blob: ea94dbabf9a936a656675edbe57956349167ae88 [file] [log] [blame]
Jeremy Fitzhardingead9a8612007-07-17 18:37:06 -07001/******************************************************************************
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/vmalloc.h>
38#include <linux/uaccess.h>
39
40#include <xen/interface/xen.h>
41#include <xen/page.h>
42#include <xen/grant_table.h>
43
44#include <asm/pgtable.h>
45#include <asm/sync_bitops.h>
46
47
48/* External tools reserve first few grant table entries. */
49#define NR_RESERVED_ENTRIES 8
50#define GNTTAB_LIST_END 0xffffffff
51#define GREFS_PER_GRANT_FRAME (PAGE_SIZE / sizeof(struct grant_entry))
52
53static grant_ref_t **gnttab_list;
54static unsigned int nr_grant_frames;
55static unsigned int boot_max_nr_grant_frames;
56static int gnttab_free_count;
57static grant_ref_t gnttab_free_head;
58static DEFINE_SPINLOCK(gnttab_list_lock);
59
60static struct grant_entry *shared;
61
62static struct gnttab_free_callback *gnttab_free_callback_list;
63
64static int gnttab_expand(unsigned int req_entries);
65
66#define RPP (PAGE_SIZE / sizeof(grant_ref_t))
67
68static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
69{
70 return &gnttab_list[(entry) / RPP][(entry) % RPP];
71}
72/* This can be used as an l-value */
73#define gnttab_entry(entry) (*__gnttab_entry(entry))
74
75static int get_free_entries(unsigned count)
76{
77 unsigned long flags;
78 int ref, rc;
79 grant_ref_t head;
80
81 spin_lock_irqsave(&gnttab_list_lock, flags);
82
83 if ((gnttab_free_count < count) &&
84 ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
85 spin_unlock_irqrestore(&gnttab_list_lock, flags);
86 return rc;
87 }
88
89 ref = head = gnttab_free_head;
90 gnttab_free_count -= count;
91 while (count-- > 1)
92 head = gnttab_entry(head);
93 gnttab_free_head = gnttab_entry(head);
94 gnttab_entry(head) = GNTTAB_LIST_END;
95
96 spin_unlock_irqrestore(&gnttab_list_lock, flags);
97
98 return ref;
99}
100
101static void do_free_callbacks(void)
102{
103 struct gnttab_free_callback *callback, *next;
104
105 callback = gnttab_free_callback_list;
106 gnttab_free_callback_list = NULL;
107
108 while (callback != NULL) {
109 next = callback->next;
110 if (gnttab_free_count >= callback->count) {
111 callback->next = NULL;
112 callback->fn(callback->arg);
113 } else {
114 callback->next = gnttab_free_callback_list;
115 gnttab_free_callback_list = callback;
116 }
117 callback = next;
118 }
119}
120
121static inline void check_free_callbacks(void)
122{
123 if (unlikely(gnttab_free_callback_list))
124 do_free_callbacks();
125}
126
127static void put_free_entry(grant_ref_t ref)
128{
129 unsigned long flags;
130 spin_lock_irqsave(&gnttab_list_lock, flags);
131 gnttab_entry(ref) = gnttab_free_head;
132 gnttab_free_head = ref;
133 gnttab_free_count++;
134 check_free_callbacks();
135 spin_unlock_irqrestore(&gnttab_list_lock, flags);
136}
137
138static void update_grant_entry(grant_ref_t ref, domid_t domid,
139 unsigned long frame, unsigned flags)
140{
141 /*
142 * Introducing a valid entry into the grant table:
143 * 1. Write ent->domid.
144 * 2. Write ent->frame:
145 * GTF_permit_access: Frame to which access is permitted.
146 * GTF_accept_transfer: Pseudo-phys frame slot being filled by new
147 * frame, or zero if none.
148 * 3. Write memory barrier (WMB).
149 * 4. Write ent->flags, inc. valid type.
150 */
151 shared[ref].frame = frame;
152 shared[ref].domid = domid;
153 wmb();
154 shared[ref].flags = flags;
155}
156
157/*
158 * Public grant-issuing interface functions
159 */
160void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
161 unsigned long frame, int readonly)
162{
163 update_grant_entry(ref, domid, frame,
164 GTF_permit_access | (readonly ? GTF_readonly : 0));
165}
166EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
167
168int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
169 int readonly)
170{
171 int ref;
172
173 ref = get_free_entries(1);
174 if (unlikely(ref < 0))
175 return -ENOSPC;
176
177 gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
178
179 return ref;
180}
181EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
182
183int gnttab_query_foreign_access(grant_ref_t ref)
184{
185 u16 nflags;
186
187 nflags = shared[ref].flags;
188
189 return (nflags & (GTF_reading|GTF_writing));
190}
191EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
192
193int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
194{
195 u16 flags, nflags;
196
197 nflags = shared[ref].flags;
198 do {
199 flags = nflags;
200 if (flags & (GTF_reading|GTF_writing)) {
201 printk(KERN_ALERT "WARNING: g.e. still in use!\n");
202 return 0;
203 }
204 } while ((nflags = sync_cmpxchg(&shared[ref].flags, flags, 0)) != flags);
205
206 return 1;
207}
208EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
209
210void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
211 unsigned long page)
212{
213 if (gnttab_end_foreign_access_ref(ref, readonly)) {
214 put_free_entry(ref);
215 if (page != 0)
216 free_page(page);
217 } else {
218 /* XXX This needs to be fixed so that the ref and page are
219 placed on a list to be freed up later. */
220 printk(KERN_WARNING
221 "WARNING: leaking g.e. and page still in use!\n");
222 }
223}
224EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
225
226int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
227{
228 int ref;
229
230 ref = get_free_entries(1);
231 if (unlikely(ref < 0))
232 return -ENOSPC;
233 gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
234
235 return ref;
236}
237EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
238
239void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
240 unsigned long pfn)
241{
242 update_grant_entry(ref, domid, pfn, GTF_accept_transfer);
243}
244EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
245
246unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
247{
248 unsigned long frame;
249 u16 flags;
250
251 /*
252 * If a transfer is not even yet started, try to reclaim the grant
253 * reference and return failure (== 0).
254 */
255 while (!((flags = shared[ref].flags) & GTF_transfer_committed)) {
256 if (sync_cmpxchg(&shared[ref].flags, flags, 0) == flags)
257 return 0;
258 cpu_relax();
259 }
260
261 /* If a transfer is in progress then wait until it is completed. */
262 while (!(flags & GTF_transfer_completed)) {
263 flags = shared[ref].flags;
264 cpu_relax();
265 }
266
267 rmb(); /* Read the frame number /after/ reading completion status. */
268 frame = shared[ref].frame;
269 BUG_ON(frame == 0);
270
271 return frame;
272}
273EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
274
275unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
276{
277 unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
278 put_free_entry(ref);
279 return frame;
280}
281EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
282
283void gnttab_free_grant_reference(grant_ref_t ref)
284{
285 put_free_entry(ref);
286}
287EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
288
289void gnttab_free_grant_references(grant_ref_t head)
290{
291 grant_ref_t ref;
292 unsigned long flags;
293 int count = 1;
294 if (head == GNTTAB_LIST_END)
295 return;
296 spin_lock_irqsave(&gnttab_list_lock, flags);
297 ref = head;
298 while (gnttab_entry(ref) != GNTTAB_LIST_END) {
299 ref = gnttab_entry(ref);
300 count++;
301 }
302 gnttab_entry(ref) = gnttab_free_head;
303 gnttab_free_head = head;
304 gnttab_free_count += count;
305 check_free_callbacks();
306 spin_unlock_irqrestore(&gnttab_list_lock, flags);
307}
308EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
309
310int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
311{
312 int h = get_free_entries(count);
313
314 if (h < 0)
315 return -ENOSPC;
316
317 *head = h;
318
319 return 0;
320}
321EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
322
323int gnttab_empty_grant_references(const grant_ref_t *private_head)
324{
325 return (*private_head == GNTTAB_LIST_END);
326}
327EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
328
329int gnttab_claim_grant_reference(grant_ref_t *private_head)
330{
331 grant_ref_t g = *private_head;
332 if (unlikely(g == GNTTAB_LIST_END))
333 return -ENOSPC;
334 *private_head = gnttab_entry(g);
335 return g;
336}
337EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
338
339void gnttab_release_grant_reference(grant_ref_t *private_head,
340 grant_ref_t release)
341{
342 gnttab_entry(release) = *private_head;
343 *private_head = release;
344}
345EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
346
347void gnttab_request_free_callback(struct gnttab_free_callback *callback,
348 void (*fn)(void *), void *arg, u16 count)
349{
350 unsigned long flags;
351 spin_lock_irqsave(&gnttab_list_lock, flags);
352 if (callback->next)
353 goto out;
354 callback->fn = fn;
355 callback->arg = arg;
356 callback->count = count;
357 callback->next = gnttab_free_callback_list;
358 gnttab_free_callback_list = callback;
359 check_free_callbacks();
360out:
361 spin_unlock_irqrestore(&gnttab_list_lock, flags);
362}
363EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
364
365void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
366{
367 struct gnttab_free_callback **pcb;
368 unsigned long flags;
369
370 spin_lock_irqsave(&gnttab_list_lock, flags);
371 for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
372 if (*pcb == callback) {
373 *pcb = callback->next;
374 break;
375 }
376 }
377 spin_unlock_irqrestore(&gnttab_list_lock, flags);
378}
379EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
380
381static int grow_gnttab_list(unsigned int more_frames)
382{
383 unsigned int new_nr_grant_frames, extra_entries, i;
384
385 new_nr_grant_frames = nr_grant_frames + more_frames;
386 extra_entries = more_frames * GREFS_PER_GRANT_FRAME;
387
388 for (i = nr_grant_frames; i < new_nr_grant_frames; i++) {
389 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
390 if (!gnttab_list[i])
391 goto grow_nomem;
392 }
393
394
395 for (i = GREFS_PER_GRANT_FRAME * nr_grant_frames;
396 i < GREFS_PER_GRANT_FRAME * new_nr_grant_frames - 1; i++)
397 gnttab_entry(i) = i + 1;
398
399 gnttab_entry(i) = gnttab_free_head;
400 gnttab_free_head = GREFS_PER_GRANT_FRAME * nr_grant_frames;
401 gnttab_free_count += extra_entries;
402
403 nr_grant_frames = new_nr_grant_frames;
404
405 check_free_callbacks();
406
407 return 0;
408
409grow_nomem:
410 for ( ; i >= nr_grant_frames; i--)
411 free_page((unsigned long) gnttab_list[i]);
412 return -ENOMEM;
413}
414
415static unsigned int __max_nr_grant_frames(void)
416{
417 struct gnttab_query_size query;
418 int rc;
419
420 query.dom = DOMID_SELF;
421
422 rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
423 if ((rc < 0) || (query.status != GNTST_okay))
424 return 4; /* Legacy max supported number of frames */
425
426 return query.max_nr_frames;
427}
428
429static inline unsigned int max_nr_grant_frames(void)
430{
431 unsigned int xen_max = __max_nr_grant_frames();
432
433 if (xen_max > boot_max_nr_grant_frames)
434 return boot_max_nr_grant_frames;
435 return xen_max;
436}
437
438static int map_pte_fn(pte_t *pte, struct page *pmd_page,
439 unsigned long addr, void *data)
440{
441 unsigned long **frames = (unsigned long **)data;
442
443 set_pte_at(&init_mm, addr, pte, mfn_pte((*frames)[0], PAGE_KERNEL));
444 (*frames)++;
445 return 0;
446}
447
448static int unmap_pte_fn(pte_t *pte, struct page *pmd_page,
449 unsigned long addr, void *data)
450{
451
452 set_pte_at(&init_mm, addr, pte, __pte(0));
453 return 0;
454}
455
456static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
457{
458 struct gnttab_setup_table setup;
459 unsigned long *frames;
460 unsigned int nr_gframes = end_idx + 1;
461 int rc;
462
463 frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
464 if (!frames)
465 return -ENOMEM;
466
467 setup.dom = DOMID_SELF;
468 setup.nr_frames = nr_gframes;
469 setup.frame_list = frames;
470
471 rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
472 if (rc == -ENOSYS) {
473 kfree(frames);
474 return -ENOSYS;
475 }
476
477 BUG_ON(rc || setup.status);
478
479 if (shared == NULL) {
480 struct vm_struct *area;
481 area = alloc_vm_area(PAGE_SIZE * max_nr_grant_frames());
482 BUG_ON(area == NULL);
483 shared = area->addr;
484 }
485 rc = apply_to_page_range(&init_mm, (unsigned long)shared,
486 PAGE_SIZE * nr_gframes,
487 map_pte_fn, &frames);
488 BUG_ON(rc);
489 frames -= nr_gframes; /* adjust after map_pte_fn() */
490
491 kfree(frames);
492
493 return 0;
494}
495
496static int gnttab_resume(void)
497{
498 if (max_nr_grant_frames() < nr_grant_frames)
499 return -ENOSYS;
500 return gnttab_map(0, nr_grant_frames - 1);
501}
502
503static int gnttab_suspend(void)
504{
505 apply_to_page_range(&init_mm, (unsigned long)shared,
506 PAGE_SIZE * nr_grant_frames,
507 unmap_pte_fn, NULL);
508
509 return 0;
510}
511
512static int gnttab_expand(unsigned int req_entries)
513{
514 int rc;
515 unsigned int cur, extra;
516
517 cur = nr_grant_frames;
518 extra = ((req_entries + (GREFS_PER_GRANT_FRAME-1)) /
519 GREFS_PER_GRANT_FRAME);
520 if (cur + extra > max_nr_grant_frames())
521 return -ENOSPC;
522
523 rc = gnttab_map(cur, cur + extra - 1);
524 if (rc == 0)
525 rc = grow_gnttab_list(extra);
526
527 return rc;
528}
529
530static int __devinit gnttab_init(void)
531{
532 int i;
533 unsigned int max_nr_glist_frames;
534 unsigned int nr_init_grefs;
535
536 if (!is_running_on_xen())
537 return -ENODEV;
538
539 nr_grant_frames = 1;
540 boot_max_nr_grant_frames = __max_nr_grant_frames();
541
542 /* Determine the maximum number of frames required for the
543 * grant reference free list on the current hypervisor.
544 */
545 max_nr_glist_frames = (boot_max_nr_grant_frames *
546 GREFS_PER_GRANT_FRAME /
547 (PAGE_SIZE / sizeof(grant_ref_t)));
548
549 gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
550 GFP_KERNEL);
551 if (gnttab_list == NULL)
552 return -ENOMEM;
553
554 for (i = 0; i < nr_grant_frames; i++) {
555 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
556 if (gnttab_list[i] == NULL)
557 goto ini_nomem;
558 }
559
560 if (gnttab_resume() < 0)
561 return -ENODEV;
562
563 nr_init_grefs = nr_grant_frames * GREFS_PER_GRANT_FRAME;
564
565 for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
566 gnttab_entry(i) = i + 1;
567
568 gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
569 gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
570 gnttab_free_head = NR_RESERVED_ENTRIES;
571
572 printk("Grant table initialized\n");
573 return 0;
574
575 ini_nomem:
576 for (i--; i >= 0; i--)
577 free_page((unsigned long)gnttab_list[i]);
578 kfree(gnttab_list);
579 return -ENOMEM;
580}
581
582core_initcall(gnttab_init);