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