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