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     VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
  35
  36     VHOST_USER_PROTOCOL_F_MAX
  37 };
  38
  39 #define VHOST_USER_PROTOCOL_FEATURE_MASK ((1 << VHOST_USER_PROTOCOL_F_MAX) - 1)
  40
  41 typedef enum VhostUserRequest {
  42     VHOST_USER_NONE = 0,
  43     VHOST_USER_GET_FEATURES = 1,
  44     VHOST_USER_SET_FEATURES = 2,
  45     VHOST_USER_SET_OWNER = 3,
  46     VHOST_USER_RESET_OWNER = 4,
  47     VHOST_USER_SET_MEM_TABLE = 5,
  48     VHOST_USER_SET_LOG_BASE = 6,
  49     VHOST_USER_SET_LOG_FD = 7,
  50     VHOST_USER_SET_VRING_NUM = 8,
  51     VHOST_USER_SET_VRING_ADDR = 9,
  52     VHOST_USER_SET_VRING_BASE = 10,
  53     VHOST_USER_GET_VRING_BASE = 11,
  54     VHOST_USER_SET_VRING_KICK = 12,
  55     VHOST_USER_SET_VRING_CALL = 13,
  56     VHOST_USER_SET_VRING_ERR = 14,
  57     VHOST_USER_GET_PROTOCOL_FEATURES = 15,
  58     VHOST_USER_SET_PROTOCOL_FEATURES = 16,
  59     VHOST_USER_GET_QUEUE_NUM = 17,
  60     VHOST_USER_SET_VRING_ENABLE = 18,
  61     VHOST_USER_SEND_RARP = 19,
  62     VHOST_USER_MAX
  63 } VhostUserRequest;
  64
  65 typedef struct VhostUserMemoryRegion {
  66     uint64_t guest_phys_addr;
  67     uint64_t memory_size;
  68     uint64_t userspace_addr;
  69     uint64_t mmap_offset;
  70 } VhostUserMemoryRegion;
  71
  72 typedef struct VhostUserMemory {
  73     uint32_t nregions;
  74     uint32_t padding;
  75     VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
  76 } VhostUserMemory;
  77
  78 typedef struct VhostUserLog {
  79     uint64_t mmap_size;
  80     uint64_t mmap_offset;
  81 } VhostUserLog;
  82
  83 typedef struct VhostUserMsg {
  84     VhostUserRequest request;
  85
  86 #define VHOST_USER_VERSION_MASK     (0x3)
  87 #define VHOST_USER_REPLY_MASK       (0x1<<2)
  88 #define VHOST_USER_NEED_REPLY_MASK  (0x1 << 3)
  89     uint32_t flags;
  90     uint32_t size; /* the following payload size */
  91     union {
  92 #define VHOST_USER_VRING_IDX_MASK   (0xff)
  93 #define VHOST_USER_VRING_NOFD_MASK  (0x1<<8)
  94         uint64_t u64;
  95         struct vhost_vring_state state;
  96         struct vhost_vring_addr addr;
  97         VhostUserMemory memory;
  98         VhostUserLog log;
  99     } payload;
 100 } QEMU_PACKED VhostUserMsg;
 101
 102 static VhostUserMsg m __attribute__ ((unused));
 103 #define VHOST_USER_HDR_SIZE (sizeof(m.request) \
 104                             + sizeof(m.flags) \
 105                             + sizeof(m.size))
 106
 107 #define VHOST_USER_PAYLOAD_SIZE (sizeof(m) - VHOST_USER_HDR_SIZE)
 108
 109 /* The version of the protocol we support */
 110 #define VHOST_USER_VERSION    (0x1)
 111
 112 static bool ioeventfd_enabled(void)
 113 {
 114     return kvm_enabled() && kvm_eventfds_enabled();
 115 }
 116
 117 static int vhost_user_read(struct vhost_dev *dev, VhostUserMsg *msg)
 118 {
 119     CharDriverState *chr = dev->opaque;
 120     uint8_t *p = (uint8_t *) msg;
 121     int r, size = VHOST_USER_HDR_SIZE;
 122
 123     r = qemu_chr_fe_read_all(chr, p, size);
 124     if (r != size) {
 125         error_report("Failed to read msg header. Read %d instead of %d."
 126                      " Original request %d.", r, size, msg->request);
 127         goto fail;
 128     }
 129
 130     /* validate received flags */
 131     if (msg->flags != (VHOST_USER_REPLY_MASK | VHOST_USER_VERSION)) {
 132         error_report("Failed to read msg header."
 133                 " Flags 0x%x instead of 0x%x.", msg->flags,
 134                 VHOST_USER_REPLY_MASK | VHOST_USER_VERSION);
 135         goto fail;
 136     }
 137
 138     /* validate message size is sane */
 139     if (msg->size > VHOST_USER_PAYLOAD_SIZE) {
 140         error_report("Failed to read msg header."
 141                 " Size %d exceeds the maximum %zu.", msg->size,
 142                 VHOST_USER_PAYLOAD_SIZE);
 143         goto fail;
 144     }
 145
 146     if (msg->size) {
 147         p += VHOST_USER_HDR_SIZE;
 148         size = msg->size;
 149         r = qemu_chr_fe_read_all(chr, p, size);
 150         if (r != size) {
 151             error_report("Failed to read msg payload."
 152                          " Read %d instead of %d.", r, msg->size);
 153             goto fail;
 154         }
 155     }
 156
 157     return 0;
 158
 159 fail:
 160     return -1;
 161 }
 162
 163 static int process_message_reply(struct vhost_dev *dev,
 164                                  VhostUserRequest request)
 165 {
 166     VhostUserMsg msg;
 167
 168     if (vhost_user_read(dev, &msg) < 0) {
 169         return -1;
 170     }
 171
 172     if (msg.request != request) {
 173         error_report("Received unexpected msg type."
 174                      "Expected %d received %d",
 175                      request, msg.request);
 176         return -1;
 177     }
 178
 179     return msg.payload.u64 ? -1 : 0;
 180 }
 181
 182 static bool vhost_user_one_time_request(VhostUserRequest request)
 183 {
 184     switch (request) {
 185     case VHOST_USER_SET_OWNER:
 186     case VHOST_USER_RESET_OWNER:
 187     case VHOST_USER_SET_MEM_TABLE:
 188     case VHOST_USER_GET_QUEUE_NUM:
 189         return true;
 190     default:
 191         return false;
 192     }
 193 }
 194
 195 /* most non-init callers ignore the error */
 196 static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
 197                             int *fds, int fd_num)
 198 {
 199     CharDriverState *chr = dev->opaque;
 200     int ret, size = VHOST_USER_HDR_SIZE + msg->size;
 201
 202     /*
 203      * For non-vring specific requests, like VHOST_USER_SET_MEM_TABLE,
 204      * we just need send it once in the first time. For later such
 205      * request, we just ignore it.
 206      */
 207     if (vhost_user_one_time_request(msg->request) && dev->vq_index != 0) {
 208         return 0;
 209     }
 210
 211     if (qemu_chr_fe_set_msgfds(chr, fds, fd_num) < 0) {
 212         error_report("Failed to set msg fds.");
 213         return -1;
 214     }
 215
 216     ret = qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size);
 217     if (ret != size) {
 218         error_report("Failed to write msg."
 219                      " Wrote %d instead of %d.", ret, size);
 220         return -1;
 221     }
 222
 223     return 0;
 224 }
 225
 226 static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
 227                                    struct vhost_log *log)
 228 {
 229     int fds[VHOST_MEMORY_MAX_NREGIONS];
 230     size_t fd_num = 0;
 231     bool shmfd = virtio_has_feature(dev->protocol_features,
 232                                     VHOST_USER_PROTOCOL_F_LOG_SHMFD);
 233     VhostUserMsg msg = {
 234         .request = VHOST_USER_SET_LOG_BASE,
 235         .flags = VHOST_USER_VERSION,
 236         .payload.log.mmap_size = log->size * sizeof(*(log->log)),
 237         .payload.log.mmap_offset = 0,
 238         .size = sizeof(msg.payload.log),
 239     };
 240
 241     if (shmfd && log->fd != -1) {
 242         fds[fd_num++] = log->fd;
 243     }
 244
 245     if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
 246         return -1;
 247     }
 248
 249     if (shmfd) {
 250         msg.size = 0;
 251         if (vhost_user_read(dev, &msg) < 0) {
 252             return -1;
 253         }
 254
 255         if (msg.request != VHOST_USER_SET_LOG_BASE) {
 256             error_report("Received unexpected msg type. "
 257                          "Expected %d received %d",
 258                          VHOST_USER_SET_LOG_BASE, msg.request);
 259             return -1;
 260         }
 261     }
 262
 263     return 0;
 264 }
 265
 266 static int vhost_user_set_vring_addr(struct vhost_dev *dev,
 267                                      struct vhost_vring_addr *addr)
 268 {
 269     VhostUserMsg msg = {
 270         .request = VHOST_USER_SET_VRING_ADDR,
 271         .flags = VHOST_USER_VERSION,
 272         .payload.addr = *addr,
 273         .size = sizeof(msg.payload.addr),
 274     };
 275
 276     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
 277         return -1;
 278     }
 279
 280     return 0;
 281 }
 282
 283 static int vhost_user_set_vring_endian(struct vhost_dev *dev,
 284                                        struct vhost_vring_state *ring)
 285 {
 286     error_report("vhost-user trying to send unhandled ioctl");
 287     return -1;
 288 }
 289
 290 static int vhost_set_vring(struct vhost_dev *dev,
 291                            unsigned long int request,
 292                            struct vhost_vring_state *ring)
 293 {
 294     VhostUserMsg msg = {
 295         .request = request,
 296         .flags = VHOST_USER_VERSION,
 297         .payload.state = *ring,
 298         .size = sizeof(msg.payload.state),
 299     };
 300
 301     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
 302         return -1;
 303     }
 304
 305     return 0;
 306 }
 307
 308 static int vhost_user_set_vring_num(struct vhost_dev *dev,
 309                                     struct vhost_vring_state *ring)
 310 {
 311     return vhost_set_vring(dev, VHOST_USER_SET_VRING_NUM, ring);
 312 }
 313
 314 static int vhost_user_set_vring_base(struct vhost_dev *dev,
 315                                      struct vhost_vring_state *ring)
 316 {
 317     return vhost_set_vring(dev, VHOST_USER_SET_VRING_BASE, ring);
 318 }
 319
 320 static int vhost_user_set_vring_enable(struct vhost_dev *dev, int enable)
 321 {
 322     int i;
 323
 324     if (!virtio_has_feature(dev->features, VHOST_USER_F_PROTOCOL_FEATURES)) {
 325         return -1;
 326     }
 327
 328     for (i = 0; i < dev->nvqs; ++i) {
 329         struct vhost_vring_state state = {
 330             .index = dev->vq_index + i,
 331             .num   = enable,
 332         };
 333
 334         vhost_set_vring(dev, VHOST_USER_SET_VRING_ENABLE, &state);
 335     }
 336
 337     return 0;
 338 }
 339
 340 static int vhost_user_get_vring_base(struct vhost_dev *dev,
 341                                      struct vhost_vring_state *ring)
 342 {
 343     VhostUserMsg msg = {
 344         .request = VHOST_USER_GET_VRING_BASE,
 345         .flags = VHOST_USER_VERSION,
 346         .payload.state = *ring,
 347         .size = sizeof(msg.payload.state),
 348     };
 349
 350     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
 351         return -1;
 352     }
 353
 354     if (vhost_user_read(dev, &msg) < 0) {
 355         return -1;
 356     }
 357
 358     if (msg.request != VHOST_USER_GET_VRING_BASE) {
 359         error_report("Received unexpected msg type. Expected %d received %d",
 360                      VHOST_USER_GET_VRING_BASE, msg.request);
 361         return -1;
 362     }
 363
 364     if (msg.size != sizeof(msg.payload.state)) {
 365         error_report("Received bad msg size.");
 366         return -1;
 367     }
 368
 369     *ring = msg.payload.state;
 370
 371     return 0;
 372 }
 373
 374 static int vhost_set_vring_file(struct vhost_dev *dev,
 375                                 VhostUserRequest request,
 376                                 struct vhost_vring_file *file)
 377 {
 378     int fds[VHOST_MEMORY_MAX_NREGIONS];
 379     size_t fd_num = 0;
 380     VhostUserMsg msg = {
 381         .request = request,
 382         .flags = VHOST_USER_VERSION,
 383         .payload.u64 = file->index & VHOST_USER_VRING_IDX_MASK,
 384         .size = sizeof(msg.payload.u64),
 385     };
 386
 387     if (ioeventfd_enabled() && file->fd > 0) {
 388         fds[fd_num++] = file->fd;
 389     } else {
 390         msg.payload.u64 |= VHOST_USER_VRING_NOFD_MASK;
 391     }
 392
 393     if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
 394         return -1;
 395     }
 396
 397     return 0;
 398 }
 399
 400 static int vhost_user_set_vring_kick(struct vhost_dev *dev,
 401                                      struct vhost_vring_file *file)
 402 {
 403     return vhost_set_vring_file(dev, VHOST_USER_SET_VRING_KICK, file);
 404 }
 405
 406 static int vhost_user_set_vring_call(struct vhost_dev *dev,
 407                                      struct vhost_vring_file *file)
 408 {
 409     return vhost_set_vring_file(dev, VHOST_USER_SET_VRING_CALL, file);
 410 }
 411
 412 static int vhost_user_set_u64(struct vhost_dev *dev, int request, uint64_t u64)
 413 {
 414     VhostUserMsg msg = {
 415         .request = request,
 416         .flags = VHOST_USER_VERSION,
 417         .payload.u64 = u64,
 418         .size = sizeof(msg.payload.u64),
 419     };
 420
 421     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
 422         return -1;
 423     }
 424
 425     return 0;
 426 }
 427
 428 static int vhost_user_set_features(struct vhost_dev *dev,
 429                                    uint64_t features)
 430 {
 431     return vhost_user_set_u64(dev, VHOST_USER_SET_FEATURES, features);
 432 }
 433
 434 static int vhost_user_set_protocol_features(struct vhost_dev *dev,
 435                                             uint64_t features)
 436 {
 437     return vhost_user_set_u64(dev, VHOST_USER_SET_PROTOCOL_FEATURES, features);
 438 }
 439
 440 static int vhost_user_get_u64(struct vhost_dev *dev, int request, uint64_t *u64)
 441 {
 442     VhostUserMsg msg = {
 443         .request = request,
 444         .flags = VHOST_USER_VERSION,
 445     };
 446
 447     if (vhost_user_one_time_request(request) && dev->vq_index != 0) {
 448         return 0;
 449     }
 450
 451     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
 452         return -1;
 453     }
 454
 455     if (vhost_user_read(dev, &msg) < 0) {
 456         return -1;
 457     }
 458
 459     if (msg.request != request) {
 460         error_report("Received unexpected msg type. Expected %d received %d",
 461                      request, msg.request);
 462         return -1;
 463     }
 464
 465     if (msg.size != sizeof(msg.payload.u64)) {
 466         error_report("Received bad msg size.");
 467         return -1;
 468     }
 469
 470     *u64 = msg.payload.u64;
 471
 472     return 0;
 473 }
 474
 475 static int vhost_user_get_features(struct vhost_dev *dev, uint64_t *features)
 476 {
 477     return vhost_user_get_u64(dev, VHOST_USER_GET_FEATURES, features);
 478 }
 479
 480 static int vhost_user_set_mem_table(struct vhost_dev *dev,
 481                                     struct vhost_memory *mem)
 482 {
 483     int fds[VHOST_MEMORY_MAX_NREGIONS];
 484     int i, fd;
 485     size_t fd_num = 0;
 486     uint64_t features;
 487     bool reply_supported = virtio_has_feature(dev->protocol_features,
 488                                               VHOST_USER_PROTOCOL_F_REPLY_ACK);
 489
 490     VhostUserMsg msg = {
 491         .request = VHOST_USER_SET_MEM_TABLE,
 492         .flags = VHOST_USER_VERSION,
 493     };
 494
 495     if (reply_supported) {
 496         msg.flags |= VHOST_USER_NEED_REPLY_MASK;
 497     }
 498
 499     for (i = 0; i < dev->mem->nregions; ++i) {
 500         struct vhost_memory_region *reg = dev->mem->regions + i;
 501         ram_addr_t offset;
 502         MemoryRegion *mr;
 503
 504         assert((uintptr_t)reg->userspace_addr == reg->userspace_addr);
 505         mr = memory_region_from_host((void *)(uintptr_t)reg->userspace_addr,
 506                                      &offset);
 507         fd = memory_region_get_fd(mr);
 508         if (fd > 0) {
 509             msg.payload.memory.regions[fd_num].userspace_addr
 510                                              = reg->userspace_addr;
 511             msg.payload.memory.regions[fd_num].memory_size  = reg->memory_size;
 512             msg.payload.memory.regions[fd_num].guest_phys_addr
 513                                              = reg->guest_phys_addr;
 514             msg.payload.memory.regions[fd_num].mmap_offset = offset;
 515             assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
 516             fds[fd_num++] = fd;
 517         }
 518     }
 519
 520     msg.payload.memory.nregions = fd_num;
 521
 522     if (!fd_num) {
 523         error_report("Failed initializing vhost-user memory map, "
 524                      "consider using -object memory-backend-file share=on");
 525         return -1;
 526     }
 527
 528     msg.size = sizeof(msg.payload.memory.nregions);
 529     msg.size += sizeof(msg.payload.memory.padding);
 530     msg.size += fd_num * sizeof(VhostUserMemoryRegion);
 531
 532     vhost_user_write(dev, &msg, fds, fd_num);
 533
 534     if (reply_supported) {
 535         return process_message_reply(dev, msg.request);
 536     } else {
 537         /* Note: It is (yet) unknown when the client application has finished
 538          * remapping the GPA.
 539          * Attempt to prevent a race by sending a command that requires a reply.
 540          */
 541         vhost_user_get_features(dev, &features);
 542     }
 543
 544     return 0;
 545 }
 546
 547 static int vhost_user_set_owner(struct vhost_dev *dev)
 548 {
 549     VhostUserMsg msg = {
 550         .request = VHOST_USER_SET_OWNER,
 551         .flags = VHOST_USER_VERSION,
 552     };
 553
 554     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
 555         return -1;
 556     }
 557
 558     return 0;
 559 }
 560
 561 static int vhost_user_reset_device(struct vhost_dev *dev)
 562 {
 563     VhostUserMsg msg = {
 564         .request = VHOST_USER_RESET_OWNER,
 565         .flags = VHOST_USER_VERSION,
 566     };
 567
 568     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
 569         return -1;
 570     }
 571
 572     return 0;
 573 }
 574
 575 static int vhost_user_init(struct vhost_dev *dev, void *opaque)
 576 {
 577     uint64_t features;
 578     int err;
 579
 580     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 581
 582     dev->opaque = opaque;
 583
 584     err = vhost_user_get_features(dev, &features);
 585     if (err < 0) {
 586         return err;
 587     }
 588
 589     if (virtio_has_feature(features, VHOST_USER_F_PROTOCOL_FEATURES)) {
 590         dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
 591
 592         err = vhost_user_get_u64(dev, VHOST_USER_GET_PROTOCOL_FEATURES,
 593                                  &features);
 594         if (err < 0) {
 595             return err;
 596         }
 597
 598         dev->protocol_features = features & VHOST_USER_PROTOCOL_FEATURE_MASK;
 599         err = vhost_user_set_protocol_features(dev, dev->protocol_features);
 600         if (err < 0) {
 601             return err;
 602         }
 603
 604         /* query the max queues we support if backend supports Multiple Queue */
 605         if (dev->protocol_features & (1ULL << VHOST_USER_PROTOCOL_F_MQ)) {
 606             err = vhost_user_get_u64(dev, VHOST_USER_GET_QUEUE_NUM,
 607                                      &dev->max_queues);
 608             if (err < 0) {
 609                 return err;
 610             }
 611         }
 612     }
 613
 614     if (dev->migration_blocker == NULL &&
 615         !virtio_has_feature(dev->protocol_features,
 616                             VHOST_USER_PROTOCOL_F_LOG_SHMFD)) {
 617         error_setg(&dev->migration_blocker,
 618                    "Migration disabled: vhost-user backend lacks "
 619                    "VHOST_USER_PROTOCOL_F_LOG_SHMFD feature.");
 620     }
 621
 622     return 0;
 623 }
 624
 625 static int vhost_user_cleanup(struct vhost_dev *dev)
 626 {
 627     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 628
 629     dev->opaque = 0;
 630
 631     return 0;
 632 }
 633
 634 static int vhost_user_get_vq_index(struct vhost_dev *dev, int idx)
 635 {
 636     assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
 637
 638     return idx;
 639 }
 640
 641 static int vhost_user_memslots_limit(struct vhost_dev *dev)
 642 {
 643     return VHOST_MEMORY_MAX_NREGIONS;
 644 }
 645
 646 static bool vhost_user_requires_shm_log(struct vhost_dev *dev)
 647 {
 648     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 649
 650     return virtio_has_feature(dev->protocol_features,
 651                               VHOST_USER_PROTOCOL_F_LOG_SHMFD);
 652 }
 653
 654 static int vhost_user_migration_done(struct vhost_dev *dev, char* mac_addr)
 655 {
 656     VhostUserMsg msg = { 0 };
 657
 658     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 659
 660     /* If guest supports GUEST_ANNOUNCE do nothing */
 661     if (virtio_has_feature(dev->acked_features, VIRTIO_NET_F_GUEST_ANNOUNCE)) {
 662         return 0;
 663     }
 664
 665     /* if backend supports VHOST_USER_PROTOCOL_F_RARP ask it to send the RARP */
 666     if (virtio_has_feature(dev->protocol_features,
 667                            VHOST_USER_PROTOCOL_F_RARP)) {
 668         msg.request = VHOST_USER_SEND_RARP;
 669         msg.flags = VHOST_USER_VERSION;
 670         memcpy((char *)&msg.payload.u64, mac_addr, 6);
 671         msg.size = sizeof(msg.payload.u64);
 672
 673         return vhost_user_write(dev, &msg, NULL, 0);
 674     }
 675     return -1;
 676 }
 677
 678 static bool vhost_user_can_merge(struct vhost_dev *dev,
 679                                  uint64_t start1, uint64_t size1,
 680                                  uint64_t start2, uint64_t size2)
 681 {
 682     ram_addr_t offset;
 683     int mfd, rfd;
 684     MemoryRegion *mr;
 685
 686     mr = memory_region_from_host((void *)(uintptr_t)start1, &offset);
 687     mfd = memory_region_get_fd(mr);
 688
 689     mr = memory_region_from_host((void *)(uintptr_t)start2, &offset);
 690     rfd = memory_region_get_fd(mr);
 691
 692     return mfd == rfd;
 693 }
 694
 695 const VhostOps user_ops = {
 696         .backend_type = VHOST_BACKEND_TYPE_USER,
 697         .vhost_backend_init = vhost_user_init,
 698         .vhost_backend_cleanup = vhost_user_cleanup,
 699         .vhost_backend_memslots_limit = vhost_user_memslots_limit,
 700         .vhost_set_log_base = vhost_user_set_log_base,
 701         .vhost_set_mem_table = vhost_user_set_mem_table,
 702         .vhost_set_vring_addr = vhost_user_set_vring_addr,
 703         .vhost_set_vring_endian = vhost_user_set_vring_endian,
 704         .vhost_set_vring_num = vhost_user_set_vring_num,
 705         .vhost_set_vring_base = vhost_user_set_vring_base,
 706         .vhost_get_vring_base = vhost_user_get_vring_base,
 707         .vhost_set_vring_kick = vhost_user_set_vring_kick,
 708         .vhost_set_vring_call = vhost_user_set_vring_call,
 709         .vhost_set_features = vhost_user_set_features,
 710         .vhost_get_features = vhost_user_get_features,
 711         .vhost_set_owner = vhost_user_set_owner,
 712         .vhost_reset_device = vhost_user_reset_device,
 713         .vhost_get_vq_index = vhost_user_get_vq_index,
 714         .vhost_set_vring_enable = vhost_user_set_vring_enable,
 715         .vhost_requires_shm_log = vhost_user_requires_shm_log,
 716         .vhost_migration_done = vhost_user_migration_done,
 717         .vhost_backend_can_merge = vhost_user_can_merge,
 718 };