aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/xen
diff options
context:
space:
mode:
authorGerd Hoffmann <kraxel@redhat.com>2010-12-14 13:40:46 -0500
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-01-11 14:30:52 -0500
commitab31523c2fcac557226bac72cbdf5fafe01f9a26 (patch)
treed846311151a68cb0c3bf55b2c77f34a33e0b02fd /drivers/xen
parentf07745325cbd93afc5d8bcf7539a063d33134075 (diff)
xen/gntdev: allow usermode to map granted pages
The gntdev driver allows usermode to map granted pages from other domains. This is typically used to implement a Xen backend driver in user mode. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Signed-off-by: Stefano Stabellini <Stefano.Stabellini@eu.citrix.com> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers/xen')
-rw-r--r--drivers/xen/Kconfig7
-rw-r--r--drivers/xen/Makefile2
-rw-r--r--drivers/xen/gntdev.c635
3 files changed, 644 insertions, 0 deletions
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index 6e6180ccd726..bd3095f0dff2 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -62,6 +62,13 @@ config XEN_SYS_HYPERVISOR
62 virtual environment, /sys/hypervisor will still be present, 62 virtual environment, /sys/hypervisor will still be present,
63 but will have no xen contents. 63 but will have no xen contents.
64 64
65config XEN_GNTDEV
66 tristate "userspace grant access device driver"
67 depends on XEN
68 select MMU_NOTIFIER
69 help
70 Allows userspace processes to use grants.
71
65config XEN_PLATFORM_PCI 72config XEN_PLATFORM_PCI
66 tristate "xen platform pci device driver" 73 tristate "xen platform pci device driver"
67 depends on XEN_PVHVM 74 depends on XEN_PVHVM
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index 533a199e7a3f..674fdb5fee49 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o
9obj-$(CONFIG_XEN_XENCOMM) += xencomm.o 9obj-$(CONFIG_XEN_XENCOMM) += xencomm.o
10obj-$(CONFIG_XEN_BALLOON) += balloon.o 10obj-$(CONFIG_XEN_BALLOON) += balloon.o
11obj-$(CONFIG_XEN_DEV_EVTCHN) += xen-evtchn.o 11obj-$(CONFIG_XEN_DEV_EVTCHN) += xen-evtchn.o
12obj-$(CONFIG_XEN_GNTDEV) += xen-gntdev.o
12obj-$(CONFIG_XENFS) += xenfs/ 13obj-$(CONFIG_XENFS) += xenfs/
13obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o 14obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o
14obj-$(CONFIG_XEN_PLATFORM_PCI) += platform-pci.o 15obj-$(CONFIG_XEN_PLATFORM_PCI) += platform-pci.o
@@ -16,4 +17,5 @@ obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o
16obj-$(CONFIG_XEN_DOM0) += pci.o 17obj-$(CONFIG_XEN_DOM0) += pci.o
17 18
18xen-evtchn-y := evtchn.o 19xen-evtchn-y := evtchn.o
20xen-gntdev-y := gntdev.o
19 21
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
new file mode 100644
index 000000000000..cfe063372aa4
--- /dev/null
+++ b/drivers/xen/gntdev.c
@@ -0,0 +1,635 @@
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
36#include <xen/xen.h>
37#include <xen/grant_table.h>
38#include <xen/gntdev.h>
39#include <asm/xen/hypervisor.h>
40#include <asm/xen/hypercall.h>
41#include <asm/xen/page.h>
42
43MODULE_LICENSE("GPL");
44MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
45 "Gerd Hoffmann <kraxel@redhat.com>");
46MODULE_DESCRIPTION("User-space granted page access driver");
47
48static int limit = 1024;
49module_param(limit, int, 0644);
50MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped at "
51 "once by a gntdev instance");
52
53struct gntdev_priv {
54 struct list_head maps;
55 uint32_t used;
56 uint32_t limit;
57 /* lock protects maps from concurrent changes */
58 spinlock_t lock;
59 struct mm_struct *mm;
60 struct mmu_notifier mn;
61};
62
63struct grant_map {
64 struct list_head next;
65 struct gntdev_priv *priv;
66 struct vm_area_struct *vma;
67 int index;
68 int count;
69 int flags;
70 int is_mapped;
71 struct ioctl_gntdev_grant_ref *grants;
72 struct gnttab_map_grant_ref *map_ops;
73 struct gnttab_unmap_grant_ref *unmap_ops;
74};
75
76/* ------------------------------------------------------------------ */
77
78static void gntdev_print_maps(struct gntdev_priv *priv,
79 char *text, int text_index)
80{
81#ifdef DEBUG
82 struct grant_map *map;
83
84 pr_debug("maps list (priv %p, usage %d/%d)\n",
85 priv, priv->used, priv->limit);
86
87 list_for_each_entry(map, &priv->maps, next)
88 pr_debug(" index %2d, count %2d %s\n",
89 map->index, map->count,
90 map->index == text_index && text ? text : "");
91#endif
92}
93
94static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
95{
96 struct grant_map *add;
97
98 add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
99 if (NULL == add)
100 return NULL;
101
102 add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL);
103 add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL);
104 add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL);
105 if (NULL == add->grants ||
106 NULL == add->map_ops ||
107 NULL == add->unmap_ops)
108 goto err;
109
110 add->index = 0;
111 add->count = count;
112 add->priv = priv;
113
114 if (add->count + priv->used > priv->limit)
115 goto err;
116
117 return add;
118
119err:
120 kfree(add->grants);
121 kfree(add->map_ops);
122 kfree(add->unmap_ops);
123 kfree(add);
124 return NULL;
125}
126
127static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
128{
129 struct grant_map *map;
130
131 list_for_each_entry(map, &priv->maps, next) {
132 if (add->index + add->count < map->index) {
133 list_add_tail(&add->next, &map->next);
134 goto done;
135 }
136 add->index = map->index + map->count;
137 }
138 list_add_tail(&add->next, &priv->maps);
139
140done:
141 priv->used += add->count;
142 gntdev_print_maps(priv, "[new]", add->index);
143}
144
145static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
146 int index, int count)
147{
148 struct grant_map *map;
149
150 list_for_each_entry(map, &priv->maps, next) {
151 if (map->index != index)
152 continue;
153 if (map->count != count)
154 continue;
155 return map;
156 }
157 return NULL;
158}
159
160static struct grant_map *gntdev_find_map_vaddr(struct gntdev_priv *priv,
161 unsigned long vaddr)
162{
163 struct grant_map *map;
164
165 list_for_each_entry(map, &priv->maps, next) {
166 if (!map->vma)
167 continue;
168 if (vaddr < map->vma->vm_start)
169 continue;
170 if (vaddr >= map->vma->vm_end)
171 continue;
172 return map;
173 }
174 return NULL;
175}
176
177static int gntdev_del_map(struct grant_map *map)
178{
179 int i;
180
181 if (map->vma)
182 return -EBUSY;
183 for (i = 0; i < map->count; i++)
184 if (map->unmap_ops[i].handle)
185 return -EBUSY;
186
187 map->priv->used -= map->count;
188 list_del(&map->next);
189 return 0;
190}
191
192static void gntdev_free_map(struct grant_map *map)
193{
194 if (!map)
195 return;
196 kfree(map->grants);
197 kfree(map->map_ops);
198 kfree(map->unmap_ops);
199 kfree(map);
200}
201
202/* ------------------------------------------------------------------ */
203
204static int find_grant_ptes(pte_t *pte, pgtable_t token,
205 unsigned long addr, void *data)
206{
207 struct grant_map *map = data;
208 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
209 u64 pte_maddr;
210
211 BUG_ON(pgnr >= map->count);
212 pte_maddr = (u64)pfn_to_mfn(page_to_pfn(token)) << PAGE_SHIFT;
213 pte_maddr += (unsigned long)pte & ~PAGE_MASK;
214 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, map->flags,
215 map->grants[pgnr].ref,
216 map->grants[pgnr].domid);
217 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, map->flags,
218 0 /* handle */);
219 return 0;
220}
221
222static int map_grant_pages(struct grant_map *map)
223{
224 int i, err = 0;
225
226 pr_debug("map %d+%d\n", map->index, map->count);
227 err = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
228 map->map_ops, map->count);
229 if (err)
230 return err;
231
232 for (i = 0; i < map->count; i++) {
233 if (map->map_ops[i].status)
234 err = -EINVAL;
235 map->unmap_ops[i].handle = map->map_ops[i].handle;
236 }
237 return err;
238}
239
240static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
241{
242 int i, err = 0;
243
244 pr_debug("map %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
245 err = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
246 map->unmap_ops + offset, pages);
247 if (err)
248 return err;
249
250 for (i = 0; i < pages; i++) {
251 if (map->unmap_ops[offset+i].status)
252 err = -EINVAL;
253 map->unmap_ops[offset+i].handle = 0;
254 }
255 return err;
256}
257
258/* ------------------------------------------------------------------ */
259
260static void gntdev_vma_close(struct vm_area_struct *vma)
261{
262 struct grant_map *map = vma->vm_private_data;
263
264 pr_debug("close %p\n", vma);
265 map->is_mapped = 0;
266 map->vma = NULL;
267 vma->vm_private_data = NULL;
268}
269
270static int gntdev_vma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
271{
272 pr_debug("vaddr %p, pgoff %ld (shouldn't happen)\n",
273 vmf->virtual_address, vmf->pgoff);
274 vmf->flags = VM_FAULT_ERROR;
275 return 0;
276}
277
278static struct vm_operations_struct gntdev_vmops = {
279 .close = gntdev_vma_close,
280 .fault = gntdev_vma_fault,
281};
282
283/* ------------------------------------------------------------------ */
284
285static void mn_invl_range_start(struct mmu_notifier *mn,
286 struct mm_struct *mm,
287 unsigned long start, unsigned long end)
288{
289 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
290 struct grant_map *map;
291 unsigned long mstart, mend;
292 int err;
293
294 spin_lock(&priv->lock);
295 list_for_each_entry(map, &priv->maps, next) {
296 if (!map->vma)
297 continue;
298 if (!map->is_mapped)
299 continue;
300 if (map->vma->vm_start >= end)
301 continue;
302 if (map->vma->vm_end <= start)
303 continue;
304 mstart = max(start, map->vma->vm_start);
305 mend = min(end, map->vma->vm_end);
306 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
307 map->index, map->count,
308 map->vma->vm_start, map->vma->vm_end,
309 start, end, mstart, mend);
310 err = unmap_grant_pages(map,
311 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
312 (mend - mstart) >> PAGE_SHIFT);
313 WARN_ON(err);
314 }
315 spin_unlock(&priv->lock);
316}
317
318static void mn_invl_page(struct mmu_notifier *mn,
319 struct mm_struct *mm,
320 unsigned long address)
321{
322 mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
323}
324
325static void mn_release(struct mmu_notifier *mn,
326 struct mm_struct *mm)
327{
328 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
329 struct grant_map *map;
330 int err;
331
332 spin_lock(&priv->lock);
333 list_for_each_entry(map, &priv->maps, next) {
334 if (!map->vma)
335 continue;
336 pr_debug("map %d+%d (%lx %lx)\n",
337 map->index, map->count,
338 map->vma->vm_start, map->vma->vm_end);
339 err = unmap_grant_pages(map, /* offset */ 0, map->count);
340 WARN_ON(err);
341 }
342 spin_unlock(&priv->lock);
343}
344
345struct mmu_notifier_ops gntdev_mmu_ops = {
346 .release = mn_release,
347 .invalidate_page = mn_invl_page,
348 .invalidate_range_start = mn_invl_range_start,
349};
350
351/* ------------------------------------------------------------------ */
352
353static int gntdev_open(struct inode *inode, struct file *flip)
354{
355 struct gntdev_priv *priv;
356 int ret = 0;
357
358 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
359 if (!priv)
360 return -ENOMEM;
361
362 INIT_LIST_HEAD(&priv->maps);
363 spin_lock_init(&priv->lock);
364 priv->limit = limit;
365
366 priv->mm = get_task_mm(current);
367 if (!priv->mm) {
368 kfree(priv);
369 return -ENOMEM;
370 }
371 priv->mn.ops = &gntdev_mmu_ops;
372 ret = mmu_notifier_register(&priv->mn, priv->mm);
373 mmput(priv->mm);
374
375 if (ret) {
376 kfree(priv);
377 return ret;
378 }
379
380 flip->private_data = priv;
381 pr_debug("priv %p\n", priv);
382
383 return 0;
384}
385
386static int gntdev_release(struct inode *inode, struct file *flip)
387{
388 struct gntdev_priv *priv = flip->private_data;
389 struct grant_map *map;
390 int err;
391
392 pr_debug("priv %p\n", priv);
393
394 spin_lock(&priv->lock);
395 while (!list_empty(&priv->maps)) {
396 map = list_entry(priv->maps.next, struct grant_map, next);
397 err = gntdev_del_map(map);
398 if (WARN_ON(err))
399 gntdev_free_map(map);
400
401 }
402 spin_unlock(&priv->lock);
403
404 mmu_notifier_unregister(&priv->mn, priv->mm);
405 kfree(priv);
406 return 0;
407}
408
409static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
410 struct ioctl_gntdev_map_grant_ref __user *u)
411{
412 struct ioctl_gntdev_map_grant_ref op;
413 struct grant_map *map;
414 int err;
415
416 if (copy_from_user(&op, u, sizeof(op)) != 0)
417 return -EFAULT;
418 pr_debug("priv %p, add %d\n", priv, op.count);
419 if (unlikely(op.count <= 0))
420 return -EINVAL;
421 if (unlikely(op.count > priv->limit))
422 return -EINVAL;
423
424 err = -ENOMEM;
425 map = gntdev_alloc_map(priv, op.count);
426 if (!map)
427 return err;
428 if (copy_from_user(map->grants, &u->refs,
429 sizeof(map->grants[0]) * op.count) != 0) {
430 gntdev_free_map(map);
431 return err;
432 }
433
434 spin_lock(&priv->lock);
435 gntdev_add_map(priv, map);
436 op.index = map->index << PAGE_SHIFT;
437 spin_unlock(&priv->lock);
438
439 if (copy_to_user(u, &op, sizeof(op)) != 0) {
440 spin_lock(&priv->lock);
441 gntdev_del_map(map);
442 spin_unlock(&priv->lock);
443 gntdev_free_map(map);
444 return err;
445 }
446 return 0;
447}
448
449static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
450 struct ioctl_gntdev_unmap_grant_ref __user *u)
451{
452 struct ioctl_gntdev_unmap_grant_ref op;
453 struct grant_map *map;
454 int err = -ENOENT;
455
456 if (copy_from_user(&op, u, sizeof(op)) != 0)
457 return -EFAULT;
458 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
459
460 spin_lock(&priv->lock);
461 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
462 if (map)
463 err = gntdev_del_map(map);
464 spin_unlock(&priv->lock);
465 if (!err)
466 gntdev_free_map(map);
467 return err;
468}
469
470static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
471 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
472{
473 struct ioctl_gntdev_get_offset_for_vaddr op;
474 struct grant_map *map;
475
476 if (copy_from_user(&op, u, sizeof(op)) != 0)
477 return -EFAULT;
478 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
479
480 spin_lock(&priv->lock);
481 map = gntdev_find_map_vaddr(priv, op.vaddr);
482 if (map == NULL ||
483 map->vma->vm_start != op.vaddr) {
484 spin_unlock(&priv->lock);
485 return -EINVAL;
486 }
487 op.offset = map->index << PAGE_SHIFT;
488 op.count = map->count;
489 spin_unlock(&priv->lock);
490
491 if (copy_to_user(u, &op, sizeof(op)) != 0)
492 return -EFAULT;
493 return 0;
494}
495
496static long gntdev_ioctl_set_max_grants(struct gntdev_priv *priv,
497 struct ioctl_gntdev_set_max_grants __user *u)
498{
499 struct ioctl_gntdev_set_max_grants op;
500
501 if (copy_from_user(&op, u, sizeof(op)) != 0)
502 return -EFAULT;
503 pr_debug("priv %p, limit %d\n", priv, op.count);
504 if (op.count > limit)
505 return -E2BIG;
506
507 spin_lock(&priv->lock);
508 priv->limit = op.count;
509 spin_unlock(&priv->lock);
510 return 0;
511}
512
513static long gntdev_ioctl(struct file *flip,
514 unsigned int cmd, unsigned long arg)
515{
516 struct gntdev_priv *priv = flip->private_data;
517 void __user *ptr = (void __user *)arg;
518
519 switch (cmd) {
520 case IOCTL_GNTDEV_MAP_GRANT_REF:
521 return gntdev_ioctl_map_grant_ref(priv, ptr);
522
523 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
524 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
525
526 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
527 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
528
529 case IOCTL_GNTDEV_SET_MAX_GRANTS:
530 return gntdev_ioctl_set_max_grants(priv, ptr);
531
532 default:
533 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
534 return -ENOIOCTLCMD;
535 }
536
537 return 0;
538}
539
540static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
541{
542 struct gntdev_priv *priv = flip->private_data;
543 int index = vma->vm_pgoff;
544 int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
545 struct grant_map *map;
546 int err = -EINVAL;
547
548 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
549 return -EINVAL;
550
551 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
552 index, count, vma->vm_start, vma->vm_pgoff);
553
554 spin_lock(&priv->lock);
555 map = gntdev_find_map_index(priv, index, count);
556 if (!map)
557 goto unlock_out;
558 if (map->vma)
559 goto unlock_out;
560 if (priv->mm != vma->vm_mm) {
561 printk(KERN_WARNING "Huh? Other mm?\n");
562 goto unlock_out;
563 }
564
565 vma->vm_ops = &gntdev_vmops;
566
567 vma->vm_flags |= VM_RESERVED|VM_DONTCOPY|VM_DONTEXPAND;
568
569 vma->vm_private_data = map;
570 map->vma = vma;
571
572 map->flags = GNTMAP_host_map | GNTMAP_application_map | GNTMAP_contains_pte;
573 if (!(vma->vm_flags & VM_WRITE))
574 map->flags |= GNTMAP_readonly;
575
576 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
577 vma->vm_end - vma->vm_start,
578 find_grant_ptes, map);
579 if (err) {
580 printk(KERN_WARNING "find_grant_ptes() failure.\n");
581 goto unlock_out;
582 }
583
584 err = map_grant_pages(map);
585 if (err) {
586 printk(KERN_WARNING "map_grant_pages() failure.\n");
587 goto unlock_out;
588 }
589 map->is_mapped = 1;
590
591unlock_out:
592 spin_unlock(&priv->lock);
593 return err;
594}
595
596static const struct file_operations gntdev_fops = {
597 .owner = THIS_MODULE,
598 .open = gntdev_open,
599 .release = gntdev_release,
600 .mmap = gntdev_mmap,
601 .unlocked_ioctl = gntdev_ioctl
602};
603
604static struct miscdevice gntdev_miscdev = {
605 .minor = MISC_DYNAMIC_MINOR,
606 .name = "xen/gntdev",
607 .fops = &gntdev_fops,
608};
609
610/* ------------------------------------------------------------------ */
611
612static int __init gntdev_init(void)
613{
614 int err;
615
616 if (!xen_domain())
617 return -ENODEV;
618
619 err = misc_register(&gntdev_miscdev);
620 if (err != 0) {
621 printk(KERN_ERR "Could not register gntdev device\n");
622 return err;
623 }
624 return 0;
625}
626
627static void __exit gntdev_exit(void)
628{
629 misc_deregister(&gntdev_miscdev);
630}
631
632module_init(gntdev_init);
633module_exit(gntdev_exit);
634
635/* ------------------------------------------------------------------ */