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 "qemu/osdep.h"
  27 #include "tap_int.h"
  28
  29
  30 #include <sys/ioctl.h>
  31 #include <sys/wait.h>
  32 #include <sys/socket.h>
  33 #include <net/if.h>
  34
  35 #include "net/net.h"
  36 #include "clients.h"
  37 #include "monitor/monitor.h"
  38 #include "sysemu/sysemu.h"
  39 #include "qapi/error.h"
  40 #include "qemu-common.h"
  41 #include "qemu/cutils.h"
  42 #include "qemu/error-report.h"
  43 #include "qemu/main-loop.h"
  44 #include "qemu/sockets.h"
  45
  46 #include "net/tap.h"
  47
  48 #include "net/vhost_net.h"
  49
  50 typedef struct TAPState {
  51     NetClientState nc;
  52     int fd;
  53     char down_script[1024];
  54     char down_script_arg[128];
  55     uint8_t buf[NET_BUFSIZE];
  56     bool read_poll;
  57     bool write_poll;
  58     bool using_vnet_hdr;
  59     bool has_ufo;
  60     bool enabled;
  61     VHostNetState *vhost_net;
  62     unsigned host_vnet_hdr_len;
  63     Notifier exit;
  64 } TAPState;
  65
  66 static void launch_script(const char *setup_script, const char *ifname,
  67                           int fd, Error **errp);
  68
  69 static void tap_send(void *opaque);
  70 static void tap_writable(void *opaque);
  71
  72 static void tap_update_fd_handler(TAPState *s)
  73 {
  74     qemu_set_fd_handler(s->fd,
  75                         s->read_poll && s->enabled ? tap_send : NULL,
  76                         s->write_poll && s->enabled ? tap_writable : NULL,
  77                         s);
  78 }
  79
  80 static void tap_read_poll(TAPState *s, bool enable)
  81 {
  82     s->read_poll = enable;
  83     tap_update_fd_handler(s);
  84 }
  85
  86 static void tap_write_poll(TAPState *s, bool 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, false);
  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, true);
 111         return 0;
 112     }
 113
 114     return len;
 115 }
 116
 117 static ssize_t tap_receive_iov(NetClientState *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(NetClientState *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(NetClientState *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 #ifndef __sun__
 172 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
 173 {
 174     return read(tapfd, buf, maxlen);
 175 }
 176 #endif
 177
 178 static void tap_send_completed(NetClientState *nc, ssize_t len)
 179 {
 180     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 181     tap_read_poll(s, true);
 182 }
 183
 184 static void tap_send(void *opaque)
 185 {
 186     TAPState *s = opaque;
 187     int size;
 188     int packets = 0;
 189
 190     while (true) {
 191         uint8_t *buf = s->buf;
 192
 193         size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
 194         if (size <= 0) {
 195             break;
 196         }
 197
 198         if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 199             buf  += s->host_vnet_hdr_len;
 200             size -= s->host_vnet_hdr_len;
 201         }
 202
 203         size = qemu_send_packet_async(&s->nc, buf, size, tap_send_completed);
 204         if (size == 0) {
 205             tap_read_poll(s, false);
 206             break;
 207         } else if (size < 0) {
 208             break;
 209         }
 210
 211         /*
 212          * When the host keeps receiving more packets while tap_send() is
 213          * running we can hog the QEMU global mutex.  Limit the number of
 214          * packets that are processed per tap_send() callback to prevent
 215          * stalling the guest.
 216          */
 217         packets++;
 218         if (packets >= 50) {
 219             break;
 220         }
 221     }
 222 }
 223
 224 static bool tap_has_ufo(NetClientState *nc)
 225 {
 226     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 227
 228     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 229
 230     return s->has_ufo;
 231 }
 232
 233 static bool tap_has_vnet_hdr(NetClientState *nc)
 234 {
 235     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 236
 237     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 238
 239     return !!s->host_vnet_hdr_len;
 240 }
 241
 242 static bool tap_has_vnet_hdr_len(NetClientState *nc, int len)
 243 {
 244     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 245
 246     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 247
 248     return !!tap_probe_vnet_hdr_len(s->fd, len);
 249 }
 250
 251 static void tap_set_vnet_hdr_len(NetClientState *nc, int len)
 252 {
 253     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 254
 255     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 256     assert(len == sizeof(struct virtio_net_hdr_mrg_rxbuf) ||
 257            len == sizeof(struct virtio_net_hdr));
 258
 259     tap_fd_set_vnet_hdr_len(s->fd, len);
 260     s->host_vnet_hdr_len = len;
 261 }
 262
 263 static void tap_using_vnet_hdr(NetClientState *nc, bool using_vnet_hdr)
 264 {
 265     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 266
 267     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 268     assert(!!s->host_vnet_hdr_len == using_vnet_hdr);
 269
 270     s->using_vnet_hdr = using_vnet_hdr;
 271 }
 272
 273 static int tap_set_vnet_le(NetClientState *nc, bool is_le)
 274 {
 275     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 276
 277     return tap_fd_set_vnet_le(s->fd, is_le);
 278 }
 279
 280 static int tap_set_vnet_be(NetClientState *nc, bool is_be)
 281 {
 282     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 283
 284     return tap_fd_set_vnet_be(s->fd, is_be);
 285 }
 286
 287 static void tap_set_offload(NetClientState *nc, int csum, int tso4,
 288                      int tso6, int ecn, int ufo)
 289 {
 290     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 291     if (s->fd < 0) {
 292         return;
 293     }
 294
 295     tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
 296 }
 297
 298 static void tap_exit_notify(Notifier *notifier, void *data)
 299 {
 300     TAPState *s = container_of(notifier, TAPState, exit);
 301     Error *err = NULL;
 302
 303     if (s->down_script[0]) {
 304         launch_script(s->down_script, s->down_script_arg, s->fd, &err);
 305         if (err) {
 306             error_report_err(err);
 307         }
 308     }
 309 }
 310
 311 static void tap_cleanup(NetClientState *nc)
 312 {
 313     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 314
 315     if (s->vhost_net) {
 316         vhost_net_cleanup(s->vhost_net);
 317         g_free(s->vhost_net);
 318         s->vhost_net = NULL;
 319     }
 320
 321     qemu_purge_queued_packets(nc);
 322
 323     tap_exit_notify(&s->exit, NULL);
 324     qemu_remove_exit_notifier(&s->exit);
 325
 326     tap_read_poll(s, false);
 327     tap_write_poll(s, false);
 328     close(s->fd);
 329     s->fd = -1;
 330 }
 331
 332 static void tap_poll(NetClientState *nc, bool enable)
 333 {
 334     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 335     tap_read_poll(s, enable);
 336     tap_write_poll(s, enable);
 337 }
 338
 339 int tap_get_fd(NetClientState *nc)
 340 {
 341     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 342     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 343     return s->fd;
 344 }
 345
 346 /* fd support */
 347
 348 static NetClientInfo net_tap_info = {
 349     .type = NET_CLIENT_DRIVER_TAP,
 350     .size = sizeof(TAPState),
 351     .receive = tap_receive,
 352     .receive_raw = tap_receive_raw,
 353     .receive_iov = tap_receive_iov,
 354     .poll = tap_poll,
 355     .cleanup = tap_cleanup,
 356     .has_ufo = tap_has_ufo,
 357     .has_vnet_hdr = tap_has_vnet_hdr,
 358     .has_vnet_hdr_len = tap_has_vnet_hdr_len,
 359     .using_vnet_hdr = tap_using_vnet_hdr,
 360     .set_offload = tap_set_offload,
 361     .set_vnet_hdr_len = tap_set_vnet_hdr_len,
 362     .set_vnet_le = tap_set_vnet_le,
 363     .set_vnet_be = tap_set_vnet_be,
 364 };
 365
 366 static TAPState *net_tap_fd_init(NetClientState *peer,
 367                                  const char *model,
 368                                  const char *name,
 369                                  int fd,
 370                                  int vnet_hdr)
 371 {
 372     NetClientState *nc;
 373     TAPState *s;
 374
 375     nc = qemu_new_net_client(&net_tap_info, peer, model, name);
 376
 377     s = DO_UPCAST(TAPState, nc, nc);
 378
 379     s->fd = fd;
 380     s->host_vnet_hdr_len = vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
 381     s->using_vnet_hdr = false;
 382     s->has_ufo = tap_probe_has_ufo(s->fd);
 383     s->enabled = true;
 384     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
 385     /*
 386      * Make sure host header length is set correctly in tap:
 387      * it might have been modified by another instance of qemu.
 388      */
 389     if (tap_probe_vnet_hdr_len(s->fd, s->host_vnet_hdr_len)) {
 390         tap_fd_set_vnet_hdr_len(s->fd, s->host_vnet_hdr_len);
 391     }
 392     tap_read_poll(s, true);
 393     s->vhost_net = NULL;
 394
 395     s->exit.notify = tap_exit_notify;
 396     qemu_add_exit_notifier(&s->exit);
 397
 398     return s;
 399 }
 400
 401 static void launch_script(const char *setup_script, const char *ifname,
 402                           int fd, Error **errp)
 403 {
 404     int pid, status;
 405     char *args[3];
 406     char **parg;
 407
 408     /* try to launch network script */
 409     pid = fork();
 410     if (pid < 0) {
 411         error_setg_errno(errp, errno, "could not launch network script %s",
 412                          setup_script);
 413         return;
 414     }
 415     if (pid == 0) {
 416         int open_max = sysconf(_SC_OPEN_MAX), i;
 417
 418         for (i = 3; i < open_max; i++) {
 419             if (i != fd) {
 420                 close(i);
 421             }
 422         }
 423         parg = args;
 424         *parg++ = (char *)setup_script;
 425         *parg++ = (char *)ifname;
 426         *parg = NULL;
 427         execv(setup_script, args);
 428         _exit(1);
 429     } else {
 430         while (waitpid(pid, &status, 0) != pid) {
 431             /* loop */
 432         }
 433
 434         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 435             return;
 436         }
 437         error_setg(errp, "network script %s failed with status %d",
 438                    setup_script, status);
 439     }
 440 }
 441
 442 static int recv_fd(int c)
 443 {
 444     int fd;
 445     uint8_t msgbuf[CMSG_SPACE(sizeof(fd))];
 446     struct msghdr msg = {
 447         .msg_control = msgbuf,
 448         .msg_controllen = sizeof(msgbuf),
 449     };
 450     struct cmsghdr *cmsg;
 451     struct iovec iov;
 452     uint8_t req[1];
 453     ssize_t len;
 454
 455     cmsg = CMSG_FIRSTHDR(&msg);
 456     cmsg->cmsg_level = SOL_SOCKET;
 457     cmsg->cmsg_type = SCM_RIGHTS;
 458     cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
 459     msg.msg_controllen = cmsg->cmsg_len;
 460
 461     iov.iov_base = req;
 462     iov.iov_len = sizeof(req);
 463
 464     msg.msg_iov = &iov;
 465     msg.msg_iovlen = 1;
 466
 467     len = recvmsg(c, &msg, 0);
 468     if (len > 0) {
 469         memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));
 470         return fd;
 471     }
 472
 473     return len;
 474 }
 475
 476 static int net_bridge_run_helper(const char *helper, const char *bridge,
 477                                  Error **errp)
 478 {
 479     sigset_t oldmask, mask;
 480     int pid, status;
 481     char *args[5];
 482     char **parg;
 483     int sv[2];
 484
 485     sigemptyset(&mask);
 486     sigaddset(&mask, SIGCHLD);
 487     sigprocmask(SIG_BLOCK, &mask, &oldmask);
 488
 489     if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
 490         error_setg_errno(errp, errno, "socketpair() failed");
 491         return -1;
 492     }
 493
 494     /* try to launch bridge helper */
 495     pid = fork();
 496     if (pid < 0) {
 497         error_setg_errno(errp, errno, "Can't fork bridge helper");
 498         return -1;
 499     }
 500     if (pid == 0) {
 501         int open_max = sysconf(_SC_OPEN_MAX), i;
 502         char *fd_buf = NULL;
 503         char *br_buf = NULL;
 504         char *helper_cmd = NULL;
 505
 506         for (i = 3; i < open_max; i++) {
 507             if (i != sv[1]) {
 508                 close(i);
 509             }
 510         }
 511
 512         fd_buf = g_strdup_printf("%s%d", "--fd=", sv[1]);
 513
 514         if (strrchr(helper, ' ') || strrchr(helper, '\t')) {
 515             /* assume helper is a command */
 516
 517             if (strstr(helper, "--br=") == NULL) {
 518                 br_buf = g_strdup_printf("%s%s", "--br=", bridge);
 519             }
 520
 521             helper_cmd = g_strdup_printf("%s %s %s %s", helper,
 522                             "--use-vnet", fd_buf, br_buf ? br_buf : "");
 523
 524             parg = args;
 525             *parg++ = (char *)"sh";
 526             *parg++ = (char *)"-c";
 527             *parg++ = helper_cmd;
 528             *parg++ = NULL;
 529
 530             execv("/bin/sh", args);
 531             g_free(helper_cmd);
 532         } else {
 533             /* assume helper is just the executable path name */
 534
 535             br_buf = g_strdup_printf("%s%s", "--br=", bridge);
 536
 537             parg = args;
 538             *parg++ = (char *)helper;
 539             *parg++ = (char *)"--use-vnet";
 540             *parg++ = fd_buf;
 541             *parg++ = br_buf;
 542             *parg++ = NULL;
 543
 544             execv(helper, args);
 545         }
 546         g_free(fd_buf);
 547         g_free(br_buf);
 548         _exit(1);
 549
 550     } else {
 551         int fd;
 552         int saved_errno;
 553
 554         close(sv[1]);
 555
 556         do {
 557             fd = recv_fd(sv[0]);
 558         } while (fd == -1 && errno == EINTR);
 559         saved_errno = errno;
 560
 561         close(sv[0]);
 562
 563         while (waitpid(pid, &status, 0) != pid) {
 564             /* loop */
 565         }
 566         sigprocmask(SIG_SETMASK, &oldmask, NULL);
 567         if (fd < 0) {
 568             error_setg_errno(errp, saved_errno,
 569                              "failed to recv file descriptor");
 570             return -1;
 571         }
 572         if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 573             error_setg(errp, "bridge helper failed");
 574             return -1;
 575         }
 576         return fd;
 577     }
 578 }
 579
 580 int net_init_bridge(const Netdev *netdev, const char *name,
 581                     NetClientState *peer, Error **errp)
 582 {
 583     const NetdevBridgeOptions *bridge;
 584     const char *helper, *br;
 585     TAPState *s;
 586     int fd, vnet_hdr;
 587
 588     assert(netdev->type == NET_CLIENT_DRIVER_BRIDGE);
 589     bridge = &netdev->u.bridge;
 590
 591     helper = bridge->has_helper ? bridge->helper : DEFAULT_BRIDGE_HELPER;
 592     br     = bridge->has_br     ? bridge->br     : DEFAULT_BRIDGE_INTERFACE;
 593
 594     fd = net_bridge_run_helper(helper, br, errp);
 595     if (fd == -1) {
 596         return -1;
 597     }
 598
 599     qemu_set_nonblock(fd);
 600     vnet_hdr = tap_probe_vnet_hdr(fd);
 601     s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
 602
 603     snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
 604              br);
 605
 606     return 0;
 607 }
 608
 609 static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
 610                         const char *setup_script, char *ifname,
 611                         size_t ifname_sz, int mq_required, Error **errp)
 612 {
 613     Error *err = NULL;
 614     int fd, vnet_hdr_required;
 615
 616     if (tap->has_vnet_hdr) {
 617         *vnet_hdr = tap->vnet_hdr;
 618         vnet_hdr_required = *vnet_hdr;
 619     } else {
 620         *vnet_hdr = 1;
 621         vnet_hdr_required = 0;
 622     }
 623
 624     TFR(fd = tap_open(ifname, ifname_sz, vnet_hdr, vnet_hdr_required,
 625                       mq_required, errp));
 626     if (fd < 0) {
 627         return -1;
 628     }
 629
 630     if (setup_script &&
 631         setup_script[0] != '\0' &&
 632         strcmp(setup_script, "no") != 0) {
 633         launch_script(setup_script, ifname, fd, &err);
 634         if (err) {
 635             error_propagate(errp, err);
 636             close(fd);
 637             return -1;
 638         }
 639     }
 640
 641     return fd;
 642 }
 643
 644 #define MAX_TAP_QUEUES 1024
 645
 646 static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
 647                              const char *model, const char *name,
 648                              const char *ifname, const char *script,
 649                              const char *downscript, const char *vhostfdname,
 650                              int vnet_hdr, int fd, Error **errp)
 651 {
 652     Error *err = NULL;
 653     TAPState *s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
 654     int vhostfd;
 655
 656     tap_set_sndbuf(s->fd, tap, &err);
 657     if (err) {
 658         error_propagate(errp, err);
 659         return;
 660     }
 661
 662     if (tap->has_fd || tap->has_fds) {
 663         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
 664     } else if (tap->has_helper) {
 665         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
 666                  tap->helper);
 667     } else {
 668         snprintf(s->nc.info_str, sizeof(s->nc.info_str),
 669                  "ifname=%s,script=%s,downscript=%s", ifname, script,
 670                  downscript);
 671
 672         if (strcmp(downscript, "no") != 0) {
 673             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
 674             snprintf(s->down_script_arg, sizeof(s->down_script_arg),
 675                      "%s", ifname);
 676         }
 677     }
 678
 679     if (tap->has_vhost ? tap->vhost :
 680         vhostfdname || (tap->has_vhostforce && tap->vhostforce)) {
 681         VhostNetOptions options;
 682
 683         options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
 684         options.net_backend = &s->nc;
 685         if (tap->has_poll_us) {
 686             options.busyloop_timeout = tap->poll_us;
 687         } else {
 688             options.busyloop_timeout = 0;
 689         }
 690
 691         if (vhostfdname) {
 692             vhostfd = monitor_fd_param(cur_mon, vhostfdname, &err);
 693             if (vhostfd == -1) {
 694                 if (tap->has_vhostforce && tap->vhostforce) {
 695                     error_propagate(errp, err);
 696                 } else {
 697                     warn_report_err(err);
 698                 }
 699                 return;
 700             }
 701             qemu_set_nonblock(vhostfd);
 702         } else {
 703             vhostfd = open("/dev/vhost-net", O_RDWR);
 704             if (vhostfd < 0) {
 705                 if (tap->has_vhostforce && tap->vhostforce) {
 706                     error_setg_errno(errp, errno,
 707                                      "tap: open vhost char device failed");
 708                 } else {
 709                     warn_report("tap: open vhost char device failed: %s",
 710                                 strerror(errno));
 711                 }
 712                 return;
 713             }
 714             qemu_set_nonblock(vhostfd);
 715         }
 716         options.opaque = (void *)(uintptr_t)vhostfd;
 717
 718         s->vhost_net = vhost_net_init(&options);
 719         if (!s->vhost_net) {
 720             if (tap->has_vhostforce && tap->vhostforce) {
 721                 error_setg(errp, VHOST_NET_INIT_FAILED);
 722             } else {
 723                 warn_report(VHOST_NET_INIT_FAILED);
 724             }
 725             return;
 726         }
 727     } else if (vhostfdname) {
 728         error_setg(errp, "vhostfd(s)= is not valid without vhost");
 729     }
 730 }
 731
 732 static int get_fds(char *str, char *fds[], int max)
 733 {
 734     char *ptr = str, *this;
 735     size_t len = strlen(str);
 736     int i = 0;
 737
 738     while (i < max && ptr < str + len) {
 739         this = strchr(ptr, ':');
 740
 741         if (this == NULL) {
 742             fds[i] = g_strdup(ptr);
 743         } else {
 744             fds[i] = g_strndup(ptr, this - ptr);
 745         }
 746
 747         i++;
 748         if (this == NULL) {
 749             break;
 750         } else {
 751             ptr = this + 1;
 752         }
 753     }
 754
 755     return i;
 756 }
 757
 758 int net_init_tap(const Netdev *netdev, const char *name,
 759                  NetClientState *peer, Error **errp)
 760 {
 761     const NetdevTapOptions *tap;
 762     int fd, vnet_hdr = 0, i = 0, queues;
 763     /* for the no-fd, no-helper case */
 764     const char *script = NULL; /* suppress wrong "uninit'd use" gcc warning */
 765     const char *downscript = NULL;
 766     Error *err = NULL;
 767     const char *vhostfdname;
 768     char ifname[128];
 769
 770     assert(netdev->type == NET_CLIENT_DRIVER_TAP);
 771     tap = &netdev->u.tap;
 772     queues = tap->has_queues ? tap->queues : 1;
 773     vhostfdname = tap->has_vhostfd ? tap->vhostfd : NULL;
 774
 775     /* QEMU hubs do not support multiqueue tap, in this case peer is set.
 776      * For -netdev, peer is always NULL. */
 777     if (peer && (tap->has_queues || tap->has_fds || tap->has_vhostfds)) {
 778         error_setg(errp, "Multiqueue tap cannot be used with hubs");
 779         return -1;
 780     }
 781
 782     if (tap->has_fd) {
 783         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 784             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
 785             tap->has_fds || tap->has_vhostfds) {
 786             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 787                        "helper=, queues=, fds=, and vhostfds= "
 788                        "are invalid with fd=");
 789             return -1;
 790         }
 791
 792         fd = monitor_fd_param(cur_mon, tap->fd, &err);
 793         if (fd == -1) {
 794             error_propagate(errp, err);
 795             return -1;
 796         }
 797
 798         qemu_set_nonblock(fd);
 799
 800         vnet_hdr = tap_probe_vnet_hdr(fd);
 801
 802         net_init_tap_one(tap, peer, "tap", name, NULL,
 803                          script, downscript,
 804                          vhostfdname, vnet_hdr, fd, &err);
 805         if (err) {
 806             error_propagate(errp, err);
 807             return -1;
 808         }
 809     } else if (tap->has_fds) {
 810         char **fds;
 811         char **vhost_fds;
 812         int nfds = 0, nvhosts = 0;
 813         int ret = 0;
 814
 815         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 816             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
 817             tap->has_vhostfd) {
 818             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 819                        "helper=, queues=, and vhostfd= "
 820                        "are invalid with fds=");
 821             return -1;
 822         }
 823
 824         fds = g_new0(char *, MAX_TAP_QUEUES);
 825         vhost_fds = g_new0(char *, MAX_TAP_QUEUES);
 826
 827         nfds = get_fds(tap->fds, fds, MAX_TAP_QUEUES);
 828         if (tap->has_vhostfds) {
 829             nvhosts = get_fds(tap->vhostfds, vhost_fds, MAX_TAP_QUEUES);
 830             if (nfds != nvhosts) {
 831                 error_setg(errp, "The number of fds passed does not match "
 832                            "the number of vhostfds passed");
 833                 ret = -1;
 834                 goto free_fail;
 835             }
 836         }
 837
 838         for (i = 0; i < nfds; i++) {
 839             fd = monitor_fd_param(cur_mon, fds[i], &err);
 840             if (fd == -1) {
 841                 error_propagate(errp, err);
 842                 ret = -1;
 843                 goto free_fail;
 844             }
 845
 846             qemu_set_nonblock(fd);
 847
 848             if (i == 0) {
 849                 vnet_hdr = tap_probe_vnet_hdr(fd);
 850             } else if (vnet_hdr != tap_probe_vnet_hdr(fd)) {
 851                 error_setg(errp,
 852                            "vnet_hdr not consistent across given tap fds");
 853                 ret = -1;
 854                 goto free_fail;
 855             }
 856
 857             net_init_tap_one(tap, peer, "tap", name, ifname,
 858                              script, downscript,
 859                              tap->has_vhostfds ? vhost_fds[i] : NULL,
 860                              vnet_hdr, fd, &err);
 861             if (err) {
 862                 error_propagate(errp, err);
 863                 ret = -1;
 864                 goto free_fail;
 865             }
 866         }
 867
 868 free_fail:
 869         for (i = 0; i < nvhosts; i++) {
 870             g_free(vhost_fds[i]);
 871         }
 872         for (i = 0; i < nfds; i++) {
 873             g_free(fds[i]);
 874         }
 875         g_free(fds);
 876         g_free(vhost_fds);
 877         return ret;
 878     } else if (tap->has_helper) {
 879         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 880             tap->has_vnet_hdr || tap->has_queues || tap->has_vhostfds) {
 881             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 882                        "queues=, and vhostfds= are invalid with helper=");
 883             return -1;
 884         }
 885
 886         fd = net_bridge_run_helper(tap->helper,
 887                                    tap->has_br ?
 888                                    tap->br : DEFAULT_BRIDGE_INTERFACE,
 889                                    errp);
 890         if (fd == -1) {
 891             return -1;
 892         }
 893
 894         qemu_set_nonblock(fd);
 895         vnet_hdr = tap_probe_vnet_hdr(fd);
 896
 897         net_init_tap_one(tap, peer, "bridge", name, ifname,
 898                          script, downscript, vhostfdname,
 899                          vnet_hdr, fd, &err);
 900         if (err) {
 901             error_propagate(errp, err);
 902             close(fd);
 903             return -1;
 904         }
 905     } else {
 906         if (tap->has_vhostfds) {
 907             error_setg(errp, "vhostfds= is invalid if fds= wasn't specified");
 908             return -1;
 909         }
 910         script = tap->has_script ? tap->script : DEFAULT_NETWORK_SCRIPT;
 911         downscript = tap->has_downscript ? tap->downscript :
 912             DEFAULT_NETWORK_DOWN_SCRIPT;
 913
 914         if (tap->has_ifname) {
 915             pstrcpy(ifname, sizeof ifname, tap->ifname);
 916         } else {
 917             ifname[0] = '\0';
 918         }
 919
 920         for (i = 0; i < queues; i++) {
 921             fd = net_tap_init(tap, &vnet_hdr, i >= 1 ? "no" : script,
 922                               ifname, sizeof ifname, queues > 1, errp);
 923             if (fd == -1) {
 924                 return -1;
 925             }
 926
 927             if (queues > 1 && i == 0 && !tap->has_ifname) {
 928                 if (tap_fd_get_ifname(fd, ifname)) {
 929                     error_setg(errp, "Fail to get ifname");
 930                     close(fd);
 931                     return -1;
 932                 }
 933             }
 934
 935             net_init_tap_one(tap, peer, "tap", name, ifname,
 936                              i >= 1 ? "no" : script,
 937                              i >= 1 ? "no" : downscript,
 938                              vhostfdname, vnet_hdr, fd, &err);
 939             if (err) {
 940                 error_propagate(errp, err);
 941                 close(fd);
 942                 return -1;
 943             }
 944         }
 945     }
 946
 947     return 0;
 948 }
 949
 950 VHostNetState *tap_get_vhost_net(NetClientState *nc)
 951 {
 952     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 953     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 954     return s->vhost_net;
 955 }
 956
 957 int tap_enable(NetClientState *nc)
 958 {
 959     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 960     int ret;
 961
 962     if (s->enabled) {
 963         return 0;
 964     } else {
 965         ret = tap_fd_enable(s->fd);
 966         if (ret == 0) {
 967             s->enabled = true;
 968             tap_update_fd_handler(s);
 969         }
 970         return ret;
 971     }
 972 }
 973
 974 int tap_disable(NetClientState *nc)
 975 {
 976     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 977     int ret;
 978
 979     if (s->enabled == 0) {
 980         return 0;
 981     } else {
 982         ret = tap_fd_disable(s->fd);
 983         if (ret == 0) {
 984             qemu_purge_queued_packets(nc);
 985             s->enabled = false;
 986             tap_update_fd_handler(s);
 987         }
 988         return ret;
 989     }
 990 }