hw/virtio/vhost-user.c

   1 /*
   2  * vhost-user
   3  *
   4  * Copyright (c) 2013 Virtual Open Systems Sarl.
   5  *
   6  * This work is licensed under the terms of the GNU GPL, version 2 or later.
   7  * See the COPYING file in the top-level directory.
   8  *
   9  */
  10
  11 #include "qemu/osdep.h"
  12 #include "qapi/error.h"
  13 #include "hw/virtio/vhost.h"
  14 #include "hw/virtio/vhost-backend.h"
  15 #include "hw/virtio/virtio-net.h"
  16 #include "sysemu/char.h"
  17 #include "sysemu/kvm.h"
  18 #include "qemu/error-report.h"
  19 #include "qemu/sockets.h"
  20 #include "migration/migration.h"
  21
  22 #include <sys/ioctl.h>
  23 #include <sys/socket.h>
  24 #include <sys/un.h>
  25 #include <linux/vhost.h>
  26
  27 #define VHOST_MEMORY_MAX_NREGIONS    8
  28 #define VHOST_USER_F_PROTOCOL_FEATURES 30
  29
  30 enum VhostUserProtocolFeature {
  31     VHOST_USER_PROTOCOL_F_MQ = 0,
  32     VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
  33     VHOST_USER_PROTOCOL_F_RARP = 2,
  34
  35     VHOST_USER_PROTOCOL_F_MAX
  36 };
  37
  38 #define VHOST_USER_PROTOCOL_FEATURE_MASK ((1 << VHOST_USER_PROTOCOL_F_MAX) - 1)
  39
  40 typedef enum VhostUserRequest {
  41     VHOST_USER_NONE = 0,
  42     VHOST_USER_GET_FEATURES = 1,
  43     VHOST_USER_SET_FEATURES = 2,
  44     VHOST_USER_SET_OWNER = 3,
  45     VHOST_USER_RESET_OWNER = 4,
  46     VHOST_USER_SET_MEM_TABLE = 5,
  47     VHOST_USER_SET_LOG_BASE = 6,
  48     VHOST_USER_SET_LOG_FD = 7,
  49     VHOST_USER_SET_VRING_NUM = 8,
  50     VHOST_USER_SET_VRING_ADDR = 9,
  51     VHOST_USER_SET_VRING_BASE = 10,
  52     VHOST_USER_GET_VRING_BASE = 11,
  53     VHOST_USER_SET_VRING_KICK = 12,
  54     VHOST_USER_SET_VRING_CALL = 13,
  55     VHOST_USER_SET_VRING_ERR = 14,
  56     VHOST_USER_GET_PROTOCOL_FEATURES = 15,
  57     VHOST_USER_SET_PROTOCOL_FEATURES = 16,
  58     VHOST_USER_GET_QUEUE_NUM = 17,
  59     VHOST_USER_SET_VRING_ENABLE = 18,
  60     VHOST_USER_SEND_RARP = 19,
  61     VHOST_USER_MAX
  62 } VhostUserRequest;
  63
  64 typedef struct VhostUserMemoryRegion {
  65     uint64_t guest_phys_addr;
  66     uint64_t memory_size;
  67     uint64_t userspace_addr;
  68     uint64_t mmap_offset;
  69 } VhostUserMemoryRegion;
  70
  71 typedef struct VhostUserMemory {
  72     uint32_t nregions;
  73     uint32_t padding;
  74     VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
  75 } VhostUserMemory;
  76
  77 typedef struct VhostUserLog {
  78     uint64_t mmap_size;
  79     uint64_t mmap_offset;
  80 } VhostUserLog;
  81
  82 typedef struct VhostUserMsg {
  83     VhostUserRequest request;
  84
  85 #define VHOST_USER_VERSION_MASK     (0x3)
  86 #define VHOST_USER_REPLY_MASK       (0x1<<2)
  87     uint32_t flags;
  88     uint32_t size; /* the following payload size */
  89     union {
  90 #define VHOST_USER_VRING_IDX_MASK   (0xff)
  91 #define VHOST_USER_VRING_NOFD_MASK  (0x1<<8)
  92         uint64_t u64;
  93         struct vhost_vring_state state;
  94         struct vhost_vring_addr addr;
  95         VhostUserMemory memory;
  96         VhostUserLog log;
  97     } payload;
  98 } QEMU_PACKED VhostUserMsg;
  99
 100 static VhostUserMsg m __attribute__ ((unused));
 101 #define VHOST_USER_HDR_SIZE (sizeof(m.request) \
 102                             + sizeof(m.flags) \
 103                             + sizeof(m.size))
 104
 105 #define VHOST_USER_PAYLOAD_SIZE (sizeof(m) - VHOST_USER_HDR_SIZE)
 106
 107 /* The version of the protocol we support */
 108 #define VHOST_USER_VERSION    (0x1)
 109
 110 static bool ioeventfd_enabled(void)
 111 {
 112     return kvm_enabled() && kvm_eventfds_enabled();
 113 }
 114
 115 static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg)
 116 {
 117     CharDriverState *chr = dev->opaque;
 118     uint8_t *p = (uint8_t *) msg;
 119     int r, size = VHOST_USER_HDR_SIZE;
 120
 121     r = qemu_chr_fe_read_all(chr, p, size);
 122     if (r != size) {
 123         error_report("Failed to read msg header. Read %d instead of %d."
 124                      " Original request %d.", r, size, msg->request);
 125         goto fail;
 126     }
 127
 128     /* validate received flags */
 129     if (msg->flags != (VHOST_USER_REPLY_MASK | VHOST_USER_VERSION)) {
 130         error_report("Failed to read msg header."
 131                 " Flags 0x%x instead of 0x%x.", msg->flags,
 132                 VHOST_USER_REPLY_MASK | VHOST_USER_VERSION);
 133         goto fail;
 134     }
 135
 136     /* validate message size is sane */
 137     if (msg->size > VHOST_USER_PAYLOAD_SIZE) {
 138         error_report("Failed to read msg header."
 139                 " Size %d exceeds the maximum %zu.", msg->size,
 140                 VHOST_USER_PAYLOAD_SIZE);
 141         goto fail;
 142     }
 143
 144     if (msg->size) {
 145         p += VHOST_USER_HDR_SIZE;
 146         size = msg->size;
 147         r = qemu_chr_fe_read_all(chr, p, size);
 148         if (r != size) {
 149             error_report("Failed to read msg payload."
 150                          " Read %d instead of %d.", r, msg->size);
 151             goto fail;
 152         }
 153     }
 154
 155     return 0;
 156
 157 fail:
 158     return -1;
 159 }
 160
 161 static bool vhost_user_one_time_request(VhostUserRequest request)
 162 {
 163     switch (request) {
 164     case VHOST_USER_SET_OWNER:
 165     case VHOST_USER_RESET_OWNER:
 166     case VHOST_USER_SET_MEM_TABLE:
 167     case VHOST_USER_GET_QUEUE_NUM:
 168         return true;
 169     default:
 170         return false;
 171     }
 172 }
 173
 174 /* most non-init callers ignore the error */
 175 static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
 176                             int *fds, int fd_num)
 177 {
 178     CharDriverState *chr = dev->opaque;
 179     int size = VHOST_USER_HDR_SIZE + msg->size;
 180
 181     /*
 182      * For non-vring specific requests, like VHOST_USER_SET_MEM_TABLE,
 183      * we just need send it once in the first time. For later such
 184      * request, we just ignore it.
 185      */
 186     if (vhost_user_one_time_request(msg->request) && dev->vq_index != 0) {
 187         return 0;
 188     }
 189
 190     if (fd_num) {
 191         qemu_chr_fe_set_msgfds(chr, fds, fd_num);
 192     }
 193
 194     return qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size) == size ?
 195             0 : -1;
 196 }
 197
 198 static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
 199                                    struct vhost_log *log)
 200 {
 201     int fds[VHOST_MEMORY_MAX_NREGIONS];
 202     size_t fd_num = 0;
 203     bool shmfd = virtio_has_feature(dev->protocol_features,
 204                                     VHOST_USER_PROTOCOL_F_LOG_SHMFD);
 205     VhostUserMsg msg = {
 206         .request = VHOST_USER_SET_LOG_BASE,
 207         .flags = VHOST_USER_VERSION,
 208         .payload.log.mmap_size = log->size * sizeof(*(log->log)),
 209         .payload.log.mmap_offset = 0,
 210         .size = sizeof(msg.payload.log),
 211     };
 212
 213     if (shmfd && log->fd != -1) {
 214         fds[fd_num++] = log->fd;
 215     }
 216
 217     vhost_user_write(dev, &msg, fds, fd_num);
 218
 219     if (shmfd) {
 220         msg.size = 0;
 221         if (vhost_user_read(dev, &msg) < 0) {
 222             return 0;
 223         }
 224
 225         if (msg.request != VHOST_USER_SET_LOG_BASE) {
 226             error_report("Received unexpected msg type. "
 227                          "Expected %d received %d",
 228                          VHOST_USER_SET_LOG_BASE, msg.request);
 229             return -1;
 230         }
 231     }
 232
 233     return 0;
 234 }
 235
 236 static int vhost_user_set_mem_table(struct vhost_dev *dev,
 237                                     struct vhost_memory *mem)
 238 {
 239     int fds[VHOST_MEMORY_MAX_NREGIONS];
 240     int i, fd;
 241     size_t fd_num = 0;
 242     VhostUserMsg msg = {
 243         .request = VHOST_USER_SET_MEM_TABLE,
 244         .flags = VHOST_USER_VERSION,
 245     };
 246
 247     for (i = 0; i < dev->mem->nregions; ++i) {
 248         struct vhost_memory_region *reg = dev->mem->regions + i;
 249         ram_addr_t offset;
 250         MemoryRegion *mr;
 251
 252         assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
 253         mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
 254                                      &offset);
 255         fd = memory_region_get_fd(mr);
 256         if (fd > 0) {
 257             msg.payload.memory.regions[fd_num].userspace_addr = reg->userspace_addr;
 258             msg.payload.memory.regions[fd_num].memory_size  = reg->memory_size;
 259             msg.payload.memory.regions[fd_num].guest_phys_addr = reg->guest_phys_addr;
 260             msg.payload.memory.regions[fd_num].mmap_offset = offset;
 261             assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
 262             fds[fd_num++] = fd;
 263         }
 264     }
 265
 266     msg.payload.memory.nregions = fd_num;
 267
 268     if (!fd_num) {
 269         error_report("Failed initializing vhost-user memory map, "
 270                      "consider using -object memory-backend-file share=on");
 271         return -1;
 272     }
 273
 274     msg.size = sizeof(msg.payload.memory.nregions);
 275     msg.size += sizeof(msg.payload.memory.padding);
 276     msg.size += fd_num * sizeof(VhostUserMemoryRegion);
 277
 278     vhost_user_write(dev, &msg, fds, fd_num);
 279
 280     return 0;
 281 }
 282
 283 static int vhost_user_set_vring_addr(struct vhost_dev *dev,
 284                                      struct vhost_vring_addr *addr)
 285 {
 286     VhostUserMsg msg = {
 287         .request = VHOST_USER_SET_VRING_ADDR,
 288         .flags = VHOST_USER_VERSION,
 289         .payload.addr = *addr,
 290         .size = sizeof(msg.payload.addr),
 291     };
 292
 293     vhost_user_write(dev, &msg, NULL, 0);
 294
 295     return 0;
 296 }
 297
 298 static int vhost_user_set_vring_endian(struct vhost_dev *dev,
 299                                        struct vhost_vring_state *ring)
 300 {
 301     error_report("vhost-user trying to send unhandled ioctl");
 302     return -1;
 303 }
 304
 305 static int vhost_set_vring(struct vhost_dev *dev,
 306                            unsigned long int request,
 307                            struct vhost_vring_state *ring)
 308 {
 309     VhostUserMsg msg = {
 310         .request = request,
 311         .flags = VHOST_USER_VERSION,
 312         .payload.state = *ring,
 313         .size = sizeof(msg.payload.state),
 314     };
 315
 316     vhost_user_write(dev, &msg, NULL, 0);
 317
 318     return 0;
 319 }
 320
 321 static int vhost_user_set_vring_num(struct vhost_dev *dev,
 322                                     struct vhost_vring_state *ring)
 323 {
 324     return vhost_set_vring(dev, VHOST_USER_SET_VRING_NUM, ring);
 325 }
 326
 327 static int vhost_user_set_vring_base(struct vhost_dev *dev,
 328                                      struct vhost_vring_state *ring)
 329 {
 330     return vhost_set_vring(dev, VHOST_USER_SET_VRING_BASE, ring);
 331 }
 332
 333 static int vhost_user_set_vring_enable(struct vhost_dev *dev, int enable)
 334 {
 335     int i;
 336
 337     if (!virtio_has_feature(dev->features, VHOST_USER_F_PROTOCOL_FEATURES)) {
 338         return -1;
 339     }
 340
 341     for (i = 0; i < dev->nvqs; ++i) {
 342         struct vhost_vring_state state = {
 343             .index = dev->vq_index + i,
 344             .num   = enable,
 345         };
 346
 347         vhost_set_vring(dev, VHOST_USER_SET_VRING_ENABLE, &state);
 348     }
 349
 350     return 0;
 351 }
 352
 353 static int vhost_user_get_vring_base(struct vhost_dev *dev,
 354                                      struct vhost_vring_state *ring)
 355 {
 356     VhostUserMsg msg = {
 357         .request = VHOST_USER_GET_VRING_BASE,
 358         .flags = VHOST_USER_VERSION,
 359         .payload.state = *ring,
 360         .size = sizeof(msg.payload.state),
 361     };
 362
 363     vhost_user_write(dev, &msg, NULL, 0);
 364
 365     if (vhost_user_read(dev, &msg) < 0) {
 366         return 0;
 367     }
 368
 369     if (msg.request != VHOST_USER_GET_VRING_BASE) {
 370         error_report("Received unexpected msg type. Expected %d received %d",
 371                      VHOST_USER_GET_VRING_BASE, msg.request);
 372         return -1;
 373     }
 374
 375     if (msg.size != sizeof(msg.payload.state)) {
 376         error_report("Received bad msg size.");
 377         return -1;
 378     }
 379
 380     *ring = msg.payload.state;
 381
 382     return 0;
 383 }
 384
 385 static int vhost_set_vring_file(struct vhost_dev *dev,
 386                                 VhostUserRequest request,
 387                                 struct vhost_vring_file *file)
 388 {
 389     int fds[VHOST_MEMORY_MAX_NREGIONS];
 390     size_t fd_num = 0;
 391     VhostUserMsg msg = {
 392         .request = request,
 393         .flags = VHOST_USER_VERSION,
 394         .payload.u64 = file->index & VHOST_USER_VRING_IDX_MASK,
 395         .size = sizeof(msg.payload.u64),
 396     };
 397
 398     if (ioeventfd_enabled() && file->fd > 0) {
 399         fds[fd_num++] = file->fd;
 400     } else {
 401         msg.payload.u64 |= VHOST_USER_VRING_NOFD_MASK;
 402     }
 403
 404     vhost_user_write(dev, &msg, fds, fd_num);
 405
 406     return 0;
 407 }
 408
 409 static int vhost_user_set_vring_kick(struct vhost_dev *dev,
 410                                      struct vhost_vring_file *file)
 411 {
 412     return vhost_set_vring_file(dev, VHOST_USER_SET_VRING_KICK, file);
 413 }
 414
 415 static int vhost_user_set_vring_call(struct vhost_dev *dev,
 416                                      struct vhost_vring_file *file)
 417 {
 418     return vhost_set_vring_file(dev, VHOST_USER_SET_VRING_CALL, file);
 419 }
 420
 421 static int vhost_user_set_u64(struct vhost_dev *dev, int request, uint64_t u64)
 422 {
 423     VhostUserMsg msg = {
 424         .request = request,
 425         .flags = VHOST_USER_VERSION,
 426         .payload.u64 = u64,
 427         .size = sizeof(msg.payload.u64),
 428     };
 429
 430     vhost_user_write(dev, &msg, NULL, 0);
 431
 432     return 0;
 433 }
 434
 435 static int vhost_user_set_features(struct vhost_dev *dev,
 436                                    uint64_t features)
 437 {
 438     return vhost_user_set_u64(dev, VHOST_USER_SET_FEATURES, features);
 439 }
 440
 441 static int vhost_user_set_protocol_features(struct vhost_dev *dev,
 442                                             uint64_t features)
 443 {
 444     return vhost_user_set_u64(dev, VHOST_USER_SET_PROTOCOL_FEATURES, features);
 445 }
 446
 447 static int vhost_user_get_u64(struct vhost_dev *dev, int request, uint64_t *u64)
 448 {
 449     VhostUserMsg msg = {
 450         .request = request,
 451         .flags = VHOST_USER_VERSION,
 452     };
 453
 454     if (vhost_user_one_time_request(request) && dev->vq_index != 0) {
 455         return 0;
 456     }
 457
 458     vhost_user_write(dev, &msg, NULL, 0);
 459
 460     if (vhost_user_read(dev, &msg) < 0) {
 461         return 0;
 462     }
 463
 464     if (msg.request != request) {
 465         error_report("Received unexpected msg type. Expected %d received %d",
 466                      request, msg.request);
 467         return -1;
 468     }
 469
 470     if (msg.size != sizeof(msg.payload.u64)) {
 471         error_report("Received bad msg size.");
 472         return -1;
 473     }
 474
 475     *u64 = msg.payload.u64;
 476
 477     return 0;
 478 }
 479
 480 static int vhost_user_get_features(struct vhost_dev *dev, uint64_t *features)
 481 {
 482     return vhost_user_get_u64(dev, VHOST_USER_GET_FEATURES, features);
 483 }
 484
 485 static int vhost_user_set_owner(struct vhost_dev *dev)
 486 {
 487     VhostUserMsg msg = {
 488         .request = VHOST_USER_SET_OWNER,
 489         .flags = VHOST_USER_VERSION,
 490     };
 491
 492     vhost_user_write(dev, &msg, NULL, 0);
 493
 494     return 0;
 495 }
 496
 497 static int vhost_user_reset_device(struct vhost_dev *dev)
 498 {
 499     VhostUserMsg msg = {
 500         .request = VHOST_USER_RESET_OWNER,
 501         .flags = VHOST_USER_VERSION,
 502     };
 503
 504     vhost_user_write(dev, &msg, NULL, 0);
 505
 506     return 0;
 507 }
 508
 509 static int vhost_user_init(struct vhost_dev *dev, void *opaque)
 510 {
 511     uint64_t features;
 512     int err;
 513
 514     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 515
 516     dev->opaque = opaque;
 517
 518     err = vhost_user_get_features(dev, &features);
 519     if (err < 0) {
 520         return err;
 521     }
 522
 523     if (virtio_has_feature(features, VHOST_USER_F_PROTOCOL_FEATURES)) {
 524         dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
 525
 526         err = vhost_user_get_u64(dev, VHOST_USER_GET_PROTOCOL_FEATURES,
 527                                  &features);
 528         if (err < 0) {
 529             return err;
 530         }
 531
 532         dev->protocol_features = features & VHOST_USER_PROTOCOL_FEATURE_MASK;
 533         err = vhost_user_set_protocol_features(dev, dev->protocol_features);
 534         if (err < 0) {
 535             return err;
 536         }
 537
 538         /* query the max queues we support if backend supports Multiple Queue */
 539         if (dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ)) {
 540             err = vhost_user_get_u64(dev, VHOST_USER_GET_QUEUE_NUM,
 541                                      &dev->max_queues);
 542             if (err < 0) {
 543                 return err;
 544             }
 545         }
 546     }
 547
 548     if (dev->migration_blocker == NULL &&
 549         !virtio_has_feature(dev->protocol_features,
 550                             VHOST_USER_PROTOCOL_F_LOG_SHMFD)) {
 551         error_setg(&dev->migration_blocker,
 552                    "Migration disabled: vhost-user backend lacks "
 553                    "VHOST_USER_PROTOCOL_F_LOG_SHMFD feature.");
 554     }
 555
 556     return 0;
 557 }
 558
 559 static int vhost_user_cleanup(struct vhost_dev *dev)
 560 {
 561     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 562
 563     dev->opaque = 0;
 564
 565     return 0;
 566 }
 567
 568 static int vhost_user_get_vq_index(struct vhost_dev *dev, int idx)
 569 {
 570     assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
 571
 572     return idx;
 573 }
 574
 575 static int vhost_user_memslots_limit(struct vhost_dev *dev)
 576 {
 577     return VHOST_MEMORY_MAX_NREGIONS;
 578 }
 579
 580 static bool vhost_user_requires_shm_log(struct vhost_dev *dev)
 581 {
 582     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 583
 584     return virtio_has_feature(dev->protocol_features,
 585                               VHOST_USER_PROTOCOL_F_LOG_SHMFD);
 586 }
 587
 588 static int vhost_user_migration_done(struct vhost_dev *dev, char* mac_addr)
 589 {
 590     VhostUserMsg msg = { 0 };
 591     int err;
 592
 593     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 594
 595     /* If guest supports GUEST_ANNOUNCE do nothing */
 596     if (virtio_has_feature(dev->acked_features, VIRTIO_NET_F_GUEST_ANNOUNCE)) {
 597         return 0;
 598     }
 599
 600     /* if backend supports VHOST_USER_PROTOCOL_F_RARP ask it to send the RARP */
 601     if (virtio_has_feature(dev->protocol_features,
 602                            VHOST_USER_PROTOCOL_F_RARP)) {
 603         msg.request = VHOST_USER_SEND_RARP;
 604         msg.flags = VHOST_USER_VERSION;
 605         memcpy((char *)&msg.payload.u64, mac_addr, 6);
 606         msg.size = sizeof(msg.payload.u64);
 607
 608         err = vhost_user_write(dev, &msg, NULL, 0);
 609         return err;
 610     }
 611     return -1;
 612 }
 613
 614 static bool vhost_user_can_merge(struct vhost_dev *dev,
 615                                  uint64_t start1, uint64_t size1,
 616                                  uint64_t start2, uint64_t size2)
 617 {
 618     ram_addr_t offset;
 619     int mfd, rfd;
 620     MemoryRegion *mr;
 621
 622     mr = memory_region_from_host((void *)(uintptr_t)start1, &offset);
 623     mfd = memory_region_get_fd(mr);
 624
 625     mr = memory_region_from_host((void *)(uintptr_t)start2, &offset);
 626     rfd = memory_region_get_fd(mr);
 627
 628     return mfd == rfd;
 629 }
 630
 631 const VhostOps user_ops = {
 632         .backend_type = VHOST_BACKEND_TYPE_USER,
 633         .vhost_backend_init = vhost_user_init,
 634         .vhost_backend_cleanup = vhost_user_cleanup,
 635         .vhost_backend_memslots_limit = vhost_user_memslots_limit,
 636         .vhost_set_log_base = vhost_user_set_log_base,
 637         .vhost_set_mem_table = vhost_user_set_mem_table,
 638         .vhost_set_vring_addr = vhost_user_set_vring_addr,
 639         .vhost_set_vring_endian = vhost_user_set_vring_endian,
 640         .vhost_set_vring_num = vhost_user_set_vring_num,
 641         .vhost_set_vring_base = vhost_user_set_vring_base,
 642         .vhost_get_vring_base = vhost_user_get_vring_base,
 643         .vhost_set_vring_kick = vhost_user_set_vring_kick,
 644         .vhost_set_vring_call = vhost_user_set_vring_call,
 645         .vhost_set_features = vhost_user_set_features,
 646         .vhost_get_features = vhost_user_get_features,
 647         .vhost_set_owner = vhost_user_set_owner,
 648         .vhost_reset_device = vhost_user_reset_device,
 649         .vhost_get_vq_index = vhost_user_get_vq_index,
 650         .vhost_set_vring_enable = vhost_user_set_vring_enable,
 651         .vhost_requires_shm_log = vhost_user_requires_shm_log,
 652         .vhost_migration_done = vhost_user_migration_done,
 653         .vhost_backend_can_merge = vhost_user_can_merge,
 654 };