drivers/net/virtio/virtio_rxtx.c

   1 /*-
   2  *   BSD LICENSE
   3  *
   4  *   Copyright(c) 2010-2014 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 <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <errno.h>
  39
  40 #include <rte_cycles.h>
  41 #include <rte_memory.h>
  42 #include <rte_memzone.h>
  43 #include <rte_branch_prediction.h>
  44 #include <rte_mempool.h>
  45 #include <rte_malloc.h>
  46 #include <rte_mbuf.h>
  47 #include <rte_ether.h>
  48 #include <rte_ethdev.h>
  49 #include <rte_prefetch.h>
  50 #include <rte_string_fns.h>
  51 #include <rte_errno.h>
  52 #include <rte_byteorder.h>
  53 #include <rte_cpuflags.h>
  54 #include <rte_net.h>
  55 #include <rte_ip.h>
  56 #include <rte_udp.h>
  57 #include <rte_tcp.h>
  58
  59 #include "virtio_logs.h"
  60 #include "virtio_ethdev.h"
  61 #include "virtio_pci.h"
  62 #include "virtqueue.h"
  63 #include "virtio_rxtx.h"
  64
  65 #ifdef RTE_LIBRTE_VIRTIO_DEBUG_DUMP
  66 #define VIRTIO_DUMP_PACKET(m, len) rte_pktmbuf_dump(stdout, m, len)
  67 #else
  68 #define  VIRTIO_DUMP_PACKET(m, len) do { } while (0)
  69 #endif
  70
  71
  72 #define VIRTIO_SIMPLE_FLAGS ((uint32_t)ETH_TXQ_FLAGS_NOMULTSEGS | \
  73         ETH_TXQ_FLAGS_NOOFFLOADS)
  74
  75 int
  76 virtio_dev_rx_queue_done(void *rxq, uint16_t offset)
  77 {
  78         struct virtnet_rx *rxvq = rxq;
  79         struct virtqueue *vq = rxvq->vq;
  80
  81         return VIRTQUEUE_NUSED(vq) >= offset;
  82 }
  83
  84 static void
  85 vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx)
  86 {
  87         struct vring_desc *dp, *dp_tail;
  88         struct vq_desc_extra *dxp;
  89         uint16_t desc_idx_last = desc_idx;
  90
  91         dp  = &vq->vq_ring.desc[desc_idx];
  92         dxp = &vq->vq_descx[desc_idx];
  93         vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt + dxp->ndescs);
  94         if ((dp->flags & VRING_DESC_F_INDIRECT) == 0) {
  95                 while (dp->flags & VRING_DESC_F_NEXT) {
  96                         desc_idx_last = dp->next;
  97                         dp = &vq->vq_ring.desc[dp->next];
  98                 }
  99         }
 100         dxp->ndescs = 0;
 101
 102         /*
 103          * We must append the existing free chain, if any, to the end of
 104          * newly freed chain. If the virtqueue was completely used, then
 105          * head would be VQ_RING_DESC_CHAIN_END (ASSERTed above).
 106          */
 107         if (vq->vq_desc_tail_idx == VQ_RING_DESC_CHAIN_END) {
 108                 vq->vq_desc_head_idx = desc_idx;
 109         } else {
 110                 dp_tail = &vq->vq_ring.desc[vq->vq_desc_tail_idx];
 111                 dp_tail->next = desc_idx;
 112         }
 113
 114         vq->vq_desc_tail_idx = desc_idx_last;
 115         dp->next = VQ_RING_DESC_CHAIN_END;
 116 }
 117
 118 static uint16_t
 119 virtqueue_dequeue_burst_rx(struct virtqueue *vq, struct rte_mbuf **rx_pkts,
 120                            uint32_t *len, uint16_t num)
 121 {
 122         struct vring_used_elem *uep;
 123         struct rte_mbuf *cookie;
 124         uint16_t used_idx, desc_idx;
 125         uint16_t i;
 126
 127         /*  Caller does the check */
 128         for (i = 0; i < num ; i++) {
 129                 used_idx = (uint16_t)(vq->vq_used_cons_idx & (vq->vq_nentries - 1));
 130                 uep = &vq->vq_ring.used->ring[used_idx];
 131                 desc_idx = (uint16_t) uep->id;
 132                 len[i] = uep->len;
 133                 cookie = (struct rte_mbuf *)vq->vq_descx[desc_idx].cookie;
 134
 135                 if (unlikely(cookie == NULL)) {
 136                         PMD_DRV_LOG(ERR, "vring descriptor with no mbuf cookie at %u",
 137                                 vq->vq_used_cons_idx);
 138                         break;
 139                 }
 140
 141                 rte_prefetch0(cookie);
 142                 rte_packet_prefetch(rte_pktmbuf_mtod(cookie, void *));
 143                 rx_pkts[i]  = cookie;
 144                 vq->vq_used_cons_idx++;
 145                 vq_ring_free_chain(vq, desc_idx);
 146                 vq->vq_descx[desc_idx].cookie = NULL;
 147         }
 148
 149         return i;
 150 }
 151
 152 #ifndef DEFAULT_TX_FREE_THRESH
 153 #define DEFAULT_TX_FREE_THRESH 32
 154 #endif
 155
 156 /* Cleanup from completed transmits. */
 157 static void
 158 virtio_xmit_cleanup(struct virtqueue *vq, uint16_t num)
 159 {
 160         uint16_t i, used_idx, desc_idx;
 161         for (i = 0; i < num; i++) {
 162                 struct vring_used_elem *uep;
 163                 struct vq_desc_extra *dxp;
 164
 165                 used_idx = (uint16_t)(vq->vq_used_cons_idx & (vq->vq_nentries - 1));
 166                 uep = &vq->vq_ring.used->ring[used_idx];
 167
 168                 desc_idx = (uint16_t) uep->id;
 169                 dxp = &vq->vq_descx[desc_idx];
 170                 vq->vq_used_cons_idx++;
 171                 vq_ring_free_chain(vq, desc_idx);
 172
 173                 if (dxp->cookie != NULL) {
 174                         rte_pktmbuf_free(dxp->cookie);
 175                         dxp->cookie = NULL;
 176                 }
 177         }
 178 }
 179
 180
 181 static inline int
 182 virtqueue_enqueue_recv_refill(struct virtqueue *vq, struct rte_mbuf *cookie)
 183 {
 184         struct vq_desc_extra *dxp;
 185         struct virtio_hw *hw = vq->hw;
 186         struct vring_desc *start_dp;
 187         uint16_t needed = 1;
 188         uint16_t head_idx, idx;
 189
 190         if (unlikely(vq->vq_free_cnt == 0))
 191                 return -ENOSPC;
 192         if (unlikely(vq->vq_free_cnt < needed))
 193                 return -EMSGSIZE;
 194
 195         head_idx = vq->vq_desc_head_idx;
 196         if (unlikely(head_idx >= vq->vq_nentries))
 197                 return -EFAULT;
 198
 199         idx = head_idx;
 200         dxp = &vq->vq_descx[idx];
 201         dxp->cookie = (void *)cookie;
 202         dxp->ndescs = needed;
 203
 204         start_dp = vq->vq_ring.desc;
 205         start_dp[idx].addr =
 206                 VIRTIO_MBUF_ADDR(cookie, vq) +
 207                 RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
 208         start_dp[idx].len =
 209                 cookie->buf_len - RTE_PKTMBUF_HEADROOM + hw->vtnet_hdr_size;
 210         start_dp[idx].flags =  VRING_DESC_F_WRITE;
 211         idx = start_dp[idx].next;
 212         vq->vq_desc_head_idx = idx;
 213         if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
 214                 vq->vq_desc_tail_idx = idx;
 215         vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);
 216         vq_update_avail_ring(vq, head_idx);
 217
 218         return 0;
 219 }
 220
 221 /* When doing TSO, the IP length is not included in the pseudo header
 222  * checksum of the packet given to the PMD, but for virtio it is
 223  * expected.
 224  */
 225 static void
 226 virtio_tso_fix_cksum(struct rte_mbuf *m)
 227 {
 228         /* common case: header is not fragmented */
 229         if (likely(rte_pktmbuf_data_len(m) >= m->l2_len + m->l3_len +
 230                         m->l4_len)) {
 231                 struct ipv4_hdr *iph;
 232                 struct ipv6_hdr *ip6h;
 233                 struct tcp_hdr *th;
 234                 uint16_t prev_cksum, new_cksum, ip_len, ip_paylen;
 235                 uint32_t tmp;
 236
 237                 iph = rte_pktmbuf_mtod_offset(m, struct ipv4_hdr *, m->l2_len);
 238                 th = RTE_PTR_ADD(iph, m->l3_len);
 239                 if ((iph->version_ihl >> 4) == 4) {
 240                         iph->hdr_checksum = 0;
 241                         iph->hdr_checksum = rte_ipv4_cksum(iph);
 242                         ip_len = iph->total_length;
 243                         ip_paylen = rte_cpu_to_be_16(rte_be_to_cpu_16(ip_len) -
 244                                 m->l3_len);
 245                 } else {
 246                         ip6h = (struct ipv6_hdr *)iph;
 247                         ip_paylen = ip6h->payload_len;
 248                 }
 249
 250                 /* calculate the new phdr checksum not including ip_paylen */
 251                 prev_cksum = th->cksum;
 252                 tmp = prev_cksum;
 253                 tmp += ip_paylen;
 254                 tmp = (tmp & 0xffff) + (tmp >> 16);
 255                 new_cksum = tmp;
 256
 257                 /* replace it in the packet */
 258                 th->cksum = new_cksum;
 259         }
 260 }
 261
 262 static inline int
 263 tx_offload_enabled(struct virtio_hw *hw)
 264 {
 265         return vtpci_with_feature(hw, VIRTIO_NET_F_CSUM) ||
 266                 vtpci_with_feature(hw, VIRTIO_NET_F_HOST_TSO4) ||
 267                 vtpci_with_feature(hw, VIRTIO_NET_F_HOST_TSO6);
 268 }
 269
 270 /* avoid write operation when necessary, to lessen cache issues */
 271 #define ASSIGN_UNLESS_EQUAL(var, val) do {      \
 272         if ((var) != (val))                     \
 273                 (var) = (val);                  \
 274 } while (0)
 275
 276 static inline void
 277 virtqueue_enqueue_xmit(struct virtnet_tx *txvq, struct rte_mbuf *cookie,
 278                        uint16_t needed, int use_indirect, int can_push)
 279 {
 280         struct virtio_tx_region *txr = txvq->virtio_net_hdr_mz->addr;
 281         struct vq_desc_extra *dxp;
 282         struct virtqueue *vq = txvq->vq;
 283         struct vring_desc *start_dp;
 284         uint16_t seg_num = cookie->nb_segs;
 285         uint16_t head_idx, idx;
 286         uint16_t head_size = vq->hw->vtnet_hdr_size;
 287         struct virtio_net_hdr *hdr;
 288         int offload;
 289
 290         offload = tx_offload_enabled(vq->hw);
 291         head_idx = vq->vq_desc_head_idx;
 292         idx = head_idx;
 293         dxp = &vq->vq_descx[idx];
 294         dxp->cookie = (void *)cookie;
 295         dxp->ndescs = needed;
 296
 297         start_dp = vq->vq_ring.desc;
 298
 299         if (can_push) {
 300                 /* prepend cannot fail, checked by caller */
 301                 hdr = (struct virtio_net_hdr *)
 302                         rte_pktmbuf_prepend(cookie, head_size);
 303                 /* if offload disabled, it is not zeroed below, do it now */
 304                 if (offload == 0) {
 305                         ASSIGN_UNLESS_EQUAL(hdr->csum_start, 0);
 306                         ASSIGN_UNLESS_EQUAL(hdr->csum_offset, 0);
 307                         ASSIGN_UNLESS_EQUAL(hdr->flags, 0);
 308                         ASSIGN_UNLESS_EQUAL(hdr->gso_type, 0);
 309                         ASSIGN_UNLESS_EQUAL(hdr->gso_size, 0);
 310                         ASSIGN_UNLESS_EQUAL(hdr->hdr_len, 0);
 311                 }
 312         } else if (use_indirect) {
 313                 /* setup tx ring slot to point to indirect
 314                  * descriptor list stored in reserved region.
 315                  *
 316                  * the first slot in indirect ring is already preset
 317                  * to point to the header in reserved region
 318                  */
 319                 start_dp[idx].addr  = txvq->virtio_net_hdr_mem +
 320                         RTE_PTR_DIFF(&txr[idx].tx_indir, txr);
 321                 start_dp[idx].len   = (seg_num + 1) * sizeof(struct vring_desc);
 322                 start_dp[idx].flags = VRING_DESC_F_INDIRECT;
 323                 hdr = (struct virtio_net_hdr *)&txr[idx].tx_hdr;
 324
 325                 /* loop below will fill in rest of the indirect elements */
 326                 start_dp = txr[idx].tx_indir;
 327                 idx = 1;
 328         } else {
 329                 /* setup first tx ring slot to point to header
 330                  * stored in reserved region.
 331                  */
 332                 start_dp[idx].addr  = txvq->virtio_net_hdr_mem +
 333                         RTE_PTR_DIFF(&txr[idx].tx_hdr, txr);
 334                 start_dp[idx].len   = vq->hw->vtnet_hdr_size;
 335                 start_dp[idx].flags = VRING_DESC_F_NEXT;
 336                 hdr = (struct virtio_net_hdr *)&txr[idx].tx_hdr;
 337
 338                 idx = start_dp[idx].next;
 339         }
 340
 341         /* Checksum Offload / TSO */
 342         if (offload) {
 343                 if (cookie->ol_flags & PKT_TX_TCP_SEG)
 344                         cookie->ol_flags |= PKT_TX_TCP_CKSUM;
 345
 346                 switch (cookie->ol_flags & PKT_TX_L4_MASK) {
 347                 case PKT_TX_UDP_CKSUM:
 348                         hdr->csum_start = cookie->l2_len + cookie->l3_len;
 349                         hdr->csum_offset = offsetof(struct udp_hdr,
 350                                 dgram_cksum);
 351                         hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 352                         break;
 353
 354                 case PKT_TX_TCP_CKSUM:
 355                         hdr->csum_start = cookie->l2_len + cookie->l3_len;
 356                         hdr->csum_offset = offsetof(struct tcp_hdr, cksum);
 357                         hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 358                         break;
 359
 360                 default:
 361                         ASSIGN_UNLESS_EQUAL(hdr->csum_start, 0);
 362                         ASSIGN_UNLESS_EQUAL(hdr->csum_offset, 0);
 363                         ASSIGN_UNLESS_EQUAL(hdr->flags, 0);
 364                         break;
 365                 }
 366
 367                 /* TCP Segmentation Offload */
 368                 if (cookie->ol_flags & PKT_TX_TCP_SEG) {
 369                         virtio_tso_fix_cksum(cookie);
 370                         hdr->gso_type = (cookie->ol_flags & PKT_TX_IPV6) ?
 371                                 VIRTIO_NET_HDR_GSO_TCPV6 :
 372                                 VIRTIO_NET_HDR_GSO_TCPV4;
 373                         hdr->gso_size = cookie->tso_segsz;
 374                         hdr->hdr_len =
 375                                 cookie->l2_len +
 376                                 cookie->l3_len +
 377                                 cookie->l4_len;
 378                 } else {
 379                         ASSIGN_UNLESS_EQUAL(hdr->gso_type, 0);
 380                         ASSIGN_UNLESS_EQUAL(hdr->gso_size, 0);
 381                         ASSIGN_UNLESS_EQUAL(hdr->hdr_len, 0);
 382                 }
 383         }
 384
 385         do {
 386                 start_dp[idx].addr  = VIRTIO_MBUF_DATA_DMA_ADDR(cookie, vq);
 387                 start_dp[idx].len   = cookie->data_len;
 388                 start_dp[idx].flags = cookie->next ? VRING_DESC_F_NEXT : 0;
 389                 idx = start_dp[idx].next;
 390         } while ((cookie = cookie->next) != NULL);
 391
 392         if (use_indirect)
 393                 idx = vq->vq_ring.desc[head_idx].next;
 394
 395         vq->vq_desc_head_idx = idx;
 396         if (vq->vq_desc_head_idx == VQ_RING_DESC_CHAIN_END)
 397                 vq->vq_desc_tail_idx = idx;
 398         vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - needed);
 399         vq_update_avail_ring(vq, head_idx);
 400 }
 401
 402 void
 403 virtio_dev_cq_start(struct rte_eth_dev *dev)
 404 {
 405         struct virtio_hw *hw = dev->data->dev_private;
 406
 407         if (hw->cvq && hw->cvq->vq) {
 408                 VIRTQUEUE_DUMP((struct virtqueue *)hw->cvq->vq);
 409         }
 410 }
 411
 412 int
 413 virtio_dev_rx_queue_setup(struct rte_eth_dev *dev,
 414                         uint16_t queue_idx,
 415                         uint16_t nb_desc,
 416                         unsigned int socket_id __rte_unused,
 417                         __rte_unused const struct rte_eth_rxconf *rx_conf,
 418                         struct rte_mempool *mp)
 419 {
 420         uint16_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_RQ_QUEUE_IDX;
 421         struct virtio_hw *hw = dev->data->dev_private;
 422         struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
 423         struct virtnet_rx *rxvq;
 424
 425         PMD_INIT_FUNC_TRACE();
 426
 427         if (nb_desc == 0 || nb_desc > vq->vq_nentries)
 428                 nb_desc = vq->vq_nentries;
 429         vq->vq_free_cnt = RTE_MIN(vq->vq_free_cnt, nb_desc);
 430
 431         rxvq = &vq->rxq;
 432         rxvq->queue_id = queue_idx;
 433         rxvq->mpool = mp;
 434         if (rxvq->mpool == NULL) {
 435                 rte_exit(EXIT_FAILURE,
 436                         "Cannot allocate mbufs for rx virtqueue");
 437         }
 438         dev->data->rx_queues[queue_idx] = rxvq;
 439
 440         return 0;
 441 }
 442
 443 int
 444 virtio_dev_rx_queue_setup_finish(struct rte_eth_dev *dev, uint16_t queue_idx)
 445 {
 446         uint16_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_RQ_QUEUE_IDX;
 447         struct virtio_hw *hw = dev->data->dev_private;
 448         struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
 449         struct virtnet_rx *rxvq = &vq->rxq;
 450         struct rte_mbuf *m;
 451         uint16_t desc_idx;
 452         int error, nbufs;
 453
 454         PMD_INIT_FUNC_TRACE();
 455
 456         /* Allocate blank mbufs for the each rx descriptor */
 457         nbufs = 0;
 458
 459         if (hw->use_simple_rxtx) {
 460                 for (desc_idx = 0; desc_idx < vq->vq_nentries;
 461                      desc_idx++) {
 462                         vq->vq_ring.avail->ring[desc_idx] = desc_idx;
 463                         vq->vq_ring.desc[desc_idx].flags =
 464                                 VRING_DESC_F_WRITE;
 465                 }
 466         }
 467
 468         memset(&rxvq->fake_mbuf, 0, sizeof(rxvq->fake_mbuf));
 469         for (desc_idx = 0; desc_idx < RTE_PMD_VIRTIO_RX_MAX_BURST;
 470              desc_idx++) {
 471                 vq->sw_ring[vq->vq_nentries + desc_idx] =
 472                         &rxvq->fake_mbuf;
 473         }
 474
 475         while (!virtqueue_full(vq)) {
 476                 m = rte_mbuf_raw_alloc(rxvq->mpool);
 477                 if (m == NULL)
 478                         break;
 479
 480                 /* Enqueue allocated buffers */
 481                 if (hw->use_simple_rxtx)
 482                         error = virtqueue_enqueue_recv_refill_simple(vq, m);
 483                 else
 484                         error = virtqueue_enqueue_recv_refill(vq, m);
 485
 486                 if (error) {
 487                         rte_pktmbuf_free(m);
 488                         break;
 489                 }
 490                 nbufs++;
 491         }
 492
 493         vq_update_avail_idx(vq);
 494
 495         PMD_INIT_LOG(DEBUG, "Allocated %d bufs", nbufs);
 496
 497         virtio_rxq_vec_setup(rxvq);
 498
 499         VIRTQUEUE_DUMP(vq);
 500
 501         return 0;
 502 }
 503
 504 static void
 505 virtio_update_rxtx_handler(struct rte_eth_dev *dev,
 506                            const struct rte_eth_txconf *tx_conf)
 507 {
 508         uint8_t use_simple_rxtx = 0;
 509         struct virtio_hw *hw = dev->data->dev_private;
 510
 511 #if defined RTE_ARCH_X86
 512         if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_SSE3))
 513                 use_simple_rxtx = 1;
 514 #elif defined RTE_ARCH_ARM64 || defined CONFIG_RTE_ARCH_ARM
 515         if (rte_cpu_get_flag_enabled(RTE_CPUFLAG_NEON))
 516                 use_simple_rxtx = 1;
 517 #endif
 518         /* Use simple rx/tx func if single segment and no offloads */
 519         if (use_simple_rxtx &&
 520             (tx_conf->txq_flags & VIRTIO_SIMPLE_FLAGS) == VIRTIO_SIMPLE_FLAGS &&
 521             !vtpci_with_feature(hw, VIRTIO_NET_F_MRG_RXBUF)) {
 522                 PMD_INIT_LOG(INFO, "Using simple rx/tx path");
 523                 dev->tx_pkt_burst = virtio_xmit_pkts_simple;
 524                 dev->rx_pkt_burst = virtio_recv_pkts_vec;
 525                 hw->use_simple_rxtx = use_simple_rxtx;
 526         }
 527 }
 528
 529 /*
 530  * struct rte_eth_dev *dev: Used to update dev
 531  * uint16_t nb_desc: Defaults to values read from config space
 532  * unsigned int socket_id: Used to allocate memzone
 533  * const struct rte_eth_txconf *tx_conf: Used to setup tx engine
 534  * uint16_t queue_idx: Just used as an index in dev txq list
 535  */
 536 int
 537 virtio_dev_tx_queue_setup(struct rte_eth_dev *dev,
 538                         uint16_t queue_idx,
 539                         uint16_t nb_desc,
 540                         unsigned int socket_id __rte_unused,
 541                         const struct rte_eth_txconf *tx_conf)
 542 {
 543         uint8_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_TQ_QUEUE_IDX;
 544         struct virtio_hw *hw = dev->data->dev_private;
 545         struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
 546         struct virtnet_tx *txvq;
 547         uint16_t tx_free_thresh;
 548
 549         PMD_INIT_FUNC_TRACE();
 550
 551         virtio_update_rxtx_handler(dev, tx_conf);
 552
 553         if (nb_desc == 0 || nb_desc > vq->vq_nentries)
 554                 nb_desc = vq->vq_nentries;
 555         vq->vq_free_cnt = RTE_MIN(vq->vq_free_cnt, nb_desc);
 556
 557         txvq = &vq->txq;
 558         txvq->queue_id = queue_idx;
 559
 560         tx_free_thresh = tx_conf->tx_free_thresh;
 561         if (tx_free_thresh == 0)
 562                 tx_free_thresh =
 563                         RTE_MIN(vq->vq_nentries / 4, DEFAULT_TX_FREE_THRESH);
 564
 565         if (tx_free_thresh >= (vq->vq_nentries - 3)) {
 566                 RTE_LOG(ERR, PMD, "tx_free_thresh must be less than the "
 567                         "number of TX entries minus 3 (%u)."
 568                         " (tx_free_thresh=%u port=%u queue=%u)\n",
 569                         vq->vq_nentries - 3,
 570                         tx_free_thresh, dev->data->port_id, queue_idx);
 571                 return -EINVAL;
 572         }
 573
 574         vq->vq_free_thresh = tx_free_thresh;
 575
 576         dev->data->tx_queues[queue_idx] = txvq;
 577         return 0;
 578 }
 579
 580 int
 581 virtio_dev_tx_queue_setup_finish(struct rte_eth_dev *dev,
 582                                 uint16_t queue_idx)
 583 {
 584         uint8_t vtpci_queue_idx = 2 * queue_idx + VTNET_SQ_TQ_QUEUE_IDX;
 585         struct virtio_hw *hw = dev->data->dev_private;
 586         struct virtqueue *vq = hw->vqs[vtpci_queue_idx];
 587         uint16_t mid_idx = vq->vq_nentries >> 1;
 588         struct virtnet_tx *txvq = &vq->txq;
 589         uint16_t desc_idx;
 590
 591         PMD_INIT_FUNC_TRACE();
 592
 593         if (hw->use_simple_rxtx) {
 594                 for (desc_idx = 0; desc_idx < mid_idx; desc_idx++) {
 595                         vq->vq_ring.avail->ring[desc_idx] =
 596                                 desc_idx + mid_idx;
 597                         vq->vq_ring.desc[desc_idx + mid_idx].next =
 598                                 desc_idx;
 599                         vq->vq_ring.desc[desc_idx + mid_idx].addr =
 600                                 txvq->virtio_net_hdr_mem +
 601                                 offsetof(struct virtio_tx_region, tx_hdr);
 602                         vq->vq_ring.desc[desc_idx + mid_idx].len =
 603                                 vq->hw->vtnet_hdr_size;
 604                         vq->vq_ring.desc[desc_idx + mid_idx].flags =
 605                                 VRING_DESC_F_NEXT;
 606                         vq->vq_ring.desc[desc_idx].flags = 0;
 607                 }
 608                 for (desc_idx = mid_idx; desc_idx < vq->vq_nentries;
 609                      desc_idx++)
 610                         vq->vq_ring.avail->ring[desc_idx] = desc_idx;
 611         }
 612
 613         VIRTQUEUE_DUMP(vq);
 614
 615         return 0;
 616 }
 617
 618 static void
 619 virtio_discard_rxbuf(struct virtqueue *vq, struct rte_mbuf *m)
 620 {
 621         int error;
 622         /*
 623          * Requeue the discarded mbuf. This should always be
 624          * successful since it was just dequeued.
 625          */
 626         error = virtqueue_enqueue_recv_refill(vq, m);
 627         if (unlikely(error)) {
 628                 RTE_LOG(ERR, PMD, "cannot requeue discarded mbuf");
 629                 rte_pktmbuf_free(m);
 630         }
 631 }
 632
 633 static void
 634 virtio_update_packet_stats(struct virtnet_stats *stats, struct rte_mbuf *mbuf)
 635 {
 636         uint32_t s = mbuf->pkt_len;
 637         struct ether_addr *ea;
 638
 639         if (s == 64) {
 640                 stats->size_bins[1]++;
 641         } else if (s > 64 && s < 1024) {
 642                 uint32_t bin;
 643
 644                 /* count zeros, and offset into correct bin */
 645                 bin = (sizeof(s) * 8) - __builtin_clz(s) - 5;
 646                 stats->size_bins[bin]++;
 647         } else {
 648                 if (s < 64)
 649                         stats->size_bins[0]++;
 650                 else if (s < 1519)
 651                         stats->size_bins[6]++;
 652                 else if (s >= 1519)
 653                         stats->size_bins[7]++;
 654         }
 655
 656         ea = rte_pktmbuf_mtod(mbuf, struct ether_addr *);
 657         if (is_multicast_ether_addr(ea)) {
 658                 if (is_broadcast_ether_addr(ea))
 659                         stats->broadcast++;
 660                 else
 661                         stats->multicast++;
 662         }
 663 }
 664
 665 /* Optionally fill offload information in structure */
 666 static int
 667 virtio_rx_offload(struct rte_mbuf *m, struct virtio_net_hdr *hdr)
 668 {
 669         struct rte_net_hdr_lens hdr_lens;
 670         uint32_t hdrlen, ptype;
 671         int l4_supported = 0;
 672
 673         /* nothing to do */
 674         if (hdr->flags == 0 && hdr->gso_type == VIRTIO_NET_HDR_GSO_NONE)
 675                 return 0;
 676
 677         m->ol_flags |= PKT_RX_IP_CKSUM_UNKNOWN;
 678
 679         ptype = rte_net_get_ptype(m, &hdr_lens, RTE_PTYPE_ALL_MASK);
 680         m->packet_type = ptype;
 681         if ((ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_TCP ||
 682             (ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_UDP ||
 683             (ptype & RTE_PTYPE_L4_MASK) == RTE_PTYPE_L4_SCTP)
 684                 l4_supported = 1;
 685
 686         if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
 687                 hdrlen = hdr_lens.l2_len + hdr_lens.l3_len + hdr_lens.l4_len;
 688                 if (hdr->csum_start <= hdrlen && l4_supported) {
 689                         m->ol_flags |= PKT_RX_L4_CKSUM_NONE;
 690                 } else {
 691                         /* Unknown proto or tunnel, do sw cksum. We can assume
 692                          * the cksum field is in the first segment since the
 693                          * buffers we provided to the host are large enough.
 694                          * In case of SCTP, this will be wrong since it's a CRC
 695                          * but there's nothing we can do.
 696                          */
 697                         uint16_t csum, off;
 698
 699                         rte_raw_cksum_mbuf(m, hdr->csum_start,
 700                                 rte_pktmbuf_pkt_len(m) - hdr->csum_start,
 701                                 &csum);
 702                         if (likely(csum != 0xffff))
 703                                 csum = ~csum;
 704                         off = hdr->csum_offset + hdr->csum_start;
 705                         if (rte_pktmbuf_data_len(m) >= off + 1)
 706                                 *rte_pktmbuf_mtod_offset(m, uint16_t *,
 707                                         off) = csum;
 708                 }
 709         } else if (hdr->flags & VIRTIO_NET_HDR_F_DATA_VALID && l4_supported) {
 710                 m->ol_flags |= PKT_RX_L4_CKSUM_GOOD;
 711         }
 712
 713         /* GSO request, save required information in mbuf */
 714         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 715                 /* Check unsupported modes */
 716                 if ((hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN) ||
 717                     (hdr->gso_size == 0)) {
 718                         return -EINVAL;
 719                 }
 720
 721                 /* Update mss lengthes in mbuf */
 722                 m->tso_segsz = hdr->gso_size;
 723                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
 724                         case VIRTIO_NET_HDR_GSO_TCPV4:
 725                         case VIRTIO_NET_HDR_GSO_TCPV6:
 726                                 m->ol_flags |= PKT_RX_LRO | \
 727                                         PKT_RX_L4_CKSUM_NONE;
 728                                 break;
 729                         default:
 730                                 return -EINVAL;
 731                 }
 732         }
 733
 734         return 0;
 735 }
 736
 737 static inline int
 738 rx_offload_enabled(struct virtio_hw *hw)
 739 {
 740         return vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_CSUM) ||
 741                 vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_TSO4) ||
 742                 vtpci_with_feature(hw, VIRTIO_NET_F_GUEST_TSO6);
 743 }
 744
 745 #define VIRTIO_MBUF_BURST_SZ 64
 746 #define DESC_PER_CACHELINE (RTE_CACHE_LINE_SIZE / sizeof(struct vring_desc))
 747 uint16_t
 748 virtio_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts, uint16_t nb_pkts)
 749 {
 750         struct virtnet_rx *rxvq = rx_queue;
 751         struct virtqueue *vq = rxvq->vq;
 752         struct virtio_hw *hw = vq->hw;
 753         struct rte_mbuf *rxm, *new_mbuf;
 754         uint16_t nb_used, num, nb_rx;
 755         uint32_t len[VIRTIO_MBUF_BURST_SZ];
 756         struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
 757         int error;
 758         uint32_t i, nb_enqueued;
 759         uint32_t hdr_size;
 760         int offload;
 761         struct virtio_net_hdr *hdr;
 762
 763         nb_rx = 0;
 764         if (unlikely(hw->started == 0))
 765                 return nb_rx;
 766
 767         nb_used = VIRTQUEUE_NUSED(vq);
 768
 769         virtio_rmb();
 770
 771         num = likely(nb_used <= nb_pkts) ? nb_used : nb_pkts;
 772         if (unlikely(num > VIRTIO_MBUF_BURST_SZ))
 773                 num = VIRTIO_MBUF_BURST_SZ;
 774         if (likely(num > DESC_PER_CACHELINE))
 775                 num = num - ((vq->vq_used_cons_idx + num) % DESC_PER_CACHELINE);
 776
 777         num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, num);
 778         PMD_RX_LOG(DEBUG, "used:%d dequeue:%d", nb_used, num);
 779
 780         nb_enqueued = 0;
 781         hdr_size = hw->vtnet_hdr_size;
 782         offload = rx_offload_enabled(hw);
 783
 784         for (i = 0; i < num ; i++) {
 785                 rxm = rcv_pkts[i];
 786
 787                 PMD_RX_LOG(DEBUG, "packet len:%d", len[i]);
 788
 789                 if (unlikely(len[i] < hdr_size + ETHER_HDR_LEN)) {
 790                         PMD_RX_LOG(ERR, "Packet drop");
 791                         nb_enqueued++;
 792                         virtio_discard_rxbuf(vq, rxm);
 793                         rxvq->stats.errors++;
 794                         continue;
 795                 }
 796
 797                 rxm->port = rxvq->port_id;
 798                 rxm->data_off = RTE_PKTMBUF_HEADROOM;
 799                 rxm->ol_flags = 0;
 800                 rxm->vlan_tci = 0;
 801
 802                 rxm->pkt_len = (uint32_t)(len[i] - hdr_size);
 803                 rxm->data_len = (uint16_t)(len[i] - hdr_size);
 804
 805                 hdr = (struct virtio_net_hdr *)((char *)rxm->buf_addr +
 806                         RTE_PKTMBUF_HEADROOM - hdr_size);
 807
 808                 if (hw->vlan_strip)
 809                         rte_vlan_strip(rxm);
 810
 811                 if (offload && virtio_rx_offload(rxm, hdr) < 0) {
 812                         virtio_discard_rxbuf(vq, rxm);
 813                         rxvq->stats.errors++;
 814                         continue;
 815                 }
 816
 817                 VIRTIO_DUMP_PACKET(rxm, rxm->data_len);
 818
 819                 rx_pkts[nb_rx++] = rxm;
 820
 821                 rxvq->stats.bytes += rxm->pkt_len;
 822                 virtio_update_packet_stats(&rxvq->stats, rxm);
 823         }
 824
 825         rxvq->stats.packets += nb_rx;
 826
 827         /* Allocate new mbuf for the used descriptor */
 828         error = ENOSPC;
 829         while (likely(!virtqueue_full(vq))) {
 830                 new_mbuf = rte_mbuf_raw_alloc(rxvq->mpool);
 831                 if (unlikely(new_mbuf == NULL)) {
 832                         struct rte_eth_dev *dev
 833                                 = &rte_eth_devices[rxvq->port_id];
 834                         dev->data->rx_mbuf_alloc_failed++;
 835                         break;
 836                 }
 837                 error = virtqueue_enqueue_recv_refill(vq, new_mbuf);
 838                 if (unlikely(error)) {
 839                         rte_pktmbuf_free(new_mbuf);
 840                         break;
 841                 }
 842                 nb_enqueued++;
 843         }
 844
 845         if (likely(nb_enqueued)) {
 846                 vq_update_avail_idx(vq);
 847
 848                 if (unlikely(virtqueue_kick_prepare(vq))) {
 849                         virtqueue_notify(vq);
 850                         PMD_RX_LOG(DEBUG, "Notified");
 851                 }
 852         }
 853
 854         return nb_rx;
 855 }
 856
 857 uint16_t
 858 virtio_recv_mergeable_pkts(void *rx_queue,
 859                         struct rte_mbuf **rx_pkts,
 860                         uint16_t nb_pkts)
 861 {
 862         struct virtnet_rx *rxvq = rx_queue;
 863         struct virtqueue *vq = rxvq->vq;
 864         struct virtio_hw *hw = vq->hw;
 865         struct rte_mbuf *rxm, *new_mbuf;
 866         uint16_t nb_used, num, nb_rx;
 867         uint32_t len[VIRTIO_MBUF_BURST_SZ];
 868         struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
 869         struct rte_mbuf *prev;
 870         int error;
 871         uint32_t i, nb_enqueued;
 872         uint32_t seg_num;
 873         uint16_t extra_idx;
 874         uint32_t seg_res;
 875         uint32_t hdr_size;
 876         int offload;
 877
 878         nb_rx = 0;
 879         if (unlikely(hw->started == 0))
 880                 return nb_rx;
 881
 882         nb_used = VIRTQUEUE_NUSED(vq);
 883
 884         virtio_rmb();
 885
 886         PMD_RX_LOG(DEBUG, "used:%d", nb_used);
 887
 888         i = 0;
 889         nb_enqueued = 0;
 890         seg_num = 0;
 891         extra_idx = 0;
 892         seg_res = 0;
 893         hdr_size = hw->vtnet_hdr_size;
 894         offload = rx_offload_enabled(hw);
 895
 896         while (i < nb_used) {
 897                 struct virtio_net_hdr_mrg_rxbuf *header;
 898
 899                 if (nb_rx == nb_pkts)
 900                         break;
 901
 902                 num = virtqueue_dequeue_burst_rx(vq, rcv_pkts, len, 1);
 903                 if (num != 1)
 904                         continue;
 905
 906                 i++;
 907
 908                 PMD_RX_LOG(DEBUG, "dequeue:%d", num);
 909                 PMD_RX_LOG(DEBUG, "packet len:%d", len[0]);
 910
 911                 rxm = rcv_pkts[0];
 912
 913                 if (unlikely(len[0] < hdr_size + ETHER_HDR_LEN)) {
 914                         PMD_RX_LOG(ERR, "Packet drop");
 915                         nb_enqueued++;
 916                         virtio_discard_rxbuf(vq, rxm);
 917                         rxvq->stats.errors++;
 918                         continue;
 919                 }
 920
 921                 header = (struct virtio_net_hdr_mrg_rxbuf *)((char *)rxm->buf_addr +
 922                         RTE_PKTMBUF_HEADROOM - hdr_size);
 923                 seg_num = header->num_buffers;
 924
 925                 if (seg_num == 0)
 926                         seg_num = 1;
 927
 928                 rxm->data_off = RTE_PKTMBUF_HEADROOM;
 929                 rxm->nb_segs = seg_num;
 930                 rxm->ol_flags = 0;
 931                 rxm->vlan_tci = 0;
 932                 rxm->pkt_len = (uint32_t)(len[0] - hdr_size);
 933                 rxm->data_len = (uint16_t)(len[0] - hdr_size);
 934
 935                 rxm->port = rxvq->port_id;
 936                 rx_pkts[nb_rx] = rxm;
 937                 prev = rxm;
 938
 939                 if (offload && virtio_rx_offload(rxm, &header->hdr) < 0) {
 940                         virtio_discard_rxbuf(vq, rxm);
 941                         rxvq->stats.errors++;
 942                         continue;
 943                 }
 944
 945                 seg_res = seg_num - 1;
 946
 947                 while (seg_res != 0) {
 948                         /*
 949                          * Get extra segments for current uncompleted packet.
 950                          */
 951                         uint16_t  rcv_cnt =
 952                                 RTE_MIN(seg_res, RTE_DIM(rcv_pkts));
 953                         if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
 954                                 uint32_t rx_num =
 955                                         virtqueue_dequeue_burst_rx(vq,
 956                                         rcv_pkts, len, rcv_cnt);
 957                                 i += rx_num;
 958                                 rcv_cnt = rx_num;
 959                         } else {
 960                                 PMD_RX_LOG(ERR,
 961                                            "No enough segments for packet.");
 962                                 nb_enqueued++;
 963                                 virtio_discard_rxbuf(vq, rxm);
 964                                 rxvq->stats.errors++;
 965                                 break;
 966                         }
 967
 968                         extra_idx = 0;
 969
 970                         while (extra_idx < rcv_cnt) {
 971                                 rxm = rcv_pkts[extra_idx];
 972
 973                                 rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
 974                                 rxm->pkt_len = (uint32_t)(len[extra_idx]);
 975                                 rxm->data_len = (uint16_t)(len[extra_idx]);
 976
 977                                 if (prev)
 978                                         prev->next = rxm;
 979
 980                                 prev = rxm;
 981                                 rx_pkts[nb_rx]->pkt_len += rxm->pkt_len;
 982                                 extra_idx++;
 983                         };
 984                         seg_res -= rcv_cnt;
 985                 }
 986
 987                 if (hw->vlan_strip)
 988                         rte_vlan_strip(rx_pkts[nb_rx]);
 989
 990                 VIRTIO_DUMP_PACKET(rx_pkts[nb_rx],
 991                         rx_pkts[nb_rx]->data_len);
 992
 993                 rxvq->stats.bytes += rx_pkts[nb_rx]->pkt_len;
 994                 virtio_update_packet_stats(&rxvq->stats, rx_pkts[nb_rx]);
 995                 nb_rx++;
 996         }
 997
 998         rxvq->stats.packets += nb_rx;
 999
1000         /* Allocate new mbuf for the used descriptor */
1001         error = ENOSPC;
1002         while (likely(!virtqueue_full(vq))) {
1003                 new_mbuf = rte_mbuf_raw_alloc(rxvq->mpool);
1004                 if (unlikely(new_mbuf == NULL)) {
1005                         struct rte_eth_dev *dev
1006                                 = &rte_eth_devices[rxvq->port_id];
1007                         dev->data->rx_mbuf_alloc_failed++;
1008                         break;
1009                 }
1010                 error = virtqueue_enqueue_recv_refill(vq, new_mbuf);
1011                 if (unlikely(error)) {
1012                         rte_pktmbuf_free(new_mbuf);
1013                         break;
1014                 }
1015                 nb_enqueued++;
1016         }
1017
1018         if (likely(nb_enqueued)) {
1019                 vq_update_avail_idx(vq);
1020
1021                 if (unlikely(virtqueue_kick_prepare(vq))) {
1022                         virtqueue_notify(vq);
1023                         PMD_RX_LOG(DEBUG, "Notified");
1024                 }
1025         }
1026
1027         return nb_rx;
1028 }
1029
1030 uint16_t
1031 virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
1032 {
1033         struct virtnet_tx *txvq = tx_queue;
1034         struct virtqueue *vq = txvq->vq;
1035         struct virtio_hw *hw = vq->hw;
1036         uint16_t hdr_size = hw->vtnet_hdr_size;
1037         uint16_t nb_used, nb_tx = 0;
1038         int error;
1039
1040         if (unlikely(hw->started == 0))
1041                 return nb_tx;
1042
1043         if (unlikely(nb_pkts < 1))
1044                 return nb_pkts;
1045
1046         PMD_TX_LOG(DEBUG, "%d packets to xmit", nb_pkts);
1047         nb_used = VIRTQUEUE_NUSED(vq);
1048
1049         virtio_rmb();
1050         if (likely(nb_used > vq->vq_nentries - vq->vq_free_thresh))
1051                 virtio_xmit_cleanup(vq, nb_used);
1052
1053         for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
1054                 struct rte_mbuf *txm = tx_pkts[nb_tx];
1055                 int can_push = 0, use_indirect = 0, slots, need;
1056
1057                 /* Do VLAN tag insertion */
1058                 if (unlikely(txm->ol_flags & PKT_TX_VLAN_PKT)) {
1059                         error = rte_vlan_insert(&txm);
1060                         if (unlikely(error)) {
1061                                 rte_pktmbuf_free(txm);
1062                                 continue;
1063                         }
1064                 }
1065
1066                 /* optimize ring usage */
1067                 if ((vtpci_with_feature(hw, VIRTIO_F_ANY_LAYOUT) ||
1068                       vtpci_with_feature(hw, VIRTIO_F_VERSION_1)) &&
1069                     rte_mbuf_refcnt_read(txm) == 1 &&
1070                     RTE_MBUF_DIRECT(txm) &&
1071                     txm->nb_segs == 1 &&
1072                     rte_pktmbuf_headroom(txm) >= hdr_size &&
1073                     rte_is_aligned(rte_pktmbuf_mtod(txm, char *),
1074                                    __alignof__(struct virtio_net_hdr_mrg_rxbuf)))
1075                         can_push = 1;
1076                 else if (vtpci_with_feature(hw, VIRTIO_RING_F_INDIRECT_DESC) &&
1077                          txm->nb_segs < VIRTIO_MAX_TX_INDIRECT)
1078                         use_indirect = 1;
1079
1080                 /* How many main ring entries are needed to this Tx?
1081                  * any_layout => number of segments
1082                  * indirect   => 1
1083                  * default    => number of segments + 1
1084                  */
1085                 slots = use_indirect ? 1 : (txm->nb_segs + !can_push);
1086                 need = slots - vq->vq_free_cnt;
1087
1088                 /* Positive value indicates it need free vring descriptors */
1089                 if (unlikely(need > 0)) {
1090                         nb_used = VIRTQUEUE_NUSED(vq);
1091                         virtio_rmb();
1092                         need = RTE_MIN(need, (int)nb_used);
1093
1094                         virtio_xmit_cleanup(vq, need);
1095                         need = slots - vq->vq_free_cnt;
1096                         if (unlikely(need > 0)) {
1097                                 PMD_TX_LOG(ERR,
1098                                            "No free tx descriptors to transmit");
1099                                 break;
1100                         }
1101                 }
1102
1103                 /* Enqueue Packet buffers */
1104                 virtqueue_enqueue_xmit(txvq, txm, slots, use_indirect, can_push);
1105
1106                 txvq->stats.bytes += txm->pkt_len;
1107                 virtio_update_packet_stats(&txvq->stats, txm);
1108         }
1109
1110         txvq->stats.packets += nb_tx;
1111
1112         if (likely(nb_tx)) {
1113                 vq_update_avail_idx(vq);
1114
1115                 if (unlikely(virtqueue_kick_prepare(vq))) {
1116                         virtqueue_notify(vq);
1117                         PMD_TX_LOG(DEBUG, "Notified backend after xmit");
1118                 }
1119         }
1120
1121         return nb_tx;
1122 }