm_end,
461 start, end, mstart, mend);
462 err = unmap_grant_pages(map,
463 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
464 (mend - mstart) >> PAGE_SHIFT);
465 WARN_ON(err);
466}
467
468static void mn_invl_range_start(struct mmu_notifier *mn,
469 struct mm_struct *mm,
470 unsigned long start, unsigned long end)
471{
472 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
473 struct grant_map *map;
474
475 mutex_lock(&priv->lock);
476 list_for_each_entry(map, &priv->maps, next) {
477 unmap_if_in_range(map, start, end);
478 }
479 list_for_each_entry(map, &priv->freeable_maps, next) {
480 unmap_if_in_range(map, start, end);
481 }
482 mutex_unlock(&priv->lock);
483}
484
485static void mn_invl_page(struct mmu_notifier *mn,
486 struct mm_struct *mm,
487 unsigned long address)
488{
489 mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
490}
491
492static void mn_release(struct mmu_notifier *mn,
493 struct mm_struct *mm)
494{
495 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
496 struct grant_map *map;
497 int err;
498
499 mutex_lock(&priv->lock);
500 list_for_each_entry(map, &priv->maps, next) {
501 if (!map->vma)
502 continue;
503 pr_debug("map %d+%d (%lx %lx)\n",
504 map->index, map->count,
505 map->vma->vm_start, map->vma->vm_end);
506 err = unmap_grant_pages(map, /* offset */ 0, map->count);
507 WARN_ON(err);
508 }
509 list_for_each_entry(map, &priv->freeable_maps, next) {
510 if (!map->vma)
511 continue;
512 pr_debug("map %d+%d (%lx %lx)\n",
513 map->index, map->count,
514 map->vma->vm_start, map->vma->vm_end);
515 err = unmap_grant_pages(map, /* offset */ 0, map->count);
516 WARN_ON(err);
517 }
518 mutex_unlock(&priv->lock);
519}
520
521static const struct mmu_notifier_ops gntdev_mmu_ops = {
522 .release = mn_release,
523 .invalidate_page = mn_invl_page,
524 .invalidate_range_start = mn_invl_range_start,
525};
526
527/* ------------------------------------------------------------------ */
528
529static int gntdev_open(struct inode *inode, struct file *flip)
530{
531 struct gntdev_priv *priv;
532 int ret = 0;
533
534 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
535 if (!priv)
536 return -ENOMEM;
537
538 INIT_LIST_HEAD(&priv->maps);
539 INIT_LIST_HEAD(&priv->freeable_maps);
540 mutex_init(&priv->lock);
541
542 if (use_ptemod) {
543 priv->mm = get_task_mm(current);
544 if (!priv->mm) {
545 kfree(priv);
546 return -ENOMEM;
547 }
548 priv->mn.ops = &gntdev_mmu_ops;
549 ret = mmu_notifier_register(&priv->mn, priv->mm);
550 mmput(priv->mm);
551 }
552
553 if (ret) {
554 kfree(priv);
555 return ret;
556 }
557
558 flip->private_data = priv;
559 pr_debug("priv %p\n", priv);
560
561 return 0;
562}
563
564static int gntdev_release(struct inode *inode, struct file *flip)
565{
566 struct gntdev_priv *priv = flip->private_data;
567 struct grant_map *map;
568
569 pr_debug("priv %p\n", priv);
570
571 mutex_lock(&priv->lock);
572 while (!list_empty(&priv->maps)) {
573 map = list_entry(priv->maps.next, struct grant_map, next);
574 list_del(&map->next);
575 gntdev_put_map(NULL /* already removed */, map);
576 }
577 WARN_ON(!list_empty(&priv->freeable_maps));
578 mutex_unlock(&priv->lock);
579
580 if (use_ptemod)
581 mmu_notifier_unregister(&priv->mn, priv->mm);
582 kfree(priv);
583 return 0;
584}
585
586static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
587 struct ioctl_gntdev_map_grant_ref __user *u)
588{
589 struct ioctl_gntdev_map_grant_ref op;
590 struct grant_map *map;
591 int err;
592
593 if (copy_from_user(&op, u, sizeof(op)) != 0)
594 return -EFAULT;
595 pr_debug("priv %p, add %d\n", priv, op.count);
596 if (unlikely(op.count <= 0))
597 return -EINVAL;
598
599 err = -ENOMEM;
600 map = gntdev_alloc_map(priv, op.count);
601 if (!map)
602 return err;
603
604 if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
605 pr_debug("can't map: over limit\n");
606 gntdev_put_map(NULL, map);
607 return err;
608 }
609
610 if (copy_from_user(map->grants, &u->refs,
611 sizeof(map->grants[0]) * op.count) != 0) {
612 gntdev_put_map(NULL, map);
613 return -EFAULT;
614 }
615
616 mutex_lock(&priv->lock);
617 gntdev_add_map(priv, map);
618 op.index = map->index << PAGE_SHIFT;
619 mutex_unlock(&priv->lock);
620
621 if (copy_to_user(u, &op, sizeof(op)) != 0)
622 return -EFAULT;
623
624 return 0;
625}
626
627static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
628 struct ioctl_gntdev_unmap_grant_ref __user *u)
629{
630 struct ioctl_gntdev_unmap_grant_ref op;
631 struct grant_map *map;
632 int err = -ENOENT;
633
634 if (copy_from_user(&op, u, sizeof(op)) != 0)
635 return -EFAULT;
636 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
637
638 mutex_lock(&priv->lock);
639 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
640 if (map) {
641 list_del(&map->next);
642 if (populate_freeable_maps)
643 list_add_tail(&map->next, &priv->freeable_maps);
644 err = 0;
645 }
646 mutex_unlock(&priv->lock);
647 if (map)
648 gntdev_put_map(priv, map);
649 return err;
650}
651
652static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
653 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
654{
655 struct ioctl_gntdev_get_offset_for_vaddr op;
656 struct vm_area_struct *vma;
657 struct grant_map *map;
658 int rv = -EINVAL;
659
660 if (copy_from_user(&op, u, sizeof(op)) != 0)
661 return -EFAULT;
662 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
663
664 down_read(¤t->mm->mmap_sem);
665 vma = find_vma(current->mm, op.vaddr);
666 if (!vma || vma->vm_ops != &gntdev_vmops)
667 goto out_unlock;
668
669 map = vma->vm_private_data;
670 if (!map)
671 goto out_unlock;
672
673 op.offset = map->index << PAGE_SHIFT;
674 op.count = map->count;
675 rv = 0;
676
677 out_unlock:
678 up_read(¤t->mm->mmap_sem);
679
680 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
681 return -EFAULT;
682 return rv;
683}
684
685static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
686{
687 struct ioctl_gntdev_unmap_notify op;
688 struct grant_map *map;
689 int rc;
690 int out_flags;
691 unsigned int out_event;
692
693 if (copy_from_user(&op, u, sizeof(op)))
694 return -EFAULT;
695
696 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
697 return -EINVAL;
698
699 /* We need to grab a reference to the event channel we are going to use
700 * to send the notify before releasing the reference we may already have
701 * (if someone has called this ioctl twice). This is required so that
702 * it is possible to change the clear_byte part of the notification
703 * without disturbing the event channel part, which may now be the last
704 * reference to that event channel.
705 */
706 if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
707 if (evtchn_get(op.event_channel_port))
708 return -EINVAL;
709 }
710
711 out_flags = op.action;
712 out_event = op.event_channel_port;
713
714 mutex_lock(&priv->lock);
715
716 list_for_each_entry(map, &priv->maps, next) {
717 uint64_t begin = map->index << PAGE_SHIFT;
718 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
719 if (op.index >= begin && op.index < end)
720 goto found;
721 }
722 rc = -ENOENT;
723 goto unlock_out;
724
725 found:
726 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
727 (map->flags & GNTMAP_readonly)) {
728 rc = -EINVAL;
729 goto unlock_out;
730 }
731
732 out_flags = map->notify.flags;
733 out_event = map->notify.event;
734
735 map->notify.flags = op.action;
736 map->notify.addr = op.index - (map->index << PAGE_SHIFT);
737 map->notify.event = op.event_channel_port;
738
739 rc = 0;
740
741 unlock_out:
742 mutex_unlock(&priv->lock);
743
744 /* Drop the reference to the event channel we did not save in the map */
745 if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
746 evtchn_put(out_event);
747
748 return rc;
749}
750
751#define GNTDEV_COPY_BATCH 16
752
753struct gntdev_copy_batch {
754 struct gnttab_copy ops[GNTDEV_COPY_BATCH];
755 struct page *pages[GNTDEV_COPY_BATCH];
756 s16 __user *status[GNTDEV_COPY_BATCH];
757 unsigned int nr_ops;
758 unsigned int nr_pages;
759};
760
761static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
762 bool writeable, unsigned long *gfn)
763{
764 unsigned long addr = (unsigned long)virt;
765 struct page *page;
766 unsigned long xen_pfn;
767 int ret;
768
769 ret = get_user_pages_fast(addr, 1, writeable, &page);
770 if (ret < 0)
771 return ret;
772
773 batch->pages[batch->nr_pages++] = page;
774
775 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK);
776 *gfn = pfn_to_gfn(xen_pfn);
777
778 return 0;
779}
780
781static void gntdev_put_pages(struct gntdev_copy_batch *batch)
782{
783 unsigned int i;
784
785 for (i = 0; i < batch->nr_pages; i++)
786 put_page(batch->pages[i]);
787 batch->nr_pages = 0;
788}
789
790static int gntdev_copy(struct gntdev_copy_batch *batch)
791{
792 unsigned int i;
793
794 gnttab_batch_copy(batch->ops, batch->nr_ops);
795 gntdev_put_pages(batch);
796
797 /*
798 * For each completed op, update the status if the op failed
799 * and all previous ops for the segment were successful.
800 */
801 for (i = 0; i < batch->nr_ops; i++) {
802 s16 status = batch->ops[i].status;
803 s16 old_status;
804
805 if (status == GNTST_okay)
806 continue;
807
808 if (__get_user(old_status, batch->status[i]))
809 return -EFAULT;
810
811 if (old_status != GNTST_okay)
812 continue;
813
814 if (__put_user(status, batch->status[i]))
815 return -EFAULT;
816 }
817
818 batch->nr_ops = 0;
819 return 0;
820}
821
822static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
823 struct gntdev_grant_copy_segment *seg,
824 s16 __user *status)
825{
826 uint16_t copied = 0;
827
828 /*
829 * Disallow local -> local copies since there is only space in
830 * batch->pages for one page per-op and this would be a very
831 * expensive memcpy().
832 */
833 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref)))
834 return -EINVAL;
835
836 /* Can't cross page if source/dest is a grant ref. */
837 if (seg->flags & GNTCOPY_source_gref) {
838 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE)
839 return -EINVAL;
840 }
841 if (seg->flags & GNTCOPY_dest_gref) {
842 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE)
843 return -EINVAL;
844 }
845
846 if (put_user(GNTST_okay, status))
847 return -EFAULT;
848
849 while (copied < seg->len) {
850 struct gnttab_copy *op;
851 void __user *virt;
852 size_t len, off;
853 unsigned long gfn;
854 int ret;
855
856 if (batch->nr_ops >= GNTDEV_COPY_BATCH) {
857 ret = gntdev_copy(batch);
858 if (ret < 0)
859 return ret;
860 }
861
862 len = seg->len - copied;
863
864 op = &batch->ops[batch->nr_ops];
865 op->flags = 0;
866
867 if (seg->flags & GNTCOPY_source_gref) {
868 op->source.u.ref = seg->source.foreign.ref;
869 op->source.domid = seg->source.foreign.domid;
870 op->source.offset = seg->source.foreign.offset + copied;
871 op->flags |= GNTCOPY_source_gref;
872 } else {
873 virt = seg->source.virt + copied;
874 off = (unsigned long)virt & ~XEN_PAGE_MASK;
875 len = min(len, (size_t)XEN_PAGE_SIZE - off);
876
877 ret = gntdev_get_page(batch, virt, false, &gfn);
878 if (ret < 0)
879 return ret;
880
881 op->source.u.gmfn = gfn;
882 op->source.domid = DOMID_SELF;
883 op->source.offset = off;
884 }
885
886 if (seg->flags & GNTCOPY_dest_gref) {
887 op->dest.u.ref = seg->dest.foreign.ref;
888 op->dest.domid = seg->dest.foreign.domid;
889 op->dest.offset = seg->dest.foreign.offset + copied;
890 op->flags |= GNTCOPY_dest_gref;
891 } else {
892 virt = seg->dest.virt + copied;
893 off = (unsigned long)virt & ~XEN_PAGE_MASK;
894 len = min(len, (size_t)XEN_PAGE_SIZE - off);
895
896 ret = gntdev_get_page(batch, virt, true, &gfn);
897 if (ret < 0)
898 return ret;
899
900 op->dest.u.gmfn = gfn;
901 op->dest.domid = DOMID_SELF;
902 op->dest.offset = off;
903 }
904
905 op->len = len;
906 copied += len;
907
908 batch->status[batch->nr_ops] = status;
909 batch->nr_ops++;
910 }
911
912 return 0;
913}
914
915static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
916{
917 struct ioctl_gntdev_grant_copy copy;
918 struct gntdev_copy_batch batch;
919 unsigned int i;
920 int ret = 0;
921
922 if (copy_from_user(©, u, sizeof(copy)))
923 return -EFAULT;
924
925 batch.nr_ops = 0;
926 batch.nr_pages = 0;
927
928 for (i = 0; i < copy.count; i++) {
929 struct gntdev_grant_copy_segment seg;
930
931 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) {
932 ret = -EFAULT;
933 goto out;
934 }
935
936 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status);
937 if (ret < 0)
938 goto out;
939
940 cond_resched();
941 }
942 if (batch.nr_ops)
943 ret = gntdev_copy(&batch);
944 return ret;
945
946 out:
947 gntdev_put_pages(&batch);
948 return ret;
949}
950
951static long gntdev_ioctl(struct file *flip,
952 unsigned int cmd, unsigned long arg)
953{
954 struct gntdev_priv *priv = flip->private_data;
955 void __user *ptr = (void __user *)arg;
956
957 switch (cmd) {
958 case IOCTL_GNTDEV_MAP_GRANT_REF:
959 return gntdev_ioctl_map_grant_ref(priv, ptr);
960
961 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
962 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
963
964 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
965 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
966
967 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
968 return gntdev_ioctl_notify(priv, ptr);
969
970 case IOCTL_GNTDEV_GRANT_COPY:
971 return gntdev_ioctl_grant_copy(priv, ptr);
972
973 default:
974 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
975 return -ENOIOCTLCMD;
976 }
977
978 return 0;
979}
980
981static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
982{
983 struct gntdev_priv *priv = flip->private_data;
984 int index = vma->vm_pgoff;
985 int count = vma_pages(vma);
986 struct grant_map *map;
987 int i, err = -EINVAL;
988
989 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
990 return -EINVAL;
991
992 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
993 index, count, vma->vm_start, vma->vm_pgoff);
994
995 mutex_lock(&priv->lock);
996 map = gntdev_find_map_index(priv, index, count);
997 if (!map)
998 goto unlock_out;
999 if (use_ptemod && map->vma)
1000 goto unlock_out;
1001 if (use_ptemod && priv->mm != vma->vm_mm) {
1002 pr_warn("Huh? Other mm?\n");
1003 goto unlock_out;
1004 }
1005
1006 atomic_inc(&map->users);
1007
1008 vma->vm_ops = &gntdev_vmops;
1009
1010 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP;
1011
1012 if (use_ptemod)
1013 vma->vm_flags |= VM_DONTCOPY;
1014
1015 vma->vm_private_data = map;
1016
1017 if (use_ptemod)
1018 map->vma = vma;
1019
1020 if (map->flags) {
1021 if ((vma->vm_flags & VM_WRITE) &&
1022 (map->flags & GNTMAP_readonly))
1023 goto out_unlock_put;
1024 } else {
1025 map->flags = GNTMAP_host_map;
1026 if (!(vma->vm_flags & VM_WRITE))
1027 map->flags |= GNTMAP_readonly;
1028 }
1029
1030 mutex_unlock(&priv->lock);
1031
1032 if (use_ptemod) {
1033 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
1034 vma->vm_end - vma->vm_start,
1035 find_grant_ptes, map);
1036 if (err) {
1037 pr_warn("find_grant_ptes() failure.\n");
1038 goto out_put_map;
1039 }
1040 }
1041
1042 err = map_grant_pages(map);
1043 if (err)
1044 goto out_put_map;
1045
1046 if (!use_ptemod) {
1047 for (i = 0; i < count; i++) {
1048 err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
1049 map->pages[i]);
1050 if (err)
1051 goto out_put_map;
1052 }
1053 } else {
1054#ifdef CONFIG_X86
1055 /*
1056 * If the PTEs were not made special by the grant map
1057 * hypercall, do so here.
1058 *
1059 * This is racy since the mapping is already visible
1060 * to userspace but userspace should be well-behaved
1061 * enough to not touch it until the mmap() call
1062 * returns.
1063 */
1064 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) {
1065 apply_to_page_range(vma->vm_mm, vma->vm_start,
1066 vma->vm_end - vma->vm_start,
1067 set_grant_ptes_as_special, NULL);
1068 }
1069#endif
1070 map->pages_vm_start = vma->vm_start;
1071 }
1072
1073 return 0;
1074
1075unlock_out:
1076 mutex_unlock(&priv->lock);
1077 return err;
1078
1079out_unlock_put:
1080 mutex_unlock(&priv->lock);
1081out_put_map:
1082 if (use_ptemod)
1083 map->vma = NULL;
1084 gntdev_put_map(priv, map);
1085 return err;
1086}
1087
1088static const struct file_operations gntdev_fops = {
1089 .owner = THIS_MODULE,
1090 .open = gntdev_open,
1091 .release = gntdev_release,
1092 .mmap = gntdev_mmap,
1093 .unlocked_ioctl = gntdev_ioctl
1094};
1095
1096static struct miscdevice gntdev_miscdev = {
1097 .minor = MISC_DYNAMIC_MINOR,
1098 .name = "xen/gntdev",
1099 .fops = &gntdev_fops,
1100};
1101
1102/* ------------------------------------------------------------------ */
1103
1104static int __init gntdev_init(void)
1105{
1106 int err;
1107
1108 if (!xen_domain())
1109 return -ENODEV;
1110
1111 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
1112
1113 err = misc_register(&gntdev_miscdev);
1114 if (err != 0) {
1115 pr_err("Could not register gntdev device\n");
1116 return err;
1117 }
1118 return 0;
1119}
1120
1121static void __exit gntdev_exit(void)
1122{
1123 misc_deregister(&gntdev_miscdev);
1124}
1125
1126module_init(gntdev_init);
1127module_exit(gntdev_exit);
1128
1129/* ------------------------------------------------------------------ */