Loading...
1/******************************************************************************
2 * grant_table.c
3 *
4 * Granting foreign access to our memory reservation.
5 *
6 * Copyright (c) 2005-2006, Christopher Clark
7 * Copyright (c) 2004-2005, K A Fraser
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version 2
11 * as published by the Free Software Foundation; or, when distributed
12 * separately from the Linux kernel or incorporated into other
13 * software packages, subject to the following license:
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining a copy
16 * of this source file (the "Software"), to deal in the Software without
17 * restriction, including without limitation the rights to use, copy, modify,
18 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19 * and to permit persons to whom the Software is furnished to do so, subject to
20 * the following conditions:
21 *
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31 * IN THE SOFTWARE.
32 */
33
34#include <linux/module.h>
35#include <linux/sched.h>
36#include <linux/mm.h>
37#include <linux/slab.h>
38#include <linux/vmalloc.h>
39#include <linux/uaccess.h>
40#include <linux/io.h>
41
42#include <xen/xen.h>
43#include <xen/interface/xen.h>
44#include <xen/page.h>
45#include <xen/grant_table.h>
46#include <xen/interface/memory.h>
47#include <asm/xen/hypercall.h>
48
49#include <asm/pgtable.h>
50#include <asm/sync_bitops.h>
51
52
53/* External tools reserve first few grant table entries. */
54#define NR_RESERVED_ENTRIES 8
55#define GNTTAB_LIST_END 0xffffffff
56#define GREFS_PER_GRANT_FRAME (PAGE_SIZE / sizeof(struct grant_entry))
57
58static grant_ref_t **gnttab_list;
59static unsigned int nr_grant_frames;
60static unsigned int boot_max_nr_grant_frames;
61static int gnttab_free_count;
62static grant_ref_t gnttab_free_head;
63static DEFINE_SPINLOCK(gnttab_list_lock);
64unsigned long xen_hvm_resume_frames;
65EXPORT_SYMBOL_GPL(xen_hvm_resume_frames);
66
67static struct grant_entry *shared;
68
69static struct gnttab_free_callback *gnttab_free_callback_list;
70
71static int gnttab_expand(unsigned int req_entries);
72
73#define RPP (PAGE_SIZE / sizeof(grant_ref_t))
74
75static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
76{
77 return &gnttab_list[(entry) / RPP][(entry) % RPP];
78}
79/* This can be used as an l-value */
80#define gnttab_entry(entry) (*__gnttab_entry(entry))
81
82static int get_free_entries(unsigned count)
83{
84 unsigned long flags;
85 int ref, rc = 0;
86 grant_ref_t head;
87
88 spin_lock_irqsave(&gnttab_list_lock, flags);
89
90 if ((gnttab_free_count < count) &&
91 ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
92 spin_unlock_irqrestore(&gnttab_list_lock, flags);
93 return rc;
94 }
95
96 ref = head = gnttab_free_head;
97 gnttab_free_count -= count;
98 while (count-- > 1)
99 head = gnttab_entry(head);
100 gnttab_free_head = gnttab_entry(head);
101 gnttab_entry(head) = GNTTAB_LIST_END;
102
103 spin_unlock_irqrestore(&gnttab_list_lock, flags);
104
105 return ref;
106}
107
108static void do_free_callbacks(void)
109{
110 struct gnttab_free_callback *callback, *next;
111
112 callback = gnttab_free_callback_list;
113 gnttab_free_callback_list = NULL;
114
115 while (callback != NULL) {
116 next = callback->next;
117 if (gnttab_free_count >= callback->count) {
118 callback->next = NULL;
119 callback->fn(callback->arg);
120 } else {
121 callback->next = gnttab_free_callback_list;
122 gnttab_free_callback_list = callback;
123 }
124 callback = next;
125 }
126}
127
128static inline void check_free_callbacks(void)
129{
130 if (unlikely(gnttab_free_callback_list))
131 do_free_callbacks();
132}
133
134static void put_free_entry(grant_ref_t ref)
135{
136 unsigned long flags;
137 spin_lock_irqsave(&gnttab_list_lock, flags);
138 gnttab_entry(ref) = gnttab_free_head;
139 gnttab_free_head = ref;
140 gnttab_free_count++;
141 check_free_callbacks();
142 spin_unlock_irqrestore(&gnttab_list_lock, flags);
143}
144
145static void update_grant_entry(grant_ref_t ref, domid_t domid,
146 unsigned long frame, unsigned flags)
147{
148 /*
149 * Introducing a valid entry into the grant table:
150 * 1. Write ent->domid.
151 * 2. Write ent->frame:
152 * GTF_permit_access: Frame to which access is permitted.
153 * GTF_accept_transfer: Pseudo-phys frame slot being filled by new
154 * frame, or zero if none.
155 * 3. Write memory barrier (WMB).
156 * 4. Write ent->flags, inc. valid type.
157 */
158 shared[ref].frame = frame;
159 shared[ref].domid = domid;
160 wmb();
161 shared[ref].flags = flags;
162}
163
164/*
165 * Public grant-issuing interface functions
166 */
167void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
168 unsigned long frame, int readonly)
169{
170 update_grant_entry(ref, domid, frame,
171 GTF_permit_access | (readonly ? GTF_readonly : 0));
172}
173EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
174
175int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
176 int readonly)
177{
178 int ref;
179
180 ref = get_free_entries(1);
181 if (unlikely(ref < 0))
182 return -ENOSPC;
183
184 gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
185
186 return ref;
187}
188EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
189
190int gnttab_query_foreign_access(grant_ref_t ref)
191{
192 u16 nflags;
193
194 nflags = shared[ref].flags;
195
196 return (nflags & (GTF_reading|GTF_writing));
197}
198EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
199
200int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
201{
202 u16 flags, nflags;
203
204 nflags = shared[ref].flags;
205 do {
206 flags = nflags;
207 if (flags & (GTF_reading|GTF_writing)) {
208 printk(KERN_ALERT "WARNING: g.e. still in use!\n");
209 return 0;
210 }
211 } while ((nflags = sync_cmpxchg(&shared[ref].flags, flags, 0)) != flags);
212
213 return 1;
214}
215EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
216
217void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
218 unsigned long page)
219{
220 if (gnttab_end_foreign_access_ref(ref, readonly)) {
221 put_free_entry(ref);
222 if (page != 0)
223 free_page(page);
224 } else {
225 /* XXX This needs to be fixed so that the ref and page are
226 placed on a list to be freed up later. */
227 printk(KERN_WARNING
228 "WARNING: leaking g.e. and page still in use!\n");
229 }
230}
231EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
232
233int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
234{
235 int ref;
236
237 ref = get_free_entries(1);
238 if (unlikely(ref < 0))
239 return -ENOSPC;
240 gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
241
242 return ref;
243}
244EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
245
246void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
247 unsigned long pfn)
248{
249 update_grant_entry(ref, domid, pfn, GTF_accept_transfer);
250}
251EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
252
253unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
254{
255 unsigned long frame;
256 u16 flags;
257
258 /*
259 * If a transfer is not even yet started, try to reclaim the grant
260 * reference and return failure (== 0).
261 */
262 while (!((flags = shared[ref].flags) & GTF_transfer_committed)) {
263 if (sync_cmpxchg(&shared[ref].flags, flags, 0) == flags)
264 return 0;
265 cpu_relax();
266 }
267
268 /* If a transfer is in progress then wait until it is completed. */
269 while (!(flags & GTF_transfer_completed)) {
270 flags = shared[ref].flags;
271 cpu_relax();
272 }
273
274 rmb(); /* Read the frame number /after/ reading completion status. */
275 frame = shared[ref].frame;
276 BUG_ON(frame == 0);
277
278 return frame;
279}
280EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
281
282unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
283{
284 unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
285 put_free_entry(ref);
286 return frame;
287}
288EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
289
290void gnttab_free_grant_reference(grant_ref_t ref)
291{
292 put_free_entry(ref);
293}
294EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
295
296void gnttab_free_grant_references(grant_ref_t head)
297{
298 grant_ref_t ref;
299 unsigned long flags;
300 int count = 1;
301 if (head == GNTTAB_LIST_END)
302 return;
303 spin_lock_irqsave(&gnttab_list_lock, flags);
304 ref = head;
305 while (gnttab_entry(ref) != GNTTAB_LIST_END) {
306 ref = gnttab_entry(ref);
307 count++;
308 }
309 gnttab_entry(ref) = gnttab_free_head;
310 gnttab_free_head = head;
311 gnttab_free_count += count;
312 check_free_callbacks();
313 spin_unlock_irqrestore(&gnttab_list_lock, flags);
314}
315EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
316
317int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
318{
319 int h = get_free_entries(count);
320
321 if (h < 0)
322 return -ENOSPC;
323
324 *head = h;
325
326 return 0;
327}
328EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
329
330int gnttab_empty_grant_references(const grant_ref_t *private_head)
331{
332 return (*private_head == GNTTAB_LIST_END);
333}
334EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
335
336int gnttab_claim_grant_reference(grant_ref_t *private_head)
337{
338 grant_ref_t g = *private_head;
339 if (unlikely(g == GNTTAB_LIST_END))
340 return -ENOSPC;
341 *private_head = gnttab_entry(g);
342 return g;
343}
344EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
345
346void gnttab_release_grant_reference(grant_ref_t *private_head,
347 grant_ref_t release)
348{
349 gnttab_entry(release) = *private_head;
350 *private_head = release;
351}
352EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
353
354void gnttab_request_free_callback(struct gnttab_free_callback *callback,
355 void (*fn)(void *), void *arg, u16 count)
356{
357 unsigned long flags;
358 spin_lock_irqsave(&gnttab_list_lock, flags);
359 if (callback->next)
360 goto out;
361 callback->fn = fn;
362 callback->arg = arg;
363 callback->count = count;
364 callback->next = gnttab_free_callback_list;
365 gnttab_free_callback_list = callback;
366 check_free_callbacks();
367out:
368 spin_unlock_irqrestore(&gnttab_list_lock, flags);
369}
370EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
371
372void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
373{
374 struct gnttab_free_callback **pcb;
375 unsigned long flags;
376
377 spin_lock_irqsave(&gnttab_list_lock, flags);
378 for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
379 if (*pcb == callback) {
380 *pcb = callback->next;
381 break;
382 }
383 }
384 spin_unlock_irqrestore(&gnttab_list_lock, flags);
385}
386EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
387
388static int grow_gnttab_list(unsigned int more_frames)
389{
390 unsigned int new_nr_grant_frames, extra_entries, i;
391 unsigned int nr_glist_frames, new_nr_glist_frames;
392
393 new_nr_grant_frames = nr_grant_frames + more_frames;
394 extra_entries = more_frames * GREFS_PER_GRANT_FRAME;
395
396 nr_glist_frames = (nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
397 new_nr_glist_frames =
398 (new_nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
399 for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
400 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
401 if (!gnttab_list[i])
402 goto grow_nomem;
403 }
404
405
406 for (i = GREFS_PER_GRANT_FRAME * nr_grant_frames;
407 i < GREFS_PER_GRANT_FRAME * new_nr_grant_frames - 1; i++)
408 gnttab_entry(i) = i + 1;
409
410 gnttab_entry(i) = gnttab_free_head;
411 gnttab_free_head = GREFS_PER_GRANT_FRAME * nr_grant_frames;
412 gnttab_free_count += extra_entries;
413
414 nr_grant_frames = new_nr_grant_frames;
415
416 check_free_callbacks();
417
418 return 0;
419
420grow_nomem:
421 for ( ; i >= nr_glist_frames; i--)
422 free_page((unsigned long) gnttab_list[i]);
423 return -ENOMEM;
424}
425
426static unsigned int __max_nr_grant_frames(void)
427{
428 struct gnttab_query_size query;
429 int rc;
430
431 query.dom = DOMID_SELF;
432
433 rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
434 if ((rc < 0) || (query.status != GNTST_okay))
435 return 4; /* Legacy max supported number of frames */
436
437 return query.max_nr_frames;
438}
439
440unsigned int gnttab_max_grant_frames(void)
441{
442 unsigned int xen_max = __max_nr_grant_frames();
443
444 if (xen_max > boot_max_nr_grant_frames)
445 return boot_max_nr_grant_frames;
446 return xen_max;
447}
448EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
449
450int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
451 struct page **pages, unsigned int count)
452{
453 int i, ret;
454 pte_t *pte;
455 unsigned long mfn;
456
457 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
458 if (ret)
459 return ret;
460
461 if (xen_feature(XENFEAT_auto_translated_physmap))
462 return ret;
463
464 for (i = 0; i < count; i++) {
465 /* Do not add to override if the map failed. */
466 if (map_ops[i].status)
467 continue;
468
469 if (map_ops[i].flags & GNTMAP_contains_pte) {
470 pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
471 (map_ops[i].host_addr & ~PAGE_MASK));
472 mfn = pte_mfn(*pte);
473 } else {
474 /* If you really wanted to do this:
475 * mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
476 *
477 * The reason we do not implement it is b/c on the
478 * unmap path (gnttab_unmap_refs) we have no means of
479 * checking whether the page is !GNTMAP_contains_pte.
480 *
481 * That is without some extra data-structure to carry
482 * the struct page, bool clear_pte, and list_head next
483 * tuples and deal with allocation/delallocation, etc.
484 *
485 * The users of this API set the GNTMAP_contains_pte
486 * flag so lets just return not supported until it
487 * becomes neccessary to implement.
488 */
489 return -EOPNOTSUPP;
490 }
491 ret = m2p_add_override(mfn, pages[i],
492 map_ops[i].flags & GNTMAP_contains_pte);
493 if (ret)
494 return ret;
495 }
496
497 return ret;
498}
499EXPORT_SYMBOL_GPL(gnttab_map_refs);
500
501int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
502 struct page **pages, unsigned int count)
503{
504 int i, ret;
505
506 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
507 if (ret)
508 return ret;
509
510 if (xen_feature(XENFEAT_auto_translated_physmap))
511 return ret;
512
513 for (i = 0; i < count; i++) {
514 ret = m2p_remove_override(pages[i], true /* clear the PTE */);
515 if (ret)
516 return ret;
517 }
518
519 return ret;
520}
521EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
522
523static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
524{
525 struct gnttab_setup_table setup;
526 unsigned long *frames;
527 unsigned int nr_gframes = end_idx + 1;
528 int rc;
529
530 if (xen_hvm_domain()) {
531 struct xen_add_to_physmap xatp;
532 unsigned int i = end_idx;
533 rc = 0;
534 /*
535 * Loop backwards, so that the first hypercall has the largest
536 * index, ensuring that the table will grow only once.
537 */
538 do {
539 xatp.domid = DOMID_SELF;
540 xatp.idx = i;
541 xatp.space = XENMAPSPACE_grant_table;
542 xatp.gpfn = (xen_hvm_resume_frames >> PAGE_SHIFT) + i;
543 rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
544 if (rc != 0) {
545 printk(KERN_WARNING
546 "grant table add_to_physmap failed, err=%d\n", rc);
547 break;
548 }
549 } while (i-- > start_idx);
550
551 return rc;
552 }
553
554 frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
555 if (!frames)
556 return -ENOMEM;
557
558 setup.dom = DOMID_SELF;
559 setup.nr_frames = nr_gframes;
560 set_xen_guest_handle(setup.frame_list, frames);
561
562 rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
563 if (rc == -ENOSYS) {
564 kfree(frames);
565 return -ENOSYS;
566 }
567
568 BUG_ON(rc || setup.status);
569
570 rc = arch_gnttab_map_shared(frames, nr_gframes, gnttab_max_grant_frames(),
571 &shared);
572 BUG_ON(rc);
573
574 kfree(frames);
575
576 return 0;
577}
578
579int gnttab_resume(void)
580{
581 unsigned int max_nr_gframes;
582
583 max_nr_gframes = gnttab_max_grant_frames();
584 if (max_nr_gframes < nr_grant_frames)
585 return -ENOSYS;
586
587 if (xen_pv_domain())
588 return gnttab_map(0, nr_grant_frames - 1);
589
590 if (!shared) {
591 shared = ioremap(xen_hvm_resume_frames, PAGE_SIZE * max_nr_gframes);
592 if (shared == NULL) {
593 printk(KERN_WARNING
594 "Failed to ioremap gnttab share frames!");
595 return -ENOMEM;
596 }
597 }
598
599 gnttab_map(0, nr_grant_frames - 1);
600
601 return 0;
602}
603
604int gnttab_suspend(void)
605{
606 arch_gnttab_unmap_shared(shared, nr_grant_frames);
607 return 0;
608}
609
610static int gnttab_expand(unsigned int req_entries)
611{
612 int rc;
613 unsigned int cur, extra;
614
615 cur = nr_grant_frames;
616 extra = ((req_entries + (GREFS_PER_GRANT_FRAME-1)) /
617 GREFS_PER_GRANT_FRAME);
618 if (cur + extra > gnttab_max_grant_frames())
619 return -ENOSPC;
620
621 rc = gnttab_map(cur, cur + extra - 1);
622 if (rc == 0)
623 rc = grow_gnttab_list(extra);
624
625 return rc;
626}
627
628int gnttab_init(void)
629{
630 int i;
631 unsigned int max_nr_glist_frames, nr_glist_frames;
632 unsigned int nr_init_grefs;
633
634 nr_grant_frames = 1;
635 boot_max_nr_grant_frames = __max_nr_grant_frames();
636
637 /* Determine the maximum number of frames required for the
638 * grant reference free list on the current hypervisor.
639 */
640 max_nr_glist_frames = (boot_max_nr_grant_frames *
641 GREFS_PER_GRANT_FRAME / RPP);
642
643 gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
644 GFP_KERNEL);
645 if (gnttab_list == NULL)
646 return -ENOMEM;
647
648 nr_glist_frames = (nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
649 for (i = 0; i < nr_glist_frames; i++) {
650 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
651 if (gnttab_list[i] == NULL)
652 goto ini_nomem;
653 }
654
655 if (gnttab_resume() < 0)
656 return -ENODEV;
657
658 nr_init_grefs = nr_grant_frames * GREFS_PER_GRANT_FRAME;
659
660 for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
661 gnttab_entry(i) = i + 1;
662
663 gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
664 gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
665 gnttab_free_head = NR_RESERVED_ENTRIES;
666
667 printk("Grant table initialized\n");
668 return 0;
669
670 ini_nomem:
671 for (i--; i >= 0; i--)
672 free_page((unsigned long)gnttab_list[i]);
673 kfree(gnttab_list);
674 return -ENOMEM;
675}
676EXPORT_SYMBOL_GPL(gnttab_init);
677
678static int __devinit __gnttab_init(void)
679{
680 /* Delay grant-table initialization in the PV on HVM case */
681 if (xen_hvm_domain())
682 return 0;
683
684 if (!xen_pv_domain())
685 return -ENODEV;
686
687 return gnttab_init();
688}
689
690core_initcall(__gnttab_init);
1/******************************************************************************
2 * grant_table.c
3 *
4 * Granting foreign access to our memory reservation.
5 *
6 * Copyright (c) 2005-2006, Christopher Clark
7 * Copyright (c) 2004-2005, K A Fraser
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License version 2
11 * as published by the Free Software Foundation; or, when distributed
12 * separately from the Linux kernel or incorporated into other
13 * software packages, subject to the following license:
14 *
15 * Permission is hereby granted, free of charge, to any person obtaining a copy
16 * of this source file (the "Software"), to deal in the Software without
17 * restriction, including without limitation the rights to use, copy, modify,
18 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
19 * and to permit persons to whom the Software is furnished to do so, subject to
20 * the following conditions:
21 *
22 * The above copyright notice and this permission notice shall be included in
23 * all copies or substantial portions of the Software.
24 *
25 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
26 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
27 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
28 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
29 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
30 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
31 * IN THE SOFTWARE.
32 */
33
34#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
35
36#include <linux/module.h>
37#include <linux/sched.h>
38#include <linux/mm.h>
39#include <linux/slab.h>
40#include <linux/vmalloc.h>
41#include <linux/uaccess.h>
42#include <linux/io.h>
43#include <linux/delay.h>
44#include <linux/hardirq.h>
45
46#include <xen/xen.h>
47#include <xen/interface/xen.h>
48#include <xen/page.h>
49#include <xen/grant_table.h>
50#include <xen/interface/memory.h>
51#include <xen/hvc-console.h>
52#include <xen/swiotlb-xen.h>
53#include <asm/xen/hypercall.h>
54#include <asm/xen/interface.h>
55
56#include <asm/pgtable.h>
57#include <asm/sync_bitops.h>
58
59/* External tools reserve first few grant table entries. */
60#define NR_RESERVED_ENTRIES 8
61#define GNTTAB_LIST_END 0xffffffff
62
63static grant_ref_t **gnttab_list;
64static unsigned int nr_grant_frames;
65static int gnttab_free_count;
66static grant_ref_t gnttab_free_head;
67static DEFINE_SPINLOCK(gnttab_list_lock);
68struct grant_frames xen_auto_xlat_grant_frames;
69
70static union {
71 struct grant_entry_v1 *v1;
72 union grant_entry_v2 *v2;
73 void *addr;
74} gnttab_shared;
75
76/*This is a structure of function pointers for grant table*/
77struct gnttab_ops {
78 /*
79 * Mapping a list of frames for storing grant entries. Frames parameter
80 * is used to store grant table address when grant table being setup,
81 * nr_gframes is the number of frames to map grant table. Returning
82 * GNTST_okay means success and negative value means failure.
83 */
84 int (*map_frames)(xen_pfn_t *frames, unsigned int nr_gframes);
85 /*
86 * Release a list of frames which are mapped in map_frames for grant
87 * entry status.
88 */
89 void (*unmap_frames)(void);
90 /*
91 * Introducing a valid entry into the grant table, granting the frame of
92 * this grant entry to domain for accessing or transfering. Ref
93 * parameter is reference of this introduced grant entry, domid is id of
94 * granted domain, frame is the page frame to be granted, and flags is
95 * status of the grant entry to be updated.
96 */
97 void (*update_entry)(grant_ref_t ref, domid_t domid,
98 unsigned long frame, unsigned flags);
99 /*
100 * Stop granting a grant entry to domain for accessing. Ref parameter is
101 * reference of a grant entry whose grant access will be stopped,
102 * readonly is not in use in this function. If the grant entry is
103 * currently mapped for reading or writing, just return failure(==0)
104 * directly and don't tear down the grant access. Otherwise, stop grant
105 * access for this entry and return success(==1).
106 */
107 int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
108 /*
109 * Stop granting a grant entry to domain for transfer. Ref parameter is
110 * reference of a grant entry whose grant transfer will be stopped. If
111 * tranfer has not started, just reclaim the grant entry and return
112 * failure(==0). Otherwise, wait for the transfer to complete and then
113 * return the frame.
114 */
115 unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
116 /*
117 * Query the status of a grant entry. Ref parameter is reference of
118 * queried grant entry, return value is the status of queried entry.
119 * Detailed status(writing/reading) can be gotten from the return value
120 * by bit operations.
121 */
122 int (*query_foreign_access)(grant_ref_t ref);
123 /*
124 * Grant a domain to access a range of bytes within the page referred by
125 * an available grant entry. Ref parameter is reference of a grant entry
126 * which will be sub-page accessed, domid is id of grantee domain, frame
127 * is frame address of subpage grant, flags is grant type and flag
128 * information, page_off is offset of the range of bytes, and length is
129 * length of bytes to be accessed.
130 */
131 void (*update_subpage_entry)(grant_ref_t ref, domid_t domid,
132 unsigned long frame, int flags,
133 unsigned page_off, unsigned length);
134 /*
135 * Redirect an available grant entry on domain A to another grant
136 * reference of domain B, then allow domain C to use grant reference
137 * of domain B transitively. Ref parameter is an available grant entry
138 * reference on domain A, domid is id of domain C which accesses grant
139 * entry transitively, flags is grant type and flag information,
140 * trans_domid is id of domain B whose grant entry is finally accessed
141 * transitively, trans_gref is grant entry transitive reference of
142 * domain B.
143 */
144 void (*update_trans_entry)(grant_ref_t ref, domid_t domid, int flags,
145 domid_t trans_domid, grant_ref_t trans_gref);
146};
147
148static struct gnttab_ops *gnttab_interface;
149
150/*This reflects status of grant entries, so act as a global value*/
151static grant_status_t *grstatus;
152
153static int grant_table_version;
154static int grefs_per_grant_frame;
155
156static struct gnttab_free_callback *gnttab_free_callback_list;
157
158static int gnttab_expand(unsigned int req_entries);
159
160#define RPP (PAGE_SIZE / sizeof(grant_ref_t))
161#define SPP (PAGE_SIZE / sizeof(grant_status_t))
162
163static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
164{
165 return &gnttab_list[(entry) / RPP][(entry) % RPP];
166}
167/* This can be used as an l-value */
168#define gnttab_entry(entry) (*__gnttab_entry(entry))
169
170static int get_free_entries(unsigned count)
171{
172 unsigned long flags;
173 int ref, rc = 0;
174 grant_ref_t head;
175
176 spin_lock_irqsave(&gnttab_list_lock, flags);
177
178 if ((gnttab_free_count < count) &&
179 ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
180 spin_unlock_irqrestore(&gnttab_list_lock, flags);
181 return rc;
182 }
183
184 ref = head = gnttab_free_head;
185 gnttab_free_count -= count;
186 while (count-- > 1)
187 head = gnttab_entry(head);
188 gnttab_free_head = gnttab_entry(head);
189 gnttab_entry(head) = GNTTAB_LIST_END;
190
191 spin_unlock_irqrestore(&gnttab_list_lock, flags);
192
193 return ref;
194}
195
196static void do_free_callbacks(void)
197{
198 struct gnttab_free_callback *callback, *next;
199
200 callback = gnttab_free_callback_list;
201 gnttab_free_callback_list = NULL;
202
203 while (callback != NULL) {
204 next = callback->next;
205 if (gnttab_free_count >= callback->count) {
206 callback->next = NULL;
207 callback->fn(callback->arg);
208 } else {
209 callback->next = gnttab_free_callback_list;
210 gnttab_free_callback_list = callback;
211 }
212 callback = next;
213 }
214}
215
216static inline void check_free_callbacks(void)
217{
218 if (unlikely(gnttab_free_callback_list))
219 do_free_callbacks();
220}
221
222static void put_free_entry(grant_ref_t ref)
223{
224 unsigned long flags;
225 spin_lock_irqsave(&gnttab_list_lock, flags);
226 gnttab_entry(ref) = gnttab_free_head;
227 gnttab_free_head = ref;
228 gnttab_free_count++;
229 check_free_callbacks();
230 spin_unlock_irqrestore(&gnttab_list_lock, flags);
231}
232
233/*
234 * Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2.
235 * Introducing a valid entry into the grant table:
236 * 1. Write ent->domid.
237 * 2. Write ent->frame:
238 * GTF_permit_access: Frame to which access is permitted.
239 * GTF_accept_transfer: Pseudo-phys frame slot being filled by new
240 * frame, or zero if none.
241 * 3. Write memory barrier (WMB).
242 * 4. Write ent->flags, inc. valid type.
243 */
244static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
245 unsigned long frame, unsigned flags)
246{
247 gnttab_shared.v1[ref].domid = domid;
248 gnttab_shared.v1[ref].frame = frame;
249 wmb();
250 gnttab_shared.v1[ref].flags = flags;
251}
252
253static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid,
254 unsigned long frame, unsigned flags)
255{
256 gnttab_shared.v2[ref].hdr.domid = domid;
257 gnttab_shared.v2[ref].full_page.frame = frame;
258 wmb();
259 gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags;
260}
261
262/*
263 * Public grant-issuing interface functions
264 */
265void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
266 unsigned long frame, int readonly)
267{
268 gnttab_interface->update_entry(ref, domid, frame,
269 GTF_permit_access | (readonly ? GTF_readonly : 0));
270}
271EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
272
273int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
274 int readonly)
275{
276 int ref;
277
278 ref = get_free_entries(1);
279 if (unlikely(ref < 0))
280 return -ENOSPC;
281
282 gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
283
284 return ref;
285}
286EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
287
288static void gnttab_update_subpage_entry_v2(grant_ref_t ref, domid_t domid,
289 unsigned long frame, int flags,
290 unsigned page_off, unsigned length)
291{
292 gnttab_shared.v2[ref].sub_page.frame = frame;
293 gnttab_shared.v2[ref].sub_page.page_off = page_off;
294 gnttab_shared.v2[ref].sub_page.length = length;
295 gnttab_shared.v2[ref].hdr.domid = domid;
296 wmb();
297 gnttab_shared.v2[ref].hdr.flags =
298 GTF_permit_access | GTF_sub_page | flags;
299}
300
301int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid,
302 unsigned long frame, int flags,
303 unsigned page_off,
304 unsigned length)
305{
306 if (flags & (GTF_accept_transfer | GTF_reading |
307 GTF_writing | GTF_transitive))
308 return -EPERM;
309
310 if (gnttab_interface->update_subpage_entry == NULL)
311 return -ENOSYS;
312
313 gnttab_interface->update_subpage_entry(ref, domid, frame, flags,
314 page_off, length);
315
316 return 0;
317}
318EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage_ref);
319
320int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
321 int flags, unsigned page_off,
322 unsigned length)
323{
324 int ref, rc;
325
326 ref = get_free_entries(1);
327 if (unlikely(ref < 0))
328 return -ENOSPC;
329
330 rc = gnttab_grant_foreign_access_subpage_ref(ref, domid, frame, flags,
331 page_off, length);
332 if (rc < 0) {
333 put_free_entry(ref);
334 return rc;
335 }
336
337 return ref;
338}
339EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage);
340
341bool gnttab_subpage_grants_available(void)
342{
343 return gnttab_interface->update_subpage_entry != NULL;
344}
345EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available);
346
347static void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid,
348 int flags, domid_t trans_domid,
349 grant_ref_t trans_gref)
350{
351 gnttab_shared.v2[ref].transitive.trans_domid = trans_domid;
352 gnttab_shared.v2[ref].transitive.gref = trans_gref;
353 gnttab_shared.v2[ref].hdr.domid = domid;
354 wmb();
355 gnttab_shared.v2[ref].hdr.flags =
356 GTF_permit_access | GTF_transitive | flags;
357}
358
359int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
360 int flags, domid_t trans_domid,
361 grant_ref_t trans_gref)
362{
363 if (flags & (GTF_accept_transfer | GTF_reading |
364 GTF_writing | GTF_sub_page))
365 return -EPERM;
366
367 if (gnttab_interface->update_trans_entry == NULL)
368 return -ENOSYS;
369
370 gnttab_interface->update_trans_entry(ref, domid, flags, trans_domid,
371 trans_gref);
372
373 return 0;
374}
375EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans_ref);
376
377int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
378 domid_t trans_domid,
379 grant_ref_t trans_gref)
380{
381 int ref, rc;
382
383 ref = get_free_entries(1);
384 if (unlikely(ref < 0))
385 return -ENOSPC;
386
387 rc = gnttab_grant_foreign_access_trans_ref(ref, domid, flags,
388 trans_domid, trans_gref);
389 if (rc < 0) {
390 put_free_entry(ref);
391 return rc;
392 }
393
394 return ref;
395}
396EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans);
397
398bool gnttab_trans_grants_available(void)
399{
400 return gnttab_interface->update_trans_entry != NULL;
401}
402EXPORT_SYMBOL_GPL(gnttab_trans_grants_available);
403
404static int gnttab_query_foreign_access_v1(grant_ref_t ref)
405{
406 return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
407}
408
409static int gnttab_query_foreign_access_v2(grant_ref_t ref)
410{
411 return grstatus[ref] & (GTF_reading|GTF_writing);
412}
413
414int gnttab_query_foreign_access(grant_ref_t ref)
415{
416 return gnttab_interface->query_foreign_access(ref);
417}
418EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
419
420static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
421{
422 u16 flags, nflags;
423 u16 *pflags;
424
425 pflags = &gnttab_shared.v1[ref].flags;
426 nflags = *pflags;
427 do {
428 flags = nflags;
429 if (flags & (GTF_reading|GTF_writing))
430 return 0;
431 } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
432
433 return 1;
434}
435
436static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly)
437{
438 gnttab_shared.v2[ref].hdr.flags = 0;
439 mb();
440 if (grstatus[ref] & (GTF_reading|GTF_writing)) {
441 return 0;
442 } else {
443 /* The read of grstatus needs to have acquire
444 semantics. On x86, reads already have
445 that, and we just need to protect against
446 compiler reorderings. On other
447 architectures we may need a full
448 barrier. */
449#ifdef CONFIG_X86
450 barrier();
451#else
452 mb();
453#endif
454 }
455
456 return 1;
457}
458
459static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
460{
461 return gnttab_interface->end_foreign_access_ref(ref, readonly);
462}
463
464int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
465{
466 if (_gnttab_end_foreign_access_ref(ref, readonly))
467 return 1;
468 pr_warn("WARNING: g.e. %#x still in use!\n", ref);
469 return 0;
470}
471EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
472
473struct deferred_entry {
474 struct list_head list;
475 grant_ref_t ref;
476 bool ro;
477 uint16_t warn_delay;
478 struct page *page;
479};
480static LIST_HEAD(deferred_list);
481static void gnttab_handle_deferred(unsigned long);
482static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
483
484static void gnttab_handle_deferred(unsigned long unused)
485{
486 unsigned int nr = 10;
487 struct deferred_entry *first = NULL;
488 unsigned long flags;
489
490 spin_lock_irqsave(&gnttab_list_lock, flags);
491 while (nr--) {
492 struct deferred_entry *entry
493 = list_first_entry(&deferred_list,
494 struct deferred_entry, list);
495
496 if (entry == first)
497 break;
498 list_del(&entry->list);
499 spin_unlock_irqrestore(&gnttab_list_lock, flags);
500 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
501 put_free_entry(entry->ref);
502 if (entry->page) {
503 pr_debug("freeing g.e. %#x (pfn %#lx)\n",
504 entry->ref, page_to_pfn(entry->page));
505 __free_page(entry->page);
506 } else
507 pr_info("freeing g.e. %#x\n", entry->ref);
508 kfree(entry);
509 entry = NULL;
510 } else {
511 if (!--entry->warn_delay)
512 pr_info("g.e. %#x still pending\n", entry->ref);
513 if (!first)
514 first = entry;
515 }
516 spin_lock_irqsave(&gnttab_list_lock, flags);
517 if (entry)
518 list_add_tail(&entry->list, &deferred_list);
519 else if (list_empty(&deferred_list))
520 break;
521 }
522 if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
523 deferred_timer.expires = jiffies + HZ;
524 add_timer(&deferred_timer);
525 }
526 spin_unlock_irqrestore(&gnttab_list_lock, flags);
527}
528
529static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
530 struct page *page)
531{
532 struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
533 const char *what = KERN_WARNING "leaking";
534
535 if (entry) {
536 unsigned long flags;
537
538 entry->ref = ref;
539 entry->ro = readonly;
540 entry->page = page;
541 entry->warn_delay = 60;
542 spin_lock_irqsave(&gnttab_list_lock, flags);
543 list_add_tail(&entry->list, &deferred_list);
544 if (!timer_pending(&deferred_timer)) {
545 deferred_timer.expires = jiffies + HZ;
546 add_timer(&deferred_timer);
547 }
548 spin_unlock_irqrestore(&gnttab_list_lock, flags);
549 what = KERN_DEBUG "deferring";
550 }
551 printk("%s g.e. %#x (pfn %#lx)\n",
552 what, ref, page ? page_to_pfn(page) : -1);
553}
554
555void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
556 unsigned long page)
557{
558 if (gnttab_end_foreign_access_ref(ref, readonly)) {
559 put_free_entry(ref);
560 if (page != 0)
561 free_page(page);
562 } else
563 gnttab_add_deferred(ref, readonly,
564 page ? virt_to_page(page) : NULL);
565}
566EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
567
568int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
569{
570 int ref;
571
572 ref = get_free_entries(1);
573 if (unlikely(ref < 0))
574 return -ENOSPC;
575 gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
576
577 return ref;
578}
579EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
580
581void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
582 unsigned long pfn)
583{
584 gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
585}
586EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
587
588static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
589{
590 unsigned long frame;
591 u16 flags;
592 u16 *pflags;
593
594 pflags = &gnttab_shared.v1[ref].flags;
595
596 /*
597 * If a transfer is not even yet started, try to reclaim the grant
598 * reference and return failure (== 0).
599 */
600 while (!((flags = *pflags) & GTF_transfer_committed)) {
601 if (sync_cmpxchg(pflags, flags, 0) == flags)
602 return 0;
603 cpu_relax();
604 }
605
606 /* If a transfer is in progress then wait until it is completed. */
607 while (!(flags & GTF_transfer_completed)) {
608 flags = *pflags;
609 cpu_relax();
610 }
611
612 rmb(); /* Read the frame number /after/ reading completion status. */
613 frame = gnttab_shared.v1[ref].frame;
614 BUG_ON(frame == 0);
615
616 return frame;
617}
618
619static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref)
620{
621 unsigned long frame;
622 u16 flags;
623 u16 *pflags;
624
625 pflags = &gnttab_shared.v2[ref].hdr.flags;
626
627 /*
628 * If a transfer is not even yet started, try to reclaim the grant
629 * reference and return failure (== 0).
630 */
631 while (!((flags = *pflags) & GTF_transfer_committed)) {
632 if (sync_cmpxchg(pflags, flags, 0) == flags)
633 return 0;
634 cpu_relax();
635 }
636
637 /* If a transfer is in progress then wait until it is completed. */
638 while (!(flags & GTF_transfer_completed)) {
639 flags = *pflags;
640 cpu_relax();
641 }
642
643 rmb(); /* Read the frame number /after/ reading completion status. */
644 frame = gnttab_shared.v2[ref].full_page.frame;
645 BUG_ON(frame == 0);
646
647 return frame;
648}
649
650unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
651{
652 return gnttab_interface->end_foreign_transfer_ref(ref);
653}
654EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
655
656unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
657{
658 unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
659 put_free_entry(ref);
660 return frame;
661}
662EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
663
664void gnttab_free_grant_reference(grant_ref_t ref)
665{
666 put_free_entry(ref);
667}
668EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
669
670void gnttab_free_grant_references(grant_ref_t head)
671{
672 grant_ref_t ref;
673 unsigned long flags;
674 int count = 1;
675 if (head == GNTTAB_LIST_END)
676 return;
677 spin_lock_irqsave(&gnttab_list_lock, flags);
678 ref = head;
679 while (gnttab_entry(ref) != GNTTAB_LIST_END) {
680 ref = gnttab_entry(ref);
681 count++;
682 }
683 gnttab_entry(ref) = gnttab_free_head;
684 gnttab_free_head = head;
685 gnttab_free_count += count;
686 check_free_callbacks();
687 spin_unlock_irqrestore(&gnttab_list_lock, flags);
688}
689EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
690
691int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
692{
693 int h = get_free_entries(count);
694
695 if (h < 0)
696 return -ENOSPC;
697
698 *head = h;
699
700 return 0;
701}
702EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
703
704int gnttab_empty_grant_references(const grant_ref_t *private_head)
705{
706 return (*private_head == GNTTAB_LIST_END);
707}
708EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
709
710int gnttab_claim_grant_reference(grant_ref_t *private_head)
711{
712 grant_ref_t g = *private_head;
713 if (unlikely(g == GNTTAB_LIST_END))
714 return -ENOSPC;
715 *private_head = gnttab_entry(g);
716 return g;
717}
718EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
719
720void gnttab_release_grant_reference(grant_ref_t *private_head,
721 grant_ref_t release)
722{
723 gnttab_entry(release) = *private_head;
724 *private_head = release;
725}
726EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
727
728void gnttab_request_free_callback(struct gnttab_free_callback *callback,
729 void (*fn)(void *), void *arg, u16 count)
730{
731 unsigned long flags;
732 struct gnttab_free_callback *cb;
733
734 spin_lock_irqsave(&gnttab_list_lock, flags);
735
736 /* Check if the callback is already on the list */
737 cb = gnttab_free_callback_list;
738 while (cb) {
739 if (cb == callback)
740 goto out;
741 cb = cb->next;
742 }
743
744 callback->fn = fn;
745 callback->arg = arg;
746 callback->count = count;
747 callback->next = gnttab_free_callback_list;
748 gnttab_free_callback_list = callback;
749 check_free_callbacks();
750out:
751 spin_unlock_irqrestore(&gnttab_list_lock, flags);
752}
753EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
754
755void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
756{
757 struct gnttab_free_callback **pcb;
758 unsigned long flags;
759
760 spin_lock_irqsave(&gnttab_list_lock, flags);
761 for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
762 if (*pcb == callback) {
763 *pcb = callback->next;
764 break;
765 }
766 }
767 spin_unlock_irqrestore(&gnttab_list_lock, flags);
768}
769EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
770
771static int grow_gnttab_list(unsigned int more_frames)
772{
773 unsigned int new_nr_grant_frames, extra_entries, i;
774 unsigned int nr_glist_frames, new_nr_glist_frames;
775
776 BUG_ON(grefs_per_grant_frame == 0);
777
778 new_nr_grant_frames = nr_grant_frames + more_frames;
779 extra_entries = more_frames * grefs_per_grant_frame;
780
781 nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
782 new_nr_glist_frames =
783 (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
784 for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
785 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
786 if (!gnttab_list[i])
787 goto grow_nomem;
788 }
789
790
791 for (i = grefs_per_grant_frame * nr_grant_frames;
792 i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
793 gnttab_entry(i) = i + 1;
794
795 gnttab_entry(i) = gnttab_free_head;
796 gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
797 gnttab_free_count += extra_entries;
798
799 nr_grant_frames = new_nr_grant_frames;
800
801 check_free_callbacks();
802
803 return 0;
804
805grow_nomem:
806 for ( ; i >= nr_glist_frames; i--)
807 free_page((unsigned long) gnttab_list[i]);
808 return -ENOMEM;
809}
810
811static unsigned int __max_nr_grant_frames(void)
812{
813 struct gnttab_query_size query;
814 int rc;
815
816 query.dom = DOMID_SELF;
817
818 rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
819 if ((rc < 0) || (query.status != GNTST_okay))
820 return 4; /* Legacy max supported number of frames */
821
822 return query.max_nr_frames;
823}
824
825unsigned int gnttab_max_grant_frames(void)
826{
827 unsigned int xen_max = __max_nr_grant_frames();
828 static unsigned int boot_max_nr_grant_frames;
829
830 /* First time, initialize it properly. */
831 if (!boot_max_nr_grant_frames)
832 boot_max_nr_grant_frames = __max_nr_grant_frames();
833
834 if (xen_max > boot_max_nr_grant_frames)
835 return boot_max_nr_grant_frames;
836 return xen_max;
837}
838EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
839
840int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
841{
842 xen_pfn_t *pfn;
843 unsigned int max_nr_gframes = __max_nr_grant_frames();
844 unsigned int i;
845 void *vaddr;
846
847 if (xen_auto_xlat_grant_frames.count)
848 return -EINVAL;
849
850 vaddr = xen_remap(addr, PAGE_SIZE * max_nr_gframes);
851 if (vaddr == NULL) {
852 pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
853 &addr);
854 return -ENOMEM;
855 }
856 pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
857 if (!pfn) {
858 xen_unmap(vaddr);
859 return -ENOMEM;
860 }
861 for (i = 0; i < max_nr_gframes; i++)
862 pfn[i] = PFN_DOWN(addr) + i;
863
864 xen_auto_xlat_grant_frames.vaddr = vaddr;
865 xen_auto_xlat_grant_frames.pfn = pfn;
866 xen_auto_xlat_grant_frames.count = max_nr_gframes;
867
868 return 0;
869}
870EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
871
872void gnttab_free_auto_xlat_frames(void)
873{
874 if (!xen_auto_xlat_grant_frames.count)
875 return;
876 kfree(xen_auto_xlat_grant_frames.pfn);
877 xen_unmap(xen_auto_xlat_grant_frames.vaddr);
878
879 xen_auto_xlat_grant_frames.pfn = NULL;
880 xen_auto_xlat_grant_frames.count = 0;
881 xen_auto_xlat_grant_frames.vaddr = NULL;
882}
883EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
884
885/* Handling of paged out grant targets (GNTST_eagain) */
886#define MAX_DELAY 256
887static inline void
888gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
889 const char *func)
890{
891 unsigned delay = 1;
892
893 do {
894 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
895 if (*status == GNTST_eagain)
896 msleep(delay++);
897 } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
898
899 if (delay >= MAX_DELAY) {
900 pr_err("%s: %s eagain grant\n", func, current->comm);
901 *status = GNTST_bad_page;
902 }
903}
904
905void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
906{
907 struct gnttab_map_grant_ref *op;
908
909 if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
910 BUG();
911 for (op = batch; op < batch + count; op++)
912 if (op->status == GNTST_eagain)
913 gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
914 &op->status, __func__);
915}
916EXPORT_SYMBOL_GPL(gnttab_batch_map);
917
918void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
919{
920 struct gnttab_copy *op;
921
922 if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
923 BUG();
924 for (op = batch; op < batch + count; op++)
925 if (op->status == GNTST_eagain)
926 gnttab_retry_eagain_gop(GNTTABOP_copy, op,
927 &op->status, __func__);
928}
929EXPORT_SYMBOL_GPL(gnttab_batch_copy);
930
931int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
932 struct gnttab_map_grant_ref *kmap_ops,
933 struct page **pages, unsigned int count)
934{
935 int i, ret;
936
937 ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
938 if (ret)
939 return ret;
940
941 /* Retry eagain maps */
942 for (i = 0; i < count; i++)
943 if (map_ops[i].status == GNTST_eagain)
944 gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
945 &map_ops[i].status, __func__);
946
947 return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
948}
949EXPORT_SYMBOL_GPL(gnttab_map_refs);
950
951int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
952 struct gnttab_map_grant_ref *kmap_ops,
953 struct page **pages, unsigned int count)
954{
955 int ret;
956
957 ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
958 if (ret)
959 return ret;
960
961 return clear_foreign_p2m_mapping(unmap_ops, kmap_ops, pages, count);
962}
963EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
964
965static unsigned nr_status_frames(unsigned nr_grant_frames)
966{
967 BUG_ON(grefs_per_grant_frame == 0);
968 return (nr_grant_frames * grefs_per_grant_frame + SPP - 1) / SPP;
969}
970
971static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
972{
973 int rc;
974
975 rc = arch_gnttab_map_shared(frames, nr_gframes,
976 gnttab_max_grant_frames(),
977 &gnttab_shared.addr);
978 BUG_ON(rc);
979
980 return 0;
981}
982
983static void gnttab_unmap_frames_v1(void)
984{
985 arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
986}
987
988static int gnttab_map_frames_v2(xen_pfn_t *frames, unsigned int nr_gframes)
989{
990 uint64_t *sframes;
991 unsigned int nr_sframes;
992 struct gnttab_get_status_frames getframes;
993 int rc;
994
995 nr_sframes = nr_status_frames(nr_gframes);
996
997 /* No need for kzalloc as it is initialized in following hypercall
998 * GNTTABOP_get_status_frames.
999 */
1000 sframes = kmalloc(nr_sframes * sizeof(uint64_t), GFP_ATOMIC);
1001 if (!sframes)
1002 return -ENOMEM;
1003
1004 getframes.dom = DOMID_SELF;
1005 getframes.nr_frames = nr_sframes;
1006 set_xen_guest_handle(getframes.frame_list, sframes);
1007
1008 rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames,
1009 &getframes, 1);
1010 if (rc == -ENOSYS) {
1011 kfree(sframes);
1012 return -ENOSYS;
1013 }
1014
1015 BUG_ON(rc || getframes.status);
1016
1017 rc = arch_gnttab_map_status(sframes, nr_sframes,
1018 nr_status_frames(gnttab_max_grant_frames()),
1019 &grstatus);
1020 BUG_ON(rc);
1021 kfree(sframes);
1022
1023 rc = arch_gnttab_map_shared(frames, nr_gframes,
1024 gnttab_max_grant_frames(),
1025 &gnttab_shared.addr);
1026 BUG_ON(rc);
1027
1028 return 0;
1029}
1030
1031static void gnttab_unmap_frames_v2(void)
1032{
1033 arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
1034 arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames));
1035}
1036
1037static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
1038{
1039 struct gnttab_setup_table setup;
1040 xen_pfn_t *frames;
1041 unsigned int nr_gframes = end_idx + 1;
1042 int rc;
1043
1044 if (xen_feature(XENFEAT_auto_translated_physmap)) {
1045 struct xen_add_to_physmap xatp;
1046 unsigned int i = end_idx;
1047 rc = 0;
1048 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
1049 /*
1050 * Loop backwards, so that the first hypercall has the largest
1051 * index, ensuring that the table will grow only once.
1052 */
1053 do {
1054 xatp.domid = DOMID_SELF;
1055 xatp.idx = i;
1056 xatp.space = XENMAPSPACE_grant_table;
1057 xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
1058 rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
1059 if (rc != 0) {
1060 pr_warn("grant table add_to_physmap failed, err=%d\n",
1061 rc);
1062 break;
1063 }
1064 } while (i-- > start_idx);
1065
1066 return rc;
1067 }
1068
1069 /* No need for kzalloc as it is initialized in following hypercall
1070 * GNTTABOP_setup_table.
1071 */
1072 frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
1073 if (!frames)
1074 return -ENOMEM;
1075
1076 setup.dom = DOMID_SELF;
1077 setup.nr_frames = nr_gframes;
1078 set_xen_guest_handle(setup.frame_list, frames);
1079
1080 rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1081 if (rc == -ENOSYS) {
1082 kfree(frames);
1083 return -ENOSYS;
1084 }
1085
1086 BUG_ON(rc || setup.status);
1087
1088 rc = gnttab_interface->map_frames(frames, nr_gframes);
1089
1090 kfree(frames);
1091
1092 return rc;
1093}
1094
1095static struct gnttab_ops gnttab_v1_ops = {
1096 .map_frames = gnttab_map_frames_v1,
1097 .unmap_frames = gnttab_unmap_frames_v1,
1098 .update_entry = gnttab_update_entry_v1,
1099 .end_foreign_access_ref = gnttab_end_foreign_access_ref_v1,
1100 .end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v1,
1101 .query_foreign_access = gnttab_query_foreign_access_v1,
1102};
1103
1104static struct gnttab_ops gnttab_v2_ops = {
1105 .map_frames = gnttab_map_frames_v2,
1106 .unmap_frames = gnttab_unmap_frames_v2,
1107 .update_entry = gnttab_update_entry_v2,
1108 .end_foreign_access_ref = gnttab_end_foreign_access_ref_v2,
1109 .end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v2,
1110 .query_foreign_access = gnttab_query_foreign_access_v2,
1111 .update_subpage_entry = gnttab_update_subpage_entry_v2,
1112 .update_trans_entry = gnttab_update_trans_entry_v2,
1113};
1114
1115static void gnttab_request_version(void)
1116{
1117 int rc;
1118 struct gnttab_set_version gsv;
1119
1120 gsv.version = 1;
1121
1122 rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
1123 if (rc == 0 && gsv.version == 2) {
1124 grant_table_version = 2;
1125 grefs_per_grant_frame = PAGE_SIZE / sizeof(union grant_entry_v2);
1126 gnttab_interface = &gnttab_v2_ops;
1127 } else if (grant_table_version == 2) {
1128 /*
1129 * If we've already used version 2 features,
1130 * but then suddenly discover that they're not
1131 * available (e.g. migrating to an older
1132 * version of Xen), almost unbounded badness
1133 * can happen.
1134 */
1135 panic("we need grant tables version 2, but only version 1 is available");
1136 } else {
1137 grant_table_version = 1;
1138 grefs_per_grant_frame = PAGE_SIZE / sizeof(struct grant_entry_v1);
1139 gnttab_interface = &gnttab_v1_ops;
1140 }
1141 pr_info("Grant tables using version %d layout\n", grant_table_version);
1142}
1143
1144static int gnttab_setup(void)
1145{
1146 unsigned int max_nr_gframes;
1147
1148 max_nr_gframes = gnttab_max_grant_frames();
1149 if (max_nr_gframes < nr_grant_frames)
1150 return -ENOSYS;
1151
1152 if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
1153 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
1154 if (gnttab_shared.addr == NULL) {
1155 pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
1156 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
1157 return -ENOMEM;
1158 }
1159 }
1160 return gnttab_map(0, nr_grant_frames - 1);
1161}
1162
1163int gnttab_resume(void)
1164{
1165 gnttab_request_version();
1166 return gnttab_setup();
1167}
1168
1169int gnttab_suspend(void)
1170{
1171 gnttab_interface->unmap_frames();
1172 return 0;
1173}
1174
1175static int gnttab_expand(unsigned int req_entries)
1176{
1177 int rc;
1178 unsigned int cur, extra;
1179
1180 BUG_ON(grefs_per_grant_frame == 0);
1181 cur = nr_grant_frames;
1182 extra = ((req_entries + (grefs_per_grant_frame-1)) /
1183 grefs_per_grant_frame);
1184 if (cur + extra > gnttab_max_grant_frames())
1185 return -ENOSPC;
1186
1187 rc = gnttab_map(cur, cur + extra - 1);
1188 if (rc == 0)
1189 rc = grow_gnttab_list(extra);
1190
1191 return rc;
1192}
1193
1194int gnttab_init(void)
1195{
1196 int i;
1197 unsigned int max_nr_glist_frames, nr_glist_frames;
1198 unsigned int nr_init_grefs;
1199 int ret;
1200
1201 gnttab_request_version();
1202 nr_grant_frames = 1;
1203
1204 /* Determine the maximum number of frames required for the
1205 * grant reference free list on the current hypervisor.
1206 */
1207 BUG_ON(grefs_per_grant_frame == 0);
1208 max_nr_glist_frames = (gnttab_max_grant_frames() *
1209 grefs_per_grant_frame / RPP);
1210
1211 gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
1212 GFP_KERNEL);
1213 if (gnttab_list == NULL)
1214 return -ENOMEM;
1215
1216 nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
1217 for (i = 0; i < nr_glist_frames; i++) {
1218 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1219 if (gnttab_list[i] == NULL) {
1220 ret = -ENOMEM;
1221 goto ini_nomem;
1222 }
1223 }
1224
1225 if (gnttab_setup() < 0) {
1226 ret = -ENODEV;
1227 goto ini_nomem;
1228 }
1229
1230 nr_init_grefs = nr_grant_frames * grefs_per_grant_frame;
1231
1232 for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
1233 gnttab_entry(i) = i + 1;
1234
1235 gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
1236 gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
1237 gnttab_free_head = NR_RESERVED_ENTRIES;
1238
1239 printk("Grant table initialized\n");
1240 return 0;
1241
1242 ini_nomem:
1243 for (i--; i >= 0; i--)
1244 free_page((unsigned long)gnttab_list[i]);
1245 kfree(gnttab_list);
1246 return ret;
1247}
1248EXPORT_SYMBOL_GPL(gnttab_init);
1249
1250static int __gnttab_init(void)
1251{
1252 /* Delay grant-table initialization in the PV on HVM case */
1253 if (xen_hvm_domain())
1254 return 0;
1255
1256 if (!xen_pv_domain())
1257 return -ENODEV;
1258
1259 return gnttab_init();
1260}
1261/* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1262 * beforehand to initialize xen_auto_xlat_grant_frames. */
1263core_initcall_sync(__gnttab_init);