aboutsummaryrefslogtreecommitdiff
path: root/hw/virtio/vhost.c
blob: 85841019c006b4434f8a80f89def582e76fc819d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
/*
 * vhost support
 *
 * Copyright Red Hat, Inc. 2010
 *
 * Authors:
 *  Michael S. Tsirkin <mst@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 * Contributions after 2012-01-13 are licensed under the terms of the
 * GNU GPL, version 2 or (at your option) any later version.
 */

#include "hw/virtio/vhost.h"
#include "hw/hw.h"
#include "qemu/atomic.h"
#include "qemu/range.h"
#include <linux/vhost.h>
#include "exec/address-spaces.h"
#include "hw/virtio/virtio-bus.h"

static void vhost_dev_sync_region(struct vhost_dev *dev,
                                  MemoryRegionSection *section,
                                  uint64_t mfirst, uint64_t mlast,
                                  uint64_t rfirst, uint64_t rlast)
{
    uint64_t start = MAX(mfirst, rfirst);
    uint64_t end = MIN(mlast, rlast);
    vhost_log_chunk_t *from = dev->log + start / VHOST_LOG_CHUNK;
    vhost_log_chunk_t *to = dev->log + end / VHOST_LOG_CHUNK + 1;
    uint64_t addr = (start / VHOST_LOG_CHUNK) * VHOST_LOG_CHUNK;

    if (end < start) {
        return;
    }
    assert(end / VHOST_LOG_CHUNK < dev->log_size);
    assert(start / VHOST_LOG_CHUNK < dev->log_size);

    for (;from < to; ++from) {
        vhost_log_chunk_t log;
        /* We first check with non-atomic: much cheaper,
         * and we expect non-dirty to be the common case. */
        if (!*from) {
            addr += VHOST_LOG_CHUNK;
            continue;
        }
        /* Data must be read atomically. We don't really need barrier semantics
         * but it's easier to use atomic_* than roll our own. */
        log = atomic_xchg(from, 0);
        while (log) {
            int bit = ctzl(log);
            hwaddr page_addr;
            hwaddr section_offset;
            hwaddr mr_offset;
            page_addr = addr + bit * VHOST_LOG_PAGE;
            section_offset = page_addr - section->offset_within_address_space;
            mr_offset = section_offset + section->offset_within_region;
            memory_region_set_dirty(section->mr, mr_offset, VHOST_LOG_PAGE);
            log &= ~(0x1ull << bit);
        }
        addr += VHOST_LOG_CHUNK;
    }
}

static int vhost_sync_dirty_bitmap(struct vhost_dev *dev,
                                   MemoryRegionSection *section,
                                   hwaddr first,
                                   hwaddr last)
{
    int i;
    hwaddr start_addr;
    hwaddr end_addr;

    if (!dev->log_enabled || !dev->started) {
        return 0;
    }
    start_addr = section->offset_within_address_space;
    end_addr = range_get_last(start_addr, int128_get64(section->size));
    start_addr = MAX(first, start_addr);
    end_addr = MIN(last, end_addr);

    for (i = 0; i < dev->mem->nregions; ++i) {
        struct vhost_memory_region *reg = dev->mem->regions + i;
        vhost_dev_sync_region(dev, section, start_addr, end_addr,
                              reg->guest_phys_addr,
                              range_get_last(reg->guest_phys_addr,
                                             reg->memory_size));
    }
    for (i = 0; i < dev->nvqs; ++i) {
        struct vhost_virtqueue *vq = dev->vqs + i;
        vhost_dev_sync_region(dev, section, start_addr, end_addr, vq->used_phys,
                              range_get_last(vq->used_phys, vq->used_size));
    }
    return 0;
}

static void vhost_log_sync(MemoryListener *listener,
                          MemoryRegionSection *section)
{
    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
                                         memory_listener);
    vhost_sync_dirty_bitmap(dev, section, 0x0, ~0x0ULL);
}

static void vhost_log_sync_range(struct vhost_dev *dev,
                                 hwaddr first, hwaddr last)
{
    int i;
    /* FIXME: this is N^2 in number of sections */
    for (i = 0; i < dev->n_mem_sections; ++i) {
        MemoryRegionSection *section = &dev->mem_sections[i];
        vhost_sync_dirty_bitmap(dev, section, first, last);
    }
}

/* Assign/unassign. Keep an unsorted array of non-overlapping
 * memory regions in dev->mem. */
static void vhost_dev_unassign_memory(struct vhost_dev *dev,
                                      uint64_t start_addr,
                                      uint64_t size)
{
    int from, to, n = dev->mem->nregions;
    /* Track overlapping/split regions for sanity checking. */
    int overlap_start = 0, overlap_end = 0, overlap_middle = 0, split = 0;

    for (from = 0, to = 0; from < n; ++from, ++to) {
        struct vhost_memory_region *reg = dev->mem->regions + to;
        uint64_t reglast;
        uint64_t memlast;
        uint64_t change;

        /* clone old region */
        if (to != from) {
            memcpy(reg, dev->mem->regions + from, sizeof *reg);
        }

        /* No overlap is simple */
        if (!ranges_overlap(reg->guest_phys_addr, reg->memory_size,
                            start_addr, size)) {
            continue;
        }

        /* Split only happens if supplied region
         * is in the middle of an existing one. Thus it can not
         * overlap with any other existing region. */
        assert(!split);

        reglast = range_get_last(reg->guest_phys_addr, reg->memory_size);
        memlast = range_get_last(start_addr, size);

        /* Remove whole region */
        if (start_addr <= reg->guest_phys_addr && memlast >= reglast) {
            --dev->mem->nregions;
            --to;
            ++overlap_middle;
            continue;
        }

        /* Shrink region */
        if (memlast >= reglast) {
            reg->memory_size = start_addr - reg->guest_phys_addr;
            assert(reg->memory_size);
            assert(!overlap_end);
            ++overlap_end;
            continue;
        }

        /* Shift region */
        if (start_addr <= reg->guest_phys_addr) {
            change = memlast + 1 - reg->guest_phys_addr;
            reg->memory_size -= change;
            reg->guest_phys_addr += change;
            reg->userspace_addr += change;
            assert(reg->memory_size);
            assert(!overlap_start);
            ++overlap_start;
            continue;
        }

        /* This only happens if supplied region
         * is in the middle of an existing one. Thus it can not
         * overlap with any other existing region. */
        assert(!overlap_start);
        assert(!overlap_end);
        assert(!overlap_middle);
        /* Split region: shrink first part, shift second part. */
        memcpy(dev->mem->regions + n, reg, sizeof *reg);
        reg->memory_size = start_addr - reg->guest_phys_addr;
        assert(reg->memory_size);
        change = memlast + 1 - reg->guest_phys_addr;
        reg = dev->mem->regions + n;
        reg->memory_size -= change;
        assert(reg->memory_size);
        reg->guest_phys_addr += change;
        reg->userspace_addr += change;
        /* Never add more than 1 region */
        assert(dev->mem->nregions == n);
        ++dev->mem->nregions;
        ++split;
    }
}

/* Called after unassign, so no regions overlap the given range. */
static void vhost_dev_assign_memory(struct vhost_dev *dev,
                                    uint64_t start_addr,
                                    uint64_t size,
                                    uint64_t uaddr)
{
    int from, to;
    struct vhost_memory_region *merged = NULL;
    for (from = 0, to = 0; from < dev->mem->nregions; ++from, ++to) {
        struct vhost_memory_region *reg = dev->mem->regions + to;
        uint64_t prlast, urlast;
        uint64_t pmlast, umlast;
        uint64_t s, e, u;

        /* clone old region */
        if (to != from) {
            memcpy(reg, dev->mem->regions + from, sizeof *reg);
        }
        prlast = range_get_last(reg->guest_phys_addr, reg->memory_size);
        pmlast = range_get_last(start_addr, size);
        urlast = range_get_last(reg->userspace_addr, reg->memory_size);
        umlast = range_get_last(uaddr, size);

        /* check for overlapping regions: should never happen. */
        assert(prlast < start_addr || pmlast < reg->guest_phys_addr);
        /* Not an adjacent or overlapping region - do not merge. */
        if ((prlast + 1 != start_addr || urlast + 1 != uaddr) &&
            (pmlast + 1 != reg->guest_phys_addr ||
             umlast + 1 != reg->userspace_addr)) {
            continue;
        }

        if (merged) {
            --to;
            assert(to >= 0);
        } else {
            merged = reg;
        }
        u = MIN(uaddr, reg->userspace_addr);
        s = MIN(start_addr, reg->guest_phys_addr);
        e = MAX(pmlast, prlast);
        uaddr = merged->userspace_addr = u;
        start_addr = merged->guest_phys_addr = s;
        size = merged->memory_size = e - s + 1;
        assert(merged->memory_size);
    }

    if (!merged) {
        struct vhost_memory_region *reg = dev->mem->regions + to;
        memset(reg, 0, sizeof *reg);
        reg->memory_size = size;
        assert(reg->memory_size);
        reg->guest_phys_addr = start_addr;
        reg->userspace_addr = uaddr;
        ++to;
    }
    assert(to <= dev->mem->nregions + 1);
    dev->mem->nregions = to;
}

static uint64_t vhost_get_log_size(struct vhost_dev *dev)
{
    uint64_t log_size = 0;
    int i;
    for (i = 0; i < dev->mem->nregions; ++i) {
        struct vhost_memory_region *reg = dev->mem->regions + i;
        uint64_t last = range_get_last(reg->guest_phys_addr,
                                       reg->memory_size);
        log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1);
    }
    for (i = 0; i < dev->nvqs; ++i) {
        struct vhost_virtqueue *vq = dev->vqs + i;
        uint64_t last = vq->used_phys + vq->used_size - 1;
        log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1);
    }
    return log_size;
}

static inline void vhost_dev_log_resize(struct vhost_dev* dev, uint64_t size)
{
    vhost_log_chunk_t *log;
    uint64_t log_base;
    int r;

    log = g_malloc0(size * sizeof *log);
    log_base = (uint64_t)(unsigned long)log;
    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_LOG_BASE, &log_base);
    assert(r >= 0);
    /* Sync only the range covered by the old log */
    if (dev->log_size) {
        vhost_log_sync_range(dev, 0, dev->log_size * VHOST_LOG_CHUNK - 1);
    }
    g_free(dev->log);
    dev->log = log;
    dev->log_size = size;
}

static int vhost_verify_ring_mappings(struct vhost_dev *dev,
                                      uint64_t start_addr,
                                      uint64_t size)
{
    int i;
    for (i = 0; i < dev->nvqs; ++i) {
        struct vhost_virtqueue *vq = dev->vqs + i;
        hwaddr l;
        void *p;

        if (!ranges_overlap(start_addr, size, vq->ring_phys, vq->ring_size)) {
            continue;
        }
        l = vq->ring_size;
        p = cpu_physical_memory_map(vq->ring_phys, &l, 1);
        if (!p || l != vq->ring_size) {
            fprintf(stderr, "Unable to map ring buffer for ring %d\n", i);
            return -ENOMEM;
        }
        if (p != vq->ring) {
            fprintf(stderr, "Ring buffer relocated for ring %d\n", i);
            return -EBUSY;
        }
        cpu_physical_memory_unmap(p, l, 0, 0);
    }
    return 0;
}

static struct vhost_memory_region *vhost_dev_find_reg(struct vhost_dev *dev,
						      uint64_t start_addr,
						      uint64_t size)
{
    int i, n = dev->mem->nregions;
    for (i = 0; i < n; ++i) {
        struct vhost_memory_region *reg = dev->mem->regions + i;
        if (ranges_overlap(reg->guest_phys_addr, reg->memory_size,
                           start_addr, size)) {
            return reg;
        }
    }
    return NULL;
}

static bool vhost_dev_cmp_memory(struct vhost_dev *dev,
                                 uint64_t start_addr,
                                 uint64_t size,
                                 uint64_t uaddr)
{
    struct vhost_memory_region *reg = vhost_dev_find_reg(dev, start_addr, size);
    uint64_t reglast;
    uint64_t memlast;

    if (!reg) {
        return true;
    }

    reglast = range_get_last(reg->guest_phys_addr, reg->memory_size);
    memlast = range_get_last(start_addr, size);

    /* Need to extend region? */
    if (start_addr < reg->guest_phys_addr || memlast > reglast) {
        return true;
    }
    /* userspace_addr changed? */
    return uaddr != reg->userspace_addr + start_addr - reg->guest_phys_addr;
}

static void vhost_set_memory(MemoryListener *listener,
                             MemoryRegionSection *section,
                             bool add)
{
    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
                                         memory_listener);
    hwaddr start_addr = section->offset_within_address_space;
    ram_addr_t size = int128_get64(section->size);
    bool log_dirty = memory_region_is_logging(section->mr);
    int s = offsetof(struct vhost_memory, regions) +
        (dev->mem->nregions + 1) * sizeof dev->mem->regions[0];
    void *ram;

    dev->mem = g_realloc(dev->mem, s);

    if (log_dirty) {
        add = false;
    }

    assert(size);

    /* Optimize no-change case. At least cirrus_vga does this a lot at this time. */
    ram = memory_region_get_ram_ptr(section->mr) + section->offset_within_region;
    if (add) {
        if (!vhost_dev_cmp_memory(dev, start_addr, size, (uintptr_t)ram)) {
            /* Region exists with same address. Nothing to do. */
            return;
        }
    } else {
        if (!vhost_dev_find_reg(dev, start_addr, size)) {
            /* Removing region that we don't access. Nothing to do. */
            return;
        }
    }

    vhost_dev_unassign_memory(dev, start_addr, size);
    if (add) {
        /* Add given mapping, merging adjacent regions if any */
        vhost_dev_assign_memory(dev, start_addr, size, (uintptr_t)ram);
    } else {
        /* Remove old mapping for this memory, if any. */
        vhost_dev_unassign_memory(dev, start_addr, size);
    }
    dev->mem_changed_start_addr = MIN(dev->mem_changed_start_addr, start_addr);
    dev->mem_changed_end_addr = MAX(dev->mem_changed_end_addr, start_addr + size - 1);
    dev->memory_changed = true;
}

static bool vhost_section(MemoryRegionSection *section)
{
    return memory_region_is_ram(section->mr);
}

static void vhost_begin(MemoryListener *listener)
{
    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
                                         memory_listener);
    dev->mem_changed_end_addr = 0;
    dev->mem_changed_start_addr = -1;
}

static void vhost_commit(MemoryListener *listener)
{
    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
                                         memory_listener);
    hwaddr start_addr = 0;
    ram_addr_t size = 0;
    uint64_t log_size;
    int r;

    if (!dev->memory_changed) {
        return;
    }
    if (!dev->started) {
        return;
    }
    if (dev->mem_changed_start_addr > dev->mem_changed_end_addr) {
        return;
    }

    if (dev->started) {
        start_addr = dev->mem_changed_start_addr;
        size = dev->mem_changed_end_addr - dev->mem_changed_start_addr + 1;

        r = vhost_verify_ring_mappings(dev, start_addr, size);
        assert(r >= 0);
    }

    if (!dev->log_enabled) {
        r = dev->vhost_ops->vhost_call(dev, VHOST_SET_MEM_TABLE, dev->mem);
        assert(r >= 0);
        dev->memory_changed = false;
        return;
    }
    log_size = vhost_get_log_size(dev);
    /* We allocate an extra 4K bytes to log,
     * to reduce the * number of reallocations. */
#define VHOST_LOG_BUFFER (0x1000 / sizeof *dev->log)
    /* To log more, must increase log size before table update. */
    if (dev->log_size < log_size) {
        vhost_dev_log_resize(dev, log_size + VHOST_LOG_BUFFER);
    }
    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_MEM_TABLE, dev->mem);
    assert(r >= 0);
    /* To log less, can only decrease log size after table update. */
    if (dev->log_size > log_size + VHOST_LOG_BUFFER) {
        vhost_dev_log_resize(dev, log_size);
    }
    dev->memory_changed = false;
}

static void vhost_region_add(MemoryListener *listener,
                             MemoryRegionSection *section)
{
    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
                                         memory_listener);

    if (!vhost_section(section)) {
        return;
    }

    ++dev->n_mem_sections;
    dev->mem_sections = g_renew(MemoryRegionSection, dev->mem_sections,
                                dev->n_mem_sections);
    dev->mem_sections[dev->n_mem_sections - 1] = *section;
    memory_region_ref(section->mr);
    vhost_set_memory(listener, section, true);
}

static void vhost_region_del(MemoryListener *listener,
                             MemoryRegionSection *section)
{
    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
                                         memory_listener);
    int i;

    if (!vhost_section(section)) {
        return;
    }

    vhost_set_memory(listener, section, false);
    memory_region_unref(section->mr);
    for (i = 0; i < dev->n_mem_sections; ++i) {
        if (dev->mem_sections[i].offset_within_address_space
            == section->offset_within_address_space) {
            --dev->n_mem_sections;
            memmove(&dev->mem_sections[i], &dev->mem_sections[i+1],
                    (dev->n_mem_sections - i) * sizeof(*dev->mem_sections));
            break;
        }
    }
}

static void vhost_region_nop(MemoryListener *listener,
                             MemoryRegionSection *section)
{
}

static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
                                    struct vhost_virtqueue *vq,
                                    unsigned idx, bool enable_log)
{
    struct vhost_vring_addr addr = {
        .index = idx,
        .desc_user_addr = (uint64_t)(unsigned long)vq->desc,
        .avail_user_addr = (uint64_t)(unsigned long)vq->avail,
        .used_user_addr = (uint64_t)(unsigned long)vq->used,
        .log_guest_addr = vq->used_phys,
        .flags = enable_log ? (1 << VHOST_VRING_F_LOG) : 0,
    };
    int r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_ADDR, &addr);
    if (r < 0) {
        return -errno;
    }
    return 0;
}

static int vhost_dev_set_features(struct vhost_dev *dev, bool enable_log)
{
    uint64_t features = dev->acked_features;
    int r;
    if (enable_log) {
        features |= 0x1 << VHOST_F_LOG_ALL;
    }
    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_FEATURES, &features);
    return r < 0 ? -errno : 0;
}

static int vhost_dev_set_log(struct vhost_dev *dev, bool enable_log)
{
    int r, t, i;
    r = vhost_dev_set_features(dev, enable_log);
    if (r < 0) {
        goto err_features;
    }
    for (i = 0; i < dev->nvqs; ++i) {
        r = vhost_virtqueue_set_addr(dev, dev->vqs + i, i,
                                     enable_log);
        if (r < 0) {
            goto err_vq;
        }
    }
    return 0;
err_vq:
    for (; i >= 0; --i) {
        t = vhost_virtqueue_set_addr(dev, dev->vqs + i, i,
                                     dev->log_enabled);
        assert(t >= 0);
    }
    t = vhost_dev_set_features(dev, dev->log_enabled);
    assert(t >= 0);
err_features:
    return r;
}

static int vhost_migration_log(MemoryListener *listener, int enable)
{
    struct vhost_dev *dev = container_of(listener, struct vhost_dev,
                                         memory_listener);
    int r;
    if (!!enable == dev->log_enabled) {
        return 0;
    }
    if (!dev->started) {
        dev->log_enabled = enable;
        return 0;
    }
    if (!enable) {
        r = vhost_dev_set_log(dev, false);
        if (r < 0) {
            return r;
        }
        g_free(dev->log);
        dev->log = NULL;
        dev->log_size = 0;
    } else {
        vhost_dev_log_resize(dev, vhost_get_log_size(dev));
        r = vhost_dev_set_log(dev, true);
        if (r < 0) {
            return r;
        }
    }
    dev->log_enabled = enable;
    return 0;
}

static void vhost_log_global_start(MemoryListener *listener)
{
    int r;

    r = vhost_migration_log(listener, true);
    if (r < 0) {
        abort();
    }
}

static void vhost_log_global_stop(MemoryListener *listener)
{
    int r;

    r = vhost_migration_log(listener, false);
    if (r < 0) {
        abort();
    }
}

static void vhost_log_start(MemoryListener *listener,
                            MemoryRegionSection *section)
{
    /* FIXME: implement */
}

static void vhost_log_stop(MemoryListener *listener,
                           MemoryRegionSection *section)
{
    /* FIXME: implement */
}

static int vhost_virtqueue_start(struct vhost_dev *dev,
                                struct VirtIODevice *vdev,
                                struct vhost_virtqueue *vq,
                                unsigned idx)
{
    hwaddr s, l, a;
    int r;
    int vhost_vq_index = idx - dev->vq_index;
    struct vhost_vring_file file = {
        .index = vhost_vq_index
    };
    struct vhost_vring_state state = {
        .index = vhost_vq_index
    };
    struct VirtQueue *vvq = virtio_get_queue(vdev, idx);

    assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);

    vq->num = state.num = virtio_queue_get_num(vdev, idx);
    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_NUM, &state);
    if (r) {
        return -errno;
    }

    state.num = virtio_queue_get_last_avail_idx(vdev, idx);
    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_BASE, &state);
    if (r) {
        return -errno;
    }

    s = l = virtio_queue_get_desc_size(vdev, idx);
    a = virtio_queue_get_desc_addr(vdev, idx);
    vq->desc = cpu_physical_memory_map(a, &l, 0);
    if (!vq->desc || l != s) {
        r = -ENOMEM;
        goto fail_alloc_desc;
    }
    s = l = virtio_queue_get_avail_size(vdev, idx);
    a = virtio_queue_get_avail_addr(vdev, idx);
    vq->avail = cpu_physical_memory_map(a, &l, 0);
    if (!vq->avail || l != s) {
        r = -ENOMEM;
        goto fail_alloc_avail;
    }
    vq->used_size = s = l = virtio_queue_get_used_size(vdev, idx);
    vq->used_phys = a = virtio_queue_get_used_addr(vdev, idx);
    vq->used = cpu_physical_memory_map(a, &l, 1);
    if (!vq->used || l != s) {
        r = -ENOMEM;
        goto fail_alloc_used;
    }

    vq->ring_size = s = l = virtio_queue_get_ring_size(vdev, idx);
    vq->ring_phys = a = virtio_queue_get_ring_addr(vdev, idx);
    vq->ring = cpu_physical_memory_map(a, &l, 1);
    if (!vq->ring || l != s) {
        r = -ENOMEM;
        goto fail_alloc_ring;
    }

    r = vhost_virtqueue_set_addr(dev, vq, vhost_vq_index, dev->log_enabled);
    if (r < 0) {
        r = -errno;
        goto fail_alloc;
    }

    file.fd = event_notifier_get_fd(virtio_queue_get_host_notifier(vvq));
    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_KICK, &file);
    if (r) {
        r = -errno;
        goto fail_kick;
    }

    /* Clear and discard previous events if any. */
    event_notifier_test_and_clear(&vq->masked_notifier);

    return 0;

fail_kick:
fail_alloc:
    cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
                              0, 0);
fail_alloc_ring:
    cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),
                              0, 0);
fail_alloc_used:
    cpu_physical_memory_unmap(vq->avail, virtio_queue_get_avail_size(vdev, idx),
                              0, 0);
fail_alloc_avail:
    cpu_physical_memory_unmap(vq->desc, virtio_queue_get_desc_size(vdev, idx),
                              0, 0);
fail_alloc_desc:
    return r;
}

static void vhost_virtqueue_stop(struct vhost_dev *dev,
                                    struct VirtIODevice *vdev,
                                    struct vhost_virtqueue *vq,
                                    unsigned idx)
{
    struct vhost_vring_state state = {
        .index = idx - dev->vq_index
    };
    int r;
    assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
    r = dev->vhost_ops->vhost_call(dev, VHOST_GET_VRING_BASE, &state);
    if (r < 0) {
        fprintf(stderr, "vhost VQ %d ring restore failed: %d\n", idx, r);
        fflush(stderr);
    }
    virtio_queue_set_last_avail_idx(vdev, idx, state.num);
    virtio_queue_invalidate_signalled_used(vdev, idx);
    assert (r >= 0);
    cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
                              0, virtio_queue_get_ring_size(vdev, idx));
    cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),
                              1, virtio_queue_get_used_size(vdev, idx));
    cpu_physical_memory_unmap(vq->avail, virtio_queue_get_avail_size(vdev, idx),
                              0, virtio_queue_get_avail_size(vdev, idx));
    cpu_physical_memory_unmap(vq->desc, virtio_queue_get_desc_size(vdev, idx),
                              0, virtio_queue_get_desc_size(vdev, idx));
}

static void vhost_eventfd_add(MemoryListener *listener,
                              MemoryRegionSection *section,
                              bool match_data, uint64_t data, EventNotifier *e)
{
}

static void vhost_eventfd_del(MemoryListener *listener,
                              MemoryRegionSection *section,
                              bool match_data, uint64_t data, EventNotifier *e)
{
}

static int vhost_virtqueue_init(struct vhost_dev *dev,
                                struct vhost_virtqueue *vq, int n)
{
    struct vhost_vring_file file = {
        .index = n,
    };
    int r = event_notifier_init(&vq->masked_notifier, 0);
    if (r < 0) {
        return r;
    }

    file.fd = event_notifier_get_fd(&vq->masked_notifier);
    r = dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_CALL, &file);
    if (r) {
        r = -errno;
        goto fail_call;
    }
    return 0;
fail_call:
    event_notifier_cleanup(&vq->masked_notifier);
    return r;
}

static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
{
    event_notifier_cleanup(&vq->masked_notifier);
}

int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
                   bool force)
{
    uint64_t features;
    int i, r;

    if (hdev->vhost_ops->vhost_backend_init(hdev, opaque) < 0) {
        return -errno;
    }

    r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_OWNER, NULL);
    if (r < 0) {
        goto fail;
    }

    r = hdev->vhost_ops->vhost_call(hdev, VHOST_GET_FEATURES, &features);
    if (r < 0) {
        goto fail;
    }

    for (i = 0; i < hdev->nvqs; ++i) {
        r = vhost_virtqueue_init(hdev, hdev->vqs + i, i);
        if (r < 0) {
            goto fail_vq;
        }
    }
    hdev->features = features;

    hdev->memory_listener = (MemoryListener) {
        .begin = vhost_begin,
        .commit = vhost_commit,
        .region_add = vhost_region_add,
        .region_del = vhost_region_del,
        .region_nop = vhost_region_nop,
        .log_start = vhost_log_start,
        .log_stop = vhost_log_stop,
        .log_sync = vhost_log_sync,
        .log_global_start = vhost_log_global_start,
        .log_global_stop = vhost_log_global_stop,
        .eventfd_add = vhost_eventfd_add,
        .eventfd_del = vhost_eventfd_del,
        .priority = 10
    };
    hdev->mem = g_malloc0(offsetof(struct vhost_memory, regions));
    hdev->n_mem_sections = 0;
    hdev->mem_sections = NULL;
    hdev->log = NULL;
    hdev->log_size = 0;
    hdev->log_enabled = false;
    hdev->started = false;
    hdev->memory_changed = false;
    memory_listener_register(&hdev->memory_listener, &address_space_memory);
    hdev->force = force;
    return 0;
fail_vq:
    while (--i >= 0) {
        vhost_virtqueue_cleanup(hdev->vqs + i);
    }
fail:
    r = -errno;
    hdev->vhost_ops->vhost_backend_cleanup(hdev);
    return r;
}

void vhost_dev_cleanup(struct vhost_dev *hdev)
{
    int i;
    for (i = 0; i < hdev->nvqs; ++i) {
        vhost_virtqueue_cleanup(hdev->vqs + i);
    }
    memory_listener_unregister(&hdev->memory_listener);
    g_free(hdev->mem);
    g_free(hdev->mem_sections);
    hdev->vhost_ops->vhost_backend_cleanup(hdev);
}

bool vhost_dev_query(struct vhost_dev *hdev, VirtIODevice *vdev)
{
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
    VirtioBusState *vbus = VIRTIO_BUS(qbus);
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);

    return !k->query_guest_notifiers ||
           k->query_guest_notifiers(qbus->parent) ||
           hdev->force;
}

/* Stop processing guest IO notifications in qemu.
 * Start processing them in vhost in kernel.
 */
int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
{
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
    VirtioBusState *vbus = VIRTIO_BUS(qbus);
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
    int i, r;
    if (!k->set_host_notifier) {
        fprintf(stderr, "binding does not support host notifiers\n");
        r = -ENOSYS;
        goto fail;
    }

    for (i = 0; i < hdev->nvqs; ++i) {
        r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, true);
        if (r < 0) {
            fprintf(stderr, "vhost VQ %d notifier binding failed: %d\n", i, -r);
            goto fail_vq;
        }
    }

    return 0;
fail_vq:
    while (--i >= 0) {
        r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
        if (r < 0) {
            fprintf(stderr, "vhost VQ %d notifier cleanup error: %d\n", i, -r);
            fflush(stderr);
        }
        assert (r >= 0);
    }
fail:
    return r;
}

/* Stop processing guest IO notifications in vhost.
 * Start processing them in qemu.
 * This might actually run the qemu handlers right away,
 * so virtio in qemu must be completely setup when this is called.
 */
void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
{
    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
    VirtioBusState *vbus = VIRTIO_BUS(qbus);
    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
    int i, r;

    for (i = 0; i < hdev->nvqs; ++i) {
        r = k->set_host_notifier(qbus->parent, hdev->vq_index + i, false);
        if (r < 0) {
            fprintf(stderr, "vhost VQ %d notifier cleanup failed: %d\n", i, -r);
            fflush(stderr);
        }
        assert (r >= 0);
    }
}

/* Test and clear event pending status.
 * Should be called after unmask to avoid losing events.
 */
bool vhost_virtqueue_pending(struct vhost_dev *hdev, int n)
{
    struct vhost_virtqueue *vq = hdev->vqs + n - hdev->vq_index;
    assert(hdev->started);
    assert(n >= hdev->vq_index && n < hdev->vq_index + hdev->nvqs);
    return event_notifier_test_and_clear(&vq->masked_notifier);
}

/* Mask/unmask events from this vq. */
void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
                         bool mask)
{
    struct VirtQueue *vvq = virtio_get_queue(vdev, n);
    int r, index = n - hdev->vq_index;

    assert(hdev->started);
    assert(n >= hdev->vq_index && n < hdev->vq_index + hdev->nvqs);

    struct vhost_vring_file file = {
        .index = index
    };
    if (mask) {
        file.fd = event_notifier_get_fd(&hdev->vqs[index].masked_notifier);
    } else {
        file.fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq));
    }
    r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_VRING_CALL, &file);
    assert(r >= 0);
}

unsigned vhost_get_features(struct vhost_dev *hdev, const int *feature_bits,
        unsigned features)
{
    const int *bit = feature_bits;
    while (*bit != VHOST_INVALID_FEATURE_BIT) {
        unsigned bit_mask = (1 << *bit);
        if (!(hdev->features & bit_mask)) {
            features &= ~bit_mask;
        }
        bit++;
    }
    return features;
}

void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
        unsigned features)
{
    const int *bit = feature_bits;
    while (*bit != VHOST_INVALID_FEATURE_BIT) {
        unsigned bit_mask = (1 << *bit);
        if (features & bit_mask) {
            hdev->acked_features |= bit_mask;
        }
        bit++;
    }
}

/* Host notifiers must be enabled at this point. */
int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
{
    int i, r;

    hdev->started = true;

    r = vhost_dev_set_features(hdev, hdev->log_enabled);
    if (r < 0) {
        goto fail_features;
    }
    r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_MEM_TABLE, hdev->mem);
    if (r < 0) {
        r = -errno;
        goto fail_mem;
    }
    for (i = 0; i < hdev->nvqs; ++i) {
        r = vhost_virtqueue_start(hdev,
                                  vdev,
                                  hdev->vqs + i,
                                  hdev->vq_index + i);
        if (r < 0) {
            goto fail_vq;
        }
    }

    if (hdev->log_enabled) {
        hdev->log_size = vhost_get_log_size(hdev);
        hdev->log = hdev->log_size ?
            g_malloc0(hdev->log_size * sizeof *hdev->log) : NULL;
        r = hdev->vhost_ops->vhost_call(hdev, VHOST_SET_LOG_BASE, hdev->log);
        if (r < 0) {
            r = -errno;
            goto fail_log;
        }
    }

    return 0;
fail_log:
fail_vq:
    while (--i >= 0) {
        vhost_virtqueue_stop(hdev,
                             vdev,
                             hdev->vqs + i,
                             hdev->vq_index + i);
    }
    i = hdev->nvqs;
fail_mem:
fail_features:

    hdev->started = false;
    return r;
}

/* Host notifiers must be enabled at this point. */
void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
{
    int i;

    for (i = 0; i < hdev->nvqs; ++i) {
        vhost_virtqueue_stop(hdev,
                             vdev,
                             hdev->vqs + i,
                             hdev->vq_index + i);
    }
    vhost_log_sync_range(hdev, 0, ~0x0ull);

    hdev->started = false;
    g_free(hdev->log);
    hdev->log = NULL;
    hdev->log_size = 0;
}