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[/] [test_project/] [trunk/] [linux_sd_driver/] [drivers/] [xen/] [grant-table.c] - Blame information for rev 65

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1 62 marcus.erl
/******************************************************************************
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
 
53
static grant_ref_t **gnttab_list;
54
static unsigned int nr_grant_frames;
55
static unsigned int boot_max_nr_grant_frames;
56
static int gnttab_free_count;
57
static grant_ref_t gnttab_free_head;
58
static DEFINE_SPINLOCK(gnttab_list_lock);
59
 
60
static struct grant_entry *shared;
61
 
62
static struct gnttab_free_callback *gnttab_free_callback_list;
63
 
64
static int gnttab_expand(unsigned int req_entries);
65
 
66
#define RPP (PAGE_SIZE / sizeof(grant_ref_t))
67
 
68
static 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
 
75
static 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
 
101
static 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
 
121
static inline void check_free_callbacks(void)
122
{
123
        if (unlikely(gnttab_free_callback_list))
124
                do_free_callbacks();
125
}
126
 
127
static 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
 
138
static 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
 */
160
void 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
}
166
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
167
 
168
int 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
}
181
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
182
 
183
int 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
}
191
EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
192
 
193
int 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
}
208
EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
209
 
210
void 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
}
224
EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
225
 
226
int 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
}
237
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
238
 
239
void 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
}
244
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
245
 
246
unsigned 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
}
273
EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
274
 
275
unsigned 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
}
281
EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
282
 
283
void gnttab_free_grant_reference(grant_ref_t ref)
284
{
285
        put_free_entry(ref);
286
}
287
EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
288
 
289
void 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
}
308
EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
309
 
310
int 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
}
321
EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
322
 
323
int gnttab_empty_grant_references(const grant_ref_t *private_head)
324
{
325
        return (*private_head == GNTTAB_LIST_END);
326
}
327
EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
328
 
329
int 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
}
337
EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
338
 
339
void 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
}
345
EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
346
 
347
void 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();
360
out:
361
        spin_unlock_irqrestore(&gnttab_list_lock, flags);
362
}
363
EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
364
 
365
void 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
}
379
EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
380
 
381
static 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
 
409
grow_nomem:
410
        for ( ; i >= nr_grant_frames; i--)
411
                free_page((unsigned long) gnttab_list[i]);
412
        return -ENOMEM;
413
}
414
 
415
static 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
 
429
static 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
 
438
static 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
 
448
static 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
 
456
static 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
 
496
static 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
 
503
static 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
 
512
static 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
 
530
static 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
 
582
core_initcall(gnttab_init);

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