i40e_lan.cc

/*
 * Copyright 2021 Max Planck Institute for Software Systems, and
 * National University of Singapore
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <arpa/inet.h>
#include <stdlib.h>
#include <string.h>

#include <cassert>
#include <iostream>

#include "sims/nic/i40e_bm/headers.h"
#include "sims/nic/i40e_bm/i40e_base_wrapper.h"
#include "sims/nic/i40e_bm/i40e_bm.h"

namespace i40e {

lan::lan(i40e_bm &dev_, size_t num_qs_)
    : dev(dev_),
      log("lan", dev_),
      rss_kc(dev_.regs.pfqf_hkey),
      num_qs(num_qs_) {
  rxqs = new lan_queue_rx *[num_qs];
  txqs = new lan_queue_tx *[num_qs];

  for (size_t i = 0; i < num_qs; i++) {
    rxqs[i] =
        new lan_queue_rx(*this, dev.regs.qrx_tail[i], i, dev.regs.qrx_ena[i],
                         dev.regs.glhmc_lanrxbase[0], dev.regs.qint_rqctl[i]);
    txqs[i] =
        new lan_queue_tx(*this, dev.regs.qtx_tail[i], i, dev.regs.qtx_ena[i],
                         dev.regs.glhmc_lantxbase[0], dev.regs.qint_tqctl[i]);
  }
}

void lan::reset() {
  rss_kc.set_dirty();
  for (size_t i = 0; i < num_qs; i++) {
    rxqs[i]->reset();
    txqs[i]->reset();
  }
}

void lan::qena_updated(uint16_t idx, bool rx) {
  uint32_t &reg = (rx ? dev.regs.qrx_ena[idx] : dev.regs.qtx_ena[idx]);
#ifdef DEBUG_LAN
  log << " qena updated idx=" << idx << " rx=" << rx << " reg=" << reg
      << logger::endl;
#endif
  lan_queue_base &q = (rx ? static_cast<lan_queue_base &>(*rxqs[idx])
                          : static_cast<lan_queue_base &>(*txqs[idx]));

  if ((reg & I40E_QRX_ENA_QENA_REQ_MASK) && !q.is_enabled()) {
    q.enable();
  } else if (!(reg & I40E_QRX_ENA_QENA_REQ_MASK) && q.is_enabled()) {
    q.disable();
  }
}

void lan::tail_updated(uint16_t idx, bool rx) {
#ifdef DEBUG_LAN
  log << " tail updated idx=" << idx << " rx=" << rx << logger::endl;
#endif

  lan_queue_base &q = (rx ? static_cast<lan_queue_base &>(*rxqs[idx])
                          : static_cast<lan_queue_base &>(*txqs[idx]));

  if (q.is_enabled())
    q.reg_updated();
}

void lan::rss_key_updated() {
  rss_kc.set_dirty();
}

bool lan::rss_steering(const void *data, size_t len, uint16_t &queue,
                       uint32_t &hash) {
  hash = 0;

  const headers::pkt_tcp *tcp =
      reinterpret_cast<const headers::pkt_tcp *>(data);
  const headers::pkt_udp *udp =
      reinterpret_cast<const headers::pkt_udp *>(data);

  // should actually determine packet type and mask with enabled packet types
  // TODO(antoinek): ipv6
  if (tcp->eth.type == htons(ETH_TYPE_IP) && tcp->ip.proto == IP_PROTO_TCP) {
    hash = rss_kc.hash_ipv4(ntohl(tcp->ip.src), ntohl(tcp->ip.dest),
                            ntohs(tcp->tcp.src), ntohs(tcp->tcp.dest));
  } else if (udp->eth.type == htons(ETH_TYPE_IP) &&
             udp->ip.proto == IP_PROTO_UDP) {
    hash = rss_kc.hash_ipv4(ntohl(udp->ip.src), ntohl(udp->ip.dest),
                            ntohs(udp->udp.src), ntohs(udp->udp.dest));
  } else if (udp->eth.type == htons(ETH_TYPE_IP)) {
    hash = rss_kc.hash_ipv4(ntohl(udp->ip.src), ntohl(udp->ip.dest), 0, 0);
  } else {
    return false;
  }

  uint16_t luts =
      (!(dev.regs.pfqf_ctl_0 & I40E_PFQF_CTL_0_HASHLUTSIZE_MASK) ? 128 : 512);
  uint16_t idx = hash % luts;
  queue = (dev.regs.pfqf_hlut[idx / 4] >> (8 * (idx % 4))) & 0x3f;
#ifdef DEBUG_LAN
  log << "  q=" << queue << " h=" << hash << " i=" << idx << logger::endl;
#endif
  return true;
}

void lan::packet_received(const void *data, size_t len) {
#ifdef DEBUG_LAN
  log << " packet received len=" << len << logger::endl;
#endif

  uint32_t hash = 0;
  uint16_t queue = 0;
  rss_steering(data, len, queue, hash);
  rxqs[queue]->packet_received(data, len, hash);
}

lan_queue_base::lan_queue_base(lan &lanmgr_, const std::string &qtype,
                               uint32_t &reg_tail_, size_t idx_,
                               uint32_t &reg_ena_, uint32_t &fpm_basereg_,
                               uint32_t &reg_intqctl_, uint16_t ctx_size_)
    : queue_base(qtype + std::to_string(idx_), reg_dummy_head, reg_tail_,
                 lanmgr_.dev),
      lanmgr(lanmgr_),
      enabling(false),
      idx(idx_),
      reg_ena(reg_ena_),
      fpm_basereg(fpm_basereg_),
      reg_intqctl(reg_intqctl_),
      ctx_size(ctx_size_) {
  ctx = new uint8_t[ctx_size_];
}

void lan_queue_base::reset() {
  enabling = false;
  queue_base::reset();
}

void lan_queue_base::enable() {
  if (enabling || enabled)
    return;

#ifdef DEBUG_LAN
  log << " lan enabling queue " << idx << logger::endl;
#endif
  enabling = true;

  qctx_fetch *qf = new qctx_fetch(*this);
  qf->write_ = false;
  qf->dma_addr_ = ((fpm_basereg & I40E_GLHMC_LANTXBASE_FPMLANTXBASE_MASK) >>
                   I40E_GLHMC_LANTXBASE_FPMLANTXBASE_SHIFT) *
                  512;
  qf->dma_addr_ += ctx_size * idx;
  qf->len_ = ctx_size;
  qf->data_ = ctx;

  lanmgr.dev.hmc.issue_mem_op(*qf);
}

void lan_queue_base::ctx_fetched() {
#ifdef DEBUG_LAN
  log << " lan ctx fetched " << idx << logger::endl;
#endif

  initialize();

  enabling = false;
  enabled = true;
  reg_ena |= I40E_QRX_ENA_QENA_STAT_MASK;

  reg_updated();
}

void lan_queue_base::disable() {
#ifdef DEBUG_LAN
  log << " lan disabling queue " << idx << logger::endl;
#endif
  enabled = false;
  // TODO(antoinek): write back
  reg_ena &= ~I40E_QRX_ENA_QENA_STAT_MASK;
}

void lan_queue_base::interrupt() {
  uint32_t qctl = reg_intqctl;
  uint32_t gctl = lanmgr.dev.regs.pfint_dyn_ctl0;
#ifdef DEBUG_LAN
  log << " interrupt qctl=" << qctl << " gctl=" << gctl << logger::endl;
#endif

  uint16_t msix_idx = (qctl & I40E_QINT_TQCTL_MSIX_INDX_MASK) >>
                      I40E_QINT_TQCTL_MSIX_INDX_SHIFT;
  uint8_t msix0_idx = (qctl & I40E_QINT_TQCTL_MSIX0_INDX_MASK) >>
                      I40E_QINT_TQCTL_MSIX0_INDX_SHIFT;

  bool cause_ena = !!(qctl & I40E_QINT_TQCTL_CAUSE_ENA_MASK) &&
                   !!(gctl & I40E_PFINT_DYN_CTL0_INTENA_MASK);
  if (!cause_ena) {
#ifdef DEBUG_LAN
    log << " interrupt cause disabled" << logger::endl;
#endif
    return;
  }

  if (msix_idx == 0) {
#ifdef DEBUG_LAN
    log << "   setting int0.qidx=" << msix0_idx << logger::endl;
#endif
    lanmgr.dev.regs.pfint_icr0 |=
        I40E_PFINT_ICR0_INTEVENT_MASK |
        (1 << (I40E_PFINT_ICR0_QUEUE_0_SHIFT + msix0_idx));
  }

  uint8_t itr =
      (qctl & I40E_QINT_TQCTL_ITR_INDX_MASK) >> I40E_QINT_TQCTL_ITR_INDX_SHIFT;
  lanmgr.dev.SignalInterrupt(msix_idx, itr);
}

lan_queue_base::qctx_fetch::qctx_fetch(lan_queue_base &lq_) : lq(lq_) {
}

void lan_queue_base::qctx_fetch::done() {
  lq.ctx_fetched();
  delete this;
}

lan_queue_rx::lan_queue_rx(lan &lanmgr_, uint32_t &reg_tail_, size_t idx_,
                           uint32_t &reg_ena_, uint32_t &reg_fpmbase_,
                           uint32_t &reg_intqctl_)
    : lan_queue_base(lanmgr_, "rxq", reg_tail_, idx_, reg_ena_, reg_fpmbase_,
                     reg_intqctl_, 32) {
  // use larger value for initialization
  desc_len = 32;
  ctxs_init();
}

void lan_queue_rx::reset() {
  dcache.clear();
  queue_base::reset();
}

void lan_queue_rx::initialize() {
#ifdef DEBUG_LAN
  log << " initialize()" << logger::endl;
#endif
  uint8_t *ctx_p = reinterpret_cast<uint8_t *>(ctx);

  uint16_t *head_p = reinterpret_cast<uint16_t *>(ctx_p + 0);
  uint64_t *base_p = reinterpret_cast<uint64_t *>(ctx_p + 4);
  uint16_t *qlen_p = reinterpret_cast<uint16_t *>(ctx_p + 11);
  uint16_t *dbsz_p = reinterpret_cast<uint16_t *>(ctx_p + 12);
  uint16_t *hbsz_p = reinterpret_cast<uint16_t *>(ctx_p + 13);
  uint32_t *rxmax_p = reinterpret_cast<uint32_t *>(ctx_p + 21);

  reg_dummy_head = (*head_p) & ((1 << 13) - 1);

  base = ((*base_p) & ((1ULL << 57) - 1)) * 128;
  len = (*qlen_p >> 1) & ((1 << 13) - 1);

  dbuff_size = (((*dbsz_p) >> 6) & ((1 << 7) - 1)) * 128;
  hbuff_size = (((*hbsz_p) >> 5) & ((1 << 5) - 1)) * 64;
  uint8_t dtype = ((*hbsz_p) >> 10) & ((1 << 2) - 1);
  bool longdesc = !!(((*hbsz_p) >> 12) & 0x1);
  desc_len = (longdesc ? 32 : 16);
  crc_strip = !!(((*hbsz_p) >> 13) & 0x1);
  rxmax = (((*rxmax_p) >> 6) & ((1 << 14) - 1)) * 128;

  if (dtype != 0) {
    log << "lan_queue_rx::initialize: no header split supported"
        << logger::endl;
    abort();
  }

#ifdef DEBUG_LAN
  log << "  head=" << reg_dummy_head << " base=" << base << " len=" << len
      << " dbsz=" << dbuff_size << " hbsz=" << hbuff_size
      << " dtype=" << (unsigned)dtype << " longdesc=" << longdesc
      << " crcstrip=" << crc_strip << " rxmax=" << rxmax << logger::endl;
#endif
}

queue_base::desc_ctx &lan_queue_rx::desc_ctx_create() {
  return *new rx_desc_ctx(*this);
}

void lan_queue_rx::packet_received(const void *data, size_t pktlen,
                                   uint32_t h) {
  size_t num_descs = (pktlen + dbuff_size - 1) / dbuff_size;

  if (!enabled)
    return;

  if (dcache.size() < num_descs) {
#ifdef DEBUG_LAN
    log << " not enough rx descs (" << num_descs << ", dropping packet"
        << logger::endl;
#endif
    return;
  }

  for (size_t i = 0; i < num_descs; i++) {
    rx_desc_ctx &ctx = *dcache.front();

#ifdef DEBUG_LAN
    log << " packet part=" << i << " received didx=" << ctx.index
        << " cnt=" << dcache.size() << logger::endl;
#endif
    dcache.pop_front();

    const uint8_t *buf = (const uint8_t *)data + (dbuff_size * i);
    if (i == num_descs - 1) {
      // last packet
      ctx.packet_received(buf, pktlen - dbuff_size * i, true);
    } else {
      ctx.packet_received(buf, dbuff_size, false);
    }
  }
}

lan_queue_rx::rx_desc_ctx::rx_desc_ctx(lan_queue_rx &queue_)
    : desc_ctx(queue_), rq(queue_) {
}

void lan_queue_rx::rx_desc_ctx::data_written(uint64_t addr, size_t len) {
  processed();
}

void lan_queue_rx::rx_desc_ctx::process() {
  rq.dcache.push_back(this);
}

void lan_queue_rx::rx_desc_ctx::packet_received(const void *data, size_t pktlen,
                                                bool last) {
  // we only use fields in the lowest 16b anyways, even if set to 32b
  union i40e_16byte_rx_desc *rxd =
      reinterpret_cast<union i40e_16byte_rx_desc *>(desc);

  uint64_t addr = rxd->read.pkt_addr;

  memset(rxd, 0, sizeof(*rxd));
  // for 32b descriptors need to ensure to zero later fields
  if (desc_len > sizeof(*rxd))
    memset((uint8_t *)desc + sizeof(*rxd), 0, desc_len - sizeof(*rxd));

  rxd->wb.qword1.status_error_len |= (1 << I40E_RX_DESC_STATUS_DD_SHIFT);
  rxd->wb.qword1.status_error_len |= (pktlen << I40E_RXD_QW1_LENGTH_PBUF_SHIFT);

  if (last) {
    rxd->wb.qword1.status_error_len |= (1 << I40E_RX_DESC_STATUS_EOF_SHIFT);
    // TODO(antoinek): only if checksums are correct
    rxd->wb.qword1.status_error_len |= (1 << I40E_RX_DESC_STATUS_L3L4P_SHIFT);
  }
  data_write(addr, pktlen, data);
}

lan_queue_tx::lan_queue_tx(lan &lanmgr_, uint32_t &reg_tail_, size_t idx_,
                           uint32_t &reg_ena_, uint32_t &reg_fpmbase_,
                           uint32_t &reg_intqctl)
    : lan_queue_base(lanmgr_, "txq", reg_tail_, idx_, reg_ena_, reg_fpmbase_,
                     reg_intqctl, 128) {
  desc_len = 16;
  ctxs_init();
}

void lan_queue_tx::reset() {
  tso_off = 0;
  tso_len = 0;
  ready_segments.clear();
  queue_base::reset();
}

void lan_queue_tx::initialize() {
#ifdef DEBUG_LAN
  log << " initialize()" << logger::endl;
#endif
  uint8_t *ctx_p = reinterpret_cast<uint8_t *>(ctx);

  uint16_t *head_p = reinterpret_cast<uint16_t *>(ctx_p + 0);
  uint64_t *base_p = reinterpret_cast<uint64_t *>(ctx_p + 4);
  uint16_t *hwb_qlen_p = reinterpret_cast<uint16_t *>(ctx_p + 20);
  uint64_t *hwb_addr_p = reinterpret_cast<uint64_t *>(ctx_p + 24);

  reg_dummy_head = (*head_p) & ((1 << 13) - 1);

  base = ((*base_p) & ((1ULL << 57) - 1)) * 128;
  len = ((*hwb_qlen_p) >> 1) & ((1 << 13) - 1);

  hwb = !!(*hwb_qlen_p & (1 << 0));
  hwb_addr = *hwb_addr_p;

#ifdef DEBUG_LAN
  log << "  head=" << reg_dummy_head << " base=" << base << " len=" << len
      << " hwb=" << hwb << " hwb_addr=" << hwb_addr << logger::endl;
#endif
}

queue_base::desc_ctx &lan_queue_tx::desc_ctx_create() {
  return *new tx_desc_ctx(*this);
}

void lan_queue_tx::do_writeback(uint32_t first_idx, uint32_t first_pos,
                                uint32_t cnt) {
  if (!hwb) {
    // if head index writeback is disabled we need to write descriptor back
    lan_queue_base::do_writeback(first_idx, first_pos, cnt);
  } else {
    // else we just need to write the index back
    dma_hwb *dma = new dma_hwb(*this, first_pos, cnt, (first_idx + cnt) % len);
    dma->dma_addr_ = hwb_addr;

#ifdef DEBUG_LAN
    log << " hwb=" << *((uint32_t *)dma->data_) << logger::endl;
#endif
    dev.runner_->IssueDma(*dma);
  }
}

bool lan_queue_tx::trigger_tx_packet() {
  size_t n = ready_segments.size();
  size_t d_skip = 0, dcnt;
  bool eop = false;
  uint64_t d1;
  uint32_t iipt, l4t, pkt_len, total_len = 0, data_limit;
  bool tso = false;
  uint32_t tso_mss = 0, tso_paylen = 0;
  uint16_t maclen = 0, iplen = 0, l4len = 0;

  // abort if no queued up descriptors
  if (n == 0)
    return false;

#ifdef DEBUG_LAN
  log << "trigger_tx_packet(n=" << n
      << ", firstidx=" << ready_segments.at(0)->index << ")" << logger::endl;
  log << "  tso_off=" << tso_off << " tso_len=" << tso_len << logger::endl;
#endif

  // check if we have a context descriptor first
  tx_desc_ctx *rd = ready_segments.at(0);
  uint8_t dtype = (rd->d->cmd_type_offset_bsz & I40E_TXD_QW1_DTYPE_MASK) >>
                  I40E_TXD_QW1_DTYPE_SHIFT;
  if (dtype == I40E_TX_DESC_DTYPE_CONTEXT) {
    struct i40e_tx_context_desc *ctxd =
        reinterpret_cast<struct i40e_tx_context_desc *>(rd->d);
    d1 = ctxd->type_cmd_tso_mss;

    uint16_t cmd =
        ((d1 & I40E_TXD_CTX_QW1_CMD_MASK) >> I40E_TXD_CTX_QW1_CMD_SHIFT);
    tso = !!(cmd & I40E_TX_CTX_DESC_TSO);
    tso_mss = (d1 & I40E_TXD_CTX_QW1_MSS_MASK) >> I40E_TXD_CTX_QW1_MSS_SHIFT;

#ifdef DEBUG_LAN
    log << "  tso=" << tso << " mss=" << tso_mss << logger::endl;
#endif

    d_skip = 1;
  }

  // find EOP descriptor
  for (dcnt = d_skip; dcnt < n && !eop; dcnt++) {
    tx_desc_ctx *rd = ready_segments.at(dcnt);
    d1 = rd->d->cmd_type_offset_bsz;

#ifdef DEBUG_LAN
    log << " data fetched didx=" << rd->index << " d1=" << d1 << logger::endl;
#endif

    dtype = (d1 & I40E_TXD_QW1_DTYPE_MASK) >> I40E_TXD_QW1_DTYPE_SHIFT;
    if (dtype != I40E_TX_DESC_DTYPE_DATA) {
      log << "trigger tx desc is not a data descriptor idx=" << rd->index
          << " d1=" << d1 << logger::endl;
      abort();
    }

    uint16_t cmd = (d1 & I40E_TXD_QW1_CMD_MASK) >> I40E_TXD_QW1_CMD_SHIFT;
    eop = (cmd & I40E_TX_DESC_CMD_EOP);
    iipt = cmd & (I40E_TX_DESC_CMD_IIPT_MASK);
    l4t = (cmd & I40E_TX_DESC_CMD_L4T_EOFT_MASK);

    if (eop) {
      uint32_t off =
          (d1 & I40E_TXD_QW1_OFFSET_MASK) >> I40E_TXD_QW1_OFFSET_SHIFT;
      maclen = ((off & I40E_TXD_QW1_MACLEN_MASK) >>
                I40E_TX_DESC_LENGTH_MACLEN_SHIFT) *
               2;
      iplen =
          ((off & I40E_TXD_QW1_IPLEN_MASK) >> I40E_TX_DESC_LENGTH_IPLEN_SHIFT) *
          4;
      l4len = ((off & I40E_TXD_QW1_L4LEN_MASK) >>
               I40E_TX_DESC_LENGTH_L4_FC_LEN_SHIFT) *
              4;
    }

    pkt_len =
        (d1 & I40E_TXD_QW1_TX_BUF_SZ_MASK) >> I40E_TXD_QW1_TX_BUF_SZ_SHIFT;
    total_len += pkt_len;

#ifdef DEBUG_LAN
    log << "    eop=" << eop << " len=" << pkt_len << logger::endl;
#endif
  }

  // Unit not completely fetched yet
  if (!eop)
    return false;

  if (tso) {
    if (tso_off == 0)
      data_limit = maclen + iplen + l4len + tso_mss;
    else
      data_limit = tso_off + tso_mss;

    if (data_limit > total_len) {
      data_limit = total_len;
    }
  } else {
    if (total_len > MTU) {
      log << "    packet is longer (" << total_len << ") than MTU (" << MTU
          << ")" << logger::endl;
      abort();
    }
    data_limit = total_len;
  }

#ifdef DEBUG_LAN
  log << "    iipt=" << iipt << " l4t=" << l4t << " maclen=" << maclen
      << " iplen=" << iplen << " l4len=" << l4len << " total_len=" << total_len
      << " data_limit=" << data_limit << logger::endl;

#else
  (void)iipt;
#endif

  // copy data for this segment
  uint32_t off = 0;
  for (dcnt = d_skip; dcnt < n && off < data_limit; dcnt++) {
    tx_desc_ctx *rd = ready_segments.at(dcnt);
    d1 = rd->d->cmd_type_offset_bsz;
    uint16_t pkt_len =
        (d1 & I40E_TXD_QW1_TX_BUF_SZ_MASK) >> I40E_TXD_QW1_TX_BUF_SZ_SHIFT;

    if (off <= tso_off && off + pkt_len > tso_off) {
      uint32_t start = tso_off;
      uint32_t end = off + pkt_len;
      if (end > data_limit)
        end = data_limit;

#ifdef DEBUG_LAN
      log << "    copying data from off=" << off << " idx=" << rd->index
          << " start=" << start << " end=" << end << " tso_len=" << tso_len
          << logger::endl;
#endif

      memcpy(pktbuf + tso_len, (uint8_t *)rd->data + (start - off),
             end - start);
      tso_off = end;
      tso_len += end - start;
    }

    off += pkt_len;
  }

  assert(tso_len <= MTU);

  if (!tso) {
#ifdef DEBUG_LAN
    log << "    normal non-tso packet" << logger::endl;
#endif

    if (l4t == I40E_TX_DESC_CMD_L4T_EOFT_TCP) {
      uint16_t tcp_off = maclen + iplen;
      xsum_tcp(pktbuf + tcp_off, tso_len - tcp_off);
    } else if (l4t == I40E_TX_DESC_CMD_L4T_EOFT_UDP) {
      uint16_t udp_off = maclen + iplen;
      xsum_udp(pktbuf + udp_off, tso_len - udp_off);
    }

    dev.runner_->EthSend(pktbuf, tso_len);
  } else {
#ifdef DEBUG_LAN
    log << "    tso packet off=" << tso_off << " len=" << tso_len
        << logger::endl;
#endif

    // TSO gets hairier
    uint16_t hdrlen = maclen + iplen + l4len;

    // calculate payload size
    tso_paylen = tso_len - hdrlen;
    if (tso_paylen > tso_mss)
      tso_paylen = tso_mss;

    xsum_tcpip_tso(pktbuf + maclen, iplen, l4len, tso_paylen);

    dev.runner_->EthSend(pktbuf, tso_len);

    tso_postupdate_header(pktbuf + maclen, iplen, l4len, tso_paylen);

    // not done yet with this TSO unit
    if (tso && tso_off < total_len) {
      tso_len = hdrlen;
      return true;
    }
  }

#ifdef DEBUG_LAN
  log << "    unit done" << logger::endl;
#endif
  while (dcnt-- > 0) {
    ready_segments.front()->processed();
    ready_segments.pop_front();
  }

  tso_len = 0;
  tso_off = 0;

  return true;
}

void lan_queue_tx::trigger_tx() {
  while (trigger_tx_packet()) {
  }
}

lan_queue_tx::tx_desc_ctx::tx_desc_ctx(lan_queue_tx &queue_)
    : desc_ctx(queue_), tq(queue_) {
  d = reinterpret_cast<struct i40e_tx_desc *>(desc);
}

void lan_queue_tx::tx_desc_ctx::prepare() {
  uint64_t d1 = d->cmd_type_offset_bsz;

#ifdef DEBUG_LAN
  queue.log << " desc fetched didx=" << index << " d1=" << d1 << logger::endl;
#endif

  uint8_t dtype = (d1 & I40E_TXD_QW1_DTYPE_MASK) >> I40E_TXD_QW1_DTYPE_SHIFT;
  if (dtype == I40E_TX_DESC_DTYPE_DATA) {
    uint16_t len =
        (d1 & I40E_TXD_QW1_TX_BUF_SZ_MASK) >> I40E_TXD_QW1_TX_BUF_SZ_SHIFT;

#ifdef DEBUG_LAN
    queue.log << "  bufaddr=" << d->buffer_addr << " len=" << len
              << logger::endl;
#endif

    data_fetch(d->buffer_addr, len);
  } else if (dtype == I40E_TX_DESC_DTYPE_CONTEXT) {
#ifdef DEBUG_LAN
    struct i40e_tx_context_desc *ctxd =
        reinterpret_cast<struct i40e_tx_context_desc *>(d);
    queue.log << "  context descriptor: tp=" << ctxd->tunneling_params
              << " l2t=" << ctxd->l2tag2 << " tctm=" << ctxd->type_cmd_tso_mss
              << logger::endl;
#endif

    prepared();
  } else {
    queue.log << "txq: only support context & data descriptors" << logger::endl;
    abort();
  }
}

void lan_queue_tx::tx_desc_ctx::process() {
  tq.ready_segments.push_back(this);
  tq.trigger_tx();
}

void lan_queue_tx::tx_desc_ctx::processed() {
  d->cmd_type_offset_bsz = I40E_TX_DESC_DTYPE_DESC_DONE
                           << I40E_TXD_QW1_DTYPE_SHIFT;
  desc_ctx::processed();
}

lan_queue_tx::dma_hwb::dma_hwb(lan_queue_tx &queue_, uint32_t pos_,
                               uint32_t cnt_, uint32_t nh_)
    : queue(queue_), pos(pos_), cnt(cnt_), next_head(nh_) {
  data_ = &next_head;
  len_ = 4;
  write_ = true;
}

lan_queue_tx::dma_hwb::~dma_hwb() {
}

void lan_queue_tx::dma_hwb::done() {
#ifdef DEBUG_LAN
  queue.log << " tx head written back" << logger::endl;
#endif
  queue.writeback_done(pos, cnt);
  queue.trigger();
  delete this;
}
}  // namespace i40e