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 #include <rte_spinlock.h>
  48
  49 #include "vhost.h"
  50
  51 #define MAX_PKT_BURST 32
  52 #define VHOST_LOG_PAGE  4096
  53
  54 /*
  55  * Atomically set a bit in memory.
  56  */
  57 static inline void __attribute__((always_inline))
  58 vhost_set_bit(unsigned int nr, volatile uint8_t *addr)
  59 {
  60         __sync_fetch_and_or_8(addr, (1U << nr));
  61 }
  62
  63 static inline void __attribute__((always_inline))
  64 vhost_log_page(uint8_t *log_base, uint64_t page)
  65 {
  66         vhost_set_bit(page % 8, &log_base[page / 8]);
  67 }
  68
  69 static inline void __attribute__((always_inline))
  70 vhost_log_write(struct virtio_net *dev, uint64_t addr, uint64_t len)
  71 {
  72         uint64_t page;
  73
  74         if (likely(((dev->features & (1ULL << VHOST_F_LOG_ALL)) == 0) ||
  75                    !dev->log_base || !len))
  76                 return;
  77
  78         if (unlikely(dev->log_size <= ((addr + len - 1) / VHOST_LOG_PAGE / 8)))
  79                 return;
  80
  81         /* To make sure guest memory updates are committed before logging */
  82         rte_smp_wmb();
  83
  84         page = addr / VHOST_LOG_PAGE;
  85         while (page * VHOST_LOG_PAGE < addr + len) {
  86                 vhost_log_page((uint8_t *)(uintptr_t)dev->log_base, page);
  87                 page += 1;
  88         }
  89 }
  90
  91 static inline void __attribute__((always_inline))
  92 vhost_log_used_vring(struct virtio_net *dev, struct vhost_virtqueue *vq,
  93                      uint64_t offset, uint64_t len)
  94 {
  95         vhost_log_write(dev, vq->log_guest_addr + offset, len);
  96 }
  97
  98 static bool
  99 is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t qp_nb)
 100 {
 101         return (is_tx ^ (idx & 1)) == 0 && idx < qp_nb * VIRTIO_QNUM;
 102 }
 103
 104 static inline void __attribute__((always_inline))
 105 do_flush_shadow_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq,
 106                           uint16_t to, uint16_t from, uint16_t size)
 107 {
 108         rte_memcpy(&vq->used->ring[to],
 109                         &vq->shadow_used_ring[from],
 110                         size * sizeof(struct vring_used_elem));
 111         vhost_log_used_vring(dev, vq,
 112                         offsetof(struct vring_used, ring[to]),
 113                         size * sizeof(struct vring_used_elem));
 114 }
 115
 116 static inline void __attribute__((always_inline))
 117 flush_shadow_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq)
 118 {
 119         uint16_t used_idx = vq->last_used_idx & (vq->size - 1);
 120
 121         if (used_idx + vq->shadow_used_idx <= vq->size) {
 122                 do_flush_shadow_used_ring(dev, vq, used_idx, 0,
 123                                           vq->shadow_used_idx);
 124         } else {
 125                 uint16_t size;
 126
 127                 /* update used ring interval [used_idx, vq->size] */
 128                 size = vq->size - used_idx;
 129                 do_flush_shadow_used_ring(dev, vq, used_idx, 0, size);
 130
 131                 /* update the left half used ring interval [0, left_size] */
 132                 do_flush_shadow_used_ring(dev, vq, 0, size,
 133                                           vq->shadow_used_idx - size);
 134         }
 135         vq->last_used_idx += vq->shadow_used_idx;
 136
 137         rte_smp_wmb();
 138
 139         *(volatile uint16_t *)&vq->used->idx += vq->shadow_used_idx;
 140         vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
 141                 sizeof(vq->used->idx));
 142 }
 143
 144 static inline void __attribute__((always_inline))
 145 update_shadow_used_ring(struct vhost_virtqueue *vq,
 146                          uint16_t desc_idx, uint16_t len)
 147 {
 148         uint16_t i = vq->shadow_used_idx++;
 149
 150         vq->shadow_used_ring[i].id  = desc_idx;
 151         vq->shadow_used_ring[i].len = len;
 152 }
 153
 154 static void
 155 virtio_enqueue_offload(struct rte_mbuf *m_buf, struct virtio_net_hdr *net_hdr)
 156 {
 157         uint64_t csum_l4 = m_buf->ol_flags & PKT_TX_L4_MASK;
 158
 159         if (m_buf->ol_flags & PKT_TX_TCP_SEG)
 160                 csum_l4 |= PKT_TX_TCP_CKSUM;
 161
 162         if (csum_l4) {
 163                 net_hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 164                 net_hdr->csum_start = m_buf->l2_len + m_buf->l3_len;
 165
 166                 switch (csum_l4) {
 167                 case PKT_TX_TCP_CKSUM:
 168                         net_hdr->csum_offset = (offsetof(struct tcp_hdr,
 169                                                 cksum));
 170                         break;
 171                 case PKT_TX_UDP_CKSUM:
 172                         net_hdr->csum_offset = (offsetof(struct udp_hdr,
 173                                                 dgram_cksum));
 174                         break;
 175                 case PKT_TX_SCTP_CKSUM:
 176                         net_hdr->csum_offset = (offsetof(struct sctp_hdr,
 177                                                 cksum));
 178                         break;
 179                 }
 180         }
 181
 182         /* IP cksum verification cannot be bypassed, then calculate here */
 183         if (m_buf->ol_flags & PKT_TX_IP_CKSUM) {
 184                 struct ipv4_hdr *ipv4_hdr;
 185
 186                 ipv4_hdr = rte_pktmbuf_mtod_offset(m_buf, struct ipv4_hdr *,
 187                                                    m_buf->l2_len);
 188                 ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
 189         }
 190
 191         if (m_buf->ol_flags & PKT_TX_TCP_SEG) {
 192                 if (m_buf->ol_flags & PKT_TX_IPV4)
 193                         net_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 194                 else
 195                         net_hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 196                 net_hdr->gso_size = m_buf->tso_segsz;
 197                 net_hdr->hdr_len = m_buf->l2_len + m_buf->l3_len
 198                                         + m_buf->l4_len;
 199         }
 200 }
 201
 202 static inline void
 203 copy_virtio_net_hdr(struct virtio_net *dev, uint64_t desc_addr,
 204                     struct virtio_net_hdr_mrg_rxbuf hdr)
 205 {
 206         if (dev->vhost_hlen == sizeof(struct virtio_net_hdr_mrg_rxbuf))
 207                 *(struct virtio_net_hdr_mrg_rxbuf *)(uintptr_t)desc_addr = hdr;
 208         else
 209                 *(struct virtio_net_hdr *)(uintptr_t)desc_addr = hdr.hdr;
 210 }
 211
 212 static inline int __attribute__((always_inline))
 213 copy_mbuf_to_desc(struct virtio_net *dev, struct vring_desc *descs,
 214                   struct rte_mbuf *m, uint16_t desc_idx, uint32_t size)
 215 {
 216         uint32_t desc_avail, desc_offset;
 217         uint32_t mbuf_avail, mbuf_offset;
 218         uint32_t cpy_len;
 219         struct vring_desc *desc;
 220         uint64_t desc_addr;
 221         struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
 222         /* A counter to avoid desc dead loop chain */
 223         uint16_t nr_desc = 1;
 224
 225         desc = &descs[desc_idx];
 226         desc_addr = gpa_to_vva(dev, desc->addr);
 227         /*
 228          * Checking of 'desc_addr' placed outside of 'unlikely' macro to avoid
 229          * performance issue with some versions of gcc (4.8.4 and 5.3.0) which
 230          * otherwise stores offset on the stack instead of in a register.
 231          */
 232         if (unlikely(desc->len < dev->vhost_hlen) || !desc_addr)
 233                 return -1;
 234
 235         rte_prefetch0((void *)(uintptr_t)desc_addr);
 236
 237         virtio_enqueue_offload(m, &virtio_hdr.hdr);
 238         copy_virtio_net_hdr(dev, desc_addr, virtio_hdr);
 239         vhost_log_write(dev, desc->addr, dev->vhost_hlen);
 240         PRINT_PACKET(dev, (uintptr_t)desc_addr, dev->vhost_hlen, 0);
 241
 242         desc_offset = dev->vhost_hlen;
 243         desc_avail  = desc->len - dev->vhost_hlen;
 244
 245         mbuf_avail  = rte_pktmbuf_data_len(m);
 246         mbuf_offset = 0;
 247         while (mbuf_avail != 0 || m->next != NULL) {
 248                 /* done with current mbuf, fetch next */
 249                 if (mbuf_avail == 0) {
 250                         m = m->next;
 251
 252                         mbuf_offset = 0;
 253                         mbuf_avail  = rte_pktmbuf_data_len(m);
 254                 }
 255
 256                 /* done with current desc buf, fetch next */
 257                 if (desc_avail == 0) {
 258                         if ((desc->flags & VRING_DESC_F_NEXT) == 0) {
 259                                 /* Room in vring buffer is not enough */
 260                                 return -1;
 261                         }
 262                         if (unlikely(desc->next >= size || ++nr_desc > size))
 263                                 return -1;
 264
 265                         desc = &descs[desc->next];
 266                         desc_addr = gpa_to_vva(dev, desc->addr);
 267                         if (unlikely(!desc_addr))
 268                                 return -1;
 269
 270                         desc_offset = 0;
 271                         desc_avail  = desc->len;
 272                 }
 273
 274                 cpy_len = RTE_MIN(desc_avail, mbuf_avail);
 275                 rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
 276                         rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
 277                         cpy_len);
 278                 vhost_log_write(dev, desc->addr + desc_offset, cpy_len);
 279                 PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
 280                              cpy_len, 0);
 281
 282                 mbuf_avail  -= cpy_len;
 283                 mbuf_offset += cpy_len;
 284                 desc_avail  -= cpy_len;
 285                 desc_offset += cpy_len;
 286         }
 287
 288         return 0;
 289 }
 290
 291 /**
 292  * This function adds buffers to the virtio devices RX virtqueue. Buffers can
 293  * be received from the physical port or from another virtio device. A packet
 294  * count is returned to indicate the number of packets that are succesfully
 295  * added to the RX queue. This function works when the mbuf is scattered, but
 296  * it doesn't support the mergeable feature.
 297  */
 298 static inline uint32_t __attribute__((always_inline))
 299 virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
 300               struct rte_mbuf **pkts, uint32_t count)
 301 {
 302         struct vhost_virtqueue *vq;
 303         uint16_t avail_idx, free_entries, start_idx;
 304         uint16_t desc_indexes[MAX_PKT_BURST];
 305         struct vring_desc *descs;
 306         uint16_t used_idx;
 307         uint32_t i, sz;
 308
 309         LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
 310         if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->virt_qp_nb))) {
 311                 RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
 312                         dev->vid, __func__, queue_id);
 313                 return 0;
 314         }
 315
 316         vq = dev->virtqueue[queue_id];
 317
 318         rte_spinlock_lock(&vq->access_lock);
 319
 320         if (unlikely(vq->enabled == 0))
 321                 goto out_access_unlock;
 322
 323         avail_idx = *((volatile uint16_t *)&vq->avail->idx);
 324         start_idx = vq->last_used_idx;
 325         free_entries = avail_idx - start_idx;
 326         count = RTE_MIN(count, free_entries);
 327         count = RTE_MIN(count, (uint32_t)MAX_PKT_BURST);
 328         if (count == 0)
 329                 goto out_access_unlock;
 330
 331         LOG_DEBUG(VHOST_DATA, "(%d) start_idx %d | end_idx %d\n",
 332                 dev->vid, start_idx, start_idx + count);
 333
 334         /* Retrieve all of the desc indexes first to avoid caching issues. */
 335         rte_prefetch0(&vq->avail->ring[start_idx & (vq->size - 1)]);
 336         for (i = 0; i < count; i++) {
 337                 used_idx = (start_idx + i) & (vq->size - 1);
 338                 desc_indexes[i] = vq->avail->ring[used_idx];
 339                 vq->used->ring[used_idx].id = desc_indexes[i];
 340                 vq->used->ring[used_idx].len = pkts[i]->pkt_len +
 341                                                dev->vhost_hlen;
 342                 vhost_log_used_vring(dev, vq,
 343                         offsetof(struct vring_used, ring[used_idx]),
 344                         sizeof(vq->used->ring[used_idx]));
 345         }
 346
 347         rte_prefetch0(&vq->desc[desc_indexes[0]]);
 348         for (i = 0; i < count; i++) {
 349                 uint16_t desc_idx = desc_indexes[i];
 350                 int err;
 351
 352                 if (vq->desc[desc_idx].flags & VRING_DESC_F_INDIRECT) {
 353                         descs = (struct vring_desc *)(uintptr_t)gpa_to_vva(dev,
 354                                         vq->desc[desc_idx].addr);
 355                         if (unlikely(!descs)) {
 356                                 count = i;
 357                                 break;
 358                         }
 359
 360                         desc_idx = 0;
 361                         sz = vq->desc[desc_idx].len / sizeof(*descs);
 362                 } else {
 363                         descs = vq->desc;
 364                         sz = vq->size;
 365                 }
 366
 367                 err = copy_mbuf_to_desc(dev, descs, pkts[i], desc_idx, sz);
 368                 if (unlikely(err)) {
 369                         used_idx = (start_idx + i) & (vq->size - 1);
 370                         vq->used->ring[used_idx].len = dev->vhost_hlen;
 371                         vhost_log_used_vring(dev, vq,
 372                                 offsetof(struct vring_used, ring[used_idx]),
 373                                 sizeof(vq->used->ring[used_idx]));
 374                 }
 375
 376                 if (i + 1 < count)
 377                         rte_prefetch0(&vq->desc[desc_indexes[i+1]]);
 378         }
 379
 380         rte_smp_wmb();
 381
 382         *(volatile uint16_t *)&vq->used->idx += count;
 383         vq->last_used_idx += count;
 384         vhost_log_used_vring(dev, vq,
 385                 offsetof(struct vring_used, idx),
 386                 sizeof(vq->used->idx));
 387
 388         /* flush used->idx update before we read avail->flags. */
 389         rte_mb();
 390
 391         /* Kick the guest if necessary. */
 392         if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
 393                         && (vq->callfd >= 0))
 394                 eventfd_write(vq->callfd, (eventfd_t)1);
 395
 396 out_access_unlock:
 397         rte_spinlock_unlock(&vq->access_lock);
 398
 399         return count;
 400 }
 401
 402 static inline int __attribute__((always_inline))
 403 fill_vec_buf(struct virtio_net *dev, struct vhost_virtqueue *vq,
 404                          uint32_t avail_idx, uint32_t *vec_idx,
 405                          struct buf_vector *buf_vec, uint16_t *desc_chain_head,
 406                          uint16_t *desc_chain_len)
 407 {
 408         uint16_t idx = vq->avail->ring[avail_idx & (vq->size - 1)];
 409         uint32_t vec_id = *vec_idx;
 410         uint32_t len    = 0;
 411         struct vring_desc *descs = vq->desc;
 412
 413         *desc_chain_head = idx;
 414
 415         if (vq->desc[idx].flags & VRING_DESC_F_INDIRECT) {
 416                 descs = (struct vring_desc *)(uintptr_t)
 417                                         gpa_to_vva(dev, vq->desc[idx].addr);
 418                 if (unlikely(!descs))
 419                         return -1;
 420
 421                 idx = 0;
 422         }
 423
 424         while (1) {
 425                 if (unlikely(vec_id >= BUF_VECTOR_MAX || idx >= vq->size))
 426                         return -1;
 427
 428                 len += descs[idx].len;
 429                 buf_vec[vec_id].buf_addr = descs[idx].addr;
 430                 buf_vec[vec_id].buf_len  = descs[idx].len;
 431                 buf_vec[vec_id].desc_idx = idx;
 432                 vec_id++;
 433
 434                 if ((descs[idx].flags & VRING_DESC_F_NEXT) == 0)
 435                         break;
 436
 437                 idx = descs[idx].next;
 438         }
 439
 440         *desc_chain_len = len;
 441         *vec_idx = vec_id;
 442
 443         return 0;
 444 }
 445
 446 /*
 447  * Returns -1 on fail, 0 on success
 448  */
 449 static inline int
 450 reserve_avail_buf_mergeable(struct virtio_net *dev, struct vhost_virtqueue *vq,
 451                                 uint32_t size, struct buf_vector *buf_vec,
 452                                 uint16_t *num_buffers, uint16_t avail_head)
 453 {
 454         uint16_t cur_idx;
 455         uint32_t vec_idx = 0;
 456         uint16_t tries = 0;
 457
 458         uint16_t head_idx = 0;
 459         uint16_t len = 0;
 460
 461         *num_buffers = 0;
 462         cur_idx  = vq->last_avail_idx;
 463
 464         while (size > 0) {
 465                 if (unlikely(cur_idx == avail_head))
 466                         return -1;
 467
 468                 if (unlikely(fill_vec_buf(dev, vq, cur_idx, &vec_idx, buf_vec,
 469                                                 &head_idx, &len) < 0))
 470                         return -1;
 471                 len = RTE_MIN(len, size);
 472                 update_shadow_used_ring(vq, head_idx, len);
 473                 size -= len;
 474
 475                 cur_idx++;
 476                 tries++;
 477                 *num_buffers += 1;
 478
 479                 /*
 480                  * if we tried all available ring items, and still
 481                  * can't get enough buf, it means something abnormal
 482                  * happened.
 483                  */
 484                 if (unlikely(tries >= vq->size))
 485                         return -1;
 486         }
 487
 488         return 0;
 489 }
 490
 491 static inline int __attribute__((always_inline))
 492 copy_mbuf_to_desc_mergeable(struct virtio_net *dev, struct rte_mbuf *m,
 493                             struct buf_vector *buf_vec, uint16_t num_buffers)
 494 {
 495         struct virtio_net_hdr_mrg_rxbuf virtio_hdr = {{0, 0, 0, 0, 0, 0}, 0};
 496         uint32_t vec_idx = 0;
 497         uint64_t desc_addr;
 498         uint32_t mbuf_offset, mbuf_avail;
 499         uint32_t desc_offset, desc_avail;
 500         uint32_t cpy_len;
 501         uint64_t hdr_addr, hdr_phys_addr;
 502         struct rte_mbuf *hdr_mbuf;
 503
 504         if (unlikely(m == NULL))
 505                 return -1;
 506
 507         desc_addr = gpa_to_vva(dev, buf_vec[vec_idx].buf_addr);
 508         if (buf_vec[vec_idx].buf_len < dev->vhost_hlen || !desc_addr)
 509                 return -1;
 510
 511         hdr_mbuf = m;
 512         hdr_addr = desc_addr;
 513         hdr_phys_addr = buf_vec[vec_idx].buf_addr;
 514         rte_prefetch0((void *)(uintptr_t)hdr_addr);
 515
 516         virtio_hdr.num_buffers = num_buffers;
 517         LOG_DEBUG(VHOST_DATA, "(%d) RX: num merge buffers %d\n",
 518                 dev->vid, num_buffers);
 519
 520         desc_avail  = buf_vec[vec_idx].buf_len - dev->vhost_hlen;
 521         desc_offset = dev->vhost_hlen;
 522
 523         mbuf_avail  = rte_pktmbuf_data_len(m);
 524         mbuf_offset = 0;
 525         while (mbuf_avail != 0 || m->next != NULL) {
 526                 /* done with current desc buf, get the next one */
 527                 if (desc_avail == 0) {
 528                         vec_idx++;
 529                         desc_addr = gpa_to_vva(dev, buf_vec[vec_idx].buf_addr);
 530                         if (unlikely(!desc_addr))
 531                                 return -1;
 532
 533                         /* Prefetch buffer address. */
 534                         rte_prefetch0((void *)(uintptr_t)desc_addr);
 535                         desc_offset = 0;
 536                         desc_avail  = buf_vec[vec_idx].buf_len;
 537                 }
 538
 539                 /* done with current mbuf, get the next one */
 540                 if (mbuf_avail == 0) {
 541                         m = m->next;
 542
 543                         mbuf_offset = 0;
 544                         mbuf_avail  = rte_pktmbuf_data_len(m);
 545                 }
 546
 547                 if (hdr_addr) {
 548                         virtio_enqueue_offload(hdr_mbuf, &virtio_hdr.hdr);
 549                         copy_virtio_net_hdr(dev, hdr_addr, virtio_hdr);
 550                         vhost_log_write(dev, hdr_phys_addr, dev->vhost_hlen);
 551                         PRINT_PACKET(dev, (uintptr_t)hdr_addr,
 552                                      dev->vhost_hlen, 0);
 553
 554                         hdr_addr = 0;
 555                 }
 556
 557                 cpy_len = RTE_MIN(desc_avail, mbuf_avail);
 558                 rte_memcpy((void *)((uintptr_t)(desc_addr + desc_offset)),
 559                         rte_pktmbuf_mtod_offset(m, void *, mbuf_offset),
 560                         cpy_len);
 561                 vhost_log_write(dev, buf_vec[vec_idx].buf_addr + desc_offset,
 562                         cpy_len);
 563                 PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset),
 564                         cpy_len, 0);
 565
 566                 mbuf_avail  -= cpy_len;
 567                 mbuf_offset += cpy_len;
 568                 desc_avail  -= cpy_len;
 569                 desc_offset += cpy_len;
 570         }
 571
 572         return 0;
 573 }
 574
 575 static inline uint32_t __attribute__((always_inline))
 576 virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
 577         struct rte_mbuf **pkts, uint32_t count)
 578 {
 579         struct vhost_virtqueue *vq;
 580         uint32_t pkt_idx = 0;
 581         uint16_t num_buffers;
 582         struct buf_vector buf_vec[BUF_VECTOR_MAX];
 583         uint16_t avail_head;
 584
 585         LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
 586         if (unlikely(!is_valid_virt_queue_idx(queue_id, 0, dev->virt_qp_nb))) {
 587                 RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
 588                         dev->vid, __func__, queue_id);
 589                 return 0;
 590         }
 591
 592         vq = dev->virtqueue[queue_id];
 593
 594         rte_spinlock_lock(&vq->access_lock);
 595
 596         if (unlikely(vq->enabled == 0))
 597                 goto out_access_unlock;
 598
 599         count = RTE_MIN((uint32_t)MAX_PKT_BURST, count);
 600         if (count == 0)
 601                 goto out_access_unlock;
 602
 603         rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
 604
 605         vq->shadow_used_idx = 0;
 606         avail_head = *((volatile uint16_t *)&vq->avail->idx);
 607         for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
 608                 uint32_t pkt_len = pkts[pkt_idx]->pkt_len + dev->vhost_hlen;
 609
 610                 if (unlikely(reserve_avail_buf_mergeable(dev, vq,
 611                                                 pkt_len, buf_vec, &num_buffers,
 612                                                 avail_head) < 0)) {
 613                         LOG_DEBUG(VHOST_DATA,
 614                                 "(%d) failed to get enough desc from vring\n",
 615                                 dev->vid);
 616                         vq->shadow_used_idx -= num_buffers;
 617                         break;
 618                 }
 619
 620                 LOG_DEBUG(VHOST_DATA, "(%d) current index %d | end index %d\n",
 621                         dev->vid, vq->last_avail_idx,
 622                         vq->last_avail_idx + num_buffers);
 623
 624                 if (copy_mbuf_to_desc_mergeable(dev, pkts[pkt_idx],
 625                                                 buf_vec, num_buffers) < 0) {
 626                         vq->shadow_used_idx -= num_buffers;
 627                         break;
 628                 }
 629
 630                 vq->last_avail_idx += num_buffers;
 631         }
 632
 633         if (likely(vq->shadow_used_idx)) {
 634                 flush_shadow_used_ring(dev, vq);
 635
 636                 /* flush used->idx update before we read avail->flags. */
 637                 rte_mb();
 638
 639                 /* Kick the guest if necessary. */
 640                 if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
 641                                 && (vq->callfd >= 0))
 642                         eventfd_write(vq->callfd, (eventfd_t)1);
 643         }
 644
 645 out_access_unlock:
 646         rte_spinlock_unlock(&vq->access_lock);
 647
 648         return pkt_idx;
 649 }
 650
 651 uint16_t
 652 rte_vhost_enqueue_burst(int vid, uint16_t queue_id,
 653         struct rte_mbuf **pkts, uint16_t count)
 654 {
 655         struct virtio_net *dev = get_device(vid);
 656
 657         if (!dev)
 658                 return 0;
 659
 660         if (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF))
 661                 return virtio_dev_merge_rx(dev, queue_id, pkts, count);
 662         else
 663                 return virtio_dev_rx(dev, queue_id, pkts, count);
 664 }
 665
 666 static inline bool
 667 virtio_net_with_host_offload(struct virtio_net *dev)
 668 {
 669         if (dev->features &
 670                         ((1ULL << VIRTIO_NET_F_CSUM) |
 671                          (1ULL << VIRTIO_NET_F_HOST_ECN) |
 672                          (1ULL << VIRTIO_NET_F_HOST_TSO4) |
 673                          (1ULL << VIRTIO_NET_F_HOST_TSO6) |
 674                          (1ULL << VIRTIO_NET_F_HOST_UFO)))
 675                 return true;
 676
 677         return false;
 678 }
 679
 680 static void
 681 parse_ethernet(struct rte_mbuf *m, uint16_t *l4_proto, void **l4_hdr)
 682 {
 683         struct ipv4_hdr *ipv4_hdr;
 684         struct ipv6_hdr *ipv6_hdr;
 685         void *l3_hdr = NULL;
 686         struct ether_hdr *eth_hdr;
 687         uint16_t ethertype;
 688
 689         eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
 690
 691         m->l2_len = sizeof(struct ether_hdr);
 692         ethertype = rte_be_to_cpu_16(eth_hdr->ether_type);
 693
 694         if (ethertype == ETHER_TYPE_VLAN) {
 695                 struct vlan_hdr *vlan_hdr = (struct vlan_hdr *)(eth_hdr + 1);
 696
 697                 m->l2_len += sizeof(struct vlan_hdr);
 698                 ethertype = rte_be_to_cpu_16(vlan_hdr->eth_proto);
 699         }
 700
 701         l3_hdr = (char *)eth_hdr + m->l2_len;
 702
 703         switch (ethertype) {
 704         case ETHER_TYPE_IPv4:
 705                 ipv4_hdr = (struct ipv4_hdr *)l3_hdr;
 706                 *l4_proto = ipv4_hdr->next_proto_id;
 707                 m->l3_len = (ipv4_hdr->version_ihl & 0x0f) * 4;
 708                 *l4_hdr = (char *)l3_hdr + m->l3_len;
 709                 m->ol_flags |= PKT_TX_IPV4;
 710                 break;
 711         case ETHER_TYPE_IPv6:
 712                 ipv6_hdr = (struct ipv6_hdr *)l3_hdr;
 713                 *l4_proto = ipv6_hdr->proto;
 714                 m->l3_len = sizeof(struct ipv6_hdr);
 715                 *l4_hdr = (char *)l3_hdr + m->l3_len;
 716                 m->ol_flags |= PKT_TX_IPV6;
 717                 break;
 718         default:
 719                 m->l3_len = 0;
 720                 *l4_proto = 0;
 721                 *l4_hdr = NULL;
 722                 break;
 723         }
 724 }
 725
 726 static inline void __attribute__((always_inline))
 727 vhost_dequeue_offload(struct virtio_net_hdr *hdr, struct rte_mbuf *m)
 728 {
 729         uint16_t l4_proto = 0;
 730         void *l4_hdr = NULL;
 731         struct tcp_hdr *tcp_hdr = NULL;
 732
 733         if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
 734                 return;
 735
 736         parse_ethernet(m, &l4_proto, &l4_hdr);
 737         if (hdr->flags == VIRTIO_NET_HDR_F_NEEDS_CSUM) {
 738                 if (hdr->csum_start == (m->l2_len + m->l3_len)) {
 739                         switch (hdr->csum_offset) {
 740                         case (offsetof(struct tcp_hdr, cksum)):
 741                                 if (l4_proto == IPPROTO_TCP)
 742                                         m->ol_flags |= PKT_TX_TCP_CKSUM;
 743                                 break;
 744                         case (offsetof(struct udp_hdr, dgram_cksum)):
 745                                 if (l4_proto == IPPROTO_UDP)
 746                                         m->ol_flags |= PKT_TX_UDP_CKSUM;
 747                                 break;
 748                         case (offsetof(struct sctp_hdr, cksum)):
 749                                 if (l4_proto == IPPROTO_SCTP)
 750                                         m->ol_flags |= PKT_TX_SCTP_CKSUM;
 751                                 break;
 752                         default:
 753                                 break;
 754                         }
 755                 }
 756         }
 757
 758         if (l4_hdr && hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 759                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
 760                 case VIRTIO_NET_HDR_GSO_TCPV4:
 761                 case VIRTIO_NET_HDR_GSO_TCPV6:
 762                         tcp_hdr = (struct tcp_hdr *)l4_hdr;
 763                         m->ol_flags |= PKT_TX_TCP_SEG;
 764                         m->tso_segsz = hdr->gso_size;
 765                         m->l4_len = (tcp_hdr->data_off & 0xf0) >> 2;
 766                         break;
 767                 default:
 768                         RTE_LOG(WARNING, VHOST_DATA,
 769                                 "unsupported gso type %u.\n", hdr->gso_type);
 770                         break;
 771                 }
 772         }
 773 }
 774
 775 #define RARP_PKT_SIZE   64
 776
 777 static int
 778 make_rarp_packet(struct rte_mbuf *rarp_mbuf, const struct ether_addr *mac)
 779 {
 780         struct ether_hdr *eth_hdr;
 781         struct arp_hdr  *rarp;
 782
 783         if (rarp_mbuf->buf_len < 64) {
 784                 RTE_LOG(WARNING, VHOST_DATA,
 785                         "failed to make RARP; mbuf size too small %u (< %d)\n",
 786                         rarp_mbuf->buf_len, RARP_PKT_SIZE);
 787                 return -1;
 788         }
 789
 790         /* Ethernet header. */
 791         eth_hdr = rte_pktmbuf_mtod_offset(rarp_mbuf, struct ether_hdr *, 0);
 792         memset(eth_hdr->d_addr.addr_bytes, 0xff, ETHER_ADDR_LEN);
 793         ether_addr_copy(mac, &eth_hdr->s_addr);
 794         eth_hdr->ether_type = htons(ETHER_TYPE_RARP);
 795
 796         /* RARP header. */
 797         rarp = (struct arp_hdr *)(eth_hdr + 1);
 798         rarp->arp_hrd = htons(ARP_HRD_ETHER);
 799         rarp->arp_pro = htons(ETHER_TYPE_IPv4);
 800         rarp->arp_hln = ETHER_ADDR_LEN;
 801         rarp->arp_pln = 4;
 802         rarp->arp_op  = htons(ARP_OP_REVREQUEST);
 803
 804         ether_addr_copy(mac, &rarp->arp_data.arp_sha);
 805         ether_addr_copy(mac, &rarp->arp_data.arp_tha);
 806         memset(&rarp->arp_data.arp_sip, 0x00, 4);
 807         memset(&rarp->arp_data.arp_tip, 0x00, 4);
 808
 809         rarp_mbuf->pkt_len  = rarp_mbuf->data_len = RARP_PKT_SIZE;
 810
 811         return 0;
 812 }
 813
 814 static inline void __attribute__((always_inline))
 815 put_zmbuf(struct zcopy_mbuf *zmbuf)
 816 {
 817         zmbuf->in_use = 0;
 818 }
 819
 820 static inline int __attribute__((always_inline))
 821 copy_desc_to_mbuf(struct virtio_net *dev, struct vring_desc *descs,
 822                   uint16_t max_desc, struct rte_mbuf *m, uint16_t desc_idx,
 823                   struct rte_mempool *mbuf_pool)
 824 {
 825         struct vring_desc *desc;
 826         uint64_t desc_addr;
 827         uint32_t desc_avail, desc_offset;
 828         uint32_t mbuf_avail, mbuf_offset;
 829         uint32_t cpy_len;
 830         struct rte_mbuf *cur = m, *prev = m;
 831         struct virtio_net_hdr *hdr = NULL;
 832         /* A counter to avoid desc dead loop chain */
 833         uint32_t nr_desc = 1;
 834
 835         desc = &descs[desc_idx];
 836         if (unlikely((desc->len < dev->vhost_hlen)) ||
 837                         (desc->flags & VRING_DESC_F_INDIRECT))
 838                 return -1;
 839
 840         desc_addr = gpa_to_vva(dev, desc->addr);
 841         if (unlikely(!desc_addr))
 842                 return -1;
 843
 844         if (virtio_net_with_host_offload(dev)) {
 845                 hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
 846                 rte_prefetch0(hdr);
 847         }
 848
 849         /*
 850          * A virtio driver normally uses at least 2 desc buffers
 851          * for Tx: the first for storing the header, and others
 852          * for storing the data.
 853          */
 854         if (likely((desc->len == dev->vhost_hlen) &&
 855                    (desc->flags & VRING_DESC_F_NEXT) != 0)) {
 856                 desc = &descs[desc->next];
 857                 if (unlikely(desc->flags & VRING_DESC_F_INDIRECT))
 858                         return -1;
 859
 860                 desc_addr = gpa_to_vva(dev, desc->addr);
 861                 if (unlikely(!desc_addr))
 862                         return -1;
 863
 864                 desc_offset = 0;
 865                 desc_avail  = desc->len;
 866                 nr_desc    += 1;
 867         } else {
 868                 desc_avail  = desc->len - dev->vhost_hlen;
 869                 desc_offset = dev->vhost_hlen;
 870         }
 871
 872         rte_prefetch0((void *)(uintptr_t)(desc_addr + desc_offset));
 873
 874         PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset), desc_avail, 0);
 875
 876         mbuf_offset = 0;
 877         mbuf_avail  = m->buf_len - RTE_PKTMBUF_HEADROOM;
 878         while (1) {
 879                 uint64_t hpa;
 880
 881                 cpy_len = RTE_MIN(desc_avail, mbuf_avail);
 882
 883                 /*
 884                  * A desc buf might across two host physical pages that are
 885                  * not continuous. In such case (gpa_to_hpa returns 0), data
 886                  * will be copied even though zero copy is enabled.
 887                  */
 888                 if (unlikely(dev->dequeue_zero_copy && (hpa = gpa_to_hpa(dev,
 889                                         desc->addr + desc_offset, cpy_len)))) {
 890                         cur->data_len = cpy_len;
 891                         cur->data_off = 0;
 892                         cur->buf_addr = (void *)(uintptr_t)(desc_addr
 893                                 + desc_offset);
 894                         cur->buf_physaddr = hpa;
 895
 896                         /*
 897                          * In zero copy mode, one mbuf can only reference data
 898                          * for one or partial of one desc buff.
 899                          */
 900                         mbuf_avail = cpy_len;
 901                 } else {
 902                         rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *,
 903                                                            mbuf_offset),
 904                                 (void *)((uintptr_t)(desc_addr + desc_offset)),
 905                                 cpy_len);
 906                 }
 907
 908                 mbuf_avail  -= cpy_len;
 909                 mbuf_offset += cpy_len;
 910                 desc_avail  -= cpy_len;
 911                 desc_offset += cpy_len;
 912
 913                 /* This desc reaches to its end, get the next one */
 914                 if (desc_avail == 0) {
 915                         if ((desc->flags & VRING_DESC_F_NEXT) == 0)
 916                                 break;
 917
 918                         if (unlikely(desc->next >= max_desc ||
 919                                      ++nr_desc > max_desc))
 920                                 return -1;
 921                         desc = &descs[desc->next];
 922                         if (unlikely(desc->flags & VRING_DESC_F_INDIRECT))
 923                                 return -1;
 924
 925                         desc_addr = gpa_to_vva(dev, desc->addr);
 926                         if (unlikely(!desc_addr))
 927                                 return -1;
 928
 929                         rte_prefetch0((void *)(uintptr_t)desc_addr);
 930
 931                         desc_offset = 0;
 932                         desc_avail  = desc->len;
 933
 934                         PRINT_PACKET(dev, (uintptr_t)desc_addr, desc->len, 0);
 935                 }
 936
 937                 /*
 938                  * This mbuf reaches to its end, get a new one
 939                  * to hold more data.
 940                  */
 941                 if (mbuf_avail == 0) {
 942                         cur = rte_pktmbuf_alloc(mbuf_pool);
 943                         if (unlikely(cur == NULL)) {
 944                                 RTE_LOG(ERR, VHOST_DATA, "Failed to "
 945                                         "allocate memory for mbuf.\n");
 946                                 return -1;
 947                         }
 948                         if (unlikely(dev->dequeue_zero_copy))
 949                                 rte_mbuf_refcnt_update(cur, 1);
 950
 951                         prev->next = cur;
 952                         prev->data_len = mbuf_offset;
 953                         m->nb_segs += 1;
 954                         m->pkt_len += mbuf_offset;
 955                         prev = cur;
 956
 957                         mbuf_offset = 0;
 958                         mbuf_avail  = cur->buf_len - RTE_PKTMBUF_HEADROOM;
 959                 }
 960         }
 961
 962         prev->data_len = mbuf_offset;
 963         m->pkt_len    += mbuf_offset;
 964
 965         if (hdr)
 966                 vhost_dequeue_offload(hdr, m);
 967
 968         return 0;
 969 }
 970
 971 static inline void __attribute__((always_inline))
 972 update_used_ring(struct virtio_net *dev, struct vhost_virtqueue *vq,
 973                  uint32_t used_idx, uint32_t desc_idx)
 974 {
 975         vq->used->ring[used_idx].id  = desc_idx;
 976         vq->used->ring[used_idx].len = 0;
 977         vhost_log_used_vring(dev, vq,
 978                         offsetof(struct vring_used, ring[used_idx]),
 979                         sizeof(vq->used->ring[used_idx]));
 980 }
 981
 982 static inline void __attribute__((always_inline))
 983 update_used_idx(struct virtio_net *dev, struct vhost_virtqueue *vq,
 984                 uint32_t count)
 985 {
 986         if (unlikely(count == 0))
 987                 return;
 988
 989         rte_smp_wmb();
 990         rte_smp_rmb();
 991
 992         vq->used->idx += count;
 993         vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
 994                         sizeof(vq->used->idx));
 995
 996         /* Kick guest if required. */
 997         if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
 998                         && (vq->callfd >= 0))
 999                 eventfd_write(vq->callfd, (eventfd_t)1);
1000 }
1001
1002 static inline struct zcopy_mbuf *__attribute__((always_inline))
1003 get_zmbuf(struct vhost_virtqueue *vq)
1004 {
1005         uint16_t i;
1006         uint16_t last;
1007         int tries = 0;
1008
1009         /* search [last_zmbuf_idx, zmbuf_size) */
1010         i = vq->last_zmbuf_idx;
1011         last = vq->zmbuf_size;
1012
1013 again:
1014         for (; i < last; i++) {
1015                 if (vq->zmbufs[i].in_use == 0) {
1016                         vq->last_zmbuf_idx = i + 1;
1017                         vq->zmbufs[i].in_use = 1;
1018                         return &vq->zmbufs[i];
1019                 }
1020         }
1021
1022         tries++;
1023         if (tries == 1) {
1024                 /* search [0, last_zmbuf_idx) */
1025                 i = 0;
1026                 last = vq->last_zmbuf_idx;
1027                 goto again;
1028         }
1029
1030         return NULL;
1031 }
1032
1033 static inline bool __attribute__((always_inline))
1034 mbuf_is_consumed(struct rte_mbuf *m)
1035 {
1036         while (m) {
1037                 if (rte_mbuf_refcnt_read(m) > 1)
1038                         return false;
1039                 m = m->next;
1040         }
1041
1042         return true;
1043 }
1044
1045 static inline void __attribute__((always_inline))
1046 restore_mbuf(struct rte_mbuf *m)
1047 {
1048         uint32_t mbuf_size, priv_size;
1049
1050         while (m) {
1051                 priv_size = rte_pktmbuf_priv_size(m->pool);
1052                 mbuf_size = sizeof(struct rte_mbuf) + priv_size;
1053                 /* start of buffer is after mbuf structure and priv data */
1054
1055                 m->buf_addr = (char *)m + mbuf_size;
1056                 m->buf_physaddr = rte_mempool_virt2phy(NULL, m) + mbuf_size;
1057                 m = m->next;
1058         }
1059 }
1060
1061 uint16_t
1062 rte_vhost_dequeue_burst(int vid, uint16_t queue_id,
1063         struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts, uint16_t count)
1064 {
1065         struct virtio_net *dev;
1066         struct rte_mbuf *rarp_mbuf = NULL;
1067         struct vhost_virtqueue *vq;
1068         uint32_t desc_indexes[MAX_PKT_BURST];
1069         uint32_t used_idx;
1070         uint32_t i = 0;
1071         uint16_t free_entries;
1072         uint16_t avail_idx;
1073
1074         dev = get_device(vid);
1075         if (!dev)
1076                 return 0;
1077
1078         if (unlikely(!is_valid_virt_queue_idx(queue_id, 1, dev->virt_qp_nb))) {
1079                 RTE_LOG(ERR, VHOST_DATA, "(%d) %s: invalid virtqueue idx %d.\n",
1080                         dev->vid, __func__, queue_id);
1081                 return 0;
1082         }
1083
1084         vq = dev->virtqueue[queue_id];
1085
1086         if (unlikely(rte_spinlock_trylock(&vq->access_lock) == 0))
1087                 return 0;
1088
1089         if (unlikely(vq->enabled == 0))
1090                 goto out_access_unlock;
1091
1092         if (unlikely(dev->dequeue_zero_copy)) {
1093                 struct zcopy_mbuf *zmbuf, *next;
1094                 int nr_updated = 0;
1095
1096                 for (zmbuf = TAILQ_FIRST(&vq->zmbuf_list);
1097                      zmbuf != NULL; zmbuf = next) {
1098                         next = TAILQ_NEXT(zmbuf, next);
1099
1100                         if (mbuf_is_consumed(zmbuf->mbuf)) {
1101                                 used_idx = vq->last_used_idx++ & (vq->size - 1);
1102                                 update_used_ring(dev, vq, used_idx,
1103                                                  zmbuf->desc_idx);
1104                                 nr_updated += 1;
1105
1106                                 TAILQ_REMOVE(&vq->zmbuf_list, zmbuf, next);
1107                                 restore_mbuf(zmbuf->mbuf);
1108                                 rte_pktmbuf_free(zmbuf->mbuf);
1109                                 put_zmbuf(zmbuf);
1110                                 vq->nr_zmbuf -= 1;
1111                         }
1112                 }
1113
1114                 update_used_idx(dev, vq, nr_updated);
1115         }
1116
1117         /*
1118          * Construct a RARP broadcast packet, and inject it to the "pkts"
1119          * array, to looks like that guest actually send such packet.
1120          *
1121          * Check user_send_rarp() for more information.
1122          *
1123          * broadcast_rarp shares a cacheline in the virtio_net structure
1124          * with some fields that are accessed during enqueue and
1125          * rte_atomic16_cmpset() causes a write if using cmpxchg. This could
1126          * result in false sharing between enqueue and dequeue.
1127          *
1128          * Prevent unnecessary false sharing by reading broadcast_rarp first
1129          * and only performing cmpset if the read indicates it is likely to
1130          * be set.
1131          */
1132
1133         if (unlikely(rte_atomic16_read(&dev->broadcast_rarp) &&
1134                         rte_atomic16_cmpset((volatile uint16_t *)
1135                                 &dev->broadcast_rarp.cnt, 1, 0))) {
1136
1137                 rarp_mbuf = rte_pktmbuf_alloc(mbuf_pool);
1138                 if (rarp_mbuf == NULL) {
1139                         RTE_LOG(ERR, VHOST_DATA,
1140                                 "Failed to allocate memory for mbuf.\n");
1141                         goto out_access_unlock;
1142                 }
1143
1144                 if (make_rarp_packet(rarp_mbuf, &dev->mac)) {
1145                         rte_pktmbuf_free(rarp_mbuf);
1146                         rarp_mbuf = NULL;
1147                 } else {
1148                         count -= 1;
1149                 }
1150         }
1151
1152         free_entries = *((volatile uint16_t *)&vq->avail->idx) -
1153                         vq->last_avail_idx;
1154         if (free_entries == 0)
1155                 goto out_access_unlock;
1156
1157         LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
1158
1159         /* Prefetch available and used ring */
1160         avail_idx = vq->last_avail_idx & (vq->size - 1);
1161         used_idx  = vq->last_used_idx  & (vq->size - 1);
1162         rte_prefetch0(&vq->avail->ring[avail_idx]);
1163         rte_prefetch0(&vq->used->ring[used_idx]);
1164
1165         count = RTE_MIN(count, MAX_PKT_BURST);
1166         count = RTE_MIN(count, free_entries);
1167         LOG_DEBUG(VHOST_DATA, "(%d) about to dequeue %u buffers\n",
1168                         dev->vid, count);
1169
1170         /* Retrieve all of the head indexes first to avoid caching issues. */
1171         for (i = 0; i < count; i++) {
1172                 avail_idx = (vq->last_avail_idx + i) & (vq->size - 1);
1173                 used_idx  = (vq->last_used_idx  + i) & (vq->size - 1);
1174                 desc_indexes[i] = vq->avail->ring[avail_idx];
1175
1176                 if (likely(dev->dequeue_zero_copy == 0))
1177                         update_used_ring(dev, vq, used_idx, desc_indexes[i]);
1178         }
1179
1180         /* Prefetch descriptor index. */
1181         rte_prefetch0(&vq->desc[desc_indexes[0]]);
1182         for (i = 0; i < count; i++) {
1183                 struct vring_desc *desc;
1184                 uint16_t sz, idx;
1185                 int err;
1186
1187                 if (likely(i + 1 < count))
1188                         rte_prefetch0(&vq->desc[desc_indexes[i + 1]]);
1189
1190                 if (vq->desc[desc_indexes[i]].flags & VRING_DESC_F_INDIRECT) {
1191                         desc = (struct vring_desc *)(uintptr_t)gpa_to_vva(dev,
1192                                         vq->desc[desc_indexes[i]].addr);
1193                         if (unlikely(!desc))
1194                                 break;
1195
1196                         rte_prefetch0(desc);
1197                         sz = vq->desc[desc_indexes[i]].len / sizeof(*desc);
1198                         idx = 0;
1199                 } else {
1200                         desc = vq->desc;
1201                         sz = vq->size;
1202                         idx = desc_indexes[i];
1203                 }
1204
1205                 pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
1206                 if (unlikely(pkts[i] == NULL)) {
1207                         RTE_LOG(ERR, VHOST_DATA,
1208                                 "Failed to allocate memory for mbuf.\n");
1209                         break;
1210                 }
1211
1212                 err = copy_desc_to_mbuf(dev, desc, sz, pkts[i], idx, mbuf_pool);
1213                 if (unlikely(err)) {
1214                         rte_pktmbuf_free(pkts[i]);
1215                         break;
1216                 }
1217
1218                 if (unlikely(dev->dequeue_zero_copy)) {
1219                         struct zcopy_mbuf *zmbuf;
1220
1221                         zmbuf = get_zmbuf(vq);
1222                         if (!zmbuf) {
1223                                 rte_pktmbuf_free(pkts[i]);
1224                                 break;
1225                         }
1226                         zmbuf->mbuf = pkts[i];
1227                         zmbuf->desc_idx = desc_indexes[i];
1228
1229                         /*
1230                          * Pin lock the mbuf; we will check later to see
1231                          * whether the mbuf is freed (when we are the last
1232                          * user) or not. If that's the case, we then could
1233                          * update the used ring safely.
1234                          */
1235                         rte_mbuf_refcnt_update(pkts[i], 1);
1236
1237                         vq->nr_zmbuf += 1;
1238                         TAILQ_INSERT_TAIL(&vq->zmbuf_list, zmbuf, next);
1239                 }
1240         }
1241         vq->last_avail_idx += i;
1242
1243         if (likely(dev->dequeue_zero_copy == 0)) {
1244                 vq->last_used_idx += i;
1245                 update_used_idx(dev, vq, i);
1246         }
1247
1248 out_access_unlock:
1249         rte_spinlock_unlock(&vq->access_lock);
1250
1251         if (unlikely(rarp_mbuf != NULL)) {
1252                 /*
1253                  * Inject it to the head of "pkts" array, so that switch's mac
1254                  * learning table will get updated first.
1255                  */
1256                 memmove(&pkts[1], pkts, i * sizeof(struct rte_mbuf *));
1257                 pkts[0] = rarp_mbuf;
1258                 i += 1;
1259         }
1260
1261         return i;
1262 }