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 * (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 #undef DEBUG
22
23 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
24
25 #include <linux/dma-mapping.h>
26 #include <linux/module.h>
27 #include <linux/kernel.h>
28 #include <linux/init.h>
29 #include <linux/miscdevice.h>
30 #include <linux/fs.h>
31 #include <linux/uaccess.h>
32 #include <linux/sched.h>
33 #include <linux/sched/mm.h>
34 #include <linux/spinlock.h>
35 #include <linux/slab.h>
36 #include <linux/highmem.h>
37 #include <linux/refcount.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 <xen/page.h>
45 #include <asm/xen/hypervisor.h>
46 #include <asm/xen/hypercall.h>
47
48 #include "gntdev-common.h"
49 #ifdef CONFIG_XEN_GNTDEV_DMABUF
50 #include "gntdev-dmabuf.h"
51 #endif
52
53 MODULE_LICENSE("GPL");
54 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
55 "Gerd Hoffmann <kraxel@redhat.com>");
56 MODULE_DESCRIPTION("User-space granted page access driver");
57
58 static int limit = 1024*1024;
59 module_param(limit, int, 0644);
60 MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
61 "the gntdev device");
62
63 static atomic_t pages_mapped = ATOMIC_INIT(0);
64
65 static int use_ptemod;
66 #define populate_freeable_maps use_ptemod
67
68 static int unmap_grant_pages(struct gntdev_grant_map *map,
69 int offset, int pages);
70
71 static struct miscdevice gntdev_miscdev;
72
73 /* ------------------------------------------------------------------ */
74
gntdev_account_mapped_pages(int count)75 bool gntdev_account_mapped_pages(int count)
76 {
77 return atomic_add_return(count, &pages_mapped) > limit;
78 }
79
gntdev_print_maps(struct gntdev_priv * priv,char * text,int text_index)80 static void gntdev_print_maps(struct gntdev_priv *priv,
81 char *text, int text_index)
82 {
83 #ifdef DEBUG
84 struct gntdev_grant_map *map;
85
86 pr_debug("%s: maps list (priv %p)\n", __func__, priv);
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
gntdev_free_map(struct gntdev_grant_map * map)94 static void gntdev_free_map(struct gntdev_grant_map *map)
95 {
96 if (map == NULL)
97 return;
98
99 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
100 if (map->dma_vaddr) {
101 struct gnttab_dma_alloc_args args;
102
103 args.dev = map->dma_dev;
104 args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT);
105 args.nr_pages = map->count;
106 args.pages = map->pages;
107 args.frames = map->frames;
108 args.vaddr = map->dma_vaddr;
109 args.dev_bus_addr = map->dma_bus_addr;
110
111 gnttab_dma_free_pages(&args);
112 } else
113 #endif
114 if (map->pages)
115 gnttab_free_pages(map->count, map->pages);
116
117 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
118 kfree(map->frames);
119 #endif
120 kfree(map->pages);
121 kfree(map->grants);
122 kfree(map->map_ops);
123 kfree(map->unmap_ops);
124 kfree(map->kmap_ops);
125 kfree(map->kunmap_ops);
126 kfree(map);
127 }
128
gntdev_alloc_map(struct gntdev_priv * priv,int count,int dma_flags)129 struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count,
130 int dma_flags)
131 {
132 struct gntdev_grant_map *add;
133 int i;
134
135 add = kzalloc(sizeof(*add), 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->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]), GFP_KERNEL);
144 add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
145 if (NULL == add->grants ||
146 NULL == add->map_ops ||
147 NULL == add->unmap_ops ||
148 NULL == add->kmap_ops ||
149 NULL == add->kunmap_ops ||
150 NULL == add->pages)
151 goto err;
152
153 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
154 add->dma_flags = dma_flags;
155
156 /*
157 * Check if this mapping is requested to be backed
158 * by a DMA buffer.
159 */
160 if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) {
161 struct gnttab_dma_alloc_args args;
162
163 add->frames = kcalloc(count, sizeof(add->frames[0]),
164 GFP_KERNEL);
165 if (!add->frames)
166 goto err;
167
168 /* Remember the device, so we can free DMA memory. */
169 add->dma_dev = priv->dma_dev;
170
171 args.dev = priv->dma_dev;
172 args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT);
173 args.nr_pages = count;
174 args.pages = add->pages;
175 args.frames = add->frames;
176
177 if (gnttab_dma_alloc_pages(&args))
178 goto err;
179
180 add->dma_vaddr = args.vaddr;
181 add->dma_bus_addr = args.dev_bus_addr;
182 } else
183 #endif
184 if (gnttab_alloc_pages(count, add->pages))
185 goto err;
186
187 for (i = 0; i < count; i++) {
188 add->map_ops[i].handle = -1;
189 add->unmap_ops[i].handle = -1;
190 add->kmap_ops[i].handle = -1;
191 add->kunmap_ops[i].handle = -1;
192 }
193
194 add->index = 0;
195 add->count = count;
196 refcount_set(&add->users, 1);
197
198 return add;
199
200 err:
201 gntdev_free_map(add);
202 return NULL;
203 }
204
gntdev_add_map(struct gntdev_priv * priv,struct gntdev_grant_map * add)205 void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add)
206 {
207 struct gntdev_grant_map *map;
208
209 list_for_each_entry(map, &priv->maps, next) {
210 if (add->index + add->count < map->index) {
211 list_add_tail(&add->next, &map->next);
212 goto done;
213 }
214 add->index = map->index + map->count;
215 }
216 list_add_tail(&add->next, &priv->maps);
217
218 done:
219 gntdev_print_maps(priv, "[new]", add->index);
220 }
221
gntdev_find_map_index(struct gntdev_priv * priv,int index,int count)222 static struct gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
223 int index, int count)
224 {
225 struct gntdev_grant_map *map;
226
227 list_for_each_entry(map, &priv->maps, next) {
228 if (map->index != index)
229 continue;
230 if (count && map->count != count)
231 continue;
232 return map;
233 }
234 return NULL;
235 }
236
gntdev_put_map(struct gntdev_priv * priv,struct gntdev_grant_map * map)237 void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map)
238 {
239 if (!map)
240 return;
241
242 if (!refcount_dec_and_test(&map->users))
243 return;
244
245 atomic_sub(map->count, &pages_mapped);
246
247 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
248 notify_remote_via_evtchn(map->notify.event);
249 evtchn_put(map->notify.event);
250 }
251
252 if (populate_freeable_maps && priv) {
253 mutex_lock(&priv->lock);
254 list_del(&map->next);
255 mutex_unlock(&priv->lock);
256 }
257
258 if (map->pages && !use_ptemod)
259 unmap_grant_pages(map, 0, map->count);
260 gntdev_free_map(map);
261 }
262
263 /* ------------------------------------------------------------------ */
264
find_grant_ptes(pte_t * pte,unsigned long addr,void * data)265 static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data)
266 {
267 struct gntdev_grant_map *map = data;
268 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
269 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
270 u64 pte_maddr;
271
272 BUG_ON(pgnr >= map->count);
273 pte_maddr = arbitrary_virt_to_machine(pte).maddr;
274
275 /*
276 * Set the PTE as special to force get_user_pages_fast() fall
277 * back to the slow path. If this is not supported as part of
278 * the grant map, it will be done afterwards.
279 */
280 if (xen_feature(XENFEAT_gnttab_map_avail_bits))
281 flags |= (1 << _GNTMAP_guest_avail0);
282
283 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
284 map->grants[pgnr].ref,
285 map->grants[pgnr].domid);
286 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
287 -1 /* handle */);
288 return 0;
289 }
290
291 #ifdef CONFIG_X86
set_grant_ptes_as_special(pte_t * pte,unsigned long addr,void * data)292 static int set_grant_ptes_as_special(pte_t *pte, unsigned long addr, void *data)
293 {
294 set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte));
295 return 0;
296 }
297 #endif
298
gntdev_map_grant_pages(struct gntdev_grant_map * map)299 int gntdev_map_grant_pages(struct gntdev_grant_map *map)
300 {
301 int i, err = 0;
302
303 if (!use_ptemod) {
304 /* Note: it could already be mapped */
305 if (map->map_ops[0].handle != -1)
306 return 0;
307 for (i = 0; i < map->count; i++) {
308 unsigned long addr = (unsigned long)
309 pfn_to_kaddr(page_to_pfn(map->pages[i]));
310 gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
311 map->grants[i].ref,
312 map->grants[i].domid);
313 gnttab_set_unmap_op(&map->unmap_ops[i], addr,
314 map->flags, -1 /* handle */);
315 }
316 } else {
317 /*
318 * Setup the map_ops corresponding to the pte entries pointing
319 * to the kernel linear addresses of the struct pages.
320 * These ptes are completely different from the user ptes dealt
321 * with find_grant_ptes.
322 */
323 for (i = 0; i < map->count; i++) {
324 unsigned long address = (unsigned long)
325 pfn_to_kaddr(page_to_pfn(map->pages[i]));
326 BUG_ON(PageHighMem(map->pages[i]));
327
328 gnttab_set_map_op(&map->kmap_ops[i], address,
329 map->flags | GNTMAP_host_map,
330 map->grants[i].ref,
331 map->grants[i].domid);
332 gnttab_set_unmap_op(&map->kunmap_ops[i], address,
333 map->flags | GNTMAP_host_map, -1);
334 }
335 }
336
337 pr_debug("map %d+%d\n", map->index, map->count);
338 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
339 map->pages, map->count);
340 if (err)
341 return err;
342
343 for (i = 0; i < map->count; i++) {
344 if (map->map_ops[i].status) {
345 err = -EINVAL;
346 continue;
347 }
348
349 map->unmap_ops[i].handle = map->map_ops[i].handle;
350 if (use_ptemod)
351 map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
352 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
353 else if (map->dma_vaddr) {
354 unsigned long bfn;
355
356 bfn = pfn_to_bfn(page_to_pfn(map->pages[i]));
357 map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn);
358 }
359 #endif
360 }
361 return err;
362 }
363
__unmap_grant_pages(struct gntdev_grant_map * map,int offset,int pages)364 static int __unmap_grant_pages(struct gntdev_grant_map *map, int offset,
365 int pages)
366 {
367 int i, err = 0;
368 struct gntab_unmap_queue_data unmap_data;
369
370 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
371 int pgno = (map->notify.addr >> PAGE_SHIFT);
372 if (pgno >= offset && pgno < offset + pages) {
373 /* No need for kmap, pages are in lowmem */
374 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
375 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
376 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
377 }
378 }
379
380 unmap_data.unmap_ops = map->unmap_ops + offset;
381 unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
382 unmap_data.pages = map->pages + offset;
383 unmap_data.count = pages;
384
385 err = gnttab_unmap_refs_sync(&unmap_data);
386 if (err)
387 return err;
388
389 for (i = 0; i < pages; i++) {
390 if (map->unmap_ops[offset+i].status)
391 err = -EINVAL;
392 pr_debug("unmap handle=%d st=%d\n",
393 map->unmap_ops[offset+i].handle,
394 map->unmap_ops[offset+i].status);
395 map->unmap_ops[offset+i].handle = -1;
396 }
397 return err;
398 }
399
unmap_grant_pages(struct gntdev_grant_map * map,int offset,int pages)400 static int unmap_grant_pages(struct gntdev_grant_map *map, int offset,
401 int pages)
402 {
403 int range, err = 0;
404
405 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
406
407 /* It is possible the requested range will have a "hole" where we
408 * already unmapped some of the grants. Only unmap valid ranges.
409 */
410 while (pages && !err) {
411 while (pages && map->unmap_ops[offset].handle == -1) {
412 offset++;
413 pages--;
414 }
415 range = 0;
416 while (range < pages) {
417 if (map->unmap_ops[offset+range].handle == -1)
418 break;
419 range++;
420 }
421 err = __unmap_grant_pages(map, offset, range);
422 offset += range;
423 pages -= range;
424 }
425
426 return err;
427 }
428
429 /* ------------------------------------------------------------------ */
430
gntdev_vma_open(struct vm_area_struct * vma)431 static void gntdev_vma_open(struct vm_area_struct *vma)
432 {
433 struct gntdev_grant_map *map = vma->vm_private_data;
434
435 pr_debug("gntdev_vma_open %p\n", vma);
436 refcount_inc(&map->users);
437 }
438
gntdev_vma_close(struct vm_area_struct * vma)439 static void gntdev_vma_close(struct vm_area_struct *vma)
440 {
441 struct gntdev_grant_map *map = vma->vm_private_data;
442 struct file *file = vma->vm_file;
443 struct gntdev_priv *priv = file->private_data;
444
445 pr_debug("gntdev_vma_close %p\n", vma);
446 if (use_ptemod) {
447 /* It is possible that an mmu notifier could be running
448 * concurrently, so take priv->lock to ensure that the vma won't
449 * vanishing during the unmap_grant_pages call, since we will
450 * spin here until that completes. Such a concurrent call will
451 * not do any unmapping, since that has been done prior to
452 * closing the vma, but it may still iterate the unmap_ops list.
453 */
454 mutex_lock(&priv->lock);
455 map->vma = NULL;
456 mutex_unlock(&priv->lock);
457 }
458 vma->vm_private_data = NULL;
459 gntdev_put_map(priv, map);
460 }
461
gntdev_vma_find_special_page(struct vm_area_struct * vma,unsigned long addr)462 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma,
463 unsigned long addr)
464 {
465 struct gntdev_grant_map *map = vma->vm_private_data;
466
467 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
468 }
469
470 static const struct vm_operations_struct gntdev_vmops = {
471 .open = gntdev_vma_open,
472 .close = gntdev_vma_close,
473 .find_special_page = gntdev_vma_find_special_page,
474 };
475
476 /* ------------------------------------------------------------------ */
477
in_range(struct gntdev_grant_map * map,unsigned long start,unsigned long end)478 static bool in_range(struct gntdev_grant_map *map,
479 unsigned long start, unsigned long end)
480 {
481 if (!map->vma)
482 return false;
483 if (map->vma->vm_start >= end)
484 return false;
485 if (map->vma->vm_end <= start)
486 return false;
487
488 return true;
489 }
490
unmap_if_in_range(struct gntdev_grant_map * map,unsigned long start,unsigned long end,bool blockable)491 static int unmap_if_in_range(struct gntdev_grant_map *map,
492 unsigned long start, unsigned long end,
493 bool blockable)
494 {
495 unsigned long mstart, mend;
496 int err;
497
498 if (!in_range(map, start, end))
499 return 0;
500
501 if (!blockable)
502 return -EAGAIN;
503
504 mstart = max(start, map->vma->vm_start);
505 mend = min(end, map->vma->vm_end);
506 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
507 map->index, map->count,
508 map->vma->vm_start, map->vma->vm_end,
509 start, end, mstart, mend);
510 err = unmap_grant_pages(map,
511 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
512 (mend - mstart) >> PAGE_SHIFT);
513 WARN_ON(err);
514
515 return 0;
516 }
517
mn_invl_range_start(struct mmu_notifier * mn,const struct mmu_notifier_range * range)518 static int mn_invl_range_start(struct mmu_notifier *mn,
519 const struct mmu_notifier_range *range)
520 {
521 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
522 struct gntdev_grant_map *map;
523 int ret = 0;
524
525 if (mmu_notifier_range_blockable(range))
526 mutex_lock(&priv->lock);
527 else if (!mutex_trylock(&priv->lock))
528 return -EAGAIN;
529
530 list_for_each_entry(map, &priv->maps, next) {
531 ret = unmap_if_in_range(map, range->start, range->end,
532 mmu_notifier_range_blockable(range));
533 if (ret)
534 goto out_unlock;
535 }
536 list_for_each_entry(map, &priv->freeable_maps, next) {
537 ret = unmap_if_in_range(map, range->start, range->end,
538 mmu_notifier_range_blockable(range));
539 if (ret)
540 goto out_unlock;
541 }
542
543 out_unlock:
544 mutex_unlock(&priv->lock);
545
546 return ret;
547 }
548
mn_release(struct mmu_notifier * mn,struct mm_struct * mm)549 static void mn_release(struct mmu_notifier *mn,
550 struct mm_struct *mm)
551 {
552 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
553 struct gntdev_grant_map *map;
554 int err;
555
556 mutex_lock(&priv->lock);
557 list_for_each_entry(map, &priv->maps, next) {
558 if (!map->vma)
559 continue;
560 pr_debug("map %d+%d (%lx %lx)\n",
561 map->index, map->count,
562 map->vma->vm_start, map->vma->vm_end);
563 err = unmap_grant_pages(map, /* offset */ 0, map->count);
564 WARN_ON(err);
565 }
566 list_for_each_entry(map, &priv->freeable_maps, next) {
567 if (!map->vma)
568 continue;
569 pr_debug("map %d+%d (%lx %lx)\n",
570 map->index, map->count,
571 map->vma->vm_start, map->vma->vm_end);
572 err = unmap_grant_pages(map, /* offset */ 0, map->count);
573 WARN_ON(err);
574 }
575 mutex_unlock(&priv->lock);
576 }
577
578 static const struct mmu_notifier_ops gntdev_mmu_ops = {
579 .release = mn_release,
580 .invalidate_range_start = mn_invl_range_start,
581 };
582
583 /* ------------------------------------------------------------------ */
584
gntdev_open(struct inode * inode,struct file * flip)585 static int gntdev_open(struct inode *inode, struct file *flip)
586 {
587 struct gntdev_priv *priv;
588 int ret = 0;
589
590 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
591 if (!priv)
592 return -ENOMEM;
593
594 INIT_LIST_HEAD(&priv->maps);
595 INIT_LIST_HEAD(&priv->freeable_maps);
596 mutex_init(&priv->lock);
597
598 #ifdef CONFIG_XEN_GNTDEV_DMABUF
599 priv->dmabuf_priv = gntdev_dmabuf_init(flip);
600 if (IS_ERR(priv->dmabuf_priv)) {
601 ret = PTR_ERR(priv->dmabuf_priv);
602 kfree(priv);
603 return ret;
604 }
605 #endif
606
607 if (use_ptemod) {
608 priv->mm = get_task_mm(current);
609 if (!priv->mm) {
610 kfree(priv);
611 return -ENOMEM;
612 }
613 priv->mn.ops = &gntdev_mmu_ops;
614 ret = mmu_notifier_register(&priv->mn, priv->mm);
615 mmput(priv->mm);
616 }
617
618 if (ret) {
619 kfree(priv);
620 return ret;
621 }
622
623 flip->private_data = priv;
624 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC
625 priv->dma_dev = gntdev_miscdev.this_device;
626 dma_coerce_mask_and_coherent(priv->dma_dev, DMA_BIT_MASK(64));
627 #endif
628 pr_debug("priv %p\n", priv);
629
630 return 0;
631 }
632
gntdev_release(struct inode * inode,struct file * flip)633 static int gntdev_release(struct inode *inode, struct file *flip)
634 {
635 struct gntdev_priv *priv = flip->private_data;
636 struct gntdev_grant_map *map;
637
638 pr_debug("priv %p\n", priv);
639
640 mutex_lock(&priv->lock);
641 while (!list_empty(&priv->maps)) {
642 map = list_entry(priv->maps.next,
643 struct gntdev_grant_map, next);
644 list_del(&map->next);
645 gntdev_put_map(NULL /* already removed */, map);
646 }
647 WARN_ON(!list_empty(&priv->freeable_maps));
648 mutex_unlock(&priv->lock);
649
650 #ifdef CONFIG_XEN_GNTDEV_DMABUF
651 gntdev_dmabuf_fini(priv->dmabuf_priv);
652 #endif
653
654 if (use_ptemod)
655 mmu_notifier_unregister(&priv->mn, priv->mm);
656
657 kfree(priv);
658 return 0;
659 }
660
gntdev_ioctl_map_grant_ref(struct gntdev_priv * priv,struct ioctl_gntdev_map_grant_ref __user * u)661 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
662 struct ioctl_gntdev_map_grant_ref __user *u)
663 {
664 struct ioctl_gntdev_map_grant_ref op;
665 struct gntdev_grant_map *map;
666 int err;
667
668 if (copy_from_user(&op, u, sizeof(op)) != 0)
669 return -EFAULT;
670 pr_debug("priv %p, add %d\n", priv, op.count);
671 if (unlikely(op.count <= 0))
672 return -EINVAL;
673
674 err = -ENOMEM;
675 map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */);
676 if (!map)
677 return err;
678
679 if (unlikely(gntdev_account_mapped_pages(op.count))) {
680 pr_debug("can't map: over limit\n");
681 gntdev_put_map(NULL, map);
682 return err;
683 }
684
685 if (copy_from_user(map->grants, &u->refs,
686 sizeof(map->grants[0]) * op.count) != 0) {
687 gntdev_put_map(NULL, map);
688 return -EFAULT;
689 }
690
691 mutex_lock(&priv->lock);
692 gntdev_add_map(priv, map);
693 op.index = map->index << PAGE_SHIFT;
694 mutex_unlock(&priv->lock);
695
696 if (copy_to_user(u, &op, sizeof(op)) != 0)
697 return -EFAULT;
698
699 return 0;
700 }
701
gntdev_ioctl_unmap_grant_ref(struct gntdev_priv * priv,struct ioctl_gntdev_unmap_grant_ref __user * u)702 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
703 struct ioctl_gntdev_unmap_grant_ref __user *u)
704 {
705 struct ioctl_gntdev_unmap_grant_ref op;
706 struct gntdev_grant_map *map;
707 int err = -ENOENT;
708
709 if (copy_from_user(&op, u, sizeof(op)) != 0)
710 return -EFAULT;
711 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
712
713 mutex_lock(&priv->lock);
714 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
715 if (map) {
716 list_del(&map->next);
717 if (populate_freeable_maps)
718 list_add_tail(&map->next, &priv->freeable_maps);
719 err = 0;
720 }
721 mutex_unlock(&priv->lock);
722 if (map)
723 gntdev_put_map(priv, map);
724 return err;
725 }
726
gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv * priv,struct ioctl_gntdev_get_offset_for_vaddr __user * u)727 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
728 struct ioctl_gntdev_get_offset_for_vaddr __user *u)
729 {
730 struct ioctl_gntdev_get_offset_for_vaddr op;
731 struct vm_area_struct *vma;
732 struct gntdev_grant_map *map;
733 int rv = -EINVAL;
734
735 if (copy_from_user(&op, u, sizeof(op)) != 0)
736 return -EFAULT;
737 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
738
739 down_read(¤t->mm->mmap_sem);
740 vma = find_vma(current->mm, op.vaddr);
741 if (!vma || vma->vm_ops != &gntdev_vmops)
742 goto out_unlock;
743
744 map = vma->vm_private_data;
745 if (!map)
746 goto out_unlock;
747
748 op.offset = map->index << PAGE_SHIFT;
749 op.count = map->count;
750 rv = 0;
751
752 out_unlock:
753 up_read(¤t->mm->mmap_sem);
754
755 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
756 return -EFAULT;
757 return rv;
758 }
759
gntdev_ioctl_notify(struct gntdev_priv * priv,void __user * u)760 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
761 {
762 struct ioctl_gntdev_unmap_notify op;
763 struct gntdev_grant_map *map;
764 int rc;
765 int out_flags;
766 unsigned int out_event;
767
768 if (copy_from_user(&op, u, sizeof(op)))
769 return -EFAULT;
770
771 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
772 return -EINVAL;
773
774 /* We need to grab a reference to the event channel we are going to use
775 * to send the notify before releasing the reference we may already have
776 * (if someone has called this ioctl twice). This is required so that
777 * it is possible to change the clear_byte part of the notification
778 * without disturbing the event channel part, which may now be the last
779 * reference to that event channel.
780 */
781 if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
782 if (evtchn_get(op.event_channel_port))
783 return -EINVAL;
784 }
785
786 out_flags = op.action;
787 out_event = op.event_channel_port;
788
789 mutex_lock(&priv->lock);
790
791 list_for_each_entry(map, &priv->maps, next) {
792 uint64_t begin = map->index << PAGE_SHIFT;
793 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
794 if (op.index >= begin && op.index < end)
795 goto found;
796 }
797 rc = -ENOENT;
798 goto unlock_out;
799
800 found:
801 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
802 (map->flags & GNTMAP_readonly)) {
803 rc = -EINVAL;
804 goto unlock_out;
805 }
806
807 out_flags = map->notify.flags;
808 out_event = map->notify.event;
809
810 map->notify.flags = op.action;
811 map->notify.addr = op.index - (map->index << PAGE_SHIFT);
812 map->notify.event = op.event_channel_port;
813
814 rc = 0;
815
816 unlock_out:
817 mutex_unlock(&priv->lock);
818
819 /* Drop the reference to the event channel we did not save in the map */
820 if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
821 evtchn_put(out_event);
822
823 return rc;
824 }
825
826 #define GNTDEV_COPY_BATCH 16
827
828 struct gntdev_copy_batch {
829 struct gnttab_copy ops[GNTDEV_COPY_BATCH];
830 struct page *pages[GNTDEV_COPY_BATCH];
831 s16 __user *status[GNTDEV_COPY_BATCH];
832 unsigned int nr_ops;
833 unsigned int nr_pages;
834 };
835
gntdev_get_page(struct gntdev_copy_batch * batch,void __user * virt,bool writeable,unsigned long * gfn)836 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt,
837 bool writeable, unsigned long *gfn)
838 {
839 unsigned long addr = (unsigned long)virt;
840 struct page *page;
841 unsigned long xen_pfn;
842 int ret;
843
844 ret = get_user_pages_fast(addr, 1, writeable ? FOLL_WRITE : 0, &page);
845 if (ret < 0)
846 return ret;
847
848 batch->pages[batch->nr_pages++] = page;
849
850 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK);
851 *gfn = pfn_to_gfn(xen_pfn);
852
853 return 0;
854 }
855
gntdev_put_pages(struct gntdev_copy_batch * batch)856 static void gntdev_put_pages(struct gntdev_copy_batch *batch)
857 {
858 unsigned int i;
859
860 for (i = 0; i < batch->nr_pages; i++)
861 put_page(batch->pages[i]);
862 batch->nr_pages = 0;
863 }
864
gntdev_copy(struct gntdev_copy_batch * batch)865 static int gntdev_copy(struct gntdev_copy_batch *batch)
866 {
867 unsigned int i;
868
869 gnttab_batch_copy(batch->ops, batch->nr_ops);
870 gntdev_put_pages(batch);
871
872 /*
873 * For each completed op, update the status if the op failed
874 * and all previous ops for the segment were successful.
875 */
876 for (i = 0; i < batch->nr_ops; i++) {
877 s16 status = batch->ops[i].status;
878 s16 old_status;
879
880 if (status == GNTST_okay)
881 continue;
882
883 if (__get_user(old_status, batch->status[i]))
884 return -EFAULT;
885
886 if (old_status != GNTST_okay)
887 continue;
888
889 if (__put_user(status, batch->status[i]))
890 return -EFAULT;
891 }
892
893 batch->nr_ops = 0;
894 return 0;
895 }
896
gntdev_grant_copy_seg(struct gntdev_copy_batch * batch,struct gntdev_grant_copy_segment * seg,s16 __user * status)897 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch,
898 struct gntdev_grant_copy_segment *seg,
899 s16 __user *status)
900 {
901 uint16_t copied = 0;
902
903 /*
904 * Disallow local -> local copies since there is only space in
905 * batch->pages for one page per-op and this would be a very
906 * expensive memcpy().
907 */
908 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref)))
909 return -EINVAL;
910
911 /* Can't cross page if source/dest is a grant ref. */
912 if (seg->flags & GNTCOPY_source_gref) {
913 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE)
914 return -EINVAL;
915 }
916 if (seg->flags & GNTCOPY_dest_gref) {
917 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE)
918 return -EINVAL;
919 }
920
921 if (put_user(GNTST_okay, status))
922 return -EFAULT;
923
924 while (copied < seg->len) {
925 struct gnttab_copy *op;
926 void __user *virt;
927 size_t len, off;
928 unsigned long gfn;
929 int ret;
930
931 if (batch->nr_ops >= GNTDEV_COPY_BATCH) {
932 ret = gntdev_copy(batch);
933 if (ret < 0)
934 return ret;
935 }
936
937 len = seg->len - copied;
938
939 op = &batch->ops[batch->nr_ops];
940 op->flags = 0;
941
942 if (seg->flags & GNTCOPY_source_gref) {
943 op->source.u.ref = seg->source.foreign.ref;
944 op->source.domid = seg->source.foreign.domid;
945 op->source.offset = seg->source.foreign.offset + copied;
946 op->flags |= GNTCOPY_source_gref;
947 } else {
948 virt = seg->source.virt + copied;
949 off = (unsigned long)virt & ~XEN_PAGE_MASK;
950 len = min(len, (size_t)XEN_PAGE_SIZE - off);
951
952 ret = gntdev_get_page(batch, virt, false, &gfn);
953 if (ret < 0)
954 return ret;
955
956 op->source.u.gmfn = gfn;
957 op->source.domid = DOMID_SELF;
958 op->source.offset = off;
959 }
960
961 if (seg->flags & GNTCOPY_dest_gref) {
962 op->dest.u.ref = seg->dest.foreign.ref;
963 op->dest.domid = seg->dest.foreign.domid;
964 op->dest.offset = seg->dest.foreign.offset + copied;
965 op->flags |= GNTCOPY_dest_gref;
966 } else {
967 virt = seg->dest.virt + copied;
968 off = (unsigned long)virt & ~XEN_PAGE_MASK;
969 len = min(len, (size_t)XEN_PAGE_SIZE - off);
970
971 ret = gntdev_get_page(batch, virt, true, &gfn);
972 if (ret < 0)
973 return ret;
974
975 op->dest.u.gmfn = gfn;
976 op->dest.domid = DOMID_SELF;
977 op->dest.offset = off;
978 }
979
980 op->len = len;
981 copied += len;
982
983 batch->status[batch->nr_ops] = status;
984 batch->nr_ops++;
985 }
986
987 return 0;
988 }
989
gntdev_ioctl_grant_copy(struct gntdev_priv * priv,void __user * u)990 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u)
991 {
992 struct ioctl_gntdev_grant_copy copy;
993 struct gntdev_copy_batch batch;
994 unsigned int i;
995 int ret = 0;
996
997 if (copy_from_user(©, u, sizeof(copy)))
998 return -EFAULT;
999
1000 batch.nr_ops = 0;
1001 batch.nr_pages = 0;
1002
1003 for (i = 0; i < copy.count; i++) {
1004 struct gntdev_grant_copy_segment seg;
1005
1006 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) {
1007 ret = -EFAULT;
1008 goto out;
1009 }
1010
1011 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status);
1012 if (ret < 0)
1013 goto out;
1014
1015 cond_resched();
1016 }
1017 if (batch.nr_ops)
1018 ret = gntdev_copy(&batch);
1019 return ret;
1020
1021 out:
1022 gntdev_put_pages(&batch);
1023 return ret;
1024 }
1025
gntdev_ioctl(struct file * flip,unsigned int cmd,unsigned long arg)1026 static long gntdev_ioctl(struct file *flip,
1027 unsigned int cmd, unsigned long arg)
1028 {
1029 struct gntdev_priv *priv = flip->private_data;
1030 void __user *ptr = (void __user *)arg;
1031
1032 switch (cmd) {
1033 case IOCTL_GNTDEV_MAP_GRANT_REF:
1034 return gntdev_ioctl_map_grant_ref(priv, ptr);
1035
1036 case IOCTL_GNTDEV_UNMAP_GRANT_REF:
1037 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
1038
1039 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
1040 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
1041
1042 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
1043 return gntdev_ioctl_notify(priv, ptr);
1044
1045 case IOCTL_GNTDEV_GRANT_COPY:
1046 return gntdev_ioctl_grant_copy(priv, ptr);
1047
1048 #ifdef CONFIG_XEN_GNTDEV_DMABUF
1049 case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS:
1050 return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr);
1051
1052 case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED:
1053 return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr);
1054
1055 case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS:
1056 return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr);
1057
1058 case IOCTL_GNTDEV_DMABUF_IMP_RELEASE:
1059 return gntdev_ioctl_dmabuf_imp_release(priv, ptr);
1060 #endif
1061
1062 default:
1063 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
1064 return -ENOIOCTLCMD;
1065 }
1066
1067 return 0;
1068 }
1069
gntdev_mmap(struct file * flip,struct vm_area_struct * vma)1070 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
1071 {
1072 struct gntdev_priv *priv = flip->private_data;
1073 int index = vma->vm_pgoff;
1074 int count = vma_pages(vma);
1075 struct gntdev_grant_map *map;
1076 int err = -EINVAL;
1077
1078 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
1079 return -EINVAL;
1080
1081 pr_debug("map %d+%d at %lx (pgoff %lx)\n",
1082 index, count, vma->vm_start, vma->vm_pgoff);
1083
1084 mutex_lock(&priv->lock);
1085 map = gntdev_find_map_index(priv, index, count);
1086 if (!map)
1087 goto unlock_out;
1088 if (use_ptemod && map->vma)
1089 goto unlock_out;
1090 if (use_ptemod && priv->mm != vma->vm_mm) {
1091 pr_warn("Huh? Other mm?\n");
1092 goto unlock_out;
1093 }
1094
1095 refcount_inc(&map->users);
1096
1097 vma->vm_ops = &gntdev_vmops;
1098
1099 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP;
1100
1101 if (use_ptemod)
1102 vma->vm_flags |= VM_DONTCOPY;
1103
1104 vma->vm_private_data = map;
1105
1106 if (use_ptemod)
1107 map->vma = vma;
1108
1109 if (map->flags) {
1110 if ((vma->vm_flags & VM_WRITE) &&
1111 (map->flags & GNTMAP_readonly))
1112 goto out_unlock_put;
1113 } else {
1114 map->flags = GNTMAP_host_map;
1115 if (!(vma->vm_flags & VM_WRITE))
1116 map->flags |= GNTMAP_readonly;
1117 }
1118
1119 mutex_unlock(&priv->lock);
1120
1121 if (use_ptemod) {
1122 map->pages_vm_start = vma->vm_start;
1123 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
1124 vma->vm_end - vma->vm_start,
1125 find_grant_ptes, map);
1126 if (err) {
1127 pr_warn("find_grant_ptes() failure.\n");
1128 goto out_put_map;
1129 }
1130 }
1131
1132 err = gntdev_map_grant_pages(map);
1133 if (err)
1134 goto out_put_map;
1135
1136 if (!use_ptemod) {
1137 err = vm_map_pages_zero(vma, map->pages, map->count);
1138 if (err)
1139 goto out_put_map;
1140 } else {
1141 #ifdef CONFIG_X86
1142 /*
1143 * If the PTEs were not made special by the grant map
1144 * hypercall, do so here.
1145 *
1146 * This is racy since the mapping is already visible
1147 * to userspace but userspace should be well-behaved
1148 * enough to not touch it until the mmap() call
1149 * returns.
1150 */
1151 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) {
1152 apply_to_page_range(vma->vm_mm, vma->vm_start,
1153 vma->vm_end - vma->vm_start,
1154 set_grant_ptes_as_special, NULL);
1155 }
1156 #endif
1157 }
1158
1159 return 0;
1160
1161 unlock_out:
1162 mutex_unlock(&priv->lock);
1163 return err;
1164
1165 out_unlock_put:
1166 mutex_unlock(&priv->lock);
1167 out_put_map:
1168 if (use_ptemod) {
1169 map->vma = NULL;
1170 unmap_grant_pages(map, 0, map->count);
1171 }
1172 gntdev_put_map(priv, map);
1173 return err;
1174 }
1175
1176 static const struct file_operations gntdev_fops = {
1177 .owner = THIS_MODULE,
1178 .open = gntdev_open,
1179 .release = gntdev_release,
1180 .mmap = gntdev_mmap,
1181 .unlocked_ioctl = gntdev_ioctl
1182 };
1183
1184 static struct miscdevice gntdev_miscdev = {
1185 .minor = MISC_DYNAMIC_MINOR,
1186 .name = "xen/gntdev",
1187 .fops = &gntdev_fops,
1188 };
1189
1190 /* ------------------------------------------------------------------ */
1191
gntdev_init(void)1192 static int __init gntdev_init(void)
1193 {
1194 int err;
1195
1196 if (!xen_domain())
1197 return -ENODEV;
1198
1199 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
1200
1201 err = misc_register(&gntdev_miscdev);
1202 if (err != 0) {
1203 pr_err("Could not register gntdev device\n");
1204 return err;
1205 }
1206 return 0;
1207 }
1208
gntdev_exit(void)1209 static void __exit gntdev_exit(void)
1210 {
1211 misc_deregister(&gntdev_miscdev);
1212 }
1213
1214 module_init(gntdev_init);
1215 module_exit(gntdev_exit);
1216
1217 /* ------------------------------------------------------------------ */
1218