1 /******************************************************************************
4 * Device for accessing (in user-space) pages that have been granted by other
7 * Copyright (c) 2006-2007, D G Murray.
8 * (c) 2009 Gerd Hoffmann <kraxel@redhat.com>
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.
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
22 #include <linux/module.h>
23 #include <linux/kernel.h>
24 #include <linux/init.h>
25 #include <linux/miscdevice.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>
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>
46 MODULE_LICENSE("GPL");
47 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
48 "Gerd Hoffmann <kraxel@redhat.com>");
49 MODULE_DESCRIPTION("User-space granted page access driver");
51 static int limit = 1024*1024;
52 module_param(limit, int, 0644);
53 MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
56 static atomic_t pages_mapped = ATOMIC_INIT(0);
58 static int use_ptemod;
61 struct list_head maps;
62 /* lock protects maps from concurrent changes */
65 struct mmu_notifier mn;
70 /* Address relative to the start of the grant_map */
76 struct list_head next;
77 struct vm_area_struct *vma;
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;
90 static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
92 /* ------------------------------------------------------------------ */
94 static void gntdev_print_maps(struct gntdev_priv *priv,
95 char *text, int text_index)
98 struct grant_map *map;
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 : "");
108 static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
110 struct grant_map *add;
113 add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
117 add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL);
118 add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL);
119 add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL);
120 add->kmap_ops = kzalloc(sizeof(add->kmap_ops[0]) * count, GFP_KERNEL);
121 add->pages = kzalloc(sizeof(add->pages[0]) * count, GFP_KERNEL);
122 if (NULL == add->grants ||
123 NULL == add->map_ops ||
124 NULL == add->unmap_ops ||
125 NULL == add->kmap_ops ||
129 if (alloc_xenballooned_pages(count, add->pages, false /* lowmem */))
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;
140 atomic_set(&add->users, 1);
148 kfree(add->unmap_ops);
149 kfree(add->kmap_ops);
154 static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
156 struct grant_map *map;
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);
163 add->index = map->index + map->count;
165 list_add_tail(&add->next, &priv->maps);
168 gntdev_print_maps(priv, "[new]", add->index);
171 static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
172 int index, int count)
174 struct grant_map *map;
176 list_for_each_entry(map, &priv->maps, next) {
177 if (map->index != index)
179 if (count && map->count != count)
186 static void gntdev_put_map(struct grant_map *map)
191 if (!atomic_dec_and_test(&map->users))
194 atomic_sub(map->count, &pages_mapped);
196 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
197 notify_remote_via_evtchn(map->notify.event);
202 unmap_grant_pages(map, 0, map->count);
204 free_xenballooned_pages(map->count, map->pages);
209 kfree(map->unmap_ops);
213 /* ------------------------------------------------------------------ */
215 static int find_grant_ptes(pte_t *pte, pgtable_t token,
216 unsigned long addr, void *data)
218 struct grant_map *map = data;
219 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
220 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
223 BUG_ON(pgnr >= map->count);
224 pte_maddr = arbitrary_virt_to_machine(pte).maddr;
226 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
227 map->grants[pgnr].ref,
228 map->grants[pgnr].domid);
229 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
234 static int map_grant_pages(struct grant_map *map)
239 /* Note: it could already be mapped */
240 if (map->map_ops[0].handle != -1)
242 for (i = 0; i < map->count; i++) {
243 unsigned long addr = (unsigned long)
244 pfn_to_kaddr(page_to_pfn(map->pages[i]));
245 gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
247 map->grants[i].domid);
248 gnttab_set_unmap_op(&map->unmap_ops[i], addr,
249 map->flags, -1 /* handle */);
253 * Setup the map_ops corresponding to the pte entries pointing
254 * to the kernel linear addresses of the struct pages.
255 * These ptes are completely different from the user ptes dealt
256 * with find_grant_ptes.
258 for (i = 0; i < map->count; i++) {
260 unsigned long address = (unsigned long)
261 pfn_to_kaddr(page_to_pfn(map->pages[i]));
264 BUG_ON(PageHighMem(map->pages[i]));
266 ptep = lookup_address(address, &level);
267 pte_maddr = arbitrary_virt_to_machine(ptep).maddr;
268 gnttab_set_map_op(&map->kmap_ops[i], pte_maddr,
273 map->grants[i].domid);
277 pr_debug("map %d+%d\n", map->index, map->count);
278 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
279 map->pages, map->count);
283 for (i = 0; i < map->count; i++) {
284 if (map->map_ops[i].status)
287 BUG_ON(map->map_ops[i].handle == -1);
288 map->unmap_ops[i].handle = map->map_ops[i].handle;
289 pr_debug("map handle=%d\n", map->map_ops[i].handle);
295 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
299 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
300 int pgno = (map->notify.addr >> PAGE_SHIFT);
301 if (pgno >= offset && pgno < offset + pages && use_ptemod) {
302 void __user *tmp = (void __user *)
303 map->vma->vm_start + map->notify.addr;
304 err = copy_to_user(tmp, &err, 1);
307 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
308 } else if (pgno >= offset && pgno < offset + pages) {
309 uint8_t *tmp = kmap(map->pages[pgno]);
310 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
311 kunmap(map->pages[pgno]);
312 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
316 err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
320 for (i = 0; i < pages; i++) {
321 if (map->unmap_ops[offset+i].status)
323 pr_debug("unmap handle=%d st=%d\n",
324 map->unmap_ops[offset+i].handle,
325 map->unmap_ops[offset+i].status);
326 map->unmap_ops[offset+i].handle = -1;
331 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
335 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
337 /* It is possible the requested range will have a "hole" where we
338 * already unmapped some of the grants. Only unmap valid ranges.
340 while (pages && !err) {
341 while (pages && map->unmap_ops[offset].handle == -1) {
346 while (range < pages) {
347 if (map->unmap_ops[offset+range].handle == -1) {
353 err = __unmap_grant_pages(map, offset, range);
361 /* ------------------------------------------------------------------ */
363 static void gntdev_vma_open(struct vm_area_struct *vma)
365 struct grant_map *map = vma->vm_private_data;
367 pr_debug("gntdev_vma_open %p\n", vma);
368 atomic_inc(&map->users);
371 static void gntdev_vma_close(struct vm_area_struct *vma)
373 struct grant_map *map = vma->vm_private_data;
375 pr_debug("gntdev_vma_close %p\n", vma);
377 vma->vm_private_data = NULL;
381 static struct vm_operations_struct gntdev_vmops = {
382 .open = gntdev_vma_open,
383 .close = gntdev_vma_close,
386 /* ------------------------------------------------------------------ */
388 static void mn_invl_range_start(struct mmu_notifier *mn,
389 struct mm_struct *mm,
390 unsigned long start, unsigned long end)
392 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
393 struct grant_map *map;
394 unsigned long mstart, mend;
397 spin_lock(&priv->lock);
398 list_for_each_entry(map, &priv->maps, next) {
401 if (map->vma->vm_start >= end)
403 if (map->vma->vm_end <= start)
405 mstart = max(start, map->vma->vm_start);
406 mend = min(end, map->vma->vm_end);
407 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
408 map->index, map->count,
409 map->vma->vm_start, map->vma->vm_end,
410 start, end, mstart, mend);
411 err = unmap_grant_pages(map,
412 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
413 (mend - mstart) >> PAGE_SHIFT);
416 spin_unlock(&priv->lock);
419 static void mn_invl_page(struct mmu_notifier *mn,
420 struct mm_struct *mm,
421 unsigned long address)
423 mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
426 static void mn_release(struct mmu_notifier *mn,
427 struct mm_struct *mm)
429 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
430 struct grant_map *map;
433 spin_lock(&priv->lock);
434 list_for_each_entry(map, &priv->maps, next) {
437 pr_debug("map %d+%d (%lx %lx)\n",
438 map->index, map->count,
439 map->vma->vm_start, map->vma->vm_end);
440 err = unmap_grant_pages(map, /* offset */ 0, map->count);
443 spin_unlock(&priv->lock);
446 struct mmu_notifier_ops gntdev_mmu_ops = {
447 .release = mn_release,
448 .invalidate_page = mn_invl_page,
449 .invalidate_range_start = mn_invl_range_start,
452 /* ------------------------------------------------------------------ */
454 static int gntdev_open(struct inode *inode, struct file *flip)
456 struct gntdev_priv *priv;
459 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
463 INIT_LIST_HEAD(&priv->maps);
464 spin_lock_init(&priv->lock);
467 priv->mm = get_task_mm(current);
472 priv->mn.ops = &gntdev_mmu_ops;
473 ret = mmu_notifier_register(&priv->mn, priv->mm);
482 flip->private_data = priv;
483 pr_debug("priv %p\n", priv);
488 static int gntdev_release(struct inode *inode, struct file *flip)
490 struct gntdev_priv *priv = flip->private_data;
491 struct grant_map *map;
493 pr_debug("priv %p\n", priv);
495 spin_lock(&priv->lock);
496 while (!list_empty(&priv->maps)) {
497 map = list_entry(priv->maps.next, struct grant_map, next);
498 list_del(&map->next);
501 spin_unlock(&priv->lock);
504 mmu_notifier_unregister(&priv->mn, priv->mm);
509 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
510 struct ioctl_gntdev_map_grant_ref __user *u)
512 struct ioctl_gntdev_map_grant_ref op;
513 struct grant_map *map;
516 if (copy_from_user(&op, u, sizeof(op)) != 0)
518 pr_debug("priv %p, add %d\n", priv, op.count);
519 if (unlikely(op.count <= 0))
523 map = gntdev_alloc_map(priv, op.count);
527 if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
528 pr_debug("can't map: over limit\n");
533 if (copy_from_user(map->grants, &u->refs,
534 sizeof(map->grants[0]) * op.count) != 0) {
539 spin_lock(&priv->lock);
540 gntdev_add_map(priv, map);
541 op.index = map->index << PAGE_SHIFT;
542 spin_unlock(&priv->lock);
544 if (copy_to_user(u, &op, sizeof(op)) != 0)
550 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
551 struct ioctl_gntdev_unmap_grant_ref __user *u)
553 struct ioctl_gntdev_unmap_grant_ref op;
554 struct grant_map *map;
557 if (copy_from_user(&op, u, sizeof(op)) != 0)
559 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
561 spin_lock(&priv->lock);
562 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
564 list_del(&map->next);
568 spin_unlock(&priv->lock);
572 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
573 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
575 struct ioctl_gntdev_get_offset_for_vaddr op;
576 struct vm_area_struct *vma;
577 struct grant_map *map;
579 if (copy_from_user(&op, u, sizeof(op)) != 0)
581 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
583 vma = find_vma(current->mm, op.vaddr);
584 if (!vma || vma->vm_ops != &gntdev_vmops)
587 map = vma->vm_private_data;
591 op.offset = map->index << PAGE_SHIFT;
592 op.count = map->count;
594 if (copy_to_user(u, &op, sizeof(op)) != 0)
599 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
601 struct ioctl_gntdev_unmap_notify op;
602 struct grant_map *map;
605 if (copy_from_user(&op, u, sizeof(op)))
608 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
611 spin_lock(&priv->lock);
613 list_for_each_entry(map, &priv->maps, next) {
614 uint64_t begin = map->index << PAGE_SHIFT;
615 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
616 if (op.index >= begin && op.index < end)
623 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
624 (map->flags & GNTMAP_readonly)) {
629 map->notify.flags = op.action;
630 map->notify.addr = op.index - (map->index << PAGE_SHIFT);
631 map->notify.event = op.event_channel_port;
634 spin_unlock(&priv->lock);
638 static long gntdev_ioctl(struct file *flip,
639 unsigned int cmd, unsigned long arg)
641 struct gntdev_priv *priv = flip->private_data;
642 void __user *ptr = (void __user *)arg;
645 case IOCTL_GNTDEV_MAP_GRANT_REF:
646 return gntdev_ioctl_map_grant_ref(priv, ptr);
648 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
649 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
651 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
652 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
654 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
655 return gntdev_ioctl_notify(priv, ptr);
658 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
665 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
667 struct gntdev_priv *priv = flip->private_data;
668 int index = vma->vm_pgoff;
669 int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
670 struct grant_map *map;
671 int i, err = -EINVAL;
673 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
676 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
677 index, count, vma->vm_start, vma->vm_pgoff);
679 spin_lock(&priv->lock);
680 map = gntdev_find_map_index(priv, index, count);
683 if (use_ptemod && map->vma)
685 if (use_ptemod && priv->mm != vma->vm_mm) {
686 printk(KERN_WARNING "Huh? Other mm?\n");
690 atomic_inc(&map->users);
692 vma->vm_ops = &gntdev_vmops;
694 vma->vm_flags |= VM_RESERVED|VM_DONTEXPAND;
697 vma->vm_flags |= VM_DONTCOPY|VM_PFNMAP;
699 vma->vm_private_data = map;
705 if ((vma->vm_flags & VM_WRITE) &&
706 (map->flags & GNTMAP_readonly))
709 map->flags = GNTMAP_host_map;
710 if (!(vma->vm_flags & VM_WRITE))
711 map->flags |= GNTMAP_readonly;
714 spin_unlock(&priv->lock);
717 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
718 vma->vm_end - vma->vm_start,
719 find_grant_ptes, map);
721 printk(KERN_WARNING "find_grant_ptes() failure.\n");
726 err = map_grant_pages(map);
731 for (i = 0; i < count; i++) {
732 err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
742 spin_unlock(&priv->lock);
746 spin_unlock(&priv->lock);
754 static const struct file_operations gntdev_fops = {
755 .owner = THIS_MODULE,
757 .release = gntdev_release,
759 .unlocked_ioctl = gntdev_ioctl
762 static struct miscdevice gntdev_miscdev = {
763 .minor = MISC_DYNAMIC_MINOR,
764 .name = "xen/gntdev",
765 .fops = &gntdev_fops,
768 /* ------------------------------------------------------------------ */
770 static int __init gntdev_init(void)
777 use_ptemod = xen_pv_domain();
779 err = misc_register(&gntdev_miscdev);
781 printk(KERN_ERR "Could not register gntdev device\n");
787 static void __exit gntdev_exit(void)
789 misc_deregister(&gntdev_miscdev);
792 module_init(gntdev_init);
793 module_exit(gntdev_exit);
795 /* ------------------------------------------------------------------ */