hw/net/net_tx_pkt.c

   1 /*
   2  * QEMU TX packets abstractions
   3  *
   4  * Copyright (c) 2012 Ravello Systems LTD (http://ravellosystems.com)
   5  *
   6  * Developed by Daynix Computing LTD (http://www.daynix.com)
   7  *
   8  * Authors:
   9  * Dmitry Fleytman <dmitry@daynix.com>
  10  * Tamir Shomer <tamirs@daynix.com>
  11  * Yan Vugenfirer <yan@daynix.com>
  12  *
  13  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  14  * See the COPYING file in the top-level directory.
  15  *
  16  */
  17
  18 #include "qemu/osdep.h"
  19 #include "net_tx_pkt.h"
  20 #include "net/eth.h"
  21 #include "net/checksum.h"
  22 #include "net/tap.h"
  23 #include "net/net.h"
  24 #include "hw/pci/pci.h"
  25
  26 enum {
  27     NET_TX_PKT_VHDR_FRAG = 0,
  28     NET_TX_PKT_L2HDR_FRAG,
  29     NET_TX_PKT_L3HDR_FRAG,
  30     NET_TX_PKT_PL_START_FRAG
  31 };
  32
  33 /* TX packet private context */
  34 struct NetTxPkt {
  35     PCIDevice *pci_dev;
  36
  37     struct virtio_net_hdr virt_hdr;
  38     bool has_virt_hdr;
  39
  40     struct iovec *raw;
  41     uint32_t raw_frags;
  42     uint32_t max_raw_frags;
  43
  44     struct iovec *vec;
  45
  46     uint8_t l2_hdr[ETH_MAX_L2_HDR_LEN];
  47     uint8_t l3_hdr[ETH_MAX_IP_DGRAM_LEN];
  48
  49     uint32_t payload_len;
  50
  51     uint32_t payload_frags;
  52     uint32_t max_payload_frags;
  53
  54     uint16_t hdr_len;
  55     eth_pkt_types_e packet_type;
  56     uint8_t l4proto;
  57
  58     bool is_loopback;
  59 };
  60
  61 void net_tx_pkt_init(struct NetTxPkt **pkt, PCIDevice *pci_dev,
  62     uint32_t max_frags, bool has_virt_hdr)
  63 {
  64     struct NetTxPkt *p = g_malloc0(sizeof *p);
  65
  66     p->pci_dev = pci_dev;
  67
  68     p->vec = g_malloc((sizeof *p->vec) *
  69         (max_frags + NET_TX_PKT_PL_START_FRAG));
  70
  71     p->raw = g_malloc((sizeof *p->raw) * max_frags);
  72
  73     p->max_payload_frags = max_frags;
  74     p->max_raw_frags = max_frags;
  75     p->has_virt_hdr = has_virt_hdr;
  76     p->vec[NET_TX_PKT_VHDR_FRAG].iov_base = &p->virt_hdr;
  77     p->vec[NET_TX_PKT_VHDR_FRAG].iov_len =
  78         p->has_virt_hdr ? sizeof p->virt_hdr : 0;
  79     p->vec[NET_TX_PKT_L2HDR_FRAG].iov_base = &p->l2_hdr;
  80     p->vec[NET_TX_PKT_L3HDR_FRAG].iov_base = &p->l3_hdr;
  81
  82     *pkt = p;
  83 }
  84
  85 void net_tx_pkt_uninit(struct NetTxPkt *pkt)
  86 {
  87     if (pkt) {
  88         g_free(pkt->vec);
  89         g_free(pkt->raw);
  90         g_free(pkt);
  91     }
  92 }
  93
  94 void net_tx_pkt_update_ip_hdr_checksum(struct NetTxPkt *pkt)
  95 {
  96     uint16_t csum;
  97     assert(pkt);
  98     struct ip_header *ip_hdr;
  99     ip_hdr = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base;
 100
 101     ip_hdr->ip_len = cpu_to_be16(pkt->payload_len +
 102         pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len);
 103
 104     ip_hdr->ip_sum = 0;
 105     csum = net_raw_checksum((uint8_t *)ip_hdr,
 106         pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len);
 107     ip_hdr->ip_sum = cpu_to_be16(csum);
 108 }
 109
 110 void net_tx_pkt_update_ip_checksums(struct NetTxPkt *pkt)
 111 {
 112     uint16_t csum;
 113     uint32_t cntr, cso;
 114     assert(pkt);
 115     uint8_t gso_type = pkt->virt_hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN;
 116     void *ip_hdr = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base;
 117
 118     if (pkt->payload_len + pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len >
 119         ETH_MAX_IP_DGRAM_LEN) {
 120         return;
 121     }
 122
 123     if (gso_type == VIRTIO_NET_HDR_GSO_TCPV4 ||
 124         gso_type == VIRTIO_NET_HDR_GSO_UDP) {
 125         /* Calculate IP header checksum */
 126         net_tx_pkt_update_ip_hdr_checksum(pkt);
 127
 128         /* Calculate IP pseudo header checksum */
 129         cntr = eth_calc_ip4_pseudo_hdr_csum(ip_hdr, pkt->payload_len, &cso);
 130         csum = cpu_to_be16(~net_checksum_finish(cntr));
 131     } else if (gso_type == VIRTIO_NET_HDR_GSO_TCPV6) {
 132         /* Calculate IP pseudo header checksum */
 133         cntr = eth_calc_ip6_pseudo_hdr_csum(ip_hdr, pkt->payload_len,
 134                                             IP_PROTO_TCP, &cso);
 135         csum = cpu_to_be16(~net_checksum_finish(cntr));
 136     } else {
 137         return;
 138     }
 139
 140     iov_from_buf(&pkt->vec[NET_TX_PKT_PL_START_FRAG], pkt->payload_frags,
 141                  pkt->virt_hdr.csum_offset, &csum, sizeof(csum));
 142 }
 143
 144 static void net_tx_pkt_calculate_hdr_len(struct NetTxPkt *pkt)
 145 {
 146     pkt->hdr_len = pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len +
 147         pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len;
 148 }
 149
 150 static bool net_tx_pkt_parse_headers(struct NetTxPkt *pkt)
 151 {
 152     struct iovec *l2_hdr, *l3_hdr;
 153     size_t bytes_read;
 154     size_t full_ip6hdr_len;
 155     uint16_t l3_proto;
 156
 157     assert(pkt);
 158
 159     l2_hdr = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
 160     l3_hdr = &pkt->vec[NET_TX_PKT_L3HDR_FRAG];
 161
 162     bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, 0, l2_hdr->iov_base,
 163                             ETH_MAX_L2_HDR_LEN);
 164     if (bytes_read < sizeof(struct eth_header)) {
 165         l2_hdr->iov_len = 0;
 166         return false;
 167     }
 168
 169     l2_hdr->iov_len = sizeof(struct eth_header);
 170     switch (be16_to_cpu(PKT_GET_ETH_HDR(l2_hdr->iov_base)->h_proto)) {
 171     case ETH_P_VLAN:
 172         l2_hdr->iov_len += sizeof(struct vlan_header);
 173         break;
 174     case ETH_P_DVLAN:
 175         l2_hdr->iov_len += 2 * sizeof(struct vlan_header);
 176         break;
 177     }
 178
 179     if (bytes_read < l2_hdr->iov_len) {
 180         l2_hdr->iov_len = 0;
 181         l3_hdr->iov_len = 0;
 182         pkt->packet_type = ETH_PKT_UCAST;
 183         return false;
 184     } else {
 185         l2_hdr->iov_len = ETH_MAX_L2_HDR_LEN;
 186         l2_hdr->iov_len = eth_get_l2_hdr_length(l2_hdr->iov_base);
 187         pkt->packet_type = get_eth_packet_type(l2_hdr->iov_base);
 188     }
 189
 190     l3_proto = eth_get_l3_proto(l2_hdr, 1, l2_hdr->iov_len);
 191
 192     switch (l3_proto) {
 193     case ETH_P_IP:
 194         bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
 195                                 l3_hdr->iov_base, sizeof(struct ip_header));
 196
 197         if (bytes_read < sizeof(struct ip_header)) {
 198             l3_hdr->iov_len = 0;
 199             return false;
 200         }
 201
 202         l3_hdr->iov_len = IP_HDR_GET_LEN(l3_hdr->iov_base);
 203
 204         if (l3_hdr->iov_len < sizeof(struct ip_header)) {
 205             l3_hdr->iov_len = 0;
 206             return false;
 207         }
 208
 209         pkt->l4proto = ((struct ip_header *) l3_hdr->iov_base)->ip_p;
 210
 211         if (IP_HDR_GET_LEN(l3_hdr->iov_base) != sizeof(struct ip_header)) {
 212             /* copy optional IPv4 header data if any*/
 213             bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags,
 214                                     l2_hdr->iov_len + sizeof(struct ip_header),
 215                                     l3_hdr->iov_base + sizeof(struct ip_header),
 216                                     l3_hdr->iov_len - sizeof(struct ip_header));
 217             if (bytes_read < l3_hdr->iov_len - sizeof(struct ip_header)) {
 218                 l3_hdr->iov_len = 0;
 219                 return false;
 220             }
 221         }
 222
 223         break;
 224
 225     case ETH_P_IPV6:
 226     {
 227         eth_ip6_hdr_info hdrinfo;
 228
 229         if (!eth_parse_ipv6_hdr(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
 230                                 &hdrinfo)) {
 231             l3_hdr->iov_len = 0;
 232             return false;
 233         }
 234
 235         pkt->l4proto = hdrinfo.l4proto;
 236         full_ip6hdr_len = hdrinfo.full_hdr_len;
 237
 238         if (full_ip6hdr_len > ETH_MAX_IP_DGRAM_LEN) {
 239             l3_hdr->iov_len = 0;
 240             return false;
 241         }
 242
 243         bytes_read = iov_to_buf(pkt->raw, pkt->raw_frags, l2_hdr->iov_len,
 244                                 l3_hdr->iov_base, full_ip6hdr_len);
 245
 246         if (bytes_read < full_ip6hdr_len) {
 247             l3_hdr->iov_len = 0;
 248             return false;
 249         } else {
 250             l3_hdr->iov_len = full_ip6hdr_len;
 251         }
 252         break;
 253     }
 254     default:
 255         l3_hdr->iov_len = 0;
 256         break;
 257     }
 258
 259     net_tx_pkt_calculate_hdr_len(pkt);
 260     return true;
 261 }
 262
 263 static void net_tx_pkt_rebuild_payload(struct NetTxPkt *pkt)
 264 {
 265     pkt->payload_len = iov_size(pkt->raw, pkt->raw_frags) - pkt->hdr_len;
 266     pkt->payload_frags = iov_copy(&pkt->vec[NET_TX_PKT_PL_START_FRAG],
 267                                 pkt->max_payload_frags,
 268                                 pkt->raw, pkt->raw_frags,
 269                                 pkt->hdr_len, pkt->payload_len);
 270 }
 271
 272 bool net_tx_pkt_parse(struct NetTxPkt *pkt)
 273 {
 274     if (net_tx_pkt_parse_headers(pkt)) {
 275         net_tx_pkt_rebuild_payload(pkt);
 276         return true;
 277     } else {
 278         return false;
 279     }
 280 }
 281
 282 struct virtio_net_hdr *net_tx_pkt_get_vhdr(struct NetTxPkt *pkt)
 283 {
 284     assert(pkt);
 285     return &pkt->virt_hdr;
 286 }
 287
 288 static uint8_t net_tx_pkt_get_gso_type(struct NetTxPkt *pkt,
 289                                           bool tso_enable)
 290 {
 291     uint8_t rc = VIRTIO_NET_HDR_GSO_NONE;
 292     uint16_t l3_proto;
 293
 294     l3_proto = eth_get_l3_proto(&pkt->vec[NET_TX_PKT_L2HDR_FRAG], 1,
 295         pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len);
 296
 297     if (!tso_enable) {
 298         goto func_exit;
 299     }
 300
 301     rc = eth_get_gso_type(l3_proto, pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base,
 302                           pkt->l4proto);
 303
 304 func_exit:
 305     return rc;
 306 }
 307
 308 void net_tx_pkt_build_vheader(struct NetTxPkt *pkt, bool tso_enable,
 309     bool csum_enable, uint32_t gso_size)
 310 {
 311     struct tcp_hdr l4hdr;
 312     assert(pkt);
 313
 314     /* csum has to be enabled if tso is. */
 315     assert(csum_enable || !tso_enable);
 316
 317     pkt->virt_hdr.gso_type = net_tx_pkt_get_gso_type(pkt, tso_enable);
 318
 319     switch (pkt->virt_hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
 320     case VIRTIO_NET_HDR_GSO_NONE:
 321         pkt->virt_hdr.hdr_len = 0;
 322         pkt->virt_hdr.gso_size = 0;
 323         break;
 324
 325     case VIRTIO_NET_HDR_GSO_UDP:
 326         pkt->virt_hdr.gso_size = gso_size;
 327         pkt->virt_hdr.hdr_len = pkt->hdr_len + sizeof(struct udp_header);
 328         break;
 329
 330     case VIRTIO_NET_HDR_GSO_TCPV4:
 331     case VIRTIO_NET_HDR_GSO_TCPV6:
 332         iov_to_buf(&pkt->vec[NET_TX_PKT_PL_START_FRAG], pkt->payload_frags,
 333                    0, &l4hdr, sizeof(l4hdr));
 334         pkt->virt_hdr.hdr_len = pkt->hdr_len + l4hdr.th_off * sizeof(uint32_t);
 335         pkt->virt_hdr.gso_size = gso_size;
 336         break;
 337
 338     default:
 339         g_assert_not_reached();
 340     }
 341
 342     if (csum_enable) {
 343         switch (pkt->l4proto) {
 344         case IP_PROTO_TCP:
 345             pkt->virt_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 346             pkt->virt_hdr.csum_start = pkt->hdr_len;
 347             pkt->virt_hdr.csum_offset = offsetof(struct tcp_hdr, th_sum);
 348             break;
 349         case IP_PROTO_UDP:
 350             pkt->virt_hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 351             pkt->virt_hdr.csum_start = pkt->hdr_len;
 352             pkt->virt_hdr.csum_offset = offsetof(struct udp_hdr, uh_sum);
 353             break;
 354         default:
 355             break;
 356         }
 357     }
 358 }
 359
 360 void net_tx_pkt_setup_vlan_header_ex(struct NetTxPkt *pkt,
 361     uint16_t vlan, uint16_t vlan_ethtype)
 362 {
 363     bool is_new;
 364     assert(pkt);
 365
 366     eth_setup_vlan_headers_ex(pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_base,
 367         vlan, vlan_ethtype, &is_new);
 368
 369     /* update l2hdrlen */
 370     if (is_new) {
 371         pkt->hdr_len += sizeof(struct vlan_header);
 372         pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len +=
 373             sizeof(struct vlan_header);
 374     }
 375 }
 376
 377 bool net_tx_pkt_add_raw_fragment(struct NetTxPkt *pkt, hwaddr pa,
 378     size_t len)
 379 {
 380     hwaddr mapped_len = 0;
 381     struct iovec *ventry;
 382     assert(pkt);
 383     assert(pkt->max_raw_frags > pkt->raw_frags);
 384
 385     if (!len) {
 386         return true;
 387      }
 388
 389     ventry = &pkt->raw[pkt->raw_frags];
 390     mapped_len = len;
 391
 392     ventry->iov_base = pci_dma_map(pkt->pci_dev, pa,
 393                                    &mapped_len, DMA_DIRECTION_TO_DEVICE);
 394
 395     if ((ventry->iov_base != NULL) && (len == mapped_len)) {
 396         ventry->iov_len = mapped_len;
 397         pkt->raw_frags++;
 398         return true;
 399     } else {
 400         return false;
 401     }
 402 }
 403
 404 bool net_tx_pkt_has_fragments(struct NetTxPkt *pkt)
 405 {
 406     return pkt->raw_frags > 0;
 407 }
 408
 409 eth_pkt_types_e net_tx_pkt_get_packet_type(struct NetTxPkt *pkt)
 410 {
 411     assert(pkt);
 412
 413     return pkt->packet_type;
 414 }
 415
 416 size_t net_tx_pkt_get_total_len(struct NetTxPkt *pkt)
 417 {
 418     assert(pkt);
 419
 420     return pkt->hdr_len + pkt->payload_len;
 421 }
 422
 423 void net_tx_pkt_dump(struct NetTxPkt *pkt)
 424 {
 425 #ifdef NET_TX_PKT_DEBUG
 426     assert(pkt);
 427
 428     printf("TX PKT: hdr_len: %d, pkt_type: 0x%X, l2hdr_len: %lu, "
 429         "l3hdr_len: %lu, payload_len: %u\n", pkt->hdr_len, pkt->packet_type,
 430         pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len,
 431         pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len, pkt->payload_len);
 432 #endif
 433 }
 434
 435 void net_tx_pkt_reset(struct NetTxPkt *pkt)
 436 {
 437     int i;
 438
 439     /* no assert, as reset can be called before tx_pkt_init */
 440     if (!pkt) {
 441         return;
 442     }
 443
 444     memset(&pkt->virt_hdr, 0, sizeof(pkt->virt_hdr));
 445
 446     assert(pkt->vec);
 447
 448     pkt->payload_len = 0;
 449     pkt->payload_frags = 0;
 450
 451     assert(pkt->raw);
 452     for (i = 0; i < pkt->raw_frags; i++) {
 453         assert(pkt->raw[i].iov_base);
 454         pci_dma_unmap(pkt->pci_dev, pkt->raw[i].iov_base, pkt->raw[i].iov_len,
 455                       DMA_DIRECTION_TO_DEVICE, 0);
 456     }
 457     pkt->raw_frags = 0;
 458
 459     pkt->hdr_len = 0;
 460     pkt->l4proto = 0;
 461 }
 462
 463 static void net_tx_pkt_do_sw_csum(struct NetTxPkt *pkt)
 464 {
 465     struct iovec *iov = &pkt->vec[NET_TX_PKT_L2HDR_FRAG];
 466     uint32_t csum_cntr;
 467     uint16_t csum = 0;
 468     uint32_t cso;
 469     /* num of iovec without vhdr */
 470     uint32_t iov_len = pkt->payload_frags + NET_TX_PKT_PL_START_FRAG - 1;
 471     uint16_t csl;
 472     struct ip_header *iphdr;
 473     size_t csum_offset = pkt->virt_hdr.csum_start + pkt->virt_hdr.csum_offset;
 474
 475     /* Put zero to checksum field */
 476     iov_from_buf(iov, iov_len, csum_offset, &csum, sizeof csum);
 477
 478     /* Calculate L4 TCP/UDP checksum */
 479     csl = pkt->payload_len;
 480
 481     /* add pseudo header to csum */
 482     iphdr = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base;
 483     csum_cntr = eth_calc_ip4_pseudo_hdr_csum(iphdr, csl, &cso);
 484
 485     /* data checksum */
 486     csum_cntr +=
 487         net_checksum_add_iov(iov, iov_len, pkt->virt_hdr.csum_start, csl, cso);
 488
 489     /* Put the checksum obtained into the packet */
 490     csum = cpu_to_be16(net_checksum_finish(csum_cntr));
 491     iov_from_buf(iov, iov_len, csum_offset, &csum, sizeof csum);
 492 }
 493
 494 enum {
 495     NET_TX_PKT_FRAGMENT_L2_HDR_POS = 0,
 496     NET_TX_PKT_FRAGMENT_L3_HDR_POS,
 497     NET_TX_PKT_FRAGMENT_HEADER_NUM
 498 };
 499
 500 #define NET_MAX_FRAG_SG_LIST (64)
 501
 502 static size_t net_tx_pkt_fetch_fragment(struct NetTxPkt *pkt,
 503     int *src_idx, size_t *src_offset, struct iovec *dst, int *dst_idx)
 504 {
 505     size_t fetched = 0;
 506     struct iovec *src = pkt->vec;
 507
 508     *dst_idx = NET_TX_PKT_FRAGMENT_HEADER_NUM;
 509
 510     while (fetched < IP_FRAG_ALIGN_SIZE(pkt->virt_hdr.gso_size)) {
 511
 512         /* no more place in fragment iov */
 513         if (*dst_idx == NET_MAX_FRAG_SG_LIST) {
 514             break;
 515         }
 516
 517         /* no more data in iovec */
 518         if (*src_idx == (pkt->payload_frags + NET_TX_PKT_PL_START_FRAG)) {
 519             break;
 520         }
 521
 522
 523         dst[*dst_idx].iov_base = src[*src_idx].iov_base + *src_offset;
 524         dst[*dst_idx].iov_len = MIN(src[*src_idx].iov_len - *src_offset,
 525             IP_FRAG_ALIGN_SIZE(pkt->virt_hdr.gso_size) - fetched);
 526
 527         *src_offset += dst[*dst_idx].iov_len;
 528         fetched += dst[*dst_idx].iov_len;
 529
 530         if (*src_offset == src[*src_idx].iov_len) {
 531             *src_offset = 0;
 532             (*src_idx)++;
 533         }
 534
 535         (*dst_idx)++;
 536     }
 537
 538     return fetched;
 539 }
 540
 541 static inline void net_tx_pkt_sendv(struct NetTxPkt *pkt,
 542     NetClientState *nc, const struct iovec *iov, int iov_cnt)
 543 {
 544     if (pkt->is_loopback) {
 545         nc->info->receive_iov(nc, iov, iov_cnt);
 546     } else {
 547         qemu_sendv_packet(nc, iov, iov_cnt);
 548     }
 549 }
 550
 551 static bool net_tx_pkt_do_sw_fragmentation(struct NetTxPkt *pkt,
 552     NetClientState *nc)
 553 {
 554     struct iovec fragment[NET_MAX_FRAG_SG_LIST];
 555     size_t fragment_len = 0;
 556     bool more_frags = false;
 557
 558     /* some pointers for shorter code */
 559     void *l2_iov_base, *l3_iov_base;
 560     size_t l2_iov_len, l3_iov_len;
 561     int src_idx =  NET_TX_PKT_PL_START_FRAG, dst_idx;
 562     size_t src_offset = 0;
 563     size_t fragment_offset = 0;
 564
 565     l2_iov_base = pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_base;
 566     l2_iov_len = pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len;
 567     l3_iov_base = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_base;
 568     l3_iov_len = pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len;
 569
 570     /* Copy headers */
 571     fragment[NET_TX_PKT_FRAGMENT_L2_HDR_POS].iov_base = l2_iov_base;
 572     fragment[NET_TX_PKT_FRAGMENT_L2_HDR_POS].iov_len = l2_iov_len;
 573     fragment[NET_TX_PKT_FRAGMENT_L3_HDR_POS].iov_base = l3_iov_base;
 574     fragment[NET_TX_PKT_FRAGMENT_L3_HDR_POS].iov_len = l3_iov_len;
 575
 576
 577     /* Put as much data as possible and send */
 578     do {
 579         fragment_len = net_tx_pkt_fetch_fragment(pkt, &src_idx, &src_offset,
 580             fragment, &dst_idx);
 581
 582         more_frags = (fragment_offset + fragment_len < pkt->payload_len);
 583
 584         eth_setup_ip4_fragmentation(l2_iov_base, l2_iov_len, l3_iov_base,
 585             l3_iov_len, fragment_len, fragment_offset, more_frags);
 586
 587         eth_fix_ip4_checksum(l3_iov_base, l3_iov_len);
 588
 589         net_tx_pkt_sendv(pkt, nc, fragment, dst_idx);
 590
 591         fragment_offset += fragment_len;
 592
 593     } while (fragment_len && more_frags);
 594
 595     return true;
 596 }
 597
 598 bool net_tx_pkt_send(struct NetTxPkt *pkt, NetClientState *nc)
 599 {
 600     assert(pkt);
 601
 602     if (!pkt->has_virt_hdr &&
 603         pkt->virt_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
 604         net_tx_pkt_do_sw_csum(pkt);
 605     }
 606
 607     /*
 608      * Since underlying infrastructure does not support IP datagrams longer
 609      * than 64K we should drop such packets and don't even try to send
 610      */
 611     if (VIRTIO_NET_HDR_GSO_NONE != pkt->virt_hdr.gso_type) {
 612         if (pkt->payload_len >
 613             ETH_MAX_IP_DGRAM_LEN -
 614             pkt->vec[NET_TX_PKT_L3HDR_FRAG].iov_len) {
 615             return false;
 616         }
 617     }
 618
 619     if (pkt->has_virt_hdr ||
 620         pkt->virt_hdr.gso_type == VIRTIO_NET_HDR_GSO_NONE) {
 621         net_tx_pkt_sendv(pkt, nc, pkt->vec,
 622             pkt->payload_frags + NET_TX_PKT_PL_START_FRAG);
 623         return true;
 624     }
 625
 626     return net_tx_pkt_do_sw_fragmentation(pkt, nc);
 627 }
 628
 629 bool net_tx_pkt_send_loopback(struct NetTxPkt *pkt, NetClientState *nc)
 630 {
 631     bool res;
 632
 633     pkt->is_loopback = true;
 634     res = net_tx_pkt_send(pkt, nc);
 635     pkt->is_loopback = false;
 636
 637     return res;
 638 }