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/sockets.h"
  44
  45 #include "net/tap.h"
  46
  47 #include "net/vhost_net.h"
  48
  49 typedef struct TAPState {
  50     NetClientState nc;
  51     int fd;
  52     char down_script[1024];
  53     char down_script_arg[128];
  54     uint8_t buf[NET_BUFSIZE];
  55     bool read_poll;
  56     bool write_poll;
  57     bool using_vnet_hdr;
  58     bool has_ufo;
  59     bool enabled;
  60     VHostNetState *vhost_net;
  61     unsigned host_vnet_hdr_len;
  62     Notifier exit;
  63 } TAPState;
  64
  65 static void launch_script(const char *setup_script, const char *ifname,
  66                           int fd, Error **errp);
  67
  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_handler(s->fd,
  74                         s->read_poll && s->enabled ? tap_send : NULL,
  75                         s->write_poll && s->enabled ? tap_writable : NULL,
  76                         s);
  77 }
  78
  79 static void tap_read_poll(TAPState *s, bool enable)
  80 {
  81     s->read_poll = enable;
  82     tap_update_fd_handler(s);
  83 }
  84
  85 static void tap_write_poll(TAPState *s, bool enable)
  86 {
  87     s->write_poll = enable;
  88     tap_update_fd_handler(s);
  89 }
  90
  91 static void tap_writable(void *opaque)
  92 {
  93     TAPState *s = opaque;
  94
  95     tap_write_poll(s, false);
  96
  97     qemu_flush_queued_packets(&s->nc);
  98 }
  99
 100 static ssize_t tap_write_packet(TAPState *s, const struct iovec *iov, int iovcnt)
 101 {
 102     ssize_t len;
 103
 104     do {
 105         len = writev(s->fd, iov, iovcnt);
 106     } while (len == -1 && errno == EINTR);
 107
 108     if (len == -1 && errno == EAGAIN) {
 109         tap_write_poll(s, true);
 110         return 0;
 111     }
 112
 113     return len;
 114 }
 115
 116 static ssize_t tap_receive_iov(NetClientState *nc, const struct iovec *iov,
 117                                int iovcnt)
 118 {
 119     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 120     const struct iovec *iovp = iov;
 121     struct iovec iov_copy[iovcnt + 1];
 122     struct virtio_net_hdr_mrg_rxbuf hdr = { };
 123
 124     if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 125         iov_copy[0].iov_base = &hdr;
 126         iov_copy[0].iov_len =  s->host_vnet_hdr_len;
 127         memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
 128         iovp = iov_copy;
 129         iovcnt++;
 130     }
 131
 132     return tap_write_packet(s, iovp, iovcnt);
 133 }
 134
 135 static ssize_t tap_receive_raw(NetClientState *nc, const uint8_t *buf, size_t size)
 136 {
 137     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 138     struct iovec iov[2];
 139     int iovcnt = 0;
 140     struct virtio_net_hdr_mrg_rxbuf hdr = { };
 141
 142     if (s->host_vnet_hdr_len) {
 143         iov[iovcnt].iov_base = &hdr;
 144         iov[iovcnt].iov_len  = s->host_vnet_hdr_len;
 145         iovcnt++;
 146     }
 147
 148     iov[iovcnt].iov_base = (char *)buf;
 149     iov[iovcnt].iov_len  = size;
 150     iovcnt++;
 151
 152     return tap_write_packet(s, iov, iovcnt);
 153 }
 154
 155 static ssize_t tap_receive(NetClientState *nc, const uint8_t *buf, size_t size)
 156 {
 157     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 158     struct iovec iov[1];
 159
 160     if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 161         return tap_receive_raw(nc, buf, size);
 162     }
 163
 164     iov[0].iov_base = (char *)buf;
 165     iov[0].iov_len  = size;
 166
 167     return tap_write_packet(s, iov, 1);
 168 }
 169
 170 #ifndef __sun__
 171 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
 172 {
 173     return read(tapfd, buf, maxlen);
 174 }
 175 #endif
 176
 177 static void tap_send_completed(NetClientState *nc, ssize_t len)
 178 {
 179     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 180     tap_read_poll(s, true);
 181 }
 182
 183 static void tap_send(void *opaque)
 184 {
 185     TAPState *s = opaque;
 186     int size;
 187     int packets = 0;
 188
 189     while (true) {
 190         uint8_t *buf = s->buf;
 191
 192         size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
 193         if (size <= 0) {
 194             break;
 195         }
 196
 197         if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 198             buf  += s->host_vnet_hdr_len;
 199             size -= s->host_vnet_hdr_len;
 200         }
 201
 202         size = qemu_send_packet_async(&s->nc, buf, size, tap_send_completed);
 203         if (size == 0) {
 204             tap_read_poll(s, false);
 205             break;
 206         } else if (size < 0) {
 207             break;
 208         }
 209
 210         /*
 211          * When the host keeps receiving more packets while tap_send() is
 212          * running we can hog the QEMU global mutex.  Limit the number of
 213          * packets that are processed per tap_send() callback to prevent
 214          * stalling the guest.
 215          */
 216         packets++;
 217         if (packets >= 50) {
 218             break;
 219         }
 220     }
 221 }
 222
 223 static bool tap_has_ufo(NetClientState *nc)
 224 {
 225     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 226
 227     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 228
 229     return s->has_ufo;
 230 }
 231
 232 static bool tap_has_vnet_hdr(NetClientState *nc)
 233 {
 234     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 235
 236     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 237
 238     return !!s->host_vnet_hdr_len;
 239 }
 240
 241 static bool tap_has_vnet_hdr_len(NetClientState *nc, int len)
 242 {
 243     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 244
 245     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 246
 247     return !!tap_probe_vnet_hdr_len(s->fd, len);
 248 }
 249
 250 static void tap_set_vnet_hdr_len(NetClientState *nc, int len)
 251 {
 252     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 253
 254     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 255     assert(len == sizeof(struct virtio_net_hdr_mrg_rxbuf) ||
 256            len == sizeof(struct virtio_net_hdr));
 257
 258     tap_fd_set_vnet_hdr_len(s->fd, len);
 259     s->host_vnet_hdr_len = len;
 260 }
 261
 262 static void tap_using_vnet_hdr(NetClientState *nc, bool using_vnet_hdr)
 263 {
 264     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 265
 266     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 267     assert(!!s->host_vnet_hdr_len == using_vnet_hdr);
 268
 269     s->using_vnet_hdr = using_vnet_hdr;
 270 }
 271
 272 static int tap_set_vnet_le(NetClientState *nc, bool is_le)
 273 {
 274     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 275
 276     return tap_fd_set_vnet_le(s->fd, is_le);
 277 }
 278
 279 static int tap_set_vnet_be(NetClientState *nc, bool is_be)
 280 {
 281     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 282
 283     return tap_fd_set_vnet_be(s->fd, is_be);
 284 }
 285
 286 static void tap_set_offload(NetClientState *nc, int csum, int tso4,
 287                      int tso6, int ecn, int ufo)
 288 {
 289     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 290     if (s->fd < 0) {
 291         return;
 292     }
 293
 294     tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
 295 }
 296
 297 static void tap_exit_notify(Notifier *notifier, void *data)
 298 {
 299     TAPState *s = container_of(notifier, TAPState, exit);
 300     Error *err = NULL;
 301
 302     if (s->down_script[0]) {
 303         launch_script(s->down_script, s->down_script_arg, s->fd, &err);
 304         if (err) {
 305             error_report_err(err);
 306         }
 307     }
 308 }
 309
 310 static void tap_cleanup(NetClientState *nc)
 311 {
 312     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 313
 314     if (s->vhost_net) {
 315         vhost_net_cleanup(s->vhost_net);
 316         g_free(s->vhost_net);
 317         s->vhost_net = NULL;
 318     }
 319
 320     qemu_purge_queued_packets(nc);
 321
 322     tap_exit_notify(&s->exit, NULL);
 323     qemu_remove_exit_notifier(&s->exit);
 324
 325     tap_read_poll(s, false);
 326     tap_write_poll(s, false);
 327     close(s->fd);
 328     s->fd = -1;
 329 }
 330
 331 static void tap_poll(NetClientState *nc, bool enable)
 332 {
 333     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 334     tap_read_poll(s, enable);
 335     tap_write_poll(s, enable);
 336 }
 337
 338 int tap_get_fd(NetClientState *nc)
 339 {
 340     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 341     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 342     return s->fd;
 343 }
 344
 345 /* fd support */
 346
 347 static NetClientInfo net_tap_info = {
 348     .type = NET_CLIENT_DRIVER_TAP,
 349     .size = sizeof(TAPState),
 350     .receive = tap_receive,
 351     .receive_raw = tap_receive_raw,
 352     .receive_iov = tap_receive_iov,
 353     .poll = tap_poll,
 354     .cleanup = tap_cleanup,
 355     .has_ufo = tap_has_ufo,
 356     .has_vnet_hdr = tap_has_vnet_hdr,
 357     .has_vnet_hdr_len = tap_has_vnet_hdr_len,
 358     .using_vnet_hdr = tap_using_vnet_hdr,
 359     .set_offload = tap_set_offload,
 360     .set_vnet_hdr_len = tap_set_vnet_hdr_len,
 361     .set_vnet_le = tap_set_vnet_le,
 362     .set_vnet_be = tap_set_vnet_be,
 363 };
 364
 365 static TAPState *net_tap_fd_init(NetClientState *peer,
 366                                  const char *model,
 367                                  const char *name,
 368                                  int fd,
 369                                  int vnet_hdr)
 370 {
 371     NetClientState *nc;
 372     TAPState *s;
 373
 374     nc = qemu_new_net_client(&net_tap_info, peer, model, name);
 375
 376     s = DO_UPCAST(TAPState, nc, nc);
 377
 378     s->fd = fd;
 379     s->host_vnet_hdr_len = vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
 380     s->using_vnet_hdr = false;
 381     s->has_ufo = tap_probe_has_ufo(s->fd);
 382     s->enabled = true;
 383     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
 384     /*
 385      * Make sure host header length is set correctly in tap:
 386      * it might have been modified by another instance of qemu.
 387      */
 388     if (tap_probe_vnet_hdr_len(s->fd, s->host_vnet_hdr_len)) {
 389         tap_fd_set_vnet_hdr_len(s->fd, s->host_vnet_hdr_len);
 390     }
 391     tap_read_poll(s, true);
 392     s->vhost_net = NULL;
 393
 394     s->exit.notify = tap_exit_notify;
 395     qemu_add_exit_notifier(&s->exit);
 396
 397     return s;
 398 }
 399
 400 static void launch_script(const char *setup_script, const char *ifname,
 401                           int fd, Error **errp)
 402 {
 403     int pid, status;
 404     char *args[3];
 405     char **parg;
 406
 407     /* try to launch network script */
 408     pid = fork();
 409     if (pid < 0) {
 410         error_setg_errno(errp, errno, "could not launch network script %s",
 411                          setup_script);
 412         return;
 413     }
 414     if (pid == 0) {
 415         int open_max = sysconf(_SC_OPEN_MAX), i;
 416
 417         for (i = 3; i < open_max; i++) {
 418             if (i != fd) {
 419                 close(i);
 420             }
 421         }
 422         parg = args;
 423         *parg++ = (char *)setup_script;
 424         *parg++ = (char *)ifname;
 425         *parg = NULL;
 426         execv(setup_script, args);
 427         _exit(1);
 428     } else {
 429         while (waitpid(pid, &status, 0) != pid) {
 430             /* loop */
 431         }
 432
 433         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 434             return;
 435         }
 436         error_setg(errp, "network script %s failed with status %d",
 437                    setup_script, status);
 438     }
 439 }
 440
 441 static int recv_fd(int c)
 442 {
 443     int fd;
 444     uint8_t msgbuf[CMSG_SPACE(sizeof(fd))];
 445     struct msghdr msg = {
 446         .msg_control = msgbuf,
 447         .msg_controllen = sizeof(msgbuf),
 448     };
 449     struct cmsghdr *cmsg;
 450     struct iovec iov;
 451     uint8_t req[1];
 452     ssize_t len;
 453
 454     cmsg = CMSG_FIRSTHDR(&msg);
 455     cmsg->cmsg_level = SOL_SOCKET;
 456     cmsg->cmsg_type = SCM_RIGHTS;
 457     cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
 458     msg.msg_controllen = cmsg->cmsg_len;
 459
 460     iov.iov_base = req;
 461     iov.iov_len = sizeof(req);
 462
 463     msg.msg_iov = &iov;
 464     msg.msg_iovlen = 1;
 465
 466     len = recvmsg(c, &msg, 0);
 467     if (len > 0) {
 468         memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));
 469         return fd;
 470     }
 471
 472     return len;
 473 }
 474
 475 static int net_bridge_run_helper(const char *helper, const char *bridge,
 476                                  Error **errp)
 477 {
 478     sigset_t oldmask, mask;
 479     int pid, status;
 480     char *args[5];
 481     char **parg;
 482     int sv[2];
 483
 484     sigemptyset(&mask);
 485     sigaddset(&mask, SIGCHLD);
 486     sigprocmask(SIG_BLOCK, &mask, &oldmask);
 487
 488     if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
 489         error_setg_errno(errp, errno, "socketpair() failed");
 490         return -1;
 491     }
 492
 493     /* try to launch bridge helper */
 494     pid = fork();
 495     if (pid < 0) {
 496         error_setg_errno(errp, errno, "Can't fork bridge helper");
 497         return -1;
 498     }
 499     if (pid == 0) {
 500         int open_max = sysconf(_SC_OPEN_MAX), i;
 501         char fd_buf[6+10];
 502         char br_buf[6+IFNAMSIZ] = {0};
 503         char helper_cmd[PATH_MAX + sizeof(fd_buf) + sizeof(br_buf) + 15];
 504
 505         for (i = 3; i < open_max; i++) {
 506             if (i != sv[1]) {
 507                 close(i);
 508             }
 509         }
 510
 511         snprintf(fd_buf, sizeof(fd_buf), "%s%d", "--fd=", sv[1]);
 512
 513         if (strrchr(helper, ' ') || strrchr(helper, '\t')) {
 514             /* assume helper is a command */
 515
 516             if (strstr(helper, "--br=") == NULL) {
 517                 snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
 518             }
 519
 520             snprintf(helper_cmd, sizeof(helper_cmd), "%s %s %s %s",
 521                      helper, "--use-vnet", fd_buf, br_buf);
 522
 523             parg = args;
 524             *parg++ = (char *)"sh";
 525             *parg++ = (char *)"-c";
 526             *parg++ = helper_cmd;
 527             *parg++ = NULL;
 528
 529             execv("/bin/sh", args);
 530         } else {
 531             /* assume helper is just the executable path name */
 532
 533             snprintf(br_buf, sizeof(br_buf), "%s%s", "--br=", bridge);
 534
 535             parg = args;
 536             *parg++ = (char *)helper;
 537             *parg++ = (char *)"--use-vnet";
 538             *parg++ = fd_buf;
 539             *parg++ = br_buf;
 540             *parg++ = NULL;
 541
 542             execv(helper, args);
 543         }
 544         _exit(1);
 545
 546     } else {
 547         int fd;
 548         int saved_errno;
 549
 550         close(sv[1]);
 551
 552         do {
 553             fd = recv_fd(sv[0]);
 554         } while (fd == -1 && errno == EINTR);
 555         saved_errno = errno;
 556
 557         close(sv[0]);
 558
 559         while (waitpid(pid, &status, 0) != pid) {
 560             /* loop */
 561         }
 562         sigprocmask(SIG_SETMASK, &oldmask, NULL);
 563         if (fd < 0) {
 564             error_setg_errno(errp, saved_errno,
 565                              "failed to recv file descriptor");
 566             return -1;
 567         }
 568         if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 569             error_setg(errp, "bridge helper failed");
 570             return -1;
 571         }
 572         return fd;
 573     }
 574 }
 575
 576 int net_init_bridge(const Netdev *netdev, const char *name,
 577                     NetClientState *peer, Error **errp)
 578 {
 579     const NetdevBridgeOptions *bridge;
 580     const char *helper, *br;
 581     TAPState *s;
 582     int fd, vnet_hdr;
 583
 584     assert(netdev->type == NET_CLIENT_DRIVER_BRIDGE);
 585     bridge = &netdev->u.bridge;
 586
 587     helper = bridge->has_helper ? bridge->helper : DEFAULT_BRIDGE_HELPER;
 588     br     = bridge->has_br     ? bridge->br     : DEFAULT_BRIDGE_INTERFACE;
 589
 590     fd = net_bridge_run_helper(helper, br, errp);
 591     if (fd == -1) {
 592         return -1;
 593     }
 594
 595     qemu_set_nonblock(fd);
 596     vnet_hdr = tap_probe_vnet_hdr(fd);
 597     s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
 598
 599     snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
 600              br);
 601
 602     return 0;
 603 }
 604
 605 static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
 606                         const char *setup_script, char *ifname,
 607                         size_t ifname_sz, int mq_required, Error **errp)
 608 {
 609     Error *err = NULL;
 610     int fd, vnet_hdr_required;
 611
 612     if (tap->has_vnet_hdr) {
 613         *vnet_hdr = tap->vnet_hdr;
 614         vnet_hdr_required = *vnet_hdr;
 615     } else {
 616         *vnet_hdr = 1;
 617         vnet_hdr_required = 0;
 618     }
 619
 620     TFR(fd = tap_open(ifname, ifname_sz, vnet_hdr, vnet_hdr_required,
 621                       mq_required, errp));
 622     if (fd < 0) {
 623         return -1;
 624     }
 625
 626     if (setup_script &&
 627         setup_script[0] != '\0' &&
 628         strcmp(setup_script, "no") != 0) {
 629         launch_script(setup_script, ifname, fd, &err);
 630         if (err) {
 631             error_propagate(errp, err);
 632             close(fd);
 633             return -1;
 634         }
 635     }
 636
 637     return fd;
 638 }
 639
 640 #define MAX_TAP_QUEUES 1024
 641
 642 static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
 643                              const char *model, const char *name,
 644                              const char *ifname, const char *script,
 645                              const char *downscript, const char *vhostfdname,
 646                              int vnet_hdr, int fd, Error **errp)
 647 {
 648     Error *err = NULL;
 649     TAPState *s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
 650     int vhostfd;
 651
 652     tap_set_sndbuf(s->fd, tap, &err);
 653     if (err) {
 654         error_propagate(errp, err);
 655         return;
 656     }
 657
 658     if (tap->has_fd || tap->has_fds) {
 659         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
 660     } else if (tap->has_helper) {
 661         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
 662                  tap->helper);
 663     } else {
 664         snprintf(s->nc.info_str, sizeof(s->nc.info_str),
 665                  "ifname=%s,script=%s,downscript=%s", ifname, script,
 666                  downscript);
 667
 668         if (strcmp(downscript, "no") != 0) {
 669             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
 670             snprintf(s->down_script_arg, sizeof(s->down_script_arg),
 671                      "%s", ifname);
 672         }
 673     }
 674
 675     if (tap->has_vhost ? tap->vhost :
 676         vhostfdname || (tap->has_vhostforce && tap->vhostforce)) {
 677         VhostNetOptions options;
 678
 679         options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
 680         options.net_backend = &s->nc;
 681         if (tap->has_poll_us) {
 682             options.busyloop_timeout = tap->poll_us;
 683         } else {
 684             options.busyloop_timeout = 0;
 685         }
 686
 687         if (vhostfdname) {
 688             vhostfd = monitor_fd_param(cur_mon, vhostfdname, &err);
 689             if (vhostfd == -1) {
 690                 if (tap->has_vhostforce && tap->vhostforce) {
 691                     error_propagate(errp, err);
 692                 } else {
 693                     warn_report_err(err);
 694                 }
 695                 return;
 696             }
 697             qemu_set_nonblock(vhostfd);
 698         } else {
 699             vhostfd = open("/dev/vhost-net", O_RDWR);
 700             if (vhostfd < 0) {
 701                 if (tap->has_vhostforce && tap->vhostforce) {
 702                     error_setg_errno(errp, errno,
 703                                      "tap: open vhost char device failed");
 704                 } else {
 705                     warn_report("tap: open vhost char device failed: %s",
 706                                 strerror(errno));
 707                 }
 708                 return;
 709             }
 710             qemu_set_nonblock(vhostfd);
 711         }
 712         options.opaque = (void *)(uintptr_t)vhostfd;
 713
 714         s->vhost_net = vhost_net_init(&options);
 715         if (!s->vhost_net) {
 716             if (tap->has_vhostforce && tap->vhostforce) {
 717                 error_setg(errp, VHOST_NET_INIT_FAILED);
 718             } else {
 719                 warn_report(VHOST_NET_INIT_FAILED);
 720             }
 721             return;
 722         }
 723     } else if (vhostfdname) {
 724         error_setg(errp, "vhostfd(s)= is not valid without vhost");
 725     }
 726 }
 727
 728 static int get_fds(char *str, char *fds[], int max)
 729 {
 730     char *ptr = str, *this;
 731     size_t len = strlen(str);
 732     int i = 0;
 733
 734     while (i < max && ptr < str + len) {
 735         this = strchr(ptr, ':');
 736
 737         if (this == NULL) {
 738             fds[i] = g_strdup(ptr);
 739         } else {
 740             fds[i] = g_strndup(ptr, this - ptr);
 741         }
 742
 743         i++;
 744         if (this == NULL) {
 745             break;
 746         } else {
 747             ptr = this + 1;
 748         }
 749     }
 750
 751     return i;
 752 }
 753
 754 int net_init_tap(const Netdev *netdev, const char *name,
 755                  NetClientState *peer, Error **errp)
 756 {
 757     const NetdevTapOptions *tap;
 758     int fd, vnet_hdr = 0, i = 0, queues;
 759     /* for the no-fd, no-helper case */
 760     const char *script = NULL; /* suppress wrong "uninit'd use" gcc warning */
 761     const char *downscript = NULL;
 762     Error *err = NULL;
 763     const char *vhostfdname;
 764     char ifname[128];
 765
 766     assert(netdev->type == NET_CLIENT_DRIVER_TAP);
 767     tap = &netdev->u.tap;
 768     queues = tap->has_queues ? tap->queues : 1;
 769     vhostfdname = tap->has_vhostfd ? tap->vhostfd : NULL;
 770
 771     /* QEMU hubs do not support multiqueue tap, in this case peer is set.
 772      * For -netdev, peer is always NULL. */
 773     if (peer && (tap->has_queues || tap->has_fds || tap->has_vhostfds)) {
 774         error_setg(errp, "Multiqueue tap cannot be used with hubs");
 775         return -1;
 776     }
 777
 778     if (tap->has_fd) {
 779         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 780             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
 781             tap->has_fds || tap->has_vhostfds) {
 782             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 783                        "helper=, queues=, fds=, and vhostfds= "
 784                        "are invalid with fd=");
 785             return -1;
 786         }
 787
 788         fd = monitor_fd_param(cur_mon, tap->fd, &err);
 789         if (fd == -1) {
 790             error_propagate(errp, err);
 791             return -1;
 792         }
 793
 794         qemu_set_nonblock(fd);
 795
 796         vnet_hdr = tap_probe_vnet_hdr(fd);
 797
 798         net_init_tap_one(tap, peer, "tap", name, NULL,
 799                          script, downscript,
 800                          vhostfdname, vnet_hdr, fd, &err);
 801         if (err) {
 802             error_propagate(errp, err);
 803             return -1;
 804         }
 805     } else if (tap->has_fds) {
 806         char **fds;
 807         char **vhost_fds;
 808         int nfds = 0, nvhosts = 0;
 809         int ret = 0;
 810
 811         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 812             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
 813             tap->has_vhostfd) {
 814             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 815                        "helper=, queues=, and vhostfd= "
 816                        "are invalid with fds=");
 817             return -1;
 818         }
 819
 820         fds = g_new0(char *, MAX_TAP_QUEUES);
 821         vhost_fds = g_new0(char *, MAX_TAP_QUEUES);
 822
 823         nfds = get_fds(tap->fds, fds, MAX_TAP_QUEUES);
 824         if (tap->has_vhostfds) {
 825             nvhosts = get_fds(tap->vhostfds, vhost_fds, MAX_TAP_QUEUES);
 826             if (nfds != nvhosts) {
 827                 error_setg(errp, "The number of fds passed does not match "
 828                            "the number of vhostfds passed");
 829                 ret = -1;
 830                 goto free_fail;
 831             }
 832         }
 833
 834         for (i = 0; i < nfds; i++) {
 835             fd = monitor_fd_param(cur_mon, fds[i], &err);
 836             if (fd == -1) {
 837                 error_propagate(errp, err);
 838                 ret = -1;
 839                 goto free_fail;
 840             }
 841
 842             qemu_set_nonblock(fd);
 843
 844             if (i == 0) {
 845                 vnet_hdr = tap_probe_vnet_hdr(fd);
 846             } else if (vnet_hdr != tap_probe_vnet_hdr(fd)) {
 847                 error_setg(errp,
 848                            "vnet_hdr not consistent across given tap fds");
 849                 ret = -1;
 850                 goto free_fail;
 851             }
 852
 853             net_init_tap_one(tap, peer, "tap", name, ifname,
 854                              script, downscript,
 855                              tap->has_vhostfds ? vhost_fds[i] : NULL,
 856                              vnet_hdr, fd, &err);
 857             if (err) {
 858                 error_propagate(errp, err);
 859                 ret = -1;
 860                 goto free_fail;
 861             }
 862         }
 863
 864 free_fail:
 865         for (i = 0; i < nvhosts; i++) {
 866             g_free(vhost_fds[i]);
 867         }
 868         for (i = 0; i < nfds; i++) {
 869             g_free(fds[i]);
 870         }
 871         g_free(fds);
 872         g_free(vhost_fds);
 873         return ret;
 874     } else if (tap->has_helper) {
 875         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 876             tap->has_vnet_hdr || tap->has_queues || tap->has_vhostfds) {
 877             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 878                        "queues=, and vhostfds= are invalid with helper=");
 879             return -1;
 880         }
 881
 882         fd = net_bridge_run_helper(tap->helper,
 883                                    tap->has_br ?
 884                                    tap->br : DEFAULT_BRIDGE_INTERFACE,
 885                                    errp);
 886         if (fd == -1) {
 887             return -1;
 888         }
 889
 890         qemu_set_nonblock(fd);
 891         vnet_hdr = tap_probe_vnet_hdr(fd);
 892
 893         net_init_tap_one(tap, peer, "bridge", name, ifname,
 894                          script, downscript, vhostfdname,
 895                          vnet_hdr, fd, &err);
 896         if (err) {
 897             error_propagate(errp, err);
 898             close(fd);
 899             return -1;
 900         }
 901     } else {
 902         if (tap->has_vhostfds) {
 903             error_setg(errp, "vhostfds= is invalid if fds= wasn't specified");
 904             return -1;
 905         }
 906         script = tap->has_script ? tap->script : DEFAULT_NETWORK_SCRIPT;
 907         downscript = tap->has_downscript ? tap->downscript :
 908             DEFAULT_NETWORK_DOWN_SCRIPT;
 909
 910         if (tap->has_ifname) {
 911             pstrcpy(ifname, sizeof ifname, tap->ifname);
 912         } else {
 913             ifname[0] = '\0';
 914         }
 915
 916         for (i = 0; i < queues; i++) {
 917             fd = net_tap_init(tap, &vnet_hdr, i >= 1 ? "no" : script,
 918                               ifname, sizeof ifname, queues > 1, errp);
 919             if (fd == -1) {
 920                 return -1;
 921             }
 922
 923             if (queues > 1 && i == 0 && !tap->has_ifname) {
 924                 if (tap_fd_get_ifname(fd, ifname)) {
 925                     error_setg(errp, "Fail to get ifname");
 926                     close(fd);
 927                     return -1;
 928                 }
 929             }
 930
 931             net_init_tap_one(tap, peer, "tap", name, ifname,
 932                              i >= 1 ? "no" : script,
 933                              i >= 1 ? "no" : downscript,
 934                              vhostfdname, vnet_hdr, fd, &err);
 935             if (err) {
 936                 error_propagate(errp, err);
 937                 close(fd);
 938                 return -1;
 939             }
 940         }
 941     }
 942
 943     return 0;
 944 }
 945
 946 VHostNetState *tap_get_vhost_net(NetClientState *nc)
 947 {
 948     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 949     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 950     return s->vhost_net;
 951 }
 952
 953 int tap_enable(NetClientState *nc)
 954 {
 955     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 956     int ret;
 957
 958     if (s->enabled) {
 959         return 0;
 960     } else {
 961         ret = tap_fd_enable(s->fd);
 962         if (ret == 0) {
 963             s->enabled = true;
 964             tap_update_fd_handler(s);
 965         }
 966         return ret;
 967     }
 968 }
 969
 970 int tap_disable(NetClientState *nc)
 971 {
 972     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 973     int ret;
 974
 975     if (s->enabled == 0) {
 976         return 0;
 977     } else {
 978         ret = tap_fd_disable(s->fd);
 979         if (ret == 0) {
 980             qemu_purge_queued_packets(nc);
 981             s->enabled = false;
 982             tap_update_fd_handler(s);
 983         }
 984         return ret;
 985     }
 986 }