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dd314058 DDG |
1 | /****************************************************************************** |
2 | * gntalloc.c | |
3 | * | |
4 | * Device for creating grant references (in user-space) that may be shared | |
5 | * with other domains. | |
6 | * | |
7 | * This program is distributed in the hope that it will be useful, | |
8 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
9 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
10 | * GNU General Public License for more details. | |
11 | * | |
12 | * You should have received a copy of the GNU General Public License | |
13 | * along with this program; if not, write to the Free Software | |
14 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
15 | */ | |
16 | ||
17 | /* | |
18 | * This driver exists to allow userspace programs in Linux to allocate kernel | |
19 | * memory that will later be shared with another domain. Without this device, | |
20 | * Linux userspace programs cannot create grant references. | |
21 | * | |
22 | * How this stuff works: | |
23 | * X -> granting a page to Y | |
24 | * Y -> mapping the grant from X | |
25 | * | |
26 | * 1. X uses the gntalloc device to allocate a page of kernel memory, P. | |
27 | * 2. X creates an entry in the grant table that says domid(Y) can access P. | |
28 | * This is done without a hypercall unless the grant table needs expansion. | |
29 | * 3. X gives the grant reference identifier, GREF, to Y. | |
30 | * 4. Y maps the page, either directly into kernel memory for use in a backend | |
31 | * driver, or via a the gntdev device to map into the address space of an | |
32 | * application running in Y. This is the first point at which Xen does any | |
33 | * tracking of the page. | |
34 | * 5. A program in X mmap()s a segment of the gntalloc device that corresponds | |
35 | * to the shared page, and can now communicate with Y over the shared page. | |
36 | * | |
37 | * | |
38 | * NOTE TO USERSPACE LIBRARIES: | |
39 | * The grant allocation and mmap()ing are, naturally, two separate operations. | |
40 | * You set up the sharing by calling the create ioctl() and then the mmap(). | |
41 | * Teardown requires munmap() and either close() or ioctl(). | |
42 | * | |
43 | * WARNING: Since Xen does not allow a guest to forcibly end the use of a grant | |
44 | * reference, this device can be used to consume kernel memory by leaving grant | |
45 | * references mapped by another domain when an application exits. Therefore, | |
46 | * there is a global limit on the number of pages that can be allocated. When | |
47 | * all references to the page are unmapped, it will be freed during the next | |
48 | * grant operation. | |
49 | */ | |
50 | ||
283c0972 JP |
51 | #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt |
52 | ||
dd314058 DDG |
53 | #include <linux/atomic.h> |
54 | #include <linux/module.h> | |
55 | #include <linux/miscdevice.h> | |
56 | #include <linux/kernel.h> | |
57 | #include <linux/init.h> | |
58 | #include <linux/slab.h> | |
59 | #include <linux/fs.h> | |
60 | #include <linux/device.h> | |
61 | #include <linux/mm.h> | |
62 | #include <linux/uaccess.h> | |
63 | #include <linux/types.h> | |
64 | #include <linux/list.h> | |
bdc612dc | 65 | #include <linux/highmem.h> |
dd314058 DDG |
66 | |
67 | #include <xen/xen.h> | |
68 | #include <xen/page.h> | |
69 | #include <xen/grant_table.h> | |
70 | #include <xen/gntalloc.h> | |
bdc612dc | 71 | #include <xen/events.h> |
dd314058 DDG |
72 | |
73 | static int limit = 1024; | |
74 | module_param(limit, int, 0644); | |
75 | MODULE_PARM_DESC(limit, "Maximum number of grants that may be allocated by " | |
76 | "the gntalloc device"); | |
77 | ||
78 | static LIST_HEAD(gref_list); | |
8ca19a89 | 79 | static DEFINE_MUTEX(gref_mutex); |
dd314058 DDG |
80 | static int gref_size; |
81 | ||
bdc612dc DDG |
82 | struct notify_info { |
83 | uint16_t pgoff:12; /* Bits 0-11: Offset of the byte to clear */ | |
84 | uint16_t flags:2; /* Bits 12-13: Unmap notification flags */ | |
85 | int event; /* Port (event channel) to notify */ | |
86 | }; | |
87 | ||
dd314058 DDG |
88 | /* Metadata on a grant reference. */ |
89 | struct gntalloc_gref { | |
90 | struct list_head next_gref; /* list entry gref_list */ | |
91 | struct list_head next_file; /* list entry file->list, if open */ | |
92 | struct page *page; /* The shared page */ | |
93 | uint64_t file_index; /* File offset for mmap() */ | |
94 | unsigned int users; /* Use count - when zero, waiting on Xen */ | |
95 | grant_ref_t gref_id; /* The grant reference number */ | |
bdc612dc | 96 | struct notify_info notify; /* Unmap notification */ |
dd314058 DDG |
97 | }; |
98 | ||
99 | struct gntalloc_file_private_data { | |
100 | struct list_head list; | |
101 | uint64_t index; | |
102 | }; | |
103 | ||
243082e0 DDG |
104 | struct gntalloc_vma_private_data { |
105 | struct gntalloc_gref *gref; | |
106 | int users; | |
107 | int count; | |
108 | }; | |
109 | ||
dd314058 DDG |
110 | static void __del_gref(struct gntalloc_gref *gref); |
111 | ||
112 | static void do_cleanup(void) | |
113 | { | |
114 | struct gntalloc_gref *gref, *n; | |
115 | list_for_each_entry_safe(gref, n, &gref_list, next_gref) { | |
116 | if (!gref->users) | |
117 | __del_gref(gref); | |
118 | } | |
119 | } | |
120 | ||
121 | static int add_grefs(struct ioctl_gntalloc_alloc_gref *op, | |
122 | uint32_t *gref_ids, struct gntalloc_file_private_data *priv) | |
123 | { | |
124 | int i, rc, readonly; | |
125 | LIST_HEAD(queue_gref); | |
126 | LIST_HEAD(queue_file); | |
5903c6bd | 127 | struct gntalloc_gref *gref, *next; |
dd314058 DDG |
128 | |
129 | readonly = !(op->flags & GNTALLOC_FLAG_WRITABLE); | |
130 | rc = -ENOMEM; | |
131 | for (i = 0; i < op->count; i++) { | |
132 | gref = kzalloc(sizeof(*gref), GFP_KERNEL); | |
133 | if (!gref) | |
134 | goto undo; | |
135 | list_add_tail(&gref->next_gref, &queue_gref); | |
136 | list_add_tail(&gref->next_file, &queue_file); | |
137 | gref->users = 1; | |
138 | gref->file_index = op->index + i * PAGE_SIZE; | |
139 | gref->page = alloc_page(GFP_KERNEL|__GFP_ZERO); | |
140 | if (!gref->page) | |
141 | goto undo; | |
142 | ||
143 | /* Grant foreign access to the page. */ | |
e9de2e5f | 144 | rc = gnttab_grant_foreign_access(op->domid, |
dd314058 | 145 | pfn_to_mfn(page_to_pfn(gref->page)), readonly); |
e9de2e5f | 146 | if (rc < 0) |
dd314058 | 147 | goto undo; |
e9de2e5f | 148 | gref_ids[i] = gref->gref_id = rc; |
dd314058 DDG |
149 | } |
150 | ||
151 | /* Add to gref lists. */ | |
8ca19a89 | 152 | mutex_lock(&gref_mutex); |
dd314058 DDG |
153 | list_splice_tail(&queue_gref, &gref_list); |
154 | list_splice_tail(&queue_file, &priv->list); | |
8ca19a89 | 155 | mutex_unlock(&gref_mutex); |
dd314058 DDG |
156 | |
157 | return 0; | |
158 | ||
159 | undo: | |
8ca19a89 | 160 | mutex_lock(&gref_mutex); |
dd314058 DDG |
161 | gref_size -= (op->count - i); |
162 | ||
5903c6bd DV |
163 | list_for_each_entry_safe(gref, next, &queue_file, next_file) { |
164 | list_del(&gref->next_file); | |
dd314058 DDG |
165 | __del_gref(gref); |
166 | } | |
167 | ||
168 | /* It's possible for the target domain to map the just-allocated grant | |
169 | * references by blindly guessing their IDs; if this is done, then | |
170 | * __del_gref will leave them in the queue_gref list. They need to be | |
171 | * added to the global list so that we can free them when they are no | |
172 | * longer referenced. | |
173 | */ | |
174 | if (unlikely(!list_empty(&queue_gref))) | |
175 | list_splice_tail(&queue_gref, &gref_list); | |
8ca19a89 | 176 | mutex_unlock(&gref_mutex); |
dd314058 DDG |
177 | return rc; |
178 | } | |
179 | ||
180 | static void __del_gref(struct gntalloc_gref *gref) | |
181 | { | |
bdc612dc DDG |
182 | if (gref->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { |
183 | uint8_t *tmp = kmap(gref->page); | |
184 | tmp[gref->notify.pgoff] = 0; | |
185 | kunmap(gref->page); | |
186 | } | |
0cc678f8 | 187 | if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { |
bdc612dc | 188 | notify_remote_via_evtchn(gref->notify.event); |
0cc678f8 DDG |
189 | evtchn_put(gref->notify.event); |
190 | } | |
bdc612dc DDG |
191 | |
192 | gref->notify.flags = 0; | |
193 | ||
e9de2e5f | 194 | if (gref->gref_id) { |
dd314058 DDG |
195 | if (gnttab_query_foreign_access(gref->gref_id)) |
196 | return; | |
197 | ||
198 | if (!gnttab_end_foreign_access_ref(gref->gref_id, 0)) | |
199 | return; | |
0105d2b4 DDG |
200 | |
201 | gnttab_free_grant_reference(gref->gref_id); | |
dd314058 DDG |
202 | } |
203 | ||
204 | gref_size--; | |
205 | list_del(&gref->next_gref); | |
206 | ||
207 | if (gref->page) | |
208 | __free_page(gref->page); | |
209 | ||
210 | kfree(gref); | |
211 | } | |
212 | ||
213 | /* finds contiguous grant references in a file, returns the first */ | |
214 | static struct gntalloc_gref *find_grefs(struct gntalloc_file_private_data *priv, | |
215 | uint64_t index, uint32_t count) | |
216 | { | |
217 | struct gntalloc_gref *rv = NULL, *gref; | |
218 | list_for_each_entry(gref, &priv->list, next_file) { | |
219 | if (gref->file_index == index && !rv) | |
220 | rv = gref; | |
221 | if (rv) { | |
222 | if (gref->file_index != index) | |
223 | return NULL; | |
224 | index += PAGE_SIZE; | |
225 | count--; | |
226 | if (count == 0) | |
227 | return rv; | |
228 | } | |
229 | } | |
230 | return NULL; | |
231 | } | |
232 | ||
233 | /* | |
234 | * ------------------------------------- | |
235 | * File operations. | |
236 | * ------------------------------------- | |
237 | */ | |
238 | static int gntalloc_open(struct inode *inode, struct file *filp) | |
239 | { | |
240 | struct gntalloc_file_private_data *priv; | |
241 | ||
242 | priv = kzalloc(sizeof(*priv), GFP_KERNEL); | |
243 | if (!priv) | |
244 | goto out_nomem; | |
245 | INIT_LIST_HEAD(&priv->list); | |
246 | ||
247 | filp->private_data = priv; | |
248 | ||
249 | pr_debug("%s: priv %p\n", __func__, priv); | |
250 | ||
251 | return 0; | |
252 | ||
253 | out_nomem: | |
254 | return -ENOMEM; | |
255 | } | |
256 | ||
257 | static int gntalloc_release(struct inode *inode, struct file *filp) | |
258 | { | |
259 | struct gntalloc_file_private_data *priv = filp->private_data; | |
260 | struct gntalloc_gref *gref; | |
261 | ||
262 | pr_debug("%s: priv %p\n", __func__, priv); | |
263 | ||
8ca19a89 | 264 | mutex_lock(&gref_mutex); |
dd314058 DDG |
265 | while (!list_empty(&priv->list)) { |
266 | gref = list_entry(priv->list.next, | |
267 | struct gntalloc_gref, next_file); | |
268 | list_del(&gref->next_file); | |
269 | gref->users--; | |
270 | if (gref->users == 0) | |
271 | __del_gref(gref); | |
272 | } | |
273 | kfree(priv); | |
8ca19a89 | 274 | mutex_unlock(&gref_mutex); |
dd314058 DDG |
275 | |
276 | return 0; | |
277 | } | |
278 | ||
279 | static long gntalloc_ioctl_alloc(struct gntalloc_file_private_data *priv, | |
280 | struct ioctl_gntalloc_alloc_gref __user *arg) | |
281 | { | |
282 | int rc = 0; | |
283 | struct ioctl_gntalloc_alloc_gref op; | |
284 | uint32_t *gref_ids; | |
285 | ||
286 | pr_debug("%s: priv %p\n", __func__, priv); | |
287 | ||
288 | if (copy_from_user(&op, arg, sizeof(op))) { | |
289 | rc = -EFAULT; | |
290 | goto out; | |
291 | } | |
292 | ||
21643e69 | 293 | gref_ids = kcalloc(op.count, sizeof(gref_ids[0]), GFP_TEMPORARY); |
dd314058 DDG |
294 | if (!gref_ids) { |
295 | rc = -ENOMEM; | |
296 | goto out; | |
297 | } | |
298 | ||
8ca19a89 | 299 | mutex_lock(&gref_mutex); |
dd314058 DDG |
300 | /* Clean up pages that were at zero (local) users but were still mapped |
301 | * by remote domains. Since those pages count towards the limit that we | |
302 | * are about to enforce, removing them here is a good idea. | |
303 | */ | |
304 | do_cleanup(); | |
305 | if (gref_size + op.count > limit) { | |
8ca19a89 | 306 | mutex_unlock(&gref_mutex); |
dd314058 DDG |
307 | rc = -ENOSPC; |
308 | goto out_free; | |
309 | } | |
310 | gref_size += op.count; | |
311 | op.index = priv->index; | |
312 | priv->index += op.count * PAGE_SIZE; | |
8ca19a89 | 313 | mutex_unlock(&gref_mutex); |
dd314058 DDG |
314 | |
315 | rc = add_grefs(&op, gref_ids, priv); | |
316 | if (rc < 0) | |
317 | goto out_free; | |
318 | ||
319 | /* Once we finish add_grefs, it is unsafe to touch the new reference, | |
320 | * since it is possible for a concurrent ioctl to remove it (by guessing | |
321 | * its index). If the userspace application doesn't provide valid memory | |
322 | * to write the IDs to, then it will need to close the file in order to | |
323 | * release - which it will do by segfaulting when it tries to access the | |
324 | * IDs to close them. | |
325 | */ | |
326 | if (copy_to_user(arg, &op, sizeof(op))) { | |
327 | rc = -EFAULT; | |
328 | goto out_free; | |
329 | } | |
330 | if (copy_to_user(arg->gref_ids, gref_ids, | |
331 | sizeof(gref_ids[0]) * op.count)) { | |
332 | rc = -EFAULT; | |
333 | goto out_free; | |
334 | } | |
335 | ||
336 | out_free: | |
337 | kfree(gref_ids); | |
338 | out: | |
339 | return rc; | |
340 | } | |
341 | ||
342 | static long gntalloc_ioctl_dealloc(struct gntalloc_file_private_data *priv, | |
343 | void __user *arg) | |
344 | { | |
345 | int i, rc = 0; | |
346 | struct ioctl_gntalloc_dealloc_gref op; | |
347 | struct gntalloc_gref *gref, *n; | |
348 | ||
349 | pr_debug("%s: priv %p\n", __func__, priv); | |
350 | ||
351 | if (copy_from_user(&op, arg, sizeof(op))) { | |
352 | rc = -EFAULT; | |
353 | goto dealloc_grant_out; | |
354 | } | |
355 | ||
8ca19a89 | 356 | mutex_lock(&gref_mutex); |
dd314058 DDG |
357 | gref = find_grefs(priv, op.index, op.count); |
358 | if (gref) { | |
359 | /* Remove from the file list only, and decrease reference count. | |
360 | * The later call to do_cleanup() will remove from gref_list and | |
361 | * free the memory if the pages aren't mapped anywhere. | |
362 | */ | |
363 | for (i = 0; i < op.count; i++) { | |
364 | n = list_entry(gref->next_file.next, | |
365 | struct gntalloc_gref, next_file); | |
366 | list_del(&gref->next_file); | |
367 | gref->users--; | |
368 | gref = n; | |
369 | } | |
370 | } else { | |
371 | rc = -EINVAL; | |
372 | } | |
373 | ||
374 | do_cleanup(); | |
375 | ||
8ca19a89 | 376 | mutex_unlock(&gref_mutex); |
dd314058 DDG |
377 | dealloc_grant_out: |
378 | return rc; | |
379 | } | |
380 | ||
bdc612dc DDG |
381 | static long gntalloc_ioctl_unmap_notify(struct gntalloc_file_private_data *priv, |
382 | void __user *arg) | |
383 | { | |
384 | struct ioctl_gntalloc_unmap_notify op; | |
385 | struct gntalloc_gref *gref; | |
386 | uint64_t index; | |
387 | int pgoff; | |
388 | int rc; | |
389 | ||
390 | if (copy_from_user(&op, arg, sizeof(op))) | |
391 | return -EFAULT; | |
392 | ||
393 | index = op.index & ~(PAGE_SIZE - 1); | |
394 | pgoff = op.index & (PAGE_SIZE - 1); | |
395 | ||
8ca19a89 | 396 | mutex_lock(&gref_mutex); |
bdc612dc DDG |
397 | |
398 | gref = find_grefs(priv, index, 1); | |
399 | if (!gref) { | |
400 | rc = -ENOENT; | |
401 | goto unlock_out; | |
402 | } | |
403 | ||
404 | if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) { | |
405 | rc = -EINVAL; | |
406 | goto unlock_out; | |
407 | } | |
408 | ||
0cc678f8 DDG |
409 | /* We need to grab a reference to the event channel we are going to use |
410 | * to send the notify before releasing the reference we may already have | |
411 | * (if someone has called this ioctl twice). This is required so that | |
412 | * it is possible to change the clear_byte part of the notification | |
413 | * without disturbing the event channel part, which may now be the last | |
414 | * reference to that event channel. | |
415 | */ | |
416 | if (op.action & UNMAP_NOTIFY_SEND_EVENT) { | |
417 | if (evtchn_get(op.event_channel_port)) { | |
418 | rc = -EINVAL; | |
419 | goto unlock_out; | |
420 | } | |
421 | } | |
422 | ||
423 | if (gref->notify.flags & UNMAP_NOTIFY_SEND_EVENT) | |
424 | evtchn_put(gref->notify.event); | |
425 | ||
bdc612dc DDG |
426 | gref->notify.flags = op.action; |
427 | gref->notify.pgoff = pgoff; | |
428 | gref->notify.event = op.event_channel_port; | |
429 | rc = 0; | |
8ca19a89 | 430 | |
bdc612dc | 431 | unlock_out: |
8ca19a89 | 432 | mutex_unlock(&gref_mutex); |
bdc612dc DDG |
433 | return rc; |
434 | } | |
435 | ||
dd314058 DDG |
436 | static long gntalloc_ioctl(struct file *filp, unsigned int cmd, |
437 | unsigned long arg) | |
438 | { | |
439 | struct gntalloc_file_private_data *priv = filp->private_data; | |
440 | ||
441 | switch (cmd) { | |
442 | case IOCTL_GNTALLOC_ALLOC_GREF: | |
443 | return gntalloc_ioctl_alloc(priv, (void __user *)arg); | |
444 | ||
445 | case IOCTL_GNTALLOC_DEALLOC_GREF: | |
446 | return gntalloc_ioctl_dealloc(priv, (void __user *)arg); | |
447 | ||
bdc612dc DDG |
448 | case IOCTL_GNTALLOC_SET_UNMAP_NOTIFY: |
449 | return gntalloc_ioctl_unmap_notify(priv, (void __user *)arg); | |
450 | ||
dd314058 DDG |
451 | default: |
452 | return -ENOIOCTLCMD; | |
453 | } | |
454 | ||
455 | return 0; | |
456 | } | |
457 | ||
d79647ae DDG |
458 | static void gntalloc_vma_open(struct vm_area_struct *vma) |
459 | { | |
243082e0 DDG |
460 | struct gntalloc_vma_private_data *priv = vma->vm_private_data; |
461 | ||
462 | if (!priv) | |
d79647ae DDG |
463 | return; |
464 | ||
8ca19a89 | 465 | mutex_lock(&gref_mutex); |
243082e0 | 466 | priv->users++; |
8ca19a89 | 467 | mutex_unlock(&gref_mutex); |
d79647ae DDG |
468 | } |
469 | ||
dd314058 DDG |
470 | static void gntalloc_vma_close(struct vm_area_struct *vma) |
471 | { | |
243082e0 DDG |
472 | struct gntalloc_vma_private_data *priv = vma->vm_private_data; |
473 | struct gntalloc_gref *gref, *next; | |
474 | int i; | |
475 | ||
476 | if (!priv) | |
dd314058 DDG |
477 | return; |
478 | ||
8ca19a89 | 479 | mutex_lock(&gref_mutex); |
243082e0 DDG |
480 | priv->users--; |
481 | if (priv->users == 0) { | |
482 | gref = priv->gref; | |
483 | for (i = 0; i < priv->count; i++) { | |
484 | gref->users--; | |
485 | next = list_entry(gref->next_gref.next, | |
486 | struct gntalloc_gref, next_gref); | |
487 | if (gref->users == 0) | |
488 | __del_gref(gref); | |
489 | gref = next; | |
490 | } | |
491 | kfree(priv); | |
492 | } | |
8ca19a89 | 493 | mutex_unlock(&gref_mutex); |
dd314058 DDG |
494 | } |
495 | ||
496 | static struct vm_operations_struct gntalloc_vmops = { | |
d79647ae | 497 | .open = gntalloc_vma_open, |
dd314058 DDG |
498 | .close = gntalloc_vma_close, |
499 | }; | |
500 | ||
501 | static int gntalloc_mmap(struct file *filp, struct vm_area_struct *vma) | |
502 | { | |
503 | struct gntalloc_file_private_data *priv = filp->private_data; | |
243082e0 | 504 | struct gntalloc_vma_private_data *vm_priv; |
dd314058 DDG |
505 | struct gntalloc_gref *gref; |
506 | int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; | |
507 | int rv, i; | |
508 | ||
dd314058 | 509 | if (!(vma->vm_flags & VM_SHARED)) { |
283c0972 | 510 | pr_err("%s: Mapping must be shared\n", __func__); |
dd314058 DDG |
511 | return -EINVAL; |
512 | } | |
513 | ||
243082e0 DDG |
514 | vm_priv = kmalloc(sizeof(*vm_priv), GFP_KERNEL); |
515 | if (!vm_priv) | |
516 | return -ENOMEM; | |
517 | ||
8ca19a89 | 518 | mutex_lock(&gref_mutex); |
243082e0 DDG |
519 | |
520 | pr_debug("%s: priv %p,%p, page %lu+%d\n", __func__, | |
521 | priv, vm_priv, vma->vm_pgoff, count); | |
522 | ||
dd314058 DDG |
523 | gref = find_grefs(priv, vma->vm_pgoff << PAGE_SHIFT, count); |
524 | if (gref == NULL) { | |
525 | rv = -ENOENT; | |
526 | pr_debug("%s: Could not find grant reference", | |
527 | __func__); | |
2e163414 | 528 | kfree(vm_priv); |
dd314058 DDG |
529 | goto out_unlock; |
530 | } | |
531 | ||
243082e0 DDG |
532 | vm_priv->gref = gref; |
533 | vm_priv->users = 1; | |
534 | vm_priv->count = count; | |
535 | ||
536 | vma->vm_private_data = vm_priv; | |
dd314058 | 537 | |
314e51b9 | 538 | vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; |
dd314058 DDG |
539 | |
540 | vma->vm_ops = &gntalloc_vmops; | |
541 | ||
542 | for (i = 0; i < count; i++) { | |
543 | gref->users++; | |
544 | rv = vm_insert_page(vma, vma->vm_start + i * PAGE_SIZE, | |
545 | gref->page); | |
546 | if (rv) | |
547 | goto out_unlock; | |
548 | ||
549 | gref = list_entry(gref->next_file.next, | |
550 | struct gntalloc_gref, next_file); | |
551 | } | |
552 | rv = 0; | |
553 | ||
554 | out_unlock: | |
8ca19a89 | 555 | mutex_unlock(&gref_mutex); |
dd314058 DDG |
556 | return rv; |
557 | } | |
558 | ||
559 | static const struct file_operations gntalloc_fops = { | |
560 | .owner = THIS_MODULE, | |
561 | .open = gntalloc_open, | |
562 | .release = gntalloc_release, | |
563 | .unlocked_ioctl = gntalloc_ioctl, | |
564 | .mmap = gntalloc_mmap | |
565 | }; | |
566 | ||
567 | /* | |
568 | * ------------------------------------- | |
569 | * Module creation/destruction. | |
570 | * ------------------------------------- | |
571 | */ | |
572 | static struct miscdevice gntalloc_miscdev = { | |
573 | .minor = MISC_DYNAMIC_MINOR, | |
574 | .name = "xen/gntalloc", | |
575 | .fops = &gntalloc_fops, | |
576 | }; | |
577 | ||
578 | static int __init gntalloc_init(void) | |
579 | { | |
580 | int err; | |
581 | ||
582 | if (!xen_domain()) | |
583 | return -ENODEV; | |
584 | ||
585 | err = misc_register(&gntalloc_miscdev); | |
586 | if (err != 0) { | |
283c0972 | 587 | pr_err("Could not register misc gntalloc device\n"); |
dd314058 DDG |
588 | return err; |
589 | } | |
590 | ||
591 | pr_debug("Created grant allocation device at %d,%d\n", | |
592 | MISC_MAJOR, gntalloc_miscdev.minor); | |
593 | ||
594 | return 0; | |
595 | } | |
596 | ||
597 | static void __exit gntalloc_exit(void) | |
598 | { | |
599 | misc_deregister(&gntalloc_miscdev); | |
600 | } | |
601 | ||
602 | module_init(gntalloc_init); | |
603 | module_exit(gntalloc_exit); | |
604 | ||
605 | MODULE_LICENSE("GPL"); | |
606 | MODULE_AUTHOR("Carter Weatherly <carter.weatherly@jhuapl.edu>, " | |
607 | "Daniel De Graaf <dgdegra@tycho.nsa.gov>"); | |
608 | MODULE_DESCRIPTION("User-space grant reference allocator driver"); |