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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#include <linux/module.h>
23#include <linux/kernel.h>
24#include <linux/init.h>
25#include <linux/miscdevice.h>
26#include <linux/fs.h>
27#include <linux/mm.h>
28#include <linux/mman.h>
29#include <linux/mmu_notifier.h>
30#include <linux/types.h>
31#include <linux/uaccess.h>
32#include <linux/sched.h>
33#include <linux/spinlock.h>
34#include <linux/slab.h>
35#include <linux/highmem.h>
36
37#include <xen/xen.h>
38#include <xen/grant_table.h>
39#include <xen/balloon.h>
40#include <xen/gntdev.h>
41#include <xen/events.h>
42#include <asm/xen/hypervisor.h>
43#include <asm/xen/hypercall.h>
44#include <asm/xen/page.h>
45
46MODULE_LICENSE("GPL");
47MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
48 "Gerd Hoffmann <kraxel@redhat.com>");
49MODULE_DESCRIPTION("User-space granted page access driver");
50
51static int limit = 1024*1024;
52module_param(limit, int, 0644);
53MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
54 "the gntdev device");
55
56static atomic_t pages_mapped = ATOMIC_INIT(0);
57
58static int use_ptemod;
59
60struct gntdev_priv {
61 struct list_head maps;
62 /* lock protects maps from concurrent changes */
63 spinlock_t lock;
64 struct mm_struct *mm;
65 struct mmu_notifier mn;
66};
67
68struct unmap_notify {
69 int flags;
70 /* Address relative to the start of the grant_map */
71 int addr;
72 int event;
73};
74
75struct grant_map {
76 struct list_head next;
77 struct vm_area_struct *vma;
78 int index;
79 int count;
80 int flags;
81 atomic_t users;
82 struct unmap_notify notify;
83 struct ioctl_gntdev_grant_ref *grants;
84 struct gnttab_map_grant_ref *map_ops;
85 struct gnttab_unmap_grant_ref *unmap_ops;
86 struct page **pages;
87};
88
89static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
90
91/* ------------------------------------------------------------------ */
92
93static void gntdev_print_maps(struct gntdev_priv *priv,
94 char *text, int text_index)
95{
96#ifdef DEBUG
97 struct grant_map *map;
98
99 pr_debug("%s: maps list (priv %p)\n", __func__, priv);
100 list_for_each_entry(map, &priv->maps, next)
101 pr_debug(" index %2d, count %2d %s\n",
102 map->index, map->count,
103 map->index == text_index && text ? text : "");
104#endif
105}
106
107static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
108{
109 struct grant_map *add;
110 int i;
111
112 add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
113 if (NULL == add)
114 return NULL;
115
116 add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL);
117 add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL);
118 add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL);
119 add->pages = kzalloc(sizeof(add->pages[0]) * count, GFP_KERNEL);
120 if (NULL == add->grants ||
121 NULL == add->map_ops ||
122 NULL == add->unmap_ops ||
123 NULL == add->pages)
124 goto err;
125
126 if (alloc_xenballooned_pages(count, add->pages))
127 goto err;
128
129 for (i = 0; i < count; i++) {
130 add->map_ops[i].handle = -1;
131 add->unmap_ops[i].handle = -1;
132 }
133
134 add->index = 0;
135 add->count = count;
136 atomic_set(&add->users, 1);
137
138 return add;
139
140err:
141 kfree(add->pages);
142 kfree(add->grants);
143 kfree(add->map_ops);
144 kfree(add->unmap_ops);
145 kfree(add);
146 return NULL;
147}
148
149static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
150{
151 struct grant_map *map;
152
153 list_for_each_entry(map, &priv->maps, next) {
154 if (add->index + add->count < map->index) {
155 list_add_tail(&add->next, &map->next);
156 goto done;
157 }
158 add->index = map->index + map->count;
159 }
160 list_add_tail(&add->next, &priv->maps);
161
162done:
163 gntdev_print_maps(priv, "[new]", add->index);
164}
165
166static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
167 int index, int count)
168{
169 struct grant_map *map;
170
171 list_for_each_entry(map, &priv->maps, next) {
172 if (map->index != index)
173 continue;
174 if (count && map->count != count)
175 continue;
176 return map;
177 }
178 return NULL;
179}
180
181static void gntdev_put_map(struct grant_map *map)
182{
183 if (!map)
184 return;
185
186 if (!atomic_dec_and_test(&map->users))
187 return;
188
189 atomic_sub(map->count, &pages_mapped);
190
191 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
192 notify_remote_via_evtchn(map->notify.event);
193 }
194
195 if (map->pages) {
196 if (!use_ptemod)
197 unmap_grant_pages(map, 0, map->count);
198
199 free_xenballooned_pages(map->count, map->pages);
200 }
201 kfree(map->pages);
202 kfree(map->grants);
203 kfree(map->map_ops);
204 kfree(map->unmap_ops);
205 kfree(map);
206}
207
208/* ------------------------------------------------------------------ */
209
210static int find_grant_ptes(pte_t *pte, pgtable_t token,
211 unsigned long addr, void *data)
212{
213 struct grant_map *map = data;
214 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
215 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
216 u64 pte_maddr;
217
218 BUG_ON(pgnr >= map->count);
219 pte_maddr = arbitrary_virt_to_machine(pte).maddr;
220
221 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
222 map->grants[pgnr].ref,
223 map->grants[pgnr].domid);
224 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
225 -1 /* handle */);
226 return 0;
227}
228
229static int map_grant_pages(struct grant_map *map)
230{
231 int i, err = 0;
232
233 if (!use_ptemod) {
234 /* Note: it could already be mapped */
235 if (map->map_ops[0].handle != -1)
236 return 0;
237 for (i = 0; i < map->count; i++) {
238 unsigned long addr = (unsigned long)
239 pfn_to_kaddr(page_to_pfn(map->pages[i]));
240 gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
241 map->grants[i].ref,
242 map->grants[i].domid);
243 gnttab_set_unmap_op(&map->unmap_ops[i], addr,
244 map->flags, -1 /* handle */);
245 }
246 }
247
248 pr_debug("map %d+%d\n", map->index, map->count);
249 err = gnttab_map_refs(map->map_ops, map->pages, map->count);
250 if (err)
251 return err;
252
253 for (i = 0; i < map->count; i++) {
254 if (map->map_ops[i].status)
255 err = -EINVAL;
256 else {
257 BUG_ON(map->map_ops[i].handle == -1);
258 map->unmap_ops[i].handle = map->map_ops[i].handle;
259 pr_debug("map handle=%d\n", map->map_ops[i].handle);
260 }
261 }
262 return err;
263}
264
265static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
266{
267 int i, err = 0;
268
269 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
270 int pgno = (map->notify.addr >> PAGE_SHIFT);
271 if (pgno >= offset && pgno < offset + pages && use_ptemod) {
272 void __user *tmp = (void __user *)
273 map->vma->vm_start + map->notify.addr;
274 err = copy_to_user(tmp, &err, 1);
275 if (err)
276 return -EFAULT;
277 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
278 } else if (pgno >= offset && pgno < offset + pages) {
279 uint8_t *tmp = kmap(map->pages[pgno]);
280 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
281 kunmap(map->pages[pgno]);
282 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
283 }
284 }
285
286 err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
287 if (err)
288 return err;
289
290 for (i = 0; i < pages; i++) {
291 if (map->unmap_ops[offset+i].status)
292 err = -EINVAL;
293 pr_debug("unmap handle=%d st=%d\n",
294 map->unmap_ops[offset+i].handle,
295 map->unmap_ops[offset+i].status);
296 map->unmap_ops[offset+i].handle = -1;
297 }
298 return err;
299}
300
301static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
302{
303 int range, err = 0;
304
305 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
306
307 /* It is possible the requested range will have a "hole" where we
308 * already unmapped some of the grants. Only unmap valid ranges.
309 */
310 while (pages && !err) {
311 while (pages && map->unmap_ops[offset].handle == -1) {
312 offset++;
313 pages--;
314 }
315 range = 0;
316 while (range < pages) {
317 if (map->unmap_ops[offset+range].handle == -1) {
318 range--;
319 break;
320 }
321 range++;
322 }
323 err = __unmap_grant_pages(map, offset, range);
324 offset += range;
325 pages -= range;
326 }
327
328 return err;
329}
330
331/* ------------------------------------------------------------------ */
332
333static void gntdev_vma_open(struct vm_area_struct *vma)
334{
335 struct grant_map *map = vma->vm_private_data;
336
337 pr_debug("gntdev_vma_open %p\n", vma);
338 atomic_inc(&map->users);
339}
340
341static void gntdev_vma_close(struct vm_area_struct *vma)
342{
343 struct grant_map *map = vma->vm_private_data;
344
345 pr_debug("gntdev_vma_close %p\n", vma);
346 map->vma = NULL;
347 vma->vm_private_data = NULL;
348 gntdev_put_map(map);
349}
350
351static struct vm_operations_struct gntdev_vmops = {
352 .open = gntdev_vma_open,
353 .close = gntdev_vma_close,
354};
355
356/* ------------------------------------------------------------------ */
357
358static void mn_invl_range_start(struct mmu_notifier *mn,
359 struct mm_struct *mm,
360 unsigned long start, unsigned long end)
361{
362 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
363 struct grant_map *map;
364 unsigned long mstart, mend;
365 int err;
366
367 spin_lock(&priv->lock);
368 list_for_each_entry(map, &priv->maps, next) {
369 if (!map->vma)
370 continue;
371 if (map->vma->vm_start >= end)
372 continue;
373 if (map->vma->vm_end <= start)
374 continue;
375 mstart = max(start, map->vma->vm_start);
376 mend = min(end, map->vma->vm_end);
377 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
378 map->index, map->count,
379 map->vma->vm_start, map->vma->vm_end,
380 start, end, mstart, mend);
381 err = unmap_grant_pages(map,
382 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
383 (mend - mstart) >> PAGE_SHIFT);
384 WARN_ON(err);
385 }
386 spin_unlock(&priv->lock);
387}
388
389static void mn_invl_page(struct mmu_notifier *mn,
390 struct mm_struct *mm,
391 unsigned long address)
392{
393 mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
394}
395
396static void mn_release(struct mmu_notifier *mn,
397 struct mm_struct *mm)
398{
399 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
400 struct grant_map *map;
401 int err;
402
403 spin_lock(&priv->lock);
404 list_for_each_entry(map, &priv->maps, next) {
405 if (!map->vma)
406 continue;
407 pr_debug("map %d+%d (%lx %lx)\n",
408 map->index, map->count,
409 map->vma->vm_start, map->vma->vm_end);
410 err = unmap_grant_pages(map, /* offset */ 0, map->count);
411 WARN_ON(err);
412 }
413 spin_unlock(&priv->lock);
414}
415
416struct mmu_notifier_ops gntdev_mmu_ops = {
417 .release = mn_release,
418 .invalidate_page = mn_invl_page,
419 .invalidate_range_start = mn_invl_range_start,
420};
421
422/* ------------------------------------------------------------------ */
423
424static int gntdev_open(struct inode *inode, struct file *flip)
425{
426 struct gntdev_priv *priv;
427 int ret = 0;
428
429 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
430 if (!priv)
431 return -ENOMEM;
432
433 INIT_LIST_HEAD(&priv->maps);
434 spin_lock_init(&priv->lock);
435
436 if (use_ptemod) {
437 priv->mm = get_task_mm(current);
438 if (!priv->mm) {
439 kfree(priv);
440 return -ENOMEM;
441 }
442 priv->mn.ops = &gntdev_mmu_ops;
443 ret = mmu_notifier_register(&priv->mn, priv->mm);
444 mmput(priv->mm);
445 }
446
447 if (ret) {
448 kfree(priv);
449 return ret;
450 }
451
452 flip->private_data = priv;
453 pr_debug("priv %p\n", priv);
454
455 return 0;
456}
457
458static int gntdev_release(struct inode *inode, struct file *flip)
459{
460 struct gntdev_priv *priv = flip->private_data;
461 struct grant_map *map;
462
463 pr_debug("priv %p\n", priv);
464
465 spin_lock(&priv->lock);
466 while (!list_empty(&priv->maps)) {
467 map = list_entry(priv->maps.next, struct grant_map, next);
468 list_del(&map->next);
469 gntdev_put_map(map);
470 }
471 spin_unlock(&priv->lock);
472
473 if (use_ptemod)
474 mmu_notifier_unregister(&priv->mn, priv->mm);
475 kfree(priv);
476 return 0;
477}
478
479static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
480 struct ioctl_gntdev_map_grant_ref __user *u)
481{
482 struct ioctl_gntdev_map_grant_ref op;
483 struct grant_map *map;
484 int err;
485
486 if (copy_from_user(&op, u, sizeof(op)) != 0)
487 return -EFAULT;
488 pr_debug("priv %p, add %d\n", priv, op.count);
489 if (unlikely(op.count <= 0))
490 return -EINVAL;
491
492 err = -ENOMEM;
493 map = gntdev_alloc_map(priv, op.count);
494 if (!map)
495 return err;
496
497 if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
498 pr_debug("can't map: over limit\n");
499 gntdev_put_map(map);
500 return err;
501 }
502
503 if (copy_from_user(map->grants, &u->refs,
504 sizeof(map->grants[0]) * op.count) != 0) {
505 gntdev_put_map(map);
506 return err;
507 }
508
509 spin_lock(&priv->lock);
510 gntdev_add_map(priv, map);
511 op.index = map->index << PAGE_SHIFT;
512 spin_unlock(&priv->lock);
513
514 if (copy_to_user(u, &op, sizeof(op)) != 0)
515 return -EFAULT;
516
517 return 0;
518}
519
520static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
521 struct ioctl_gntdev_unmap_grant_ref __user *u)
522{
523 struct ioctl_gntdev_unmap_grant_ref op;
524 struct grant_map *map;
525 int err = -ENOENT;
526
527 if (copy_from_user(&op, u, sizeof(op)) != 0)
528 return -EFAULT;
529 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
530
531 spin_lock(&priv->lock);
532 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
533 if (map) {
534 list_del(&map->next);
535 gntdev_put_map(map);
536 err = 0;
537 }
538 spin_unlock(&priv->lock);
539 return err;
540}
541
542static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
543 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
544{
545 struct ioctl_gntdev_get_offset_for_vaddr op;
546 struct vm_area_struct *vma;
547 struct grant_map *map;
548
549 if (copy_from_user(&op, u, sizeof(op)) != 0)
550 return -EFAULT;
551 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
552
553 vma = find_vma(current->mm, op.vaddr);
554 if (!vma || vma->vm_ops != &gntdev_vmops)
555 return -EINVAL;
556
557 map = vma->vm_private_data;
558 if (!map)
559 return -EINVAL;
560
561 op.offset = map->index << PAGE_SHIFT;
562 op.count = map->count;
563
564 if (copy_to_user(u, &op, sizeof(op)) != 0)
565 return -EFAULT;
566 return 0;
567}
568
569static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
570{
571 struct ioctl_gntdev_unmap_notify op;
572 struct grant_map *map;
573 int rc;
574
575 if (copy_from_user(&op, u, sizeof(op)))
576 return -EFAULT;
577
578 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
579 return -EINVAL;
580
581 spin_lock(&priv->lock);
582
583 list_for_each_entry(map, &priv->maps, next) {
584 uint64_t begin = map->index << PAGE_SHIFT;
585 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
586 if (op.index >= begin && op.index < end)
587 goto found;
588 }
589 rc = -ENOENT;
590 goto unlock_out;
591
592 found:
593 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
594 (map->flags & GNTMAP_readonly)) {
595 rc = -EINVAL;
596 goto unlock_out;
597 }
598
599 map->notify.flags = op.action;
600 map->notify.addr = op.index - (map->index << PAGE_SHIFT);
601 map->notify.event = op.event_channel_port;
602 rc = 0;
603 unlock_out:
604 spin_unlock(&priv->lock);
605 return rc;
606}
607
608static long gntdev_ioctl(struct file *flip,
609 unsigned int cmd, unsigned long arg)
610{
611 struct gntdev_priv *priv = flip->private_data;
612 void __user *ptr = (void __user *)arg;
613
614 switch (cmd) {
615 case IOCTL_GNTDEV_MAP_GRANT_REF:
616 return gntdev_ioctl_map_grant_ref(priv, ptr);
617
618 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
619 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
620
621 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
622 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
623
624 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
625 return gntdev_ioctl_notify(priv, ptr);
626
627 default:
628 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
629 return -ENOIOCTLCMD;
630 }
631
632 return 0;
633}
634
635static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
636{
637 struct gntdev_priv *priv = flip->private_data;
638 int index = vma->vm_pgoff;
639 int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
640 struct grant_map *map;
641 int i, err = -EINVAL;
642
643 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
644 return -EINVAL;
645
646 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
647 index, count, vma->vm_start, vma->vm_pgoff);
648
649 spin_lock(&priv->lock);
650 map = gntdev_find_map_index(priv, index, count);
651 if (!map)
652 goto unlock_out;
653 if (use_ptemod && map->vma)
654 goto unlock_out;
655 if (use_ptemod && priv->mm != vma->vm_mm) {
656 printk(KERN_WARNING "Huh? Other mm?\n");
657 goto unlock_out;
658 }
659
660 atomic_inc(&map->users);
661
662 vma->vm_ops = &gntdev_vmops;
663
664 vma->vm_flags |= VM_RESERVED|VM_DONTEXPAND;
665
666 if (use_ptemod)
667 vma->vm_flags |= VM_DONTCOPY|VM_PFNMAP;
668
669 vma->vm_private_data = map;
670
671 if (use_ptemod)
672 map->vma = vma;
673
674 if (map->flags) {
675 if ((vma->vm_flags & VM_WRITE) &&
676 (map->flags & GNTMAP_readonly))
677 goto out_unlock_put;
678 } else {
679 map->flags = GNTMAP_host_map;
680 if (!(vma->vm_flags & VM_WRITE))
681 map->flags |= GNTMAP_readonly;
682 }
683
684 spin_unlock(&priv->lock);
685
686 if (use_ptemod) {
687 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
688 vma->vm_end - vma->vm_start,
689 find_grant_ptes, map);
690 if (err) {
691 printk(KERN_WARNING "find_grant_ptes() failure.\n");
692 goto out_put_map;
693 }
694 }
695
696 err = map_grant_pages(map);
697 if (err)
698 goto out_put_map;
699
700 if (!use_ptemod) {
701 for (i = 0; i < count; i++) {
702 err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
703 map->pages[i]);
704 if (err)
705 goto out_put_map;
706 }
707 }
708
709 return 0;
710
711unlock_out:
712 spin_unlock(&priv->lock);
713 return err;
714
715out_unlock_put:
716 spin_unlock(&priv->lock);
717out_put_map:
718 if (use_ptemod)
719 map->vma = NULL;
720 gntdev_put_map(map);
721 return err;
722}
723
724static const struct file_operations gntdev_fops = {
725 .owner = THIS_MODULE,
726 .open = gntdev_open,
727 .release = gntdev_release,
728 .mmap = gntdev_mmap,
729 .unlocked_ioctl = gntdev_ioctl
730};
731
732static struct miscdevice gntdev_miscdev = {
733 .minor = MISC_DYNAMIC_MINOR,
734 .name = "xen/gntdev",
735 .fops = &gntdev_fops,
736};
737
738/* ------------------------------------------------------------------ */
739
740static int __init gntdev_init(void)
741{
742 int err;
743
744 if (!xen_domain())
745 return -ENODEV;
746
747 use_ptemod = xen_pv_domain();
748
749 err = misc_register(&gntdev_miscdev);
750 if (err != 0) {
751 printk(KERN_ERR "Could not register gntdev device\n");
752 return err;
753 }
754 return 0;
755}
756
757static void __exit gntdev_exit(void)
758{
759 misc_deregister(&gntdev_miscdev);
760}
761
762module_init(gntdev_init);
763module_exit(gntdev_exit);
764
765/* ------------------------------------------------------------------ */
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 <asm/xen/hypervisor.h>
45#include <asm/xen/hypercall.h>
46#include <asm/xen/page.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 spinlock_t 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 page **pages;
95};
96
97static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
98
99/* ------------------------------------------------------------------ */
100
101static void gntdev_print_maps(struct gntdev_priv *priv,
102 char *text, int text_index)
103{
104#ifdef DEBUG
105 struct grant_map *map;
106
107 pr_debug("%s: maps list (priv %p)\n", __func__, priv);
108 list_for_each_entry(map, &priv->maps, next)
109 pr_debug(" index %2d, count %2d %s\n",
110 map->index, map->count,
111 map->index == text_index && text ? text : "");
112#endif
113}
114
115static void gntdev_free_map(struct grant_map *map)
116{
117 if (map == NULL)
118 return;
119
120 if (map->pages)
121 free_xenballooned_pages(map->count, map->pages);
122 kfree(map->pages);
123 kfree(map->grants);
124 kfree(map->map_ops);
125 kfree(map->unmap_ops);
126 kfree(map->kmap_ops);
127 kfree(map);
128}
129
130static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
131{
132 struct grant_map *add;
133 int i;
134
135 add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
136 if (NULL == add)
137 return NULL;
138
139 add->grants = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
140 add->map_ops = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
141 add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
142 add->kmap_ops = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
143 add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
144 if (NULL == add->grants ||
145 NULL == add->map_ops ||
146 NULL == add->unmap_ops ||
147 NULL == add->kmap_ops ||
148 NULL == add->pages)
149 goto err;
150
151 if (alloc_xenballooned_pages(count, add->pages, false /* lowmem */))
152 goto err;
153
154 for (i = 0; i < count; i++) {
155 add->map_ops[i].handle = -1;
156 add->unmap_ops[i].handle = -1;
157 add->kmap_ops[i].handle = -1;
158 }
159
160 add->index = 0;
161 add->count = count;
162 atomic_set(&add->users, 1);
163
164 return add;
165
166err:
167 gntdev_free_map(add);
168 return NULL;
169}
170
171static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
172{
173 struct grant_map *map;
174
175 list_for_each_entry(map, &priv->maps, next) {
176 if (add->index + add->count < map->index) {
177 list_add_tail(&add->next, &map->next);
178 goto done;
179 }
180 add->index = map->index + map->count;
181 }
182 list_add_tail(&add->next, &priv->maps);
183
184done:
185 gntdev_print_maps(priv, "[new]", add->index);
186}
187
188static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
189 int index, int count)
190{
191 struct grant_map *map;
192
193 list_for_each_entry(map, &priv->maps, next) {
194 if (map->index != index)
195 continue;
196 if (count && map->count != count)
197 continue;
198 return map;
199 }
200 return NULL;
201}
202
203static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
204{
205 if (!map)
206 return;
207
208 if (!atomic_dec_and_test(&map->users))
209 return;
210
211 atomic_sub(map->count, &pages_mapped);
212
213 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
214 notify_remote_via_evtchn(map->notify.event);
215 evtchn_put(map->notify.event);
216 }
217
218 if (populate_freeable_maps && priv) {
219 spin_lock(&priv->lock);
220 list_del(&map->next);
221 spin_unlock(&priv->lock);
222 }
223
224 if (map->pages && !use_ptemod)
225 unmap_grant_pages(map, 0, map->count);
226 gntdev_free_map(map);
227}
228
229/* ------------------------------------------------------------------ */
230
231static int find_grant_ptes(pte_t *pte, pgtable_t token,
232 unsigned long addr, void *data)
233{
234 struct grant_map *map = data;
235 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
236 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
237 u64 pte_maddr;
238
239 BUG_ON(pgnr >= map->count);
240 pte_maddr = arbitrary_virt_to_machine(pte).maddr;
241
242 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
243 map->grants[pgnr].ref,
244 map->grants[pgnr].domid);
245 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
246 -1 /* handle */);
247 return 0;
248}
249
250static int map_grant_pages(struct grant_map *map)
251{
252 int i, err = 0;
253
254 if (!use_ptemod) {
255 /* Note: it could already be mapped */
256 if (map->map_ops[0].handle != -1)
257 return 0;
258 for (i = 0; i < map->count; i++) {
259 unsigned long addr = (unsigned long)
260 pfn_to_kaddr(page_to_pfn(map->pages[i]));
261 gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
262 map->grants[i].ref,
263 map->grants[i].domid);
264 gnttab_set_unmap_op(&map->unmap_ops[i], addr,
265 map->flags, -1 /* handle */);
266 }
267 } else {
268 /*
269 * Setup the map_ops corresponding to the pte entries pointing
270 * to the kernel linear addresses of the struct pages.
271 * These ptes are completely different from the user ptes dealt
272 * with find_grant_ptes.
273 */
274 for (i = 0; i < map->count; i++) {
275 unsigned long address = (unsigned long)
276 pfn_to_kaddr(page_to_pfn(map->pages[i]));
277 BUG_ON(PageHighMem(map->pages[i]));
278
279 gnttab_set_map_op(&map->kmap_ops[i], address,
280 map->flags | GNTMAP_host_map,
281 map->grants[i].ref,
282 map->grants[i].domid);
283 }
284 }
285
286 pr_debug("map %d+%d\n", map->index, map->count);
287 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
288 map->pages, map->count);
289 if (err)
290 return err;
291
292 for (i = 0; i < map->count; i++) {
293 if (map->map_ops[i].status)
294 err = -EINVAL;
295 else {
296 BUG_ON(map->map_ops[i].handle == -1);
297 map->unmap_ops[i].handle = map->map_ops[i].handle;
298 pr_debug("map handle=%d\n", map->map_ops[i].handle);
299 }
300 }
301 return err;
302}
303
304static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
305{
306 int i, err = 0;
307
308 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
309 int pgno = (map->notify.addr >> PAGE_SHIFT);
310 if (pgno >= offset && pgno < offset + pages) {
311 /* No need for kmap, pages are in lowmem */
312 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
313 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
314 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
315 }
316 }
317
318 err = gnttab_unmap_refs(map->unmap_ops + offset,
319 use_ptemod ? map->kmap_ops + offset : NULL, map->pages + offset,
320 pages);
321 if (err)
322 return err;
323
324 for (i = 0; i < pages; i++) {
325 if (map->unmap_ops[offset+i].status)
326 err = -EINVAL;
327 pr_debug("unmap handle=%d st=%d\n",
328 map->unmap_ops[offset+i].handle,
329 map->unmap_ops[offset+i].status);
330 map->unmap_ops[offset+i].handle = -1;
331 }
332 return err;
333}
334
335static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
336{
337 int range, err = 0;
338
339 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
340
341 /* It is possible the requested range will have a "hole" where we
342 * already unmapped some of the grants. Only unmap valid ranges.
343 */
344 while (pages && !err) {
345 while (pages && map->unmap_ops[offset].handle == -1) {
346 offset++;
347 pages--;
348 }
349 range = 0;
350 while (range < pages) {
351 if (map->unmap_ops[offset+range].handle == -1) {
352 range--;
353 break;
354 }
355 range++;
356 }
357 err = __unmap_grant_pages(map, offset, range);
358 offset += range;
359 pages -= range;
360 }
361
362 return err;
363}
364
365/* ------------------------------------------------------------------ */
366
367static void gntdev_vma_open(struct vm_area_struct *vma)
368{
369 struct grant_map *map = vma->vm_private_data;
370
371 pr_debug("gntdev_vma_open %p\n", vma);
372 atomic_inc(&map->users);
373}
374
375static void gntdev_vma_close(struct vm_area_struct *vma)
376{
377 struct grant_map *map = vma->vm_private_data;
378 struct file *file = vma->vm_file;
379 struct gntdev_priv *priv = file->private_data;
380
381 pr_debug("gntdev_vma_close %p\n", vma);
382 if (use_ptemod) {
383 /* It is possible that an mmu notifier could be running
384 * concurrently, so take priv->lock to ensure that the vma won't
385 * vanishing during the unmap_grant_pages call, since we will
386 * spin here until that completes. Such a concurrent call will
387 * not do any unmapping, since that has been done prior to
388 * closing the vma, but it may still iterate the unmap_ops list.
389 */
390 spin_lock(&priv->lock);
391 map->vma = NULL;
392 spin_unlock(&priv->lock);
393 }
394 vma->vm_private_data = NULL;
395 gntdev_put_map(priv, map);
396}
397
398static struct vm_operations_struct gntdev_vmops = {
399 .open = gntdev_vma_open,
400 .close = gntdev_vma_close,
401};
402
403/* ------------------------------------------------------------------ */
404
405static void unmap_if_in_range(struct grant_map *map,
406 unsigned long start, unsigned long end)
407{
408 unsigned long mstart, mend;
409 int err;
410
411 if (!map->vma)
412 return;
413 if (map->vma->vm_start >= end)
414 return;
415 if (map->vma->vm_end <= start)
416 return;
417 mstart = max(start, map->vma->vm_start);
418 mend = min(end, map->vma->vm_end);
419 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
420 map->index, map->count,
421 map->vma->vm_start, map->vma->vm_end,
422 start, end, mstart, mend);
423 err = unmap_grant_pages(map,
424 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
425 (mend - mstart) >> PAGE_SHIFT);
426 WARN_ON(err);
427}
428
429static void mn_invl_range_start(struct mmu_notifier *mn,
430 struct mm_struct *mm,
431 unsigned long start, unsigned long end)
432{
433 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
434 struct grant_map *map;
435
436 spin_lock(&priv->lock);
437 list_for_each_entry(map, &priv->maps, next) {
438 unmap_if_in_range(map, start, end);
439 }
440 list_for_each_entry(map, &priv->freeable_maps, next) {
441 unmap_if_in_range(map, start, end);
442 }
443 spin_unlock(&priv->lock);
444}
445
446static void mn_invl_page(struct mmu_notifier *mn,
447 struct mm_struct *mm,
448 unsigned long address)
449{
450 mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
451}
452
453static void mn_release(struct mmu_notifier *mn,
454 struct mm_struct *mm)
455{
456 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
457 struct grant_map *map;
458 int err;
459
460 spin_lock(&priv->lock);
461 list_for_each_entry(map, &priv->maps, next) {
462 if (!map->vma)
463 continue;
464 pr_debug("map %d+%d (%lx %lx)\n",
465 map->index, map->count,
466 map->vma->vm_start, map->vma->vm_end);
467 err = unmap_grant_pages(map, /* offset */ 0, map->count);
468 WARN_ON(err);
469 }
470 list_for_each_entry(map, &priv->freeable_maps, next) {
471 if (!map->vma)
472 continue;
473 pr_debug("map %d+%d (%lx %lx)\n",
474 map->index, map->count,
475 map->vma->vm_start, map->vma->vm_end);
476 err = unmap_grant_pages(map, /* offset */ 0, map->count);
477 WARN_ON(err);
478 }
479 spin_unlock(&priv->lock);
480}
481
482static struct mmu_notifier_ops gntdev_mmu_ops = {
483 .release = mn_release,
484 .invalidate_page = mn_invl_page,
485 .invalidate_range_start = mn_invl_range_start,
486};
487
488/* ------------------------------------------------------------------ */
489
490static int gntdev_open(struct inode *inode, struct file *flip)
491{
492 struct gntdev_priv *priv;
493 int ret = 0;
494
495 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
496 if (!priv)
497 return -ENOMEM;
498
499 INIT_LIST_HEAD(&priv->maps);
500 INIT_LIST_HEAD(&priv->freeable_maps);
501 spin_lock_init(&priv->lock);
502
503 if (use_ptemod) {
504 priv->mm = get_task_mm(current);
505 if (!priv->mm) {
506 kfree(priv);
507 return -ENOMEM;
508 }
509 priv->mn.ops = &gntdev_mmu_ops;
510 ret = mmu_notifier_register(&priv->mn, priv->mm);
511 mmput(priv->mm);
512 }
513
514 if (ret) {
515 kfree(priv);
516 return ret;
517 }
518
519 flip->private_data = priv;
520 pr_debug("priv %p\n", priv);
521
522 return 0;
523}
524
525static int gntdev_release(struct inode *inode, struct file *flip)
526{
527 struct gntdev_priv *priv = flip->private_data;
528 struct grant_map *map;
529
530 pr_debug("priv %p\n", priv);
531
532 while (!list_empty(&priv->maps)) {
533 map = list_entry(priv->maps.next, struct grant_map, next);
534 list_del(&map->next);
535 gntdev_put_map(NULL /* already removed */, map);
536 }
537 WARN_ON(!list_empty(&priv->freeable_maps));
538
539 if (use_ptemod)
540 mmu_notifier_unregister(&priv->mn, priv->mm);
541 kfree(priv);
542 return 0;
543}
544
545static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
546 struct ioctl_gntdev_map_grant_ref __user *u)
547{
548 struct ioctl_gntdev_map_grant_ref op;
549 struct grant_map *map;
550 int err;
551
552 if (copy_from_user(&op, u, sizeof(op)) != 0)
553 return -EFAULT;
554 pr_debug("priv %p, add %d\n", priv, op.count);
555 if (unlikely(op.count <= 0))
556 return -EINVAL;
557
558 err = -ENOMEM;
559 map = gntdev_alloc_map(priv, op.count);
560 if (!map)
561 return err;
562
563 if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
564 pr_debug("can't map: over limit\n");
565 gntdev_put_map(NULL, map);
566 return err;
567 }
568
569 if (copy_from_user(map->grants, &u->refs,
570 sizeof(map->grants[0]) * op.count) != 0) {
571 gntdev_put_map(NULL, map);
572 return -EFAULT;
573 }
574
575 spin_lock(&priv->lock);
576 gntdev_add_map(priv, map);
577 op.index = map->index << PAGE_SHIFT;
578 spin_unlock(&priv->lock);
579
580 if (copy_to_user(u, &op, sizeof(op)) != 0)
581 return -EFAULT;
582
583 return 0;
584}
585
586static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
587 struct ioctl_gntdev_unmap_grant_ref __user *u)
588{
589 struct ioctl_gntdev_unmap_grant_ref op;
590 struct grant_map *map;
591 int err = -ENOENT;
592
593 if (copy_from_user(&op, u, sizeof(op)) != 0)
594 return -EFAULT;
595 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
596
597 spin_lock(&priv->lock);
598 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
599 if (map) {
600 list_del(&map->next);
601 if (populate_freeable_maps)
602 list_add_tail(&map->next, &priv->freeable_maps);
603 err = 0;
604 }
605 spin_unlock(&priv->lock);
606 if (map)
607 gntdev_put_map(priv, map);
608 return err;
609}
610
611static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
612 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
613{
614 struct ioctl_gntdev_get_offset_for_vaddr op;
615 struct vm_area_struct *vma;
616 struct grant_map *map;
617 int rv = -EINVAL;
618
619 if (copy_from_user(&op, u, sizeof(op)) != 0)
620 return -EFAULT;
621 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
622
623 down_read(¤t->mm->mmap_sem);
624 vma = find_vma(current->mm, op.vaddr);
625 if (!vma || vma->vm_ops != &gntdev_vmops)
626 goto out_unlock;
627
628 map = vma->vm_private_data;
629 if (!map)
630 goto out_unlock;
631
632 op.offset = map->index << PAGE_SHIFT;
633 op.count = map->count;
634 rv = 0;
635
636 out_unlock:
637 up_read(¤t->mm->mmap_sem);
638
639 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
640 return -EFAULT;
641 return rv;
642}
643
644static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
645{
646 struct ioctl_gntdev_unmap_notify op;
647 struct grant_map *map;
648 int rc;
649 int out_flags;
650 unsigned int out_event;
651
652 if (copy_from_user(&op, u, sizeof(op)))
653 return -EFAULT;
654
655 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
656 return -EINVAL;
657
658 /* We need to grab a reference to the event channel we are going to use
659 * to send the notify before releasing the reference we may already have
660 * (if someone has called this ioctl twice). This is required so that
661 * it is possible to change the clear_byte part of the notification
662 * without disturbing the event channel part, which may now be the last
663 * reference to that event channel.
664 */
665 if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
666 if (evtchn_get(op.event_channel_port))
667 return -EINVAL;
668 }
669
670 out_flags = op.action;
671 out_event = op.event_channel_port;
672
673 spin_lock(&priv->lock);
674
675 list_for_each_entry(map, &priv->maps, next) {
676 uint64_t begin = map->index << PAGE_SHIFT;
677 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
678 if (op.index >= begin && op.index < end)
679 goto found;
680 }
681 rc = -ENOENT;
682 goto unlock_out;
683
684 found:
685 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
686 (map->flags & GNTMAP_readonly)) {
687 rc = -EINVAL;
688 goto unlock_out;
689 }
690
691 out_flags = map->notify.flags;
692 out_event = map->notify.event;
693
694 map->notify.flags = op.action;
695 map->notify.addr = op.index - (map->index << PAGE_SHIFT);
696 map->notify.event = op.event_channel_port;
697
698 rc = 0;
699
700 unlock_out:
701 spin_unlock(&priv->lock);
702
703 /* Drop the reference to the event channel we did not save in the map */
704 if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
705 evtchn_put(out_event);
706
707 return rc;
708}
709
710static long gntdev_ioctl(struct file *flip,
711 unsigned int cmd, unsigned long arg)
712{
713 struct gntdev_priv *priv = flip->private_data;
714 void __user *ptr = (void __user *)arg;
715
716 switch (cmd) {
717 case IOCTL_GNTDEV_MAP_GRANT_REF:
718 return gntdev_ioctl_map_grant_ref(priv, ptr);
719
720 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
721 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
722
723 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
724 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
725
726 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
727 return gntdev_ioctl_notify(priv, ptr);
728
729 default:
730 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
731 return -ENOIOCTLCMD;
732 }
733
734 return 0;
735}
736
737static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
738{
739 struct gntdev_priv *priv = flip->private_data;
740 int index = vma->vm_pgoff;
741 int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
742 struct grant_map *map;
743 int i, err = -EINVAL;
744
745 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
746 return -EINVAL;
747
748 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
749 index, count, vma->vm_start, vma->vm_pgoff);
750
751 spin_lock(&priv->lock);
752 map = gntdev_find_map_index(priv, index, count);
753 if (!map)
754 goto unlock_out;
755 if (use_ptemod && map->vma)
756 goto unlock_out;
757 if (use_ptemod && priv->mm != vma->vm_mm) {
758 pr_warn("Huh? Other mm?\n");
759 goto unlock_out;
760 }
761
762 atomic_inc(&map->users);
763
764 vma->vm_ops = &gntdev_vmops;
765
766 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
767
768 if (use_ptemod)
769 vma->vm_flags |= VM_DONTCOPY;
770
771 vma->vm_private_data = map;
772
773 if (use_ptemod)
774 map->vma = vma;
775
776 if (map->flags) {
777 if ((vma->vm_flags & VM_WRITE) &&
778 (map->flags & GNTMAP_readonly))
779 goto out_unlock_put;
780 } else {
781 map->flags = GNTMAP_host_map;
782 if (!(vma->vm_flags & VM_WRITE))
783 map->flags |= GNTMAP_readonly;
784 }
785
786 spin_unlock(&priv->lock);
787
788 if (use_ptemod) {
789 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
790 vma->vm_end - vma->vm_start,
791 find_grant_ptes, map);
792 if (err) {
793 pr_warn("find_grant_ptes() failure.\n");
794 goto out_put_map;
795 }
796 }
797
798 err = map_grant_pages(map);
799 if (err)
800 goto out_put_map;
801
802 if (!use_ptemod) {
803 for (i = 0; i < count; i++) {
804 err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
805 map->pages[i]);
806 if (err)
807 goto out_put_map;
808 }
809 }
810
811 return 0;
812
813unlock_out:
814 spin_unlock(&priv->lock);
815 return err;
816
817out_unlock_put:
818 spin_unlock(&priv->lock);
819out_put_map:
820 if (use_ptemod)
821 map->vma = NULL;
822 gntdev_put_map(priv, map);
823 return err;
824}
825
826static const struct file_operations gntdev_fops = {
827 .owner = THIS_MODULE,
828 .open = gntdev_open,
829 .release = gntdev_release,
830 .mmap = gntdev_mmap,
831 .unlocked_ioctl = gntdev_ioctl
832};
833
834static struct miscdevice gntdev_miscdev = {
835 .minor = MISC_DYNAMIC_MINOR,
836 .name = "xen/gntdev",
837 .fops = &gntdev_fops,
838};
839
840/* ------------------------------------------------------------------ */
841
842static int __init gntdev_init(void)
843{
844 int err;
845
846 if (!xen_domain())
847 return -ENODEV;
848
849 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
850
851 err = misc_register(&gntdev_miscdev);
852 if (err != 0) {
853 pr_err("Could not register gntdev device\n");
854 return err;
855 }
856 return 0;
857}
858
859static void __exit gntdev_exit(void)
860{
861 misc_deregister(&gntdev_miscdev);
862}
863
864module_init(gntdev_init);
865module_exit(gntdev_exit);
866
867/* ------------------------------------------------------------------ */