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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
63 spinlock_t lock;
64 struct mm_struct *mm;
65 struct mmu_notifier mn;
66};
67
68struct unmap_notify {
69 int flags;
70
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 gnttab_map_grant_ref *kmap_ops;
87 struct page **pages;
88};
89
90static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
91
92
93
94static void gntdev_print_maps(struct gntdev_priv *priv,
95 char *text, int text_index)
96{
97#ifdef DEBUG
98 struct grant_map *map;
99
100 pr_debug("%s: maps list (priv %p)\n", __func__, priv);
101 list_for_each_entry(map, &priv->maps, next)
102 pr_debug(" index %2d, count %2d %s\n",
103 map->index, map->count,
104 map->index == text_index && text ? text : "");
105#endif
106}
107
108static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
109{
110 struct grant_map *add;
111 int i;
112
113 add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
114 if (NULL == add)
115 return NULL;
116
117 add->grants = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
118 add->map_ops = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
119 add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
120 add->kmap_ops = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
121 add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
122 if (NULL == add->grants ||
123 NULL == add->map_ops ||
124 NULL == add->unmap_ops ||
125 NULL == add->kmap_ops ||
126 NULL == add->pages)
127 goto err;
128
129 if (alloc_xenballooned_pages(count, add->pages, false ))
130 goto err;
131
132 for (i = 0; i < count; i++) {
133 add->map_ops[i].handle = -1;
134 add->unmap_ops[i].handle = -1;
135 add->kmap_ops[i].handle = -1;
136 }
137
138 add->index = 0;
139 add->count = count;
140 atomic_set(&add->users, 1);
141
142 return add;
143
144err:
145 kfree(add->pages);
146 kfree(add->grants);
147 kfree(add->map_ops);
148 kfree(add->unmap_ops);
149 kfree(add->kmap_ops);
150 kfree(add);
151 return NULL;
152}
153
154static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
155{
156 struct grant_map *map;
157
158 list_for_each_entry(map, &priv->maps, next) {
159 if (add->index + add->count < map->index) {
160 list_add_tail(&add->next, &map->next);
161 goto done;
162 }
163 add->index = map->index + map->count;
164 }
165 list_add_tail(&add->next, &priv->maps);
166
167done:
168 gntdev_print_maps(priv, "[new]", add->index);
169}
170
171static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
172 int index, int count)
173{
174 struct grant_map *map;
175
176 list_for_each_entry(map, &priv->maps, next) {
177 if (map->index != index)
178 continue;
179 if (count && map->count != count)
180 continue;
181 return map;
182 }
183 return NULL;
184}
185
186static void gntdev_put_map(struct grant_map *map)
187{
188 if (!map)
189 return;
190
191 if (!atomic_dec_and_test(&map->users))
192 return;
193
194 atomic_sub(map->count, &pages_mapped);
195
196 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT)
197 notify_remote_via_evtchn(map->notify.event);
198
199 if (map->pages) {
200 if (!use_ptemod)
201 unmap_grant_pages(map, 0, map->count);
202
203 free_xenballooned_pages(map->count, map->pages);
204 }
205 kfree(map->pages);
206 kfree(map->grants);
207 kfree(map->map_ops);
208 kfree(map->unmap_ops);
209 kfree(map);
210}
211
212
213
214static int find_grant_ptes(pte_t *pte, pgtable_t token,
215 unsigned long addr, void *data)
216{
217 struct grant_map *map = data;
218 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
219 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
220 u64 pte_maddr;
221
222 BUG_ON(pgnr >= map->count);
223 pte_maddr = arbitrary_virt_to_machine(pte).maddr;
224
225 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
226 map->grants[pgnr].ref,
227 map->grants[pgnr].domid);
228 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
229 -1 );
230 return 0;
231}
232
233static int map_grant_pages(struct grant_map *map)
234{
235 int i, err = 0;
236
237 if (!use_ptemod) {
238
239 if (map->map_ops[0].handle != -1)
240 return 0;
241 for (i = 0; i < map->count; i++) {
242 unsigned long addr = (unsigned long)
243 pfn_to_kaddr(page_to_pfn(map->pages[i]));
244 gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
245 map->grants[i].ref,
246 map->grants[i].domid);
247 gnttab_set_unmap_op(&map->unmap_ops[i], addr,
248 map->flags, -1 );
249 }
250 } else {
251
252
253
254
255
256
257 for (i = 0; i < map->count; i++) {
258 unsigned level;
259 unsigned long address = (unsigned long)
260 pfn_to_kaddr(page_to_pfn(map->pages[i]));
261 pte_t *ptep;
262 u64 pte_maddr = 0;
263 BUG_ON(PageHighMem(map->pages[i]));
264
265 ptep = lookup_address(address, &level);
266 pte_maddr = arbitrary_virt_to_machine(ptep).maddr;
267 gnttab_set_map_op(&map->kmap_ops[i], pte_maddr,
268 map->flags |
269 GNTMAP_host_map |
270 GNTMAP_contains_pte,
271 map->grants[i].ref,
272 map->grants[i].domid);
273 }
274 }
275
276 pr_debug("map %d+%d\n", map->index, map->count);
277 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
278 map->pages, map->count);
279 if (err)
280 return err;
281
282 for (i = 0; i < map->count; i++) {
283 if (map->map_ops[i].status)
284 err = -EINVAL;
285 else {
286 BUG_ON(map->map_ops[i].handle == -1);
287 map->unmap_ops[i].handle = map->map_ops[i].handle;
288 pr_debug("map handle=%d\n", map->map_ops[i].handle);
289 }
290 }
291 return err;
292}
293
294static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
295{
296 int i, err = 0;
297
298 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
299 int pgno = (map->notify.addr >> PAGE_SHIFT);
300 if (pgno >= offset && pgno < offset + pages && use_ptemod) {
301 void __user *tmp = (void __user *)
302 map->vma->vm_start + map->notify.addr;
303 err = copy_to_user(tmp, &err, 1);
304 if (err)
305 return -EFAULT;
306 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
307 } else if (pgno >= offset && pgno < offset + pages) {
308 uint8_t *tmp = kmap(map->pages[pgno]);
309 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
310 kunmap(map->pages[pgno]);
311 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
312 }
313 }
314
315 err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
316 if (err)
317 return err;
318
319 for (i = 0; i < pages; i++) {
320 if (map->unmap_ops[offset+i].status)
321 err = -EINVAL;
322 pr_debug("unmap handle=%d st=%d\n",
323 map->unmap_ops[offset+i].handle,
324 map->unmap_ops[offset+i].status);
325 map->unmap_ops[offset+i].handle = -1;
326 }
327 return err;
328}
329
330static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
331{
332 int range, err = 0;
333
334 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
335
336
337
338
339 while (pages && !err) {
340 while (pages && map->unmap_ops[offset].handle == -1) {
341 offset++;
342 pages--;
343 }
344 range = 0;
345 while (range < pages) {
346 if (map->unmap_ops[offset+range].handle == -1) {
347 range--;
348 break;
349 }
350 range++;
351 }
352 err = __unmap_grant_pages(map, offset, range);
353 offset += range;
354 pages -= range;
355 }
356
357 return err;
358}
359
360
361
362static void gntdev_vma_open(struct vm_area_struct *vma)
363{
364 struct grant_map *map = vma->vm_private_data;
365
366 pr_debug("gntdev_vma_open %p\n", vma);
367 atomic_inc(&map->users);
368}
369
370static void gntdev_vma_close(struct vm_area_struct *vma)
371{
372 struct grant_map *map = vma->vm_private_data;
373
374 pr_debug("gntdev_vma_close %p\n", vma);
375 map->vma = NULL;
376 vma->vm_private_data = NULL;
377 gntdev_put_map(map);
378}
379
380static struct vm_operations_struct gntdev_vmops = {
381 .open = gntdev_vma_open,
382 .close = gntdev_vma_close,
383};
384
385
386
387static void mn_invl_range_start(struct mmu_notifier *mn,
388 struct mm_struct *mm,
389 unsigned long start, unsigned long end)
390{
391 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
392 struct grant_map *map;
393 unsigned long mstart, mend;
394 int err;
395
396 spin_lock(&priv->lock);
397 list_for_each_entry(map, &priv->maps, next) {
398 if (!map->vma)
399 continue;
400 if (map->vma->vm_start >= end)
401 continue;
402 if (map->vma->vm_end <= start)
403 continue;
404 mstart = max(start, map->vma->vm_start);
405 mend = min(end, map->vma->vm_end);
406 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
407 map->index, map->count,
408 map->vma->vm_start, map->vma->vm_end,
409 start, end, mstart, mend);
410 err = unmap_grant_pages(map,
411 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
412 (mend - mstart) >> PAGE_SHIFT);
413 WARN_ON(err);
414 }
415 spin_unlock(&priv->lock);
416}
417
418static void mn_invl_page(struct mmu_notifier *mn,
419 struct mm_struct *mm,
420 unsigned long address)
421{
422 mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
423}
424
425static void mn_release(struct mmu_notifier *mn,
426 struct mm_struct *mm)
427{
428 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
429 struct grant_map *map;
430 int err;
431
432 spin_lock(&priv->lock);
433 list_for_each_entry(map, &priv->maps, next) {
434 if (!map->vma)
435 continue;
436 pr_debug("map %d+%d (%lx %lx)\n",
437 map->index, map->count,
438 map->vma->vm_start, map->vma->vm_end);
439 err = unmap_grant_pages(map, 0, map->count);
440 WARN_ON(err);
441 }
442 spin_unlock(&priv->lock);
443}
444
445struct mmu_notifier_ops gntdev_mmu_ops = {
446 .release = mn_release,
447 .invalidate_page = mn_invl_page,
448 .invalidate_range_start = mn_invl_range_start,
449};
450
451
452
453static int gntdev_open(struct inode *inode, struct file *flip)
454{
455 struct gntdev_priv *priv;
456 int ret = 0;
457
458 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
459 if (!priv)
460 return -ENOMEM;
461
462 INIT_LIST_HEAD(&priv->maps);
463 spin_lock_init(&priv->lock);
464
465 if (use_ptemod) {
466 priv->mm = get_task_mm(current);
467 if (!priv->mm) {
468 kfree(priv);
469 return -ENOMEM;
470 }
471 priv->mn.ops = &gntdev_mmu_ops;
472 ret = mmu_notifier_register(&priv->mn, priv->mm);
473 mmput(priv->mm);
474 }
475
476 if (ret) {
477 kfree(priv);
478 return ret;
479 }
480
481 flip->private_data = priv;
482 pr_debug("priv %p\n", priv);
483
484 return 0;
485}
486
487static int gntdev_release(struct inode *inode, struct file *flip)
488{
489 struct gntdev_priv *priv = flip->private_data;
490 struct grant_map *map;
491
492 pr_debug("priv %p\n", priv);
493
494 while (!list_empty(&priv->maps)) {
495 map = list_entry(priv->maps.next, struct grant_map, next);
496 list_del(&map->next);
497 gntdev_put_map(map);
498 }
499
500 if (use_ptemod)
501 mmu_notifier_unregister(&priv->mn, priv->mm);
502 kfree(priv);
503 return 0;
504}
505
506static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
507 struct ioctl_gntdev_map_grant_ref __user *u)
508{
509 struct ioctl_gntdev_map_grant_ref op;
510 struct grant_map *map;
511 int err;
512
513 if (copy_from_user(&op, u, sizeof(op)) != 0)
514 return -EFAULT;
515 pr_debug("priv %p, add %d\n", priv, op.count);
516 if (unlikely(op.count <= 0))
517 return -EINVAL;
518
519 err = -ENOMEM;
520 map = gntdev_alloc_map(priv, op.count);
521 if (!map)
522 return err;
523
524 if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
525 pr_debug("can't map: over limit\n");
526 gntdev_put_map(map);
527 return err;
528 }
529
530 if (copy_from_user(map->grants, &u->refs,
531 sizeof(map->grants[0]) * op.count) != 0) {
532 gntdev_put_map(map);
533 return err;
534 }
535
536 spin_lock(&priv->lock);
537 gntdev_add_map(priv, map);
538 op.index = map->index << PAGE_SHIFT;
539 spin_unlock(&priv->lock);
540
541 if (copy_to_user(u, &op, sizeof(op)) != 0)
542 return -EFAULT;
543
544 return 0;
545}
546
547static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
548 struct ioctl_gntdev_unmap_grant_ref __user *u)
549{
550 struct ioctl_gntdev_unmap_grant_ref op;
551 struct grant_map *map;
552 int err = -ENOENT;
553
554 if (copy_from_user(&op, u, sizeof(op)) != 0)
555 return -EFAULT;
556 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
557
558 spin_lock(&priv->lock);
559 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
560 if (map) {
561 list_del(&map->next);
562 err = 0;
563 }
564 spin_unlock(&priv->lock);
565 if (map)
566 gntdev_put_map(map);
567 return err;
568}
569
570static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
571 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
572{
573 struct ioctl_gntdev_get_offset_for_vaddr op;
574 struct vm_area_struct *vma;
575 struct grant_map *map;
576
577 if (copy_from_user(&op, u, sizeof(op)) != 0)
578 return -EFAULT;
579 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
580
581 vma = find_vma(current->mm, op.vaddr);
582 if (!vma || vma->vm_ops != &gntdev_vmops)
583 return -EINVAL;
584
585 map = vma->vm_private_data;
586 if (!map)
587 return -EINVAL;
588
589 op.offset = map->index << PAGE_SHIFT;
590 op.count = map->count;
591
592 if (copy_to_user(u, &op, sizeof(op)) != 0)
593 return -EFAULT;
594 return 0;
595}
596
597static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
598{
599 struct ioctl_gntdev_unmap_notify op;
600 struct grant_map *map;
601 int rc;
602
603 if (copy_from_user(&op, u, sizeof(op)))
604 return -EFAULT;
605
606 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
607 return -EINVAL;
608
609 spin_lock(&priv->lock);
610
611 list_for_each_entry(map, &priv->maps, next) {
612 uint64_t begin = map->index << PAGE_SHIFT;
613 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
614 if (op.index >= begin && op.index < end)
615 goto found;
616 }
617 rc = -ENOENT;
618 goto unlock_out;
619
620 found:
621 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
622 (map->flags & GNTMAP_readonly)) {
623 rc = -EINVAL;
624 goto unlock_out;
625 }
626
627 map->notify.flags = op.action;
628 map->notify.addr = op.index - (map->index << PAGE_SHIFT);
629 map->notify.event = op.event_channel_port;
630 rc = 0;
631 unlock_out:
632 spin_unlock(&priv->lock);
633 return rc;
634}
635
636static long gntdev_ioctl(struct file *flip,
637 unsigned int cmd, unsigned long arg)
638{
639 struct gntdev_priv *priv = flip->private_data;
640 void __user *ptr = (void __user *)arg;
641
642 switch (cmd) {
643 case IOCTL_GNTDEV_MAP_GRANT_REF:
644 return gntdev_ioctl_map_grant_ref(priv, ptr);
645
646 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
647 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
648
649 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
650 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
651
652 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
653 return gntdev_ioctl_notify(priv, ptr);
654
655 default:
656 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
657 return -ENOIOCTLCMD;
658 }
659
660 return 0;
661}
662
663static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
664{
665 struct gntdev_priv *priv = flip->private_data;
666 int index = vma->vm_pgoff;
667 int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
668 struct grant_map *map;
669 int i, err = -EINVAL;
670
671 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
672 return -EINVAL;
673
674 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
675 index, count, vma->vm_start, vma->vm_pgoff);
676
677 spin_lock(&priv->lock);
678 map = gntdev_find_map_index(priv, index, count);
679 if (!map)
680 goto unlock_out;
681 if (use_ptemod && map->vma)
682 goto unlock_out;
683 if (use_ptemod && priv->mm != vma->vm_mm) {
684 printk(KERN_WARNING "Huh? Other mm?\n");
685 goto unlock_out;
686 }
687
688 atomic_inc(&map->users);
689
690 vma->vm_ops = &gntdev_vmops;
691
692 vma->vm_flags |= VM_RESERVED|VM_DONTEXPAND;
693
694 if (use_ptemod)
695 vma->vm_flags |= VM_DONTCOPY|VM_PFNMAP;
696
697 vma->vm_private_data = map;
698
699 if (use_ptemod)
700 map->vma = vma;
701
702 if (map->flags) {
703 if ((vma->vm_flags & VM_WRITE) &&
704 (map->flags & GNTMAP_readonly))
705 goto out_unlock_put;
706 } else {
707 map->flags = GNTMAP_host_map;
708 if (!(vma->vm_flags & VM_WRITE))
709 map->flags |= GNTMAP_readonly;
710 }
711
712 spin_unlock(&priv->lock);
713
714 if (use_ptemod) {
715 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
716 vma->vm_end - vma->vm_start,
717 find_grant_ptes, map);
718 if (err) {
719 printk(KERN_WARNING "find_grant_ptes() failure.\n");
720 goto out_put_map;
721 }
722 }
723
724 err = map_grant_pages(map);
725 if (err)
726 goto out_put_map;
727
728 if (!use_ptemod) {
729 for (i = 0; i < count; i++) {
730 err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
731 map->pages[i]);
732 if (err)
733 goto out_put_map;
734 }
735 }
736
737 return 0;
738
739unlock_out:
740 spin_unlock(&priv->lock);
741 return err;
742
743out_unlock_put:
744 spin_unlock(&priv->lock);
745out_put_map:
746 if (use_ptemod)
747 map->vma = NULL;
748 gntdev_put_map(map);
749 return err;
750}
751
752static const struct file_operations gntdev_fops = {
753 .owner = THIS_MODULE,
754 .open = gntdev_open,
755 .release = gntdev_release,
756 .mmap = gntdev_mmap,
757 .unlocked_ioctl = gntdev_ioctl
758};
759
760static struct miscdevice gntdev_miscdev = {
761 .minor = MISC_DYNAMIC_MINOR,
762 .name = "xen/gntdev",
763 .fops = &gntdev_fops,
764};
765
766
767
768static int __init gntdev_init(void)
769{
770 int err;
771
772 if (!xen_domain())
773 return -ENODEV;
774
775 use_ptemod = xen_pv_domain();
776
777 err = misc_register(&gntdev_miscdev);
778 if (err != 0) {
779 printk(KERN_ERR "Could not register gntdev device\n");
780 return err;
781 }
782 return 0;
783}
784
785static void __exit gntdev_exit(void)
786{
787 misc_deregister(&gntdev_miscdev);
788}
789
790module_init(gntdev_init);
791module_exit(gntdev_exit);
792
793
794
