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