aboutsummaryrefslogtreecommitdiffstats
path: root/src/vnet/devices/tap/tap.c
blob: 6f16a4cd71d15ba7f1513f6eb8a0f8c78b2c8c9f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
/*
 *------------------------------------------------------------------
 * Copyright (c) 2017 Cisco and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *------------------------------------------------------------------
 */

#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <net/if.h>
#include <linux/if_tun.h>
#include <sys/ioctl.h>
#include <linux/virtio_net.h>
#include <linux/vhost.h>
#include <sys/eventfd.h>
#include <net/if_arp.h>
#include <sched.h>
#include <limits.h>

#include <linux/netlink.h>
#include <linux/rtnetlink.h>

#include <vlib/vlib.h>
#include <vlib/physmem.h>
#include <vlib/unix/unix.h>
#include <vnet/ethernet/ethernet.h>
#include <vnet/ip/ip4_packet.h>
#include <vnet/ip/ip6_packet.h>
#include <vnet/devices/netlink.h>
#include <vnet/devices/virtio/virtio.h>
#include <vnet/devices/tap/tap.h>

tap_main_t tap_main;

#define tap_log_err(dev, f, ...)                        \
  vlib_log (VLIB_LOG_LEVEL_ERR, tap_main.log_default, "tap%u: " f, dev->dev_instance, ## __VA_ARGS__)
#define tap_log_dbg(dev, f, ...)                        \
  vlib_log (VLIB_LOG_LEVEL_DEBUG, tap_main.log_default, "tap%u: " f, dev->dev_instance, ## __VA_ARGS__)

#define _IOCTL(fd,a,...) \
  if (ioctl (fd, a, __VA_ARGS__) < 0) \
    { \
      err = clib_error_return_unix (0, "ioctl(" #a ")"); \
      tap_log_err (vif, "%U", format_clib_error, err); \
      goto error; \
    }

static u32
virtio_eth_flag_change (vnet_main_t * vnm, vnet_hw_interface_t * hi,
			u32 flags)
{
  /* nothing for now */
  //TODO On MTU change call vnet_netlink_set_if_mtu
  return 0;
}

static int
open_netns_fd (char *netns)
{
  u8 *s = 0;
  int fd;

  if (strncmp (netns, "pid:", 4) == 0)
    s = format (0, "/proc/%u/ns/net%c", atoi (netns + 4), 0);
  else if (netns[0] == '/')
    s = format (0, "%s%c", netns, 0);
  else
    s = format (0, "/var/run/netns/%s%c", netns, 0);

  fd = open ((char *) s, O_RDONLY);
  vec_free (s);
  return fd;
}

#define TAP_MAX_INSTANCE 1024

static void
tap_free (vlib_main_t * vm, virtio_if_t * vif)
{
  virtio_main_t *mm = &virtio_main;
  tap_main_t *tm = &tap_main;
  int i;

  /* *INDENT-OFF* */
  vec_foreach_index (i, vif->vhost_fds) if (vif->vhost_fds[i] != -1)
    close (vif->vhost_fds[i]);
  vec_foreach_index (i, vif->rxq_vrings)
    virtio_vring_free_rx (vm, vif, RX_QUEUE (i));
  vec_foreach_index (i, vif->txq_vrings)
    virtio_vring_free_tx (vm, vif, TX_QUEUE (i));
  /* *INDENT-ON* */

  if (vif->tap_fd != -1)
    close (vif->tap_fd);

  vec_free (vif->vhost_fds);
  vec_free (vif->rxq_vrings);
  vec_free (vif->txq_vrings);
  vec_free (vif->host_if_name);
  vec_free (vif->net_ns);
  vec_free (vif->host_bridge);
  clib_error_free (vif->error);

  tm->tap_ids = clib_bitmap_set (tm->tap_ids, vif->id, 0);
  clib_memset (vif, 0, sizeof (*vif));
  pool_put (mm->interfaces, vif);
}

void
tap_create_if (vlib_main_t * vm, tap_create_if_args_t * args)
{
  vlib_thread_main_t *thm = vlib_get_thread_main ();
  vlib_physmem_main_t *vpm = &vm->physmem_main;
  vnet_main_t *vnm = vnet_get_main ();
  virtio_main_t *vim = &virtio_main;
  tap_main_t *tm = &tap_main;
  vnet_sw_interface_t *sw;
  vnet_hw_interface_t *hw;
  int i;
  int old_netns_fd = -1;
  struct ifreq ifr = {.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR };
  size_t hdrsz;
  struct vhost_memory *vhost_mem = 0;
  virtio_if_t *vif = 0;
  clib_error_t *err = 0;
  unsigned int tap_features;
  int tfd, vfd, nfd = -1;
  char *host_if_name = 0;
  unsigned int offload = 0;
  u16 num_q_pairs;

  if (args->id != ~0)
    {
      if (clib_bitmap_get (tm->tap_ids, args->id))
	{
	  args->rv = VNET_API_ERROR_INVALID_INTERFACE;
	  args->error = clib_error_return (0, "interface already exists");
	  return;
	}
    }
  else
    {
      args->id = clib_bitmap_first_clear (tm->tap_ids);
    }

  if (args->id > TAP_MAX_INSTANCE)
    {
      args->rv = VNET_API_ERROR_UNSPECIFIED;
      args->error = clib_error_return (0, "cannot find free interface id");
      return;
    }

  pool_get_zero (vim->interfaces, vif);
  vif->type = VIRTIO_IF_TYPE_TAP;
  vif->dev_instance = vif - vim->interfaces;
  vif->id = args->id;
  vif->num_txqs = thm->n_vlib_mains;
  vif->num_rxqs = args->num_rx_queues;
  num_q_pairs = clib_max (vif->num_rxqs, vif->num_txqs);

  if ((vif->tap_fd = tfd = open ("/dev/net/tun", O_RDWR | O_NONBLOCK)) < 0)
    {
      args->rv = VNET_API_ERROR_SYSCALL_ERROR_2;
      args->error = clib_error_return_unix (0, "open '/dev/net/tun'");
      goto error;
    }
  tap_log_dbg (vif, "open tap fd %d", tfd);

  _IOCTL (tfd, TUNGETFEATURES, &tap_features);
  tap_log_dbg (vif, "TUNGETFEATURES: features 0x%lx", tap_features);
  if ((tap_features & IFF_VNET_HDR) == 0)
    {
      args->rv = VNET_API_ERROR_SYSCALL_ERROR_2;
      args->error = clib_error_return (0, "vhost-net backend not available");
      goto error;
    }

  if ((tap_features & IFF_MULTI_QUEUE) == 0)
    {
      if (args->num_rx_queues > 1)
	{
	  args->rv = VNET_API_ERROR_SYSCALL_ERROR_2;
	  args->error = clib_error_return (0, "multiqueue not supported");
	  goto error;
	}
      vif->num_rxqs = vif->num_txqs = num_q_pairs = 1;
    }
  else
    ifr.ifr_flags |= IFF_MULTI_QUEUE;

  hdrsz = sizeof (struct virtio_net_hdr_v1);
  if (args->tap_flags & TAP_FLAG_GSO)
    {
      offload = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6;
      vif->gso_enabled = 1;
    }
  else if (args->tap_flags & TAP_FLAG_CSUM_OFFLOAD)
    {
      offload = TUN_F_CSUM;
      vif->csum_offload_enabled = 1;
    }

  _IOCTL (tfd, TUNSETIFF, (void *) &ifr);
  tap_log_dbg (vif, "TUNSETIFF fd %d name %s flags 0x%x", tfd,
	       ifr.ifr_ifrn.ifrn_name, ifr.ifr_flags);

  vif->ifindex = if_nametoindex (ifr.ifr_ifrn.ifrn_name);
  tap_log_dbg (vif, "ifindex %d", vif->ifindex);

  if (!args->host_if_name)
    host_if_name = ifr.ifr_ifrn.ifrn_name;
  else
    host_if_name = (char *) args->host_if_name;

  if (fcntl (tfd, F_SETFL, O_NONBLOCK) < 0)
    {
      err = clib_error_return_unix (0, "fcntl(tfd, F_SETFL, O_NONBLOCK)");
      tap_log_err (vif, "set nonblocking: %U", format_clib_error, err);
      goto error;
    }

  tap_log_dbg (vif, "TUNSETVNETHDRSZ: fd %d vnet_hdr_sz %u", tfd, hdrsz);
  _IOCTL (tfd, TUNSETVNETHDRSZ, &hdrsz);

  i = INT_MAX;
  tap_log_dbg (vif, "TUNSETSNDBUF: fd %d sndbuf %d", tfd, i);
  _IOCTL (tfd, TUNSETSNDBUF, &i);

  tap_log_dbg (vif, "TUNSETOFFLOAD: fd %d offload 0x%lx", tfd, offload);
  _IOCTL (tfd, TUNSETOFFLOAD, offload);

  /* open vhost-net fd for each queue pair and set ownership */
  for (i = 0; i < num_q_pairs; i++)
    {
      if ((vfd = open ("/dev/vhost-net", O_RDWR | O_NONBLOCK)) < 0)
	{
	  args->rv = VNET_API_ERROR_SYSCALL_ERROR_1;
	  args->error = clib_error_return_unix (0, "open '/dev/vhost-net'");
	  goto error;
	}
      vec_add1 (vif->vhost_fds, vfd);
      virtio_log_debug (vif, "open vhost-net fd %d qpair %u", vfd, i);
      _IOCTL (vfd, VHOST_SET_OWNER, 0);
      virtio_log_debug (vif, "VHOST_SET_OWNER: fd %u", vfd);
    }

  _IOCTL (vif->vhost_fds[0], VHOST_GET_FEATURES, &vif->remote_features);
  virtio_log_debug (vif, "VHOST_GET_FEATURES: features 0x%lx",
		    vif->remote_features);

  if ((vif->remote_features & VIRTIO_FEATURE (VIRTIO_NET_F_MRG_RXBUF)) == 0)
    {
      args->rv = VNET_API_ERROR_UNSUPPORTED;
      args->error = clib_error_return (0, "vhost-net backend doesn't support "
				       "VIRTIO_NET_F_MRG_RXBUF feature");
      goto error;
    }

  if ((vif->remote_features & VIRTIO_FEATURE (VIRTIO_RING_F_INDIRECT_DESC)) ==
      0)
    {
      args->rv = VNET_API_ERROR_UNSUPPORTED;
      args->error = clib_error_return (0, "vhost-net backend doesn't support "
				       "VIRTIO_RING_F_INDIRECT_DESC feature");
      goto error;
    }

  if ((vif->remote_features & VIRTIO_FEATURE (VIRTIO_F_VERSION_1)) == 0)
    {
      args->rv = VNET_API_ERROR_UNSUPPORTED;
      args->error = clib_error_return (0, "vhost-net backend doesn't support "
				       "VIRTIO_F_VERSION_1 features");
      goto error;
    }

  vif->features |= VIRTIO_FEATURE (VIRTIO_NET_F_MRG_RXBUF);
  vif->features |= VIRTIO_FEATURE (VIRTIO_F_VERSION_1);
  vif->features |= VIRTIO_FEATURE (VIRTIO_RING_F_INDIRECT_DESC);

  virtio_set_net_hdr_size (vif);

  /* if namespace is specified, all further netlink messages should be executed
     after we change our net namespace */
  if (args->host_namespace)
    {
      old_netns_fd = open ("/proc/self/ns/net", O_RDONLY);
      if ((nfd = open_netns_fd ((char *) args->host_namespace)) == -1)
	{
	  args->rv = VNET_API_ERROR_SYSCALL_ERROR_2;
	  args->error = clib_error_return_unix (0, "open_netns_fd '%s'",
						args->host_namespace);
	  goto error;
	}
      args->error = vnet_netlink_set_link_netns (vif->ifindex, nfd,
						 host_if_name);
      if (args->error)
	{
	  args->rv = VNET_API_ERROR_NETLINK_ERROR;
	  goto error;
	}
      if (setns (nfd, CLONE_NEWNET) == -1)
	{
	  args->rv = VNET_API_ERROR_SYSCALL_ERROR_3;
	  args->error = clib_error_return_unix (0, "setns '%s'",
						args->host_namespace);
	  goto error;
	}
      if ((vif->ifindex = if_nametoindex (host_if_name)) == 0)
	{
	  args->rv = VNET_API_ERROR_SYSCALL_ERROR_3;
	  args->error = clib_error_return_unix (0, "if_nametoindex '%s'",
						host_if_name);
	  goto error;
	}
    }
  else
    {
      if (host_if_name)
	{
	  args->error = vnet_netlink_set_link_name (vif->ifindex,
						    host_if_name);
	  if (args->error)
	    {
	      args->rv = VNET_API_ERROR_NETLINK_ERROR;
	      goto error;
	    }
	}
    }

  if (ethernet_mac_address_is_zero (args->host_mac_addr.bytes))
    ethernet_mac_address_generate (args->host_mac_addr.bytes);
  args->error = vnet_netlink_set_link_addr (vif->ifindex,
					    args->host_mac_addr.bytes);
  if (args->error)
    {
      args->rv = VNET_API_ERROR_NETLINK_ERROR;
      goto error;
    }

  if (args->host_bridge)
    {
      args->error = vnet_netlink_set_link_master (vif->ifindex,
						  (char *) args->host_bridge);
      if (args->error)
	{
	  args->rv = VNET_API_ERROR_NETLINK_ERROR;
	  goto error;
	}
    }

  if (args->host_ip4_prefix_len)
    {
      args->error = vnet_netlink_add_ip4_addr (vif->ifindex,
					       &args->host_ip4_addr,
					       args->host_ip4_prefix_len);
      if (args->error)
	{
	  args->rv = VNET_API_ERROR_NETLINK_ERROR;
	  goto error;
	}
    }

  if (args->host_ip6_prefix_len)
    {
      args->error = vnet_netlink_add_ip6_addr (vif->ifindex,
					       &args->host_ip6_addr,
					       args->host_ip6_prefix_len);
      if (args->error)
	{
	  args->rv = VNET_API_ERROR_NETLINK_ERROR;
	  goto error;
	}
    }

  args->error = vnet_netlink_set_link_state (vif->ifindex, 1 /* UP */ );
  if (args->error)
    {
      args->rv = VNET_API_ERROR_NETLINK_ERROR;
      goto error;
    }

  if (args->host_ip4_gw_set)
    {
      args->error = vnet_netlink_add_ip4_route (0, 0, &args->host_ip4_gw);
      if (args->error)
	{
	  args->rv = VNET_API_ERROR_NETLINK_ERROR;
	  goto error;
	}
    }

  if (args->host_ip6_gw_set)
    {
      args->error = vnet_netlink_add_ip6_route (0, 0, &args->host_ip6_gw);
      if (args->error)
	{
	  args->rv = VNET_API_ERROR_NETLINK_ERROR;
	  goto error;
	}
    }

  if (args->host_mtu_set)
    {
      args->error =
	vnet_netlink_set_link_mtu (vif->ifindex, args->host_mtu_size);
      if (args->error)
	{
	  args->rv = VNET_API_ERROR_NETLINK_ERROR;
	  goto error;
	}
    }
  else if (tm->host_mtu_size != 0)
    {
      args->error =
	vnet_netlink_set_link_mtu (vif->ifindex, tm->host_mtu_size);
      if (args->error)
	{
	  args->rv = VNET_API_ERROR_NETLINK_ERROR;
	  goto error;
	}
      args->host_mtu_set = 1;
      args->host_mtu_size = tm->host_mtu_size;
    }

  /* switch back to old net namespace */
  if (args->host_namespace)
    {
      if (setns (old_netns_fd, CLONE_NEWNET) == -1)
	{
	  args->rv = VNET_API_ERROR_SYSCALL_ERROR_2;
	  args->error = clib_error_return_unix (0, "setns '%s'",
						args->host_namespace);
	  goto error;
	}
    }

  for (i = 0; i < num_q_pairs; i++)
    {
      if (i < vif->num_rxqs && (args->error =
				virtio_vring_init (vm, vif, RX_QUEUE (i),
						   args->rx_ring_sz)))
	{
	  args->rv = VNET_API_ERROR_INIT_FAILED;
	  goto error;
	}

      if (i < vif->num_txqs && (args->error =
				virtio_vring_init (vm, vif, TX_QUEUE (i),
						   args->tx_ring_sz)))
	{
	  args->rv = VNET_API_ERROR_INIT_FAILED;
	  goto error;
	}
    }

  /* setup features and memtable */
  i = sizeof (struct vhost_memory) + sizeof (struct vhost_memory_region);
  vhost_mem = clib_mem_alloc (i);
  clib_memset (vhost_mem, 0, i);
  vhost_mem->nregions = 1;
  vhost_mem->regions[0].memory_size = vpm->max_size;
  vhost_mem->regions[0].guest_phys_addr = vpm->base_addr;
  vhost_mem->regions[0].userspace_addr =
    vhost_mem->regions[0].guest_phys_addr;

  for (i = 0; i < vhost_mem->nregions; i++)
    virtio_log_debug (vif, "memtable region %u memory_size 0x%lx "
		      "guest_phys_addr 0x%lx userspace_addr 0x%lx", i,
		      vhost_mem->regions[0].memory_size,
		      vhost_mem->regions[0].guest_phys_addr,
		      vhost_mem->regions[0].userspace_addr);


  for (i = 0; i < num_q_pairs; i++)
    {
      int fd = vif->vhost_fds[i];
      _IOCTL (fd, VHOST_SET_FEATURES, &vif->features);
      virtio_log_debug (vif, "VHOST_SET_FEATURES: fd %u features 0x%lx",
			fd, vif->features);
      _IOCTL (fd, VHOST_SET_MEM_TABLE, vhost_mem);
      virtio_log_debug (vif, "VHOST_SET_MEM_TABLE: fd %u", fd);
    }

  /* finish initializing queue pair */
  for (i = 0; i < num_q_pairs * 2; i++)
    {
      struct vhost_vring_addr addr = { 0 };
      struct vhost_vring_state state = { 0 };
      struct vhost_vring_file file = { 0 };
      virtio_vring_t *vring;
      u16 qp = i >> 1;
      int fd = vif->vhost_fds[qp];

      if (i & 1)
	{
	  if (qp >= vif->num_txqs)
	    continue;
	  vring = vec_elt_at_index (vif->txq_vrings, qp);
	}
      else
	{
	  if (qp >= vif->num_rxqs)
	    continue;
	  vring = vec_elt_at_index (vif->rxq_vrings, qp);
	}

      addr.index = state.index = file.index = vring->queue_id & 1;
      state.num = vring->size;
      virtio_log_debug (vif, "VHOST_SET_VRING_NUM fd %d index %u num %u", fd,
			state.index, state.num);
      _IOCTL (fd, VHOST_SET_VRING_NUM, &state);

      addr.flags = 0;
      addr.desc_user_addr = pointer_to_uword (vring->desc);
      addr.avail_user_addr = pointer_to_uword (vring->avail);
      addr.used_user_addr = pointer_to_uword (vring->used);

      virtio_log_debug (vif, "VHOST_SET_VRING_ADDR fd %d index %u flags 0x%x "
			"desc_user_addr 0x%lx avail_user_addr 0x%lx "
			"used_user_addr 0x%lx", fd, addr.index,
			addr.flags, addr.desc_user_addr, addr.avail_user_addr,
			addr.used_user_addr);
      _IOCTL (fd, VHOST_SET_VRING_ADDR, &addr);

      file.fd = vring->call_fd;
      virtio_log_debug (vif, "VHOST_SET_VRING_CALL fd %d index %u call_fd %d",
			fd, file.index, file.fd);
      _IOCTL (fd, VHOST_SET_VRING_CALL, &file);

      file.fd = vring->kick_fd;
      virtio_log_debug (vif, "VHOST_SET_VRING_KICK fd %d index %u kick_fd %d",
			fd, file.index, file.fd);
      _IOCTL (fd, VHOST_SET_VRING_KICK, &file);

      file.fd = tfd;
      virtio_log_debug (vif, "VHOST_NET_SET_BACKEND fd %d index %u tap_fd %d",
			fd, file.index, file.fd);
      _IOCTL (fd, VHOST_NET_SET_BACKEND, &file);
    }

  if (!args->mac_addr_set)
    ethernet_mac_address_generate (args->mac_addr.bytes);

  clib_memcpy (vif->mac_addr, args->mac_addr.bytes, 6);

  vif->host_if_name = format (0, "%s%c", host_if_name, 0);
  vif->net_ns = format (0, "%s%c", args->host_namespace, 0);
  vif->host_bridge = format (0, "%s%c", args->host_bridge, 0);
  vif->host_mtu_size = args->host_mtu_size;
  clib_memcpy (vif->host_mac_addr, args->host_mac_addr.bytes, 6);
  vif->host_ip4_prefix_len = args->host_ip4_prefix_len;
  vif->host_ip6_prefix_len = args->host_ip6_prefix_len;
  if (args->host_ip4_prefix_len)
    clib_memcpy (&vif->host_ip4_addr, &args->host_ip4_addr, 4);
  if (args->host_ip6_prefix_len)
    clib_memcpy (&vif->host_ip6_addr, &args->host_ip6_addr, 16);

  args->error = ethernet_register_interface (vnm, virtio_device_class.index,
					     vif->dev_instance,
					     vif->mac_addr,
					     &vif->hw_if_index,
					     virtio_eth_flag_change);
  if (args->error)
    {
      args->rv = VNET_API_ERROR_INVALID_REGISTRATION;
      goto error;
    }

  tm->tap_ids = clib_bitmap_set (tm->tap_ids, vif->id, 1);
  sw = vnet_get_hw_sw_interface (vnm, vif->hw_if_index);
  vif->sw_if_index = sw->sw_if_index;
  args->sw_if_index = vif->sw_if_index;
  args->rv = 0;
  hw = vnet_get_hw_interface (vnm, vif->hw_if_index);
  hw->flags |= VNET_HW_INTERFACE_FLAG_SUPPORTS_INT_MODE;
  if (args->tap_flags & TAP_FLAG_GSO)
    {
      hw->flags |= VNET_HW_INTERFACE_FLAG_SUPPORTS_GSO |
	VNET_HW_INTERFACE_FLAG_SUPPORTS_TX_L4_CKSUM_OFFLOAD;
    }
  else if (args->tap_flags & TAP_FLAG_CSUM_OFFLOAD)
    {
      hw->flags |= VNET_HW_INTERFACE_FLAG_SUPPORTS_TX_L4_CKSUM_OFFLOAD;
    }
  vnet_hw_interface_set_input_node (vnm, vif->hw_if_index,
				    virtio_input_node.index);

  for (i = 0; i < vif->num_rxqs; i++)
    {
      vnet_hw_interface_assign_rx_thread (vnm, vif->hw_if_index, i, ~0);
      vnet_hw_interface_set_rx_mode (vnm, vif->hw_if_index, i,
				     VNET_HW_INTERFACE_RX_MODE_DEFAULT);
    }

  vif->per_interface_next_index = ~0;
  virtio_vring_set_numa_node (vm, vif, RX_QUEUE (0));
  vif->flags |= VIRTIO_IF_FLAG_ADMIN_UP;
  vnet_hw_interface_set_flags (vnm, vif->hw_if_index,
			       VNET_HW_INTERFACE_FLAG_LINK_UP);
  vif->cxq_vring = NULL;

  goto done;

error:
  if (err)
    {
      ASSERT (args->error == 0);
      args->error = err;
      args->rv = VNET_API_ERROR_SYSCALL_ERROR_3;
    }

  tap_log_err (vif, "%U", format_clib_error, args->error);
  tap_free (vm, vif);
done:
  if (vhost_mem)
    clib_mem_free (vhost_mem);
  if (old_netns_fd != -1)
    close (old_netns_fd);
  if (nfd != -1)
    close (nfd);
}

int
tap_delete_if (vlib_main_t * vm, u32 sw_if_index)
{
  vnet_main_t *vnm = vnet_get_main ();
  virtio_main_t *mm = &virtio_main;
  int i;
  virtio_if_t *vif;
  vnet_hw_interface_t *hw;

  hw = vnet_get_sup_hw_interface_api_visible_or_null (vnm, sw_if_index);
  if (hw == NULL || virtio_device_class.index != hw->dev_class_index)
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  vif = pool_elt_at_index (mm->interfaces, hw->dev_instance);

  if (vif->type != VIRTIO_IF_TYPE_TAP)
    return VNET_API_ERROR_INVALID_INTERFACE;

  /* bring down the interface */
  vnet_hw_interface_set_flags (vnm, vif->hw_if_index, 0);
  vnet_sw_interface_set_flags (vnm, vif->sw_if_index, 0);
  for (i = 0; i < vif->num_rxqs; i++)
    vnet_hw_interface_unassign_rx_thread (vnm, vif->hw_if_index, i);

  ethernet_delete_interface (vnm, vif->hw_if_index);
  vif->hw_if_index = ~0;

  tap_free (vm, vif);

  return 0;
}

int
tap_csum_offload_enable_disable (vlib_main_t * vm, u32 sw_if_index,
				 int enable_disable)
{
  vnet_main_t *vnm = vnet_get_main ();
  virtio_main_t *mm = &virtio_main;
  virtio_if_t *vif;
  vnet_hw_interface_t *hw;
  clib_error_t *err = 0;

  hw = vnet_get_sup_hw_interface_api_visible_or_null (vnm, sw_if_index);

  if (hw == NULL || virtio_device_class.index != hw->dev_class_index)
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  vif = pool_elt_at_index (mm->interfaces, hw->dev_instance);

  const unsigned int csum_offload_on = TUN_F_CSUM;
  const unsigned int csum_offload_off = 0;
  unsigned int offload = enable_disable ? csum_offload_on : csum_offload_off;
  _IOCTL (vif->tap_fd, TUNSETOFFLOAD, offload);
  vif->gso_enabled = 0;
  vif->csum_offload_enabled = enable_disable ? 1 : 0;

  if ((hw->flags & VNET_HW_INTERFACE_FLAG_SUPPORTS_GSO) != 0)
    {
      hw->flags &= ~VNET_HW_INTERFACE_FLAG_SUPPORTS_GSO;
    }

  if (enable_disable)
    {
      if ((hw->flags & VNET_HW_INTERFACE_FLAG_SUPPORTS_TX_L4_CKSUM_OFFLOAD) ==
	  0)
	{
	  hw->flags |= VNET_HW_INTERFACE_FLAG_SUPPORTS_TX_L4_CKSUM_OFFLOAD;
	}
    }
  else
    {
      if ((hw->flags & VNET_HW_INTERFACE_FLAG_SUPPORTS_TX_L4_CKSUM_OFFLOAD) !=
	  0)
	{
	  hw->flags &= ~VNET_HW_INTERFACE_FLAG_SUPPORTS_TX_L4_CKSUM_OFFLOAD;
	}
    }

error:
  if (err)
    {
      clib_warning ("Error %s checksum offload on sw_if_index %d",
		    enable_disable ? "enabling" : "disabling", sw_if_index);
      return VNET_API_ERROR_SYSCALL_ERROR_3;
    }
  return 0;
}

int
tap_gso_enable_disable (vlib_main_t * vm, u32 sw_if_index, int enable_disable)
{
  vnet_main_t *vnm = vnet_get_main ();
  virtio_main_t *mm = &virtio_main;
  virtio_if_t *vif;
  vnet_hw_interface_t *hw;
  clib_error_t *err = 0;

  hw = vnet_get_sup_hw_interface_api_visible_or_null (vnm, sw_if_index);

  if (hw == NULL || virtio_device_class.index != hw->dev_class_index)
    return VNET_API_ERROR_INVALID_SW_IF_INDEX;

  vif = pool_elt_at_index (mm->interfaces, hw->dev_instance);

  const unsigned int gso_on = TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6;
  const unsigned int gso_off = 0;
  unsigned int offload = enable_disable ? gso_on : gso_off;
  _IOCTL (vif->tap_fd, TUNSETOFFLOAD, offload);
  vif->gso_enabled = enable_disable ? 1 : 0;
  vif->csum_offload_enabled = 0;
  if (enable_disable)
    {
      if ((hw->flags & VNET_HW_INTERFACE_FLAG_SUPPORTS_GSO) == 0)
	{
	  hw->flags |= VNET_HW_INTERFACE_FLAG_SUPPORTS_GSO |
	    VNET_HW_INTERFACE_FLAG_SUPPORTS_TX_L4_CKSUM_OFFLOAD;
	}
    }
  else
    {
      if ((hw->flags & VNET_HW_INTERFACE_FLAG_SUPPORTS_GSO) != 0)
	{
	  hw->flags &= ~(VNET_HW_INTERFACE_FLAG_SUPPORTS_GSO |
			 VNET_HW_INTERFACE_FLAG_SUPPORTS_TX_L4_CKSUM_OFFLOAD);
	}
    }

error:
  if (err)
    {
      clib_warning ("Error %s gso on sw_if_index %d",
		    enable_disable ? "enabling" : "disabling", sw_if_index);
      return VNET_API_ERROR_SYSCALL_ERROR_3;
    }
  return 0;
}

int
tap_dump_ifs (tap_interface_details_t ** out_tapids)
{
  vnet_main_t *vnm = vnet_get_main ();
  virtio_main_t *mm = &virtio_main;
  virtio_if_t *vif;
  virtio_vring_t *vring;
  vnet_hw_interface_t *hi;
  tap_interface_details_t *r_tapids = NULL;
  tap_interface_details_t *tapid = NULL;

  /* *INDENT-OFF* */
  pool_foreach (vif, mm->interfaces,
    if (vif->type != VIRTIO_IF_TYPE_TAP)
      continue;
    vec_add2(r_tapids, tapid, 1);
    clib_memset (tapid, 0, sizeof (*tapid));
    tapid->id = vif->id;
    tapid->sw_if_index = vif->sw_if_index;
    hi = vnet_get_hw_interface (vnm, vif->hw_if_index);
    clib_memcpy(tapid->dev_name, hi->name,
                MIN (ARRAY_LEN (tapid->dev_name) - 1,
                     strlen ((const char *) hi->name)));
    vring = vec_elt_at_index (vif->rxq_vrings, RX_QUEUE_ACCESS(0));
    tapid->rx_ring_sz = vring->size;
    vring = vec_elt_at_index (vif->txq_vrings, TX_QUEUE_ACCESS(0));
    tapid->tx_ring_sz = vring->size;
    clib_memcpy(&tapid->host_mac_addr, vif->host_mac_addr, 6);
    if (vif->host_if_name)
      {
        clib_memcpy(tapid->host_if_name, vif->host_if_name,
                    MIN (ARRAY_LEN (tapid->host_if_name) - 1,
                    strlen ((const char *) vif->host_if_name)));
      }
    if (vif->net_ns)
      {
        clib_memcpy(tapid->host_namespace, vif->net_ns,
                    MIN (ARRAY_LEN (tapid->host_namespace) - 1,
                    strlen ((const char *) vif->net_ns)));
      }
    if (vif->host_bridge)
      {
        clib_memcpy(tapid->host_bridge, vif->host_bridge,
                    MIN (ARRAY_LEN (tapid->host_bridge) - 1,
                    strlen ((const char *) vif->host_bridge)));
      }
    if (vif->host_ip4_prefix_len)
      clib_memcpy(tapid->host_ip4_addr.as_u8, &vif->host_ip4_addr, 4);
    tapid->host_ip4_prefix_len = vif->host_ip4_prefix_len;
    if (vif->host_ip6_prefix_len)
      clib_memcpy(tapid->host_ip6_addr.as_u8, &vif->host_ip6_addr, 16);
    tapid->host_ip6_prefix_len = vif->host_ip6_prefix_len;
    tapid->host_mtu_size = vif->host_mtu_size;
  );
  /* *INDENT-ON* */

  *out_tapids = r_tapids;

  return 0;
}

static clib_error_t *
tap_mtu_config (vlib_main_t * vm, unformat_input_t * input)
{
  tap_main_t *tm = &tap_main;

  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT)
    {
      if (unformat (input, "host-mtu %d", &tm->host_mtu_size))
	;
      else
	return clib_error_return (0, "unknown input `%U'",
				  format_unformat_error, input);
    }

  return 0;
}

/* tap { host-mtu <size> } configuration. */
VLIB_CONFIG_FUNCTION (tap_mtu_config, "tap");

static clib_error_t *
tap_init (vlib_main_t * vm)
{
  tap_main_t *tm = &tap_main;
  clib_error_t *error = 0;

  tm->log_default = vlib_log_register_class ("tap", 0);
  vlib_log_debug (tm->log_default, "initialized");

  tm->host_mtu_size = 0;

  return error;
}

VLIB_INIT_FUNCTION (tap_init);

/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */