net/tap.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  * Copyright (c) 2009 Red Hat, Inc.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #include "tap.h"
  27
  28 #include "config-host.h"
  29
  30 #include <sys/ioctl.h>
  31 #include <sys/stat.h>
  32 #include <sys/wait.h>
  33 #include <sys/socket.h>
  34 #include <net/if.h>
  35
  36 #include "net.h"
  37 #include "clients.h"
  38 #include "monitor.h"
  39 #include "sysemu.h"
  40 #include "qemu-char.h"
  41 #include "qemu-common.h"
  42 #include "qemu-error.h"
  43
  44 #include "net/tap-linux.h"
  45
  46 #include "hw/vhost_net.h"
  47
  48 /* Maximum GSO packet size (64k) plus plenty of room for
  49  * the ethernet and virtio_net headers
  50  */
  51 #define TAP_BUFSIZE (4096 + 65536)
  52
  53 typedef struct TAPState {
  54     NetClientState nc;
  55     int fd;
  56     char down_script[1024];
  57     char down_script_arg[128];
  58     uint8_t buf[TAP_BUFSIZE];
  59     unsigned int read_poll : 1;
  60     unsigned int write_poll : 1;
  61     unsigned int using_vnet_hdr : 1;
  62     unsigned int has_ufo: 1;
  63     VHostNetState *vhost_net;
  64     unsigned host_vnet_hdr_len;
  65 } TAPState;
  66
  67 static int launch_script(const char *setup_script, const char *ifname, int fd);
  68
  69 static int tap_can_send(void *opaque);
  70 static void tap_send(void *opaque);
  71 static void tap_writable(void *opaque);
  72
  73 static void tap_update_fd_handler(TAPState *s)
  74 {
  75     qemu_set_fd_handler2(s->fd,
  76                          s->read_poll  ? tap_can_send : NULL,
  77                          s->read_poll  ? tap_send     : NULL,
  78                          s->write_poll ? tap_writable : NULL,
  79                          s);
  80 }
  81
  82 static void tap_read_poll(TAPState *s, int enable)
  83 {
  84     s->read_poll = !!enable;
  85     tap_update_fd_handler(s);
  86 }
  87
  88 static void tap_write_poll(TAPState *s, int enable)
  89 {
  90     s->write_poll = !!enable;
  91     tap_update_fd_handler(s);
  92 }
  93
  94 static void tap_writable(void *opaque)
  95 {
  96     TAPState *s = opaque;
  97
  98     tap_write_poll(s, 0);
  99
 100     qemu_flush_queued_packets(&s->nc);
 101 }
 102
 103 static ssize_t tap_write_packet(TAPState *s, const struct iovec *iov, int iovcnt)
 104 {
 105     ssize_t len;
 106
 107     do {
 108         len = writev(s->fd, iov, iovcnt);
 109     } while (len == -1 && errno == EINTR);
 110
 111     if (len == -1 && errno == EAGAIN) {
 112         tap_write_poll(s, 1);
 113         return 0;
 114     }
 115
 116     return len;
 117 }
 118
 119 static ssize_t tap_receive_iov(NetClientState *nc, const struct iovec *iov,
 120                                int iovcnt)
 121 {
 122     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 123     const struct iovec *iovp = iov;
 124     struct iovec iov_copy[iovcnt + 1];
 125     struct virtio_net_hdr_mrg_rxbuf hdr = { };
 126
 127     if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 128         iov_copy[0].iov_base = &hdr;
 129         iov_copy[0].iov_len =  s->host_vnet_hdr_len;
 130         memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
 131         iovp = iov_copy;
 132         iovcnt++;
 133     }
 134
 135     return tap_write_packet(s, iovp, iovcnt);
 136 }
 137
 138 static ssize_t tap_receive_raw(NetClientState *nc, const uint8_t *buf, size_t size)
 139 {
 140     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 141     struct iovec iov[2];
 142     int iovcnt = 0;
 143     struct virtio_net_hdr_mrg_rxbuf hdr = { };
 144
 145     if (s->host_vnet_hdr_len) {
 146         iov[iovcnt].iov_base = &hdr;
 147         iov[iovcnt].iov_len  = s->host_vnet_hdr_len;
 148         iovcnt++;
 149     }
 150
 151     iov[iovcnt].iov_base = (char *)buf;
 152     iov[iovcnt].iov_len  = size;
 153     iovcnt++;
 154
 155     return tap_write_packet(s, iov, iovcnt);
 156 }
 157
 158 static ssize_t tap_receive(NetClientState *nc, const uint8_t *buf, size_t size)
 159 {
 160     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 161     struct iovec iov[1];
 162
 163     if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 164         return tap_receive_raw(nc, buf, size);
 165     }
 166
 167     iov[0].iov_base = (char *)buf;
 168     iov[0].iov_len  = size;
 169
 170     return tap_write_packet(s, iov, 1);
 171 }
 172
 173 static int tap_can_send(void *opaque)
 174 {
 175     TAPState *s = opaque;
 176
 177     return qemu_can_send_packet(&s->nc);
 178 }
 179
 180 #ifndef __sun__
 181 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
 182 {
 183     return read(tapfd, buf, maxlen);
 184 }
 185 #endif
 186
 187 static void tap_send_completed(NetClientState *nc, ssize_t len)
 188 {
 189     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 190     tap_read_poll(s, 1);
 191 }
 192
 193 static void tap_send(void *opaque)
 194 {
 195     TAPState *s = opaque;
 196     int size;
 197
 198     do {
 199         uint8_t *buf = s->buf;
 200
 201         size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
 202         if (size <= 0) {
 203             break;
 204         }
 205
 206         if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 207             buf  += s->host_vnet_hdr_len;
 208             size -= s->host_vnet_hdr_len;
 209         }
 210
 211         size = qemu_send_packet_async(&s->nc, buf, size, tap_send_completed);
 212         if (size == 0) {
 213             tap_read_poll(s, 0);
 214         }
 215     } while (size > 0 && qemu_can_send_packet(&s->nc));
 216 }
 217
 218 int tap_has_ufo(NetClientState *nc)
 219 {
 220     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 221
 222     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 223
 224     return s->has_ufo;
 225 }
 226
 227 int tap_has_vnet_hdr(NetClientState *nc)
 228 {
 229     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 230
 231     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 232
 233     return !!s->host_vnet_hdr_len;
 234 }
 235
 236 int tap_has_vnet_hdr_len(NetClientState *nc, int len)
 237 {
 238     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 239
 240     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 241
 242     return tap_probe_vnet_hdr_len(s->fd, len);
 243 }
 244
 245 void tap_set_vnet_hdr_len(NetClientState *nc, int len)
 246 {
 247     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 248
 249     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 250     assert(len == sizeof(struct virtio_net_hdr_mrg_rxbuf) ||
 251            len == sizeof(struct virtio_net_hdr));
 252
 253     tap_fd_set_vnet_hdr_len(s->fd, len);
 254     s->host_vnet_hdr_len = len;
 255 }
 256
 257 void tap_using_vnet_hdr(NetClientState *nc, int using_vnet_hdr)
 258 {
 259     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 260
 261     using_vnet_hdr = using_vnet_hdr != 0;
 262
 263     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 264     assert(!!s->host_vnet_hdr_len == using_vnet_hdr);
 265
 266     s->using_vnet_hdr = using_vnet_hdr;
 267 }
 268
 269 void tap_set_offload(NetClientState *nc, int csum, int tso4,
 270                      int tso6, int ecn, int ufo)
 271 {
 272     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 273     if (s->fd < 0) {
 274         return;
 275     }
 276
 277     tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
 278 }
 279
 280 static void tap_cleanup(NetClientState *nc)
 281 {
 282     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 283
 284     if (s->vhost_net) {
 285         vhost_net_cleanup(s->vhost_net);
 286         s->vhost_net = NULL;
 287     }
 288
 289     qemu_purge_queued_packets(nc);
 290
 291     if (s->down_script[0])
 292         launch_script(s->down_script, s->down_script_arg, s->fd);
 293
 294     tap_read_poll(s, 0);
 295     tap_write_poll(s, 0);
 296     close(s->fd);
 297     s->fd = -1;
 298 }
 299
 300 static void tap_poll(NetClientState *nc, bool enable)
 301 {
 302     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 303     tap_read_poll(s, enable);
 304     tap_write_poll(s, enable);
 305 }
 306
 307 int tap_get_fd(NetClientState *nc)
 308 {
 309     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 310     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 311     return s->fd;
 312 }
 313
 314 /* fd support */
 315
 316 static NetClientInfo net_tap_info = {
 317     .type = NET_CLIENT_OPTIONS_KIND_TAP,
 318     .size = sizeof(TAPState),
 319     .receive = tap_receive,
 320     .receive_raw = tap_receive_raw,
 321     .receive_iov = tap_receive_iov,
 322     .poll = tap_poll,
 323     .cleanup = tap_cleanup,
 324 };
 325
 326 static TAPState *net_tap_fd_init(NetClientState *peer,
 327                                  const char *model,
 328                                  const char *name,
 329                                  int fd,
 330                                  int vnet_hdr)
 331 {
 332     NetClientState *nc;
 333     TAPState *s;
 334
 335     nc = qemu_new_net_client(&net_tap_info, peer, model, name);
 336
 337     s = DO_UPCAST(TAPState, nc, nc);
 338
 339     s->fd = fd;
 340     s->host_vnet_hdr_len = vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
 341     s->using_vnet_hdr = 0;
 342     s->has_ufo = tap_probe_has_ufo(s->fd);
 343     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
 344     /*
 345      * Make sure host header length is set correctly in tap:
 346      * it might have been modified by another instance of qemu.
 347      */
 348     if (tap_probe_vnet_hdr_len(s->fd, s->host_vnet_hdr_len)) {
 349         tap_fd_set_vnet_hdr_len(s->fd, s->host_vnet_hdr_len);
 350     }
 351     tap_read_poll(s, 1);
 352     s->vhost_net = NULL;
 353     return s;
 354 }
 355
 356 static int launch_script(const char *setup_script, const char *ifname, int fd)
 357 {
 358     int pid, status;
 359     char *args[3];
 360     char **parg;
 361
 362     /* try to launch network script */
 363     pid = fork();
 364     if (pid == 0) {
 365         int open_max = sysconf(_SC_OPEN_MAX), i;
 366
 367         for (i = 0; i < open_max; i++) {
 368             if (i != STDIN_FILENO &&
 369                 i != STDOUT_FILENO &&
 370                 i != STDERR_FILENO &&
 371                 i != fd) {
 372                 close(i);
 373             }
 374         }
 375         parg = args;
 376         *parg++ = (char *)setup_script;
 377         *parg++ = (char *)ifname;
 378         *parg = NULL;
 379         execv(setup_script, args);
 380         _exit(1);
 381     } else if (pid > 0) {
 382         while (waitpid(pid, &status, 0) != pid) {
 383             /* loop */
 384         }
 385
 386         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 387             return 0;
 388         }
 389     }
 390     fprintf(stderr, "%s: could not launch network script\n", setup_script);
 391     return -1;
 392 }
 393
 394 static int recv_fd(int c)
 395 {
 396     int fd;
 397     uint8_t msgbuf[CMSG_SPACE(sizeof(fd))];
 398     struct msghdr msg = {
 399         .msg_control = msgbuf,
 400         .msg_controllen = sizeof(msgbuf),
 401     };
 402     struct cmsghdr *cmsg;
 403     struct iovec iov;
 404     uint8_t req[1];
 405     ssize_t len;
 406
 407     cmsg = CMSG_FIRSTHDR(&msg);
 408     cmsg->cmsg_level = SOL_SOCKET;
 409     cmsg->cmsg_type = SCM_RIGHTS;
 410     cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
 411     msg.msg_controllen = cmsg->cmsg_len;
 412
 413     iov.iov_base = req;
 414     iov.iov_len = sizeof(req);
 415
 416     msg.msg_iov = &iov;
 417     msg.msg_iovlen = 1;
 418
 419     len = recvmsg(c, &msg, 0);
 420     if (len > 0) {
 421         memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));
 422         return fd;
 423     }
 424
 425     return len;
 426 }
 427
 428 static int net_bridge_run_helper(const char *helper, const char *bridge)
 429 {
 430     sigset_t oldmask, mask;
 431     int pid, status;
 432     char *args[5];
 433     char **parg;
 434     int sv[2];
 435
 436     sigemptyset(&mask);
 437     sigaddset(&mask, SIGCHLD);
 438     sigprocmask(SIG_BLOCK, &mask, &oldmask);
 439
 440     if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
 441         return -1;
 442     }
 443
 444     /* try to launch bridge helper */
 445     pid = fork();
 446     if (pid == 0) {
 447         int open_max = sysconf(_SC_OPEN_MAX), i;
 448         char fd_buf[6+10];
 449         char br_buf[6+IFNAMSIZ] = {0};
 450         char helper_cmd[PATH_MAX + sizeof(fd_buf) + sizeof(br_buf) + 15];
 451
 452         for (i = 0; i < open_max; i++) {
 453             if (i != STDIN_FILENO &&
 454                 i != STDOUT_FILENO &&
 455                 i != STDERR_FILENO &&
 456                 i != sv[1]) {
 457                 close(i);
 458             }
 459         }
 460
 461         snprintf(fd_buf, sizeof(fd_buf), "%s%d", "--fd=", sv[1]);
 462
 463         if (strrchr(helper, ' ') || strrchr(helper, '\t')) {
 464             /* assume helper is a command */
 465
 466             if (strstr(helper, "--br=") == NULL) {
 467                 snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
 468             }
 469
 470             snprintf(helper_cmd, sizeof(helper_cmd), "%s %s %s %s",
 471                      helper, "--use-vnet", fd_buf, br_buf);
 472
 473             parg = args;
 474             *parg++ = (char *)"sh";
 475             *parg++ = (char *)"-c";
 476             *parg++ = helper_cmd;
 477             *parg++ = NULL;
 478
 479             execv("/bin/sh", args);
 480         } else {
 481             /* assume helper is just the executable path name */
 482
 483             snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
 484
 485             parg = args;
 486             *parg++ = (char *)helper;
 487             *parg++ = (char *)"--use-vnet";
 488             *parg++ = fd_buf;
 489             *parg++ = br_buf;
 490             *parg++ = NULL;
 491
 492             execv(helper, args);
 493         }
 494         _exit(1);
 495
 496     } else if (pid > 0) {
 497         int fd;
 498
 499         close(sv[1]);
 500
 501         do {
 502             fd = recv_fd(sv[0]);
 503         } while (fd == -1 && errno == EINTR);
 504
 505         close(sv[0]);
 506
 507         while (waitpid(pid, &status, 0) != pid) {
 508             /* loop */
 509         }
 510         sigprocmask(SIG_SETMASK, &oldmask, NULL);
 511         if (fd < 0) {
 512             fprintf(stderr, "failed to recv file descriptor\n");
 513             return -1;
 514         }
 515
 516         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 517             return fd;
 518         }
 519     }
 520     fprintf(stderr, "failed to launch bridge helper\n");
 521     return -1;
 522 }
 523
 524 int net_init_bridge(const NetClientOptions *opts, const char *name,
 525                     NetClientState *peer)
 526 {
 527     const NetdevBridgeOptions *bridge;
 528     const char *helper, *br;
 529
 530     TAPState *s;
 531     int fd, vnet_hdr;
 532
 533     assert(opts->kind == NET_CLIENT_OPTIONS_KIND_BRIDGE);
 534     bridge = opts->bridge;
 535
 536     helper = bridge->has_helper ? bridge->helper : DEFAULT_BRIDGE_HELPER;
 537     br     = bridge->has_br     ? bridge->br     : DEFAULT_BRIDGE_INTERFACE;
 538
 539     fd = net_bridge_run_helper(helper, br);
 540     if (fd == -1) {
 541         return -1;
 542     }
 543
 544     fcntl(fd, F_SETFL, O_NONBLOCK);
 545
 546     vnet_hdr = tap_probe_vnet_hdr(fd);
 547
 548     s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
 549     if (!s) {
 550         close(fd);
 551         return -1;
 552     }
 553
 554     snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
 555              br);
 556
 557     return 0;
 558 }
 559
 560 static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
 561                         const char *setup_script, char *ifname,
 562                         size_t ifname_sz)
 563 {
 564     int fd, vnet_hdr_required;
 565
 566     if (tap->has_ifname) {
 567         pstrcpy(ifname, ifname_sz, tap->ifname);
 568     } else {
 569         assert(ifname_sz > 0);
 570         ifname[0] = '\0';
 571     }
 572
 573     if (tap->has_vnet_hdr) {
 574         *vnet_hdr = tap->vnet_hdr;
 575         vnet_hdr_required = *vnet_hdr;
 576     } else {
 577         *vnet_hdr = 1;
 578         vnet_hdr_required = 0;
 579     }
 580
 581     TFR(fd = tap_open(ifname, ifname_sz, vnet_hdr, vnet_hdr_required));
 582     if (fd < 0) {
 583         return -1;
 584     }
 585
 586     if (setup_script &&
 587         setup_script[0] != '\0' &&
 588         strcmp(setup_script, "no") != 0 &&
 589         launch_script(setup_script, ifname, fd)) {
 590         close(fd);
 591         return -1;
 592     }
 593
 594     return fd;
 595 }
 596
 597 int net_init_tap(const NetClientOptions *opts, const char *name,
 598                  NetClientState *peer)
 599 {
 600     const NetdevTapOptions *tap;
 601
 602     int fd, vnet_hdr = 0;
 603     const char *model;
 604     TAPState *s;
 605
 606     /* for the no-fd, no-helper case */
 607     const char *script = NULL; /* suppress wrong "uninit'd use" gcc warning */
 608     char ifname[128];
 609
 610     assert(opts->kind == NET_CLIENT_OPTIONS_KIND_TAP);
 611     tap = opts->tap;
 612
 613     if (tap->has_fd) {
 614         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 615             tap->has_vnet_hdr || tap->has_helper) {
 616             error_report("ifname=, script=, downscript=, vnet_hdr=, "
 617                          "and helper= are invalid with fd=");
 618             return -1;
 619         }
 620
 621         fd = monitor_handle_fd_param(cur_mon, tap->fd);
 622         if (fd == -1) {
 623             return -1;
 624         }
 625
 626         fcntl(fd, F_SETFL, O_NONBLOCK);
 627
 628         vnet_hdr = tap_probe_vnet_hdr(fd);
 629
 630         model = "tap";
 631
 632     } else if (tap->has_helper) {
 633         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 634             tap->has_vnet_hdr) {
 635             error_report("ifname=, script=, downscript=, and vnet_hdr= "
 636                          "are invalid with helper=");
 637             return -1;
 638         }
 639
 640         fd = net_bridge_run_helper(tap->helper, DEFAULT_BRIDGE_INTERFACE);
 641         if (fd == -1) {
 642             return -1;
 643         }
 644
 645         fcntl(fd, F_SETFL, O_NONBLOCK);
 646
 647         vnet_hdr = tap_probe_vnet_hdr(fd);
 648
 649         model = "bridge";
 650
 651     } else {
 652         script = tap->has_script ? tap->script : DEFAULT_NETWORK_SCRIPT;
 653         fd = net_tap_init(tap, &vnet_hdr, script, ifname, sizeof ifname);
 654         if (fd == -1) {
 655             return -1;
 656         }
 657
 658         model = "tap";
 659     }
 660
 661     s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
 662     if (!s) {
 663         close(fd);
 664         return -1;
 665     }
 666
 667     if (tap_set_sndbuf(s->fd, tap) < 0) {
 668         return -1;
 669     }
 670
 671     if (tap->has_fd) {
 672         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
 673     } else if (tap->has_helper) {
 674         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
 675                  tap->helper);
 676     } else {
 677         const char *downscript;
 678
 679         downscript = tap->has_downscript ? tap->downscript :
 680                                            DEFAULT_NETWORK_DOWN_SCRIPT;
 681
 682         snprintf(s->nc.info_str, sizeof(s->nc.info_str),
 683                  "ifname=%s,script=%s,downscript=%s", ifname, script,
 684                  downscript);
 685
 686         if (strcmp(downscript, "no") != 0) {
 687             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
 688             snprintf(s->down_script_arg, sizeof(s->down_script_arg), "%s", ifname);
 689         }
 690     }
 691
 692     if (tap->has_vhost ? tap->vhost :
 693         tap->has_vhostfd || (tap->has_vhostforce && tap->vhostforce)) {
 694         int vhostfd;
 695
 696         if (tap->has_vhostfd) {
 697             vhostfd = monitor_handle_fd_param(cur_mon, tap->vhostfd);
 698             if (vhostfd == -1) {
 699                 return -1;
 700             }
 701         } else {
 702             vhostfd = -1;
 703         }
 704
 705         s->vhost_net = vhost_net_init(&s->nc, vhostfd,
 706                                       tap->has_vhostforce && tap->vhostforce);
 707         if (!s->vhost_net) {
 708             error_report("vhost-net requested but could not be initialized");
 709             return -1;
 710         }
 711     } else if (tap->has_vhostfd) {
 712         error_report("vhostfd= is not valid without vhost");
 713         return -1;
 714     }
 715
 716     return 0;
 717 }
 718
 719 VHostNetState *tap_get_vhost_net(NetClientState *nc)
 720 {
 721     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 722     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
 723     return s->vhost_net;
 724 }