lib/librte_vhost/virtio_net.c

   1 /*-
   2  *   BSD LICENSE
   3  *
   4  *   Copyright(c) 2010-2016 Intel Corporation. All rights reserved.
   5  *   All rights reserved.
   6  *
   7  *   Redistribution and use in source and binary forms, with or without
   8  *   modification, are permitted provided that the following conditions
   9  *   are met:
  10  *
  11  *     * Redistributions of source code must retain the above copyright
  12  *       notice, this list of conditions and the following disclaimer.
  13  *     * Redistributions in binary form must reproduce the above copyright
  14  *       notice, this list of conditions and the following disclaimer in
  15  *       the documentation and/or other materials provided with the
  16  *       distribution.
  17  *     * Neither the name of Intel Corporation nor the names of its
  18  *       contributors may be used to endorse or promote products derived
  19  *       from this software without specific prior written permission.
  20  *
  21  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  24  *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  25  *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  26  *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  27  *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  31  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include <stdint.h>
  35 #include <stdbool.h>
  36 #include <linux/virtio_net.h>
  37
  38 #include <rte_mbuf.h>
  39 #include <rte_memcpy.h>
  40 #include <rte_ether.h>
  41 #include <rte_ip.h>
  42 #include <rte_vhost.h>
  43 #include <rte_tcp.h>
  44 #include <rte_udp.h>
  45 #include <rte_sctp.h>
  46 #include <rte_arp.h>
  47
  48 #include "vhost.h"
  49
  50 #define MAX_PKT_BURST 32
  51
  52 static bool
  53 is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t nr_vring)
  54 {
  55         return (is_tx ^ (idx & 1)) == 0 && idx < nr_vring;
  56 }
  57
  58 static inline void __attribute__((always_inline))
  59 do_flush_shadow_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq,
  60                           uint16_t to, uint16_t from, uint16_t size)
  61 {
  62         rte_memcpy(&vq->used->ring[to],
  63                         &vq->shadow_used_ring[from],
  64                         size * sizeof(struct vring_used_elem));
  65         vhost_log_used_vring(dev, vq,
  66                         offsetof(struct vring_used, ring[to]),
  67                         size * sizeof(struct vring_used_elem));
  68 }
  69
  70 static inline void __attribute__((always_inline))
  71 flush_shadow_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq)
  72 {
  73         uint16_t used_idx = vq->last_used_idx & (vq->size - 1);
  74
  75         if (used_idx + vq->shadow_used_idx <= vq->size) {
  76                 do_flush_shadow_used_ring(dev, vq, used_idx, 0,
  77                                           vq->shadow_used_idx);
  78         } else {
  79                 uint16_t size;
  80
  81                 /* update used ring interval [used_idx, vq->size] */
  82                 size = vq->size - used_idx;
  83                 do_flush_shadow_used_ring(dev, vq, used_idx, 0, size);
  84
  85                 /* update the left half used ring interval [0, left_size] */
  86                 do_flush_shadow_used_ring(dev, vq, 0, size,
  87                                           vq->shadow_used_idx - size);
  88         }
  89         vq->last_used_idx += vq->shadow_used_idx;
  90
  91         rte_smp_wmb();
  92
  93         *(volatile uint16_t *)&vq->used->idx += vq->shadow_used_idx;
  94         vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
  95                 sizeof(vq->used->idx));
  96 }
  97
  98 static inline void __attribute__((always_inline))
  99 update_shadow_used_ring(struct vhost_virtqueue *vq,
 100                          uint16_t desc_idx, uint16_t len)
 101 {
 102         uint16_t i = vq->shadow_used_idx++;
 103
 104         vq->shadow_used_ring[i].id  = desc_idx;
 105         vq->shadow_used_ring[i].len = len;
 106 }
 107
 108 /* avoid write operation when necessary, to lessen cache issues */
 109 #define ASSIGN_UNLESS_EQUAL(var, val) do {      \
 110         if ((var) != (val))                     \
 111                 (var) = (val);                  \
 112 } while (0)
 113
 114 static void
 115 virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
 116 {
 117         if (m_buf->ol_flags & PKT_TX_L4_MASK) {
 118                 net_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 119                 net_hdr->csum_start = m_buf->l2_len + m_buf->l3_len;
 120
 121                 switch (m_buf->ol_flags & PKT_TX_L4_MASK) {
 122                 case PKT_TX_TCP_CKSUM:
 123                         net_hdr->csum_offset = (offsetof(struct tcp_hdr,
 124                                                 cksum));
 125                         break;
 126                 case PKT_TX_UDP_CKSUM:
 127                         net_hdr->csum_offset = (offsetof(struct udp_hdr,
 128                                                 dgram_cksum));
 129                         break;
 130                 case PKT_TX_SCTP_CKSUM:
 131                         net_hdr->csum_offset = (offsetof(struct sctp_hdr,
 132                                                 cksum));
 133                         break;
 134                 }
 135         } else {
 136                 ASSIGN_UNLESS_EQUAL(net_hdr->csum_start, 0);
 137                 ASSIGN_UNLESS_EQUAL(net_hdr->csum_offset, 0);
 138                 ASSIGN_UNLESS_EQUAL(net_hdr->flags, 0);
 139         }
 140
 141         if (m_buf->ol_flags & PKT_TX_TCP_SEG) {
 142                 if (m_buf->ol_flags & PKT_TX_IPV4)
 143                         net_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 144                 else
 145                         net_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 146                 net_hdr->gso_size = m_buf->tso_segsz;
 147                 net_hdr->hdr_len = m_buf->l2_len + m_buf->l3_len
 148                                         + m_buf->l4_len;
 149         } else {
 150                 ASSIGN_UNLESS_EQUAL(net_hdr->gso_type, 0);
 151                 ASSIGN_UNLESS_EQUAL(net_hdr->gso_size, 0);
 152                 ASSIGN_UNLESS_EQUAL(net_hdr->hdr_len, 0);
 153         }
 154 }
 155
 156 static inline int __attribute__((always_inline))
 157 copy_mbuf_to_desc(struct virtio_net *dev, struct vring_desc *descs,
 158                   struct rte_mbuf *m, uint16_t desc_idx, uint32_t size)
 159 {
 160         uint32_t desc_avail, desc_offset;
 161         uint32_t mbuf_avail, mbuf_offset;
 162         uint32_t cpy_len;
 163         struct vring_desc *desc;
 164         uint64_t desc_addr;
 165         /* A counter to avoid desc dead loop chain */
 166         uint16_t nr_desc = 1;
 167
 168         desc = &descs[desc_idx];
 169         desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
 170         /*
 171          * Checking of 'desc_addr' placed outside of 'unlikely' macro to avoid
 172          * performance issue with some versions of gcc (4.8.4 and 5.3.0) which
 173          * otherwise stores offset on the stack instead of in a register.
 174          */
 175         if (unlikely(desc->len < dev->vhost_hlen) || !desc_addr)
 176                 return -1;
 177
 178         rte_prefetch0((void *)(uintptr_t)desc_addr);
 179
 180         virtio_enqueue_offload(m, (struct virtio_net_hdr *)(uintptr_t)desc_addr);
 181         vhost_log_write(dev, desc->addr, dev->vhost_hlen);
 182         PRINT_PACKET(dev, (uintptr_t)desc_addr, dev->vhost_hlen, 0);
 183
 184         desc_offset = dev->vhost_hlen;
 185         desc_avail  = desc->len - dev->vhost_hlen;
 186
 187         mbuf_avail  = rte_pktmbuf_data_len(m);
 188         mbuf_offset = 0;
 189         while (mbuf_avail != 0 || m->next != NULL) {
 190                 /* done with current mbuf, fetch next */
 191                 if (mbuf_avail == 0) {
 192                         m = m->next;
 193
 194                         mbuf_offset = 0;
 195                         mbuf_avail  = rte_pktmbuf_data_len(m);
 196                 }
 197
 198                 /* done with current desc buf, fetch next */
 199                 if (desc_avail == 0) {
 200                         if ((desc->flags & VRING_DESC_F_NEXT) == 0) {
 201                                 /* Room in vring buffer is not enough */
 202                                 return -1;
 203                         }
 204                         if (unlikely(desc->next >= size || ++nr_desc > size))
 205                                 return -1;
 206
 207                         desc = &descs[desc->next];
 208                         desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
 209                         if (unlikely(!desc_addr))
 210                                 return -1;
 211
 212                         desc_offset = 0;
 213                         desc_avail  = desc->len;
 214                 }
 215
 216                 cpy_len = RTE_MIN(desc_avail, mbuf_avail);
 217                 rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
 218                         rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
 219                         cpy_len);
 220                 vhost_log_write(dev, desc->addr + desc_offset, cpy_len);
 221                 PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
 222                              cpy_len, 0);
 223
 224                 mbuf_avail  -= cpy_len;
 225                 mbuf_offset += cpy_len;
 226                 desc_avail  -= cpy_len;
 227                 desc_offset += cpy_len;
 228         }
 229
 230         return 0;
 231 }
 232
 233 /**
 234  * This function adds buffers to the virtio devices RX virtqueue. Buffers can
 235  * be received from the physical port or from another virtio device. A packet
 236  * count is returned to indicate the number of packets that are succesfully
 237  * added to the RX queue. This function works when the mbuf is scattered, but
 238  * it doesn't support the mergeable feature.
 239  */
 240 static inline uint32_t __attribute__((always_inline))
 241 virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
 242               struct rte_mbuf **pkts, uint32_t count)
 243 {
 244         struct vhost_virtqueue *vq;
 245         uint16_t avail_idx, free_entries, start_idx;
 246         uint16_t desc_indexes[MAX_PKT_BURST];
 247         struct vring_desc *descs;
 248         uint16_t used_idx;
 249         uint32_t i, sz;
 250
 251         LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
 252         if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
 253                 RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
 254                         dev->vid, __func__, queue_id);
 255                 return 0;
 256         }
 257
 258         vq = dev->virtqueue[queue_id];
 259         if (unlikely(vq->enabled == 0))
 260                 return 0;
 261
 262         avail_idx = *((volatile uint16_t *)&vq->avail->idx);
 263         start_idx = vq->last_used_idx;
 264         free_entries = avail_idx - start_idx;
 265         count = RTE_MIN(count, free_entries);
 266         count = RTE_MIN(count, (uint32_t)MAX_PKT_BURST);
 267         if (count == 0)
 268                 return 0;
 269
 270         LOG_DEBUG(VHOST_DATA, "(%d) start_idx %d | end_idx %d\n",
 271                 dev->vid, start_idx, start_idx + count);
 272
 273         /* Retrieve all of the desc indexes first to avoid caching issues. */
 274         rte_prefetch0(&vq->avail->ring[start_idx & (vq->size - 1)]);
 275         for (i = 0; i < count; i++) {
 276                 used_idx = (start_idx + i) & (vq->size - 1);
 277                 desc_indexes[i] = vq->avail->ring[used_idx];
 278                 vq->used->ring[used_idx].id = desc_indexes[i];
 279                 vq->used->ring[used_idx].len = pkts[i]->pkt_len +
 280                                                dev->vhost_hlen;
 281                 vhost_log_used_vring(dev, vq,
 282                         offsetof(struct vring_used, ring[used_idx]),
 283                         sizeof(vq->used->ring[used_idx]));
 284         }
 285
 286         rte_prefetch0(&vq->desc[desc_indexes[0]]);
 287         for (i = 0; i < count; i++) {
 288                 uint16_t desc_idx = desc_indexes[i];
 289                 int err;
 290
 291                 if (vq->desc[desc_idx].flags & VRING_DESC_F_INDIRECT) {
 292                         descs = (struct vring_desc *)(uintptr_t)
 293                                 rte_vhost_gpa_to_vva(dev->mem,
 294                                         vq->desc[desc_idx].addr);
 295                         if (unlikely(!descs)) {
 296                                 count = i;
 297                                 break;
 298                         }
 299
 300                         desc_idx = 0;
 301                         sz = vq->desc[desc_idx].len / sizeof(*descs);
 302                 } else {
 303                         descs = vq->desc;
 304                         sz = vq->size;
 305                 }
 306
 307                 err = copy_mbuf_to_desc(dev, descs, pkts[i], desc_idx, sz);
 308                 if (unlikely(err)) {
 309                         used_idx = (start_idx + i) & (vq->size - 1);
 310                         vq->used->ring[used_idx].len = dev->vhost_hlen;
 311                         vhost_log_used_vring(dev, vq,
 312                                 offsetof(struct vring_used, ring[used_idx]),
 313                                 sizeof(vq->used->ring[used_idx]));
 314                 }
 315
 316                 if (i + 1 < count)
 317                         rte_prefetch0(&vq->desc[desc_indexes[i+1]]);
 318         }
 319
 320         rte_smp_wmb();
 321
 322         *(volatile uint16_t *)&vq->used->idx += count;
 323         vq->last_used_idx += count;
 324         vhost_log_used_vring(dev, vq,
 325                 offsetof(struct vring_used, idx),
 326                 sizeof(vq->used->idx));
 327
 328         /* flush used->idx update before we read avail->flags. */
 329         rte_mb();
 330
 331         /* Kick the guest if necessary. */
 332         if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
 333                         && (vq->callfd >= 0))
 334                 eventfd_write(vq->callfd, (eventfd_t)1);
 335         return count;
 336 }
 337
 338 static inline int __attribute__((always_inline))
 339 fill_vec_buf(struct virtio_net *dev, struct vhost_virtqueue *vq,
 340                          uint32_t avail_idx, uint32_t *vec_idx,
 341                          struct buf_vector *buf_vec, uint16_t *desc_chain_head,
 342                          uint16_t *desc_chain_len)
 343 {
 344         uint16_t idx = vq->avail->ring[avail_idx & (vq->size - 1)];
 345         uint32_t vec_id = *vec_idx;
 346         uint32_t len    = 0;
 347         struct vring_desc *descs = vq->desc;
 348
 349         *desc_chain_head = idx;
 350
 351         if (vq->desc[idx].flags & VRING_DESC_F_INDIRECT) {
 352                 descs = (struct vring_desc *)(uintptr_t)
 353                         rte_vhost_gpa_to_vva(dev->mem, vq->desc[idx].addr);
 354                 if (unlikely(!descs))
 355                         return -1;
 356
 357                 idx = 0;
 358         }
 359
 360         while (1) {
 361                 if (unlikely(vec_id >= BUF_VECTOR_MAX || idx >= vq->size))
 362                         return -1;
 363
 364                 len += descs[idx].len;
 365                 buf_vec[vec_id].buf_addr = descs[idx].addr;
 366                 buf_vec[vec_id].buf_len  = descs[idx].len;
 367                 buf_vec[vec_id].desc_idx = idx;
 368                 vec_id++;
 369
 370                 if ((descs[idx].flags & VRING_DESC_F_NEXT) == 0)
 371                         break;
 372
 373                 idx = descs[idx].next;
 374         }
 375
 376         *desc_chain_len = len;
 377         *vec_idx = vec_id;
 378
 379         return 0;
 380 }
 381
 382 /*
 383  * Returns -1 on fail, 0 on success
 384  */
 385 static inline int
 386 reserve_avail_buf_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
 387                                 uint32_t size, struct buf_vector *buf_vec,
 388                                 uint16_t *num_buffers, uint16_t avail_head)
 389 {
 390         uint16_t cur_idx;
 391         uint32_t vec_idx = 0;
 392         uint16_t tries = 0;
 393
 394         uint16_t head_idx = 0;
 395         uint16_t len = 0;
 396
 397         *num_buffers = 0;
 398         cur_idx  = vq->last_avail_idx;
 399
 400         while (size > 0) {
 401                 if (unlikely(cur_idx == avail_head))
 402                         return -1;
 403
 404                 if (unlikely(fill_vec_buf(dev, vq, cur_idx, &vec_idx, buf_vec,
 405                                                 &head_idx, &len) < 0))
 406                         return -1;
 407                 len = RTE_MIN(len, size);
 408                 update_shadow_used_ring(vq, head_idx, len);
 409                 size -= len;
 410
 411                 cur_idx++;
 412                 tries++;
 413                 *num_buffers += 1;
 414
 415                 /*
 416                  * if we tried all available ring items, and still
 417                  * can't get enough buf, it means something abnormal
 418                  * happened.
 419                  */
 420                 if (unlikely(tries >= vq->size))
 421                         return -1;
 422         }
 423
 424         return 0;
 425 }
 426
 427 static inline int __attribute__((always_inline))
 428 copy_mbuf_to_desc_mergeable(struct virtio_net *dev, struct rte_mbuf *m,
 429                             struct buf_vector *buf_vec, uint16_t num_buffers)
 430 {
 431         uint32_t vec_idx = 0;
 432         uint64_t desc_addr;
 433         uint32_t mbuf_offset, mbuf_avail;
 434         uint32_t desc_offset, desc_avail;
 435         uint32_t cpy_len;
 436         uint64_t hdr_addr, hdr_phys_addr;
 437         struct rte_mbuf *hdr_mbuf;
 438
 439         if (unlikely(m == NULL))
 440                 return -1;
 441
 442         desc_addr = rte_vhost_gpa_to_vva(dev->mem, buf_vec[vec_idx].buf_addr);
 443         if (buf_vec[vec_idx].buf_len < dev->vhost_hlen || !desc_addr)
 444                 return -1;
 445
 446         hdr_mbuf = m;
 447         hdr_addr = desc_addr;
 448         hdr_phys_addr = buf_vec[vec_idx].buf_addr;
 449         rte_prefetch0((void *)(uintptr_t)hdr_addr);
 450
 451         LOG_DEBUG(VHOST_DATA, "(%d) RX: num merge buffers %d\n",
 452                 dev->vid, num_buffers);
 453
 454         desc_avail  = buf_vec[vec_idx].buf_len - dev->vhost_hlen;
 455         desc_offset = dev->vhost_hlen;
 456
 457         mbuf_avail  = rte_pktmbuf_data_len(m);
 458         mbuf_offset = 0;
 459         while (mbuf_avail != 0 || m->next != NULL) {
 460                 /* done with current desc buf, get the next one */
 461                 if (desc_avail == 0) {
 462                         vec_idx++;
 463                         desc_addr = rte_vhost_gpa_to_vva(dev->mem,
 464                                         buf_vec[vec_idx].buf_addr);
 465                         if (unlikely(!desc_addr))
 466                                 return -1;
 467
 468                         /* Prefetch buffer address. */
 469                         rte_prefetch0((void *)(uintptr_t)desc_addr);
 470                         desc_offset = 0;
 471                         desc_avail  = buf_vec[vec_idx].buf_len;
 472                 }
 473
 474                 /* done with current mbuf, get the next one */
 475                 if (mbuf_avail == 0) {
 476                         m = m->next;
 477
 478                         mbuf_offset = 0;
 479                         mbuf_avail  = rte_pktmbuf_data_len(m);
 480                 }
 481
 482                 if (hdr_addr) {
 483                         struct virtio_net_hdr_mrg_rxbuf *hdr;
 484
 485                         hdr = (struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)
 486                                 hdr_addr;
 487                         virtio_enqueue_offload(hdr_mbuf, &hdr->hdr);
 488                         ASSIGN_UNLESS_EQUAL(hdr->num_buffers, num_buffers);
 489
 490                         vhost_log_write(dev, hdr_phys_addr, dev->vhost_hlen);
 491                         PRINT_PACKET(dev, (uintptr_t)hdr_addr,
 492                                      dev->vhost_hlen, 0);
 493
 494                         hdr_addr = 0;
 495                 }
 496
 497                 cpy_len = RTE_MIN(desc_avail, mbuf_avail);
 498                 rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
 499                         rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
 500                         cpy_len);
 501                 vhost_log_write(dev, buf_vec[vec_idx].buf_addr + desc_offset,
 502                         cpy_len);
 503                 PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
 504                         cpy_len, 0);
 505
 506                 mbuf_avail  -= cpy_len;
 507                 mbuf_offset += cpy_len;
 508                 desc_avail  -= cpy_len;
 509                 desc_offset += cpy_len;
 510         }
 511
 512         return 0;
 513 }
 514
 515 static inline uint32_t __attribute__((always_inline))
 516 virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
 517         struct rte_mbuf **pkts, uint32_t count)
 518 {
 519         struct vhost_virtqueue *vq;
 520         uint32_t pkt_idx = 0;
 521         uint16_t num_buffers;
 522         struct buf_vector buf_vec[BUF_VECTOR_MAX];
 523         uint16_t avail_head;
 524
 525         LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
 526         if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->nr_vring))) {
 527                 RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
 528                         dev->vid, __func__, queue_id);
 529                 return 0;
 530         }
 531
 532         vq = dev->virtqueue[queue_id];
 533         if (unlikely(vq->enabled == 0))
 534                 return 0;
 535
 536         count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
 537         if (count == 0)
 538                 return 0;
 539
 540         rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
 541
 542         vq->shadow_used_idx = 0;
 543         avail_head = *((volatile uint16_t *)&vq->avail->idx);
 544         for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
 545                 uint32_t pkt_len = pkts[pkt_idx]->pkt_len + dev->vhost_hlen;
 546
 547                 if (unlikely(reserve_avail_buf_mergeable(dev, vq,
 548                                                 pkt_len, buf_vec, &num_buffers,
 549                                                 avail_head) < 0)) {
 550                         LOG_DEBUG(VHOST_DATA,
 551                                 "(%d) failed to get enough desc from vring\n",
 552                                 dev->vid);
 553                         vq->shadow_used_idx -= num_buffers;
 554                         break;
 555                 }
 556
 557                 LOG_DEBUG(VHOST_DATA, "(%d) current index %d | end index %d\n",
 558                         dev->vid, vq->last_avail_idx,
 559                         vq->last_avail_idx + num_buffers);
 560
 561                 if (copy_mbuf_to_desc_mergeable(dev, pkts[pkt_idx],
 562                                                 buf_vec, num_buffers) < 0) {
 563                         vq->shadow_used_idx -= num_buffers;
 564                         break;
 565                 }
 566
 567                 vq->last_avail_idx += num_buffers;
 568         }
 569
 570         if (likely(vq->shadow_used_idx)) {
 571                 flush_shadow_used_ring(dev, vq);
 572
 573                 /* flush used->idx update before we read avail->flags. */
 574                 rte_mb();
 575
 576                 /* Kick the guest if necessary. */
 577                 if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
 578                                 && (vq->callfd >= 0))
 579                         eventfd_write(vq->callfd, (eventfd_t)1);
 580         }
 581
 582         return pkt_idx;
 583 }
 584
 585 uint16_t
 586 rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
 587         struct rte_mbuf **pkts, uint16_t count)
 588 {
 589         struct virtio_net *dev = get_device(vid);
 590
 591         if (!dev)
 592                 return 0;
 593
 594         if (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF))
 595                 return virtio_dev_merge_rx(dev, queue_id, pkts, count);
 596         else
 597                 return virtio_dev_rx(dev, queue_id, pkts, count);
 598 }
 599
 600 static inline bool
 601 virtio_net_with_host_offload(struct virtio_net *dev)
 602 {
 603         if (dev->features &
 604                         (VIRTIO_NET_F_CSUM | VIRTIO_NET_F_HOST_ECN |
 605                          VIRTIO_NET_F_HOST_TSO4 | VIRTIO_NET_F_HOST_TSO6 |
 606                          VIRTIO_NET_F_HOST_UFO))
 607                 return true;
 608
 609         return false;
 610 }
 611
 612 static void
 613 parse_ethernet(struct rte_mbuf *m, uint16_t *l4_proto, void **l4_hdr)
 614 {
 615         struct ipv4_hdr *ipv4_hdr;
 616         struct ipv6_hdr *ipv6_hdr;
 617         void *l3_hdr = NULL;
 618         struct ether_hdr *eth_hdr;
 619         uint16_t ethertype;
 620
 621         eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
 622
 623         m->l2_len = sizeof(struct ether_hdr);
 624         ethertype = rte_be_to_cpu_16(eth_hdr->ether_type);
 625
 626         if (ethertype == ETHER_TYPE_VLAN) {
 627                 struct vlan_hdr *vlan_hdr = (struct vlan_hdr *)(eth_hdr + 1);
 628
 629                 m->l2_len += sizeof(struct vlan_hdr);
 630                 ethertype = rte_be_to_cpu_16(vlan_hdr->eth_proto);
 631         }
 632
 633         l3_hdr = (char *)eth_hdr + m->l2_len;
 634
 635         switch (ethertype) {
 636         case ETHER_TYPE_IPv4:
 637                 ipv4_hdr = l3_hdr;
 638                 *l4_proto = ipv4_hdr->next_proto_id;
 639                 m->l3_len = (ipv4_hdr->version_ihl & 0x0f) * 4;
 640                 *l4_hdr = (char *)l3_hdr + m->l3_len;
 641                 m->ol_flags |= PKT_TX_IPV4;
 642                 break;
 643         case ETHER_TYPE_IPv6:
 644                 ipv6_hdr = l3_hdr;
 645                 *l4_proto = ipv6_hdr->proto;
 646                 m->l3_len = sizeof(struct ipv6_hdr);
 647                 *l4_hdr = (char *)l3_hdr + m->l3_len;
 648                 m->ol_flags |= PKT_TX_IPV6;
 649                 break;
 650         default:
 651                 m->l3_len = 0;
 652                 *l4_proto = 0;
 653                 *l4_hdr = NULL;
 654                 break;
 655         }
 656 }
 657
 658 static inline void __attribute__((always_inline))
 659 vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
 660 {
 661         uint16_t l4_proto = 0;
 662         void *l4_hdr = NULL;
 663         struct tcp_hdr *tcp_hdr = NULL;
 664
 665         if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
 666                 return;
 667
 668         parse_ethernet(m, &l4_proto, &l4_hdr);
 669         if (hdr->flags == VIRTIO_NET_HDR_F_NEEDS_CSUM) {
 670                 if (hdr->csum_start == (m->l2_len + m->l3_len)) {
 671                         switch (hdr->csum_offset) {
 672                         case (offsetof(struct tcp_hdr, cksum)):
 673                                 if (l4_proto == IPPROTO_TCP)
 674                                         m->ol_flags |= PKT_TX_TCP_CKSUM;
 675                                 break;
 676                         case (offsetof(struct udp_hdr, dgram_cksum)):
 677                                 if (l4_proto == IPPROTO_UDP)
 678                                         m->ol_flags |= PKT_TX_UDP_CKSUM;
 679                                 break;
 680                         case (offsetof(struct sctp_hdr, cksum)):
 681                                 if (l4_proto == IPPROTO_SCTP)
 682                                         m->ol_flags |= PKT_TX_SCTP_CKSUM;
 683                                 break;
 684                         default:
 685                                 break;
 686                         }
 687                 }
 688         }
 689
 690         if (l4_hdr && hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 691                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
 692                 case VIRTIO_NET_HDR_GSO_TCPV4:
 693                 case VIRTIO_NET_HDR_GSO_TCPV6:
 694                         tcp_hdr = l4_hdr;
 695                         m->ol_flags |= PKT_TX_TCP_SEG;
 696                         m->tso_segsz = hdr->gso_size;
 697                         m->l4_len = (tcp_hdr->data_off & 0xf0) >> 2;
 698                         break;
 699                 default:
 700                         RTE_LOG(WARNING, VHOST_DATA,
 701                                 "unsupported gso type %u.\n", hdr->gso_type);
 702                         break;
 703                 }
 704         }
 705 }
 706
 707 #define RARP_PKT_SIZE   64
 708
 709 static int
 710 make_rarp_packet(struct rte_mbuf *rarp_mbuf, const struct ether_addr *mac)
 711 {
 712         struct ether_hdr *eth_hdr;
 713         struct arp_hdr  *rarp;
 714
 715         if (rarp_mbuf->buf_len < 64) {
 716                 RTE_LOG(WARNING, VHOST_DATA,
 717                         "failed to make RARP; mbuf size too small %u (< %d)\n",
 718                         rarp_mbuf->buf_len, RARP_PKT_SIZE);
 719                 return -1;
 720         }
 721
 722         /* Ethernet header. */
 723         eth_hdr = rte_pktmbuf_mtod_offset(rarp_mbuf, struct ether_hdr *, 0);
 724         memset(eth_hdr->d_addr.addr_bytes, 0xff, ETHER_ADDR_LEN);
 725         ether_addr_copy(mac, &eth_hdr->s_addr);
 726         eth_hdr->ether_type = htons(ETHER_TYPE_RARP);
 727
 728         /* RARP header. */
 729         rarp = (struct arp_hdr *)(eth_hdr + 1);
 730         rarp->arp_hrd = htons(ARP_HRD_ETHER);
 731         rarp->arp_pro = htons(ETHER_TYPE_IPv4);
 732         rarp->arp_hln = ETHER_ADDR_LEN;
 733         rarp->arp_pln = 4;
 734         rarp->arp_op  = htons(ARP_OP_REVREQUEST);
 735
 736         ether_addr_copy(mac, &rarp->arp_data.arp_sha);
 737         ether_addr_copy(mac, &rarp->arp_data.arp_tha);
 738         memset(&rarp->arp_data.arp_sip, 0x00, 4);
 739         memset(&rarp->arp_data.arp_tip, 0x00, 4);
 740
 741         rarp_mbuf->pkt_len  = rarp_mbuf->data_len = RARP_PKT_SIZE;
 742
 743         return 0;
 744 }
 745
 746 static inline void __attribute__((always_inline))
 747 put_zmbuf(struct zcopy_mbuf *zmbuf)
 748 {
 749         zmbuf->in_use = 0;
 750 }
 751
 752 static inline int __attribute__((always_inline))
 753 copy_desc_to_mbuf(struct virtio_net *dev, struct vring_desc *descs,
 754                   uint16_t max_desc, struct rte_mbuf *m, uint16_t desc_idx,
 755                   struct rte_mempool *mbuf_pool)
 756 {
 757         struct vring_desc *desc;
 758         uint64_t desc_addr;
 759         uint32_t desc_avail, desc_offset;
 760         uint32_t mbuf_avail, mbuf_offset;
 761         uint32_t cpy_len;
 762         struct rte_mbuf *cur = m, *prev = m;
 763         struct virtio_net_hdr *hdr = NULL;
 764         /* A counter to avoid desc dead loop chain */
 765         uint32_t nr_desc = 1;
 766
 767         desc = &descs[desc_idx];
 768         if (unlikely((desc->len < dev->vhost_hlen)) ||
 769                         (desc->flags & VRING_DESC_F_INDIRECT))
 770                 return -1;
 771
 772         desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
 773         if (unlikely(!desc_addr))
 774                 return -1;
 775
 776         if (virtio_net_with_host_offload(dev)) {
 777                 hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
 778                 rte_prefetch0(hdr);
 779         }
 780
 781         /*
 782          * A virtio driver normally uses at least 2 desc buffers
 783          * for Tx: the first for storing the header, and others
 784          * for storing the data.
 785          */
 786         if (likely((desc->len == dev->vhost_hlen) &&
 787                    (desc->flags & VRING_DESC_F_NEXT) != 0)) {
 788                 desc = &descs[desc->next];
 789                 if (unlikely(desc->flags & VRING_DESC_F_INDIRECT))
 790                         return -1;
 791
 792                 desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
 793                 if (unlikely(!desc_addr))
 794                         return -1;
 795
 796                 desc_offset = 0;
 797                 desc_avail  = desc->len;
 798                 nr_desc    += 1;
 799         } else {
 800                 desc_avail  = desc->len - dev->vhost_hlen;
 801                 desc_offset = dev->vhost_hlen;
 802         }
 803
 804         rte_prefetch0((void *)(uintptr_t)(desc_addr + desc_offset));
 805
 806         PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset), desc_avail, 0);
 807
 808         mbuf_offset = 0;
 809         mbuf_avail  = m->buf_len - RTE_PKTMBUF_HEADROOM;
 810         while (1) {
 811                 uint64_t hpa;
 812
 813                 cpy_len = RTE_MIN(desc_avail, mbuf_avail);
 814
 815                 /*
 816                  * A desc buf might across two host physical pages that are
 817                  * not continuous. In such case (gpa_to_hpa returns 0), data
 818                  * will be copied even though zero copy is enabled.
 819                  */
 820                 if (unlikely(dev->dequeue_zero_copy && (hpa = gpa_to_hpa(dev,
 821                                         desc->addr + desc_offset, cpy_len)))) {
 822                         cur->data_len = cpy_len;
 823                         cur->data_off = 0;
 824                         cur->buf_addr = (void *)(uintptr_t)desc_addr;
 825                         cur->buf_physaddr = hpa;
 826
 827                         /*
 828                          * In zero copy mode, one mbuf can only reference data
 829                          * for one or partial of one desc buff.
 830                          */
 831                         mbuf_avail = cpy_len;
 832                 } else {
 833                         rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *,
 834                                                            mbuf_offset),
 835                                 (void *)((uintptr_t)(desc_addr + desc_offset)),
 836                                 cpy_len);
 837                 }
 838
 839                 mbuf_avail  -= cpy_len;
 840                 mbuf_offset += cpy_len;
 841                 desc_avail  -= cpy_len;
 842                 desc_offset += cpy_len;
 843
 844                 /* This desc reaches to its end, get the next one */
 845                 if (desc_avail == 0) {
 846                         if ((desc->flags & VRING_DESC_F_NEXT) == 0)
 847                                 break;
 848
 849                         if (unlikely(desc->next >= max_desc ||
 850                                      ++nr_desc > max_desc))
 851                                 return -1;
 852                         desc = &descs[desc->next];
 853                         if (unlikely(desc->flags & VRING_DESC_F_INDIRECT))
 854                                 return -1;
 855
 856                         desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
 857                         if (unlikely(!desc_addr))
 858                                 return -1;
 859
 860                         rte_prefetch0((void *)(uintptr_t)desc_addr);
 861
 862                         desc_offset = 0;
 863                         desc_avail  = desc->len;
 864
 865                         PRINT_PACKET(dev, (uintptr_t)desc_addr, desc->len, 0);
 866                 }
 867
 868                 /*
 869                  * This mbuf reaches to its end, get a new one
 870                  * to hold more data.
 871                  */
 872                 if (mbuf_avail == 0) {
 873                         cur = rte_pktmbuf_alloc(mbuf_pool);
 874                         if (unlikely(cur == NULL)) {
 875                                 RTE_LOG(ERR, VHOST_DATA, "Failed to "
 876                                         "allocate memory for mbuf.\n");
 877                                 return -1;
 878                         }
 879                         if (unlikely(dev->dequeue_zero_copy))
 880                                 rte_mbuf_refcnt_update(cur, 1);
 881
 882                         prev->next = cur;
 883                         prev->data_len = mbuf_offset;
 884                         m->nb_segs += 1;
 885                         m->pkt_len += mbuf_offset;
 886                         prev = cur;
 887
 888                         mbuf_offset = 0;
 889                         mbuf_avail  = cur->buf_len - RTE_PKTMBUF_HEADROOM;
 890                 }
 891         }
 892
 893         prev->data_len = mbuf_offset;
 894         m->pkt_len    += mbuf_offset;
 895
 896         if (hdr)
 897                 vhost_dequeue_offload(hdr, m);
 898
 899         return 0;
 900 }
 901
 902 static inline void __attribute__((always_inline))
 903 update_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq,
 904                  uint32_t used_idx, uint32_t desc_idx)
 905 {
 906         vq->used->ring[used_idx].id  = desc_idx;
 907         vq->used->ring[used_idx].len = 0;
 908         vhost_log_used_vring(dev, vq,
 909                         offsetof(struct vring_used, ring[used_idx]),
 910                         sizeof(vq->used->ring[used_idx]));
 911 }
 912
 913 static inline void __attribute__((always_inline))
 914 update_used_idx(struct virtio_net *dev, struct vhost_virtqueue *vq,
 915                 uint32_t count)
 916 {
 917         if (unlikely(count == 0))
 918                 return;
 919
 920         rte_smp_wmb();
 921         rte_smp_rmb();
 922
 923         vq->used->idx += count;
 924         vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
 925                         sizeof(vq->used->idx));
 926
 927         /* Kick guest if required. */
 928         if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
 929                         && (vq->callfd >= 0))
 930                 eventfd_write(vq->callfd, (eventfd_t)1);
 931 }
 932
 933 static inline struct zcopy_mbuf *__attribute__((always_inline))
 934 get_zmbuf(struct vhost_virtqueue *vq)
 935 {
 936         uint16_t i;
 937         uint16_t last;
 938         int tries = 0;
 939
 940         /* search [last_zmbuf_idx, zmbuf_size) */
 941         i = vq->last_zmbuf_idx;
 942         last = vq->zmbuf_size;
 943
 944 again:
 945         for (; i < last; i++) {
 946                 if (vq->zmbufs[i].in_use == 0) {
 947                         vq->last_zmbuf_idx = i + 1;
 948                         vq->zmbufs[i].in_use = 1;
 949                         return &vq->zmbufs[i];
 950                 }
 951         }
 952
 953         tries++;
 954         if (tries == 1) {
 955                 /* search [0, last_zmbuf_idx) */
 956                 i = 0;
 957                 last = vq->last_zmbuf_idx;
 958                 goto again;
 959         }
 960
 961         return NULL;
 962 }
 963
 964 static inline bool __attribute__((always_inline))
 965 mbuf_is_consumed(struct rte_mbuf *m)
 966 {
 967         while (m) {
 968                 if (rte_mbuf_refcnt_read(m) > 1)
 969                         return false;
 970                 m = m->next;
 971         }
 972
 973         return true;
 974 }
 975
 976 uint16_t
 977 rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
 978         struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
 979 {
 980         struct virtio_net *dev;
 981         struct rte_mbuf *rarp_mbuf = NULL;
 982         struct vhost_virtqueue *vq;
 983         uint32_t desc_indexes[MAX_PKT_BURST];
 984         uint32_t used_idx;
 985         uint32_t i = 0;
 986         uint16_t free_entries;
 987         uint16_t avail_idx;
 988
 989         dev = get_device(vid);
 990         if (!dev)
 991                 return 0;
 992
 993         if (unlikely(!is_valid_virt_queue_idx(queue_id, 1, dev->nr_vring))) {
 994                 RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
 995                         dev->vid, __func__, queue_id);
 996                 return 0;
 997         }
 998
 999         vq = dev->virtqueue[queue_id];
1000         if (unlikely(vq->enabled == 0))
1001                 return 0;
1002
1003         if (unlikely(dev->dequeue_zero_copy)) {
1004                 struct zcopy_mbuf *zmbuf, *next;
1005                 int nr_updated = 0;
1006
1007                 for (zmbuf = TAILQ_FIRST(&vq->zmbuf_list);
1008                      zmbuf != NULL; zmbuf = next) {
1009                         next = TAILQ_NEXT(zmbuf, next);
1010
1011                         if (mbuf_is_consumed(zmbuf->mbuf)) {
1012                                 used_idx = vq->last_used_idx++ & (vq->size - 1);
1013                                 update_used_ring(dev, vq, used_idx,
1014                                                  zmbuf->desc_idx);
1015                                 nr_updated += 1;
1016
1017                                 TAILQ_REMOVE(&vq->zmbuf_list, zmbuf, next);
1018                                 rte_pktmbuf_free(zmbuf->mbuf);
1019                                 put_zmbuf(zmbuf);
1020                                 vq->nr_zmbuf -= 1;
1021                         }
1022                 }
1023
1024                 update_used_idx(dev, vq, nr_updated);
1025         }
1026
1027         /*
1028          * Construct a RARP broadcast packet, and inject it to the "pkts"
1029          * array, to looks like that guest actually send such packet.
1030          *
1031          * Check user_send_rarp() for more information.
1032          *
1033          * broadcast_rarp shares a cacheline in the virtio_net structure
1034          * with some fields that are accessed during enqueue and
1035          * rte_atomic16_cmpset() causes a write if using cmpxchg. This could
1036          * result in false sharing between enqueue and dequeue.
1037          *
1038          * Prevent unnecessary false sharing by reading broadcast_rarp first
1039          * and only performing cmpset if the read indicates it is likely to
1040          * be set.
1041          */
1042
1043         if (unlikely(rte_atomic16_read(&dev->broadcast_rarp) &&
1044                         rte_atomic16_cmpset((volatile uint16_t *)
1045                                 &dev->broadcast_rarp.cnt, 1, 0))) {
1046
1047                 rarp_mbuf = rte_pktmbuf_alloc(mbuf_pool);
1048                 if (rarp_mbuf == NULL) {
1049                         RTE_LOG(ERR, VHOST_DATA,
1050                                 "Failed to allocate memory for mbuf.\n");
1051                         return 0;
1052                 }
1053
1054                 if (make_rarp_packet(rarp_mbuf, &dev->mac)) {
1055                         rte_pktmbuf_free(rarp_mbuf);
1056                         rarp_mbuf = NULL;
1057                 } else {
1058                         count -= 1;
1059                 }
1060         }
1061
1062         free_entries = *((volatile uint16_t *)&vq->avail->idx) -
1063                         vq->last_avail_idx;
1064         if (free_entries == 0)
1065                 goto out;
1066
1067         LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
1068
1069         /* Prefetch available and used ring */
1070         avail_idx = vq->last_avail_idx & (vq->size - 1);
1071         used_idx  = vq->last_used_idx  & (vq->size - 1);
1072         rte_prefetch0(&vq->avail->ring[avail_idx]);
1073         rte_prefetch0(&vq->used->ring[used_idx]);
1074
1075         count = RTE_MIN(count, MAX_PKT_BURST);
1076         count = RTE_MIN(count, free_entries);
1077         LOG_DEBUG(VHOST_DATA, "(%d) about to dequeue %u buffers\n",
1078                         dev->vid, count);
1079
1080         /* Retrieve all of the head indexes first to avoid caching issues. */
1081         for (i = 0; i < count; i++) {
1082                 avail_idx = (vq->last_avail_idx + i) & (vq->size - 1);
1083                 used_idx  = (vq->last_used_idx  + i) & (vq->size - 1);
1084                 desc_indexes[i] = vq->avail->ring[avail_idx];
1085
1086                 if (likely(dev->dequeue_zero_copy == 0))
1087                         update_used_ring(dev, vq, used_idx, desc_indexes[i]);
1088         }
1089
1090         /* Prefetch descriptor index. */
1091         rte_prefetch0(&vq->desc[desc_indexes[0]]);
1092         for (i = 0; i < count; i++) {
1093                 struct vring_desc *desc;
1094                 uint16_t sz, idx;
1095                 int err;
1096
1097                 if (likely(i + 1 < count))
1098                         rte_prefetch0(&vq->desc[desc_indexes[i + 1]]);
1099
1100                 if (vq->desc[desc_indexes[i]].flags & VRING_DESC_F_INDIRECT) {
1101                         desc = (struct vring_desc *)(uintptr_t)
1102                                 rte_vhost_gpa_to_vva(dev->mem,
1103                                         vq->desc[desc_indexes[i]].addr);
1104                         if (unlikely(!desc))
1105                                 break;
1106
1107                         rte_prefetch0(desc);
1108                         sz = vq->desc[desc_indexes[i]].len / sizeof(*desc);
1109                         idx = 0;
1110                 } else {
1111                         desc = vq->desc;
1112                         sz = vq->size;
1113                         idx = desc_indexes[i];
1114                 }
1115
1116                 pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
1117                 if (unlikely(pkts[i] == NULL)) {
1118                         RTE_LOG(ERR, VHOST_DATA,
1119                                 "Failed to allocate memory for mbuf.\n");
1120                         break;
1121                 }
1122
1123                 err = copy_desc_to_mbuf(dev, desc, sz, pkts[i], idx, mbuf_pool);
1124                 if (unlikely(err)) {
1125                         rte_pktmbuf_free(pkts[i]);
1126                         break;
1127                 }
1128
1129                 if (unlikely(dev->dequeue_zero_copy)) {
1130                         struct zcopy_mbuf *zmbuf;
1131
1132                         zmbuf = get_zmbuf(vq);
1133                         if (!zmbuf) {
1134                                 rte_pktmbuf_free(pkts[i]);
1135                                 break;
1136                         }
1137                         zmbuf->mbuf = pkts[i];
1138                         zmbuf->desc_idx = desc_indexes[i];
1139
1140                         /*
1141                          * Pin lock the mbuf; we will check later to see
1142                          * whether the mbuf is freed (when we are the last
1143                          * user) or not. If that's the case, we then could
1144                          * update the used ring safely.
1145                          */
1146                         rte_mbuf_refcnt_update(pkts[i], 1);
1147
1148                         vq->nr_zmbuf += 1;
1149                         TAILQ_INSERT_TAIL(&vq->zmbuf_list, zmbuf, next);
1150                 }
1151         }
1152         vq->last_avail_idx += i;
1153
1154         if (likely(dev->dequeue_zero_copy == 0)) {
1155                 vq->last_used_idx += i;
1156                 update_used_idx(dev, vq, i);
1157         }
1158
1159 out:
1160         if (unlikely(rarp_mbuf != NULL)) {
1161                 /*
1162                  * Inject it to the head of "pkts" array, so that switch's mac
1163                  * learning table will get updated first.
1164                  */
1165                 memmove(&pkts[1], pkts, i * sizeof(struct rte_mbuf *));
1166                 pkts[0] = rarp_mbuf;
1167                 i += 1;
1168         }
1169
1170         return i;
1171 }