update sources to ceph Nautilus 14.2.1

[ceph.git] / ceph / src / seastar / dpdk / drivers / net / sfc / sfc_tx.c

/*-
 *   BSD LICENSE
 *
 * Copyright (c) 2016-2017 Solarflare Communications Inc.
 * All rights reserved.
 *
 * This software was jointly developed between OKTET Labs (under contract
 * for Solarflare) and Solarflare Communications, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "sfc.h"
#include "sfc_debug.h"
#include "sfc_log.h"
#include "sfc_ev.h"
#include "sfc_tx.h"
#include "sfc_tweak.h"
#include "sfc_kvargs.h"

/*
 * Maximum number of TX queue flush attempts in case of
 * failure or flush timeout
 */
#define SFC_TX_QFLUSH_ATTEMPTS          (3)

/*
 * Time to wait between event queue polling attempts when waiting for TX
 * queue flush done or flush failed events
 */
#define SFC_TX_QFLUSH_POLL_WAIT_MS      (1)

/*
 * Maximum number of event queue polling attempts when waiting for TX queue
 * flush done or flush failed events; it defines TX queue flush attempt timeout
 * together with SFC_TX_QFLUSH_POLL_WAIT_MS
 */
#define SFC_TX_QFLUSH_POLL_ATTEMPTS     (2000)

static int
sfc_tx_qcheck_conf(struct sfc_adapter *sa, uint16_t nb_tx_desc,
                   const struct rte_eth_txconf *tx_conf)
{
        unsigned int flags = tx_conf->txq_flags;
        const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
        int rc = 0;

        if (tx_conf->tx_rs_thresh != 0) {
                sfc_err(sa, "RS bit in transmit descriptor is not supported");
                rc = EINVAL;
        }

        if (tx_conf->tx_free_thresh > EFX_TXQ_LIMIT(nb_tx_desc)) {
                sfc_err(sa,
                        "TxQ free threshold too large: %u vs maximum %u",
                        tx_conf->tx_free_thresh, EFX_TXQ_LIMIT(nb_tx_desc));
                rc = EINVAL;
        }

        if (tx_conf->tx_thresh.pthresh != 0 ||
            tx_conf->tx_thresh.hthresh != 0 ||
            tx_conf->tx_thresh.wthresh != 0) {
                sfc_err(sa,
                        "prefetch/host/writeback thresholds are not supported");
                rc = EINVAL;
        }

        if (((flags & ETH_TXQ_FLAGS_NOMULTSEGS) == 0) &&
            (~sa->dp_tx->features & SFC_DP_TX_FEAT_MULTI_SEG)) {
                sfc_err(sa, "Multi-segment is not supported by %s datapath",
                        sa->dp_tx->dp.name);
                rc = EINVAL;
        }

        if ((flags & ETH_TXQ_FLAGS_NOVLANOFFL) == 0) {
                if (!encp->enc_hw_tx_insert_vlan_enabled) {
                        sfc_err(sa, "VLAN offload is not supported");
                        rc = EINVAL;
                } else if (~sa->dp_tx->features & SFC_DP_TX_FEAT_VLAN_INSERT) {
                        sfc_err(sa,
                                "VLAN offload is not supported by %s datapath",
                                sa->dp_tx->dp.name);
                        rc = EINVAL;
                }
        }

        if ((flags & ETH_TXQ_FLAGS_NOXSUMSCTP) == 0) {
                sfc_err(sa, "SCTP offload is not supported");
                rc = EINVAL;
        }

        /* We either perform both TCP and UDP offload, or no offload at all */
        if (((flags & ETH_TXQ_FLAGS_NOXSUMTCP) == 0) !=
            ((flags & ETH_TXQ_FLAGS_NOXSUMUDP) == 0)) {
                sfc_err(sa, "TCP and UDP offloads can't be set independently");
                rc = EINVAL;
        }

        return rc;
}

void
sfc_tx_qflush_done(struct sfc_txq *txq)
{
        txq->state |= SFC_TXQ_FLUSHED;
        txq->state &= ~SFC_TXQ_FLUSHING;
}

int
sfc_tx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
             uint16_t nb_tx_desc, unsigned int socket_id,
             const struct rte_eth_txconf *tx_conf)
{
        const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
        struct sfc_txq_info *txq_info;
        struct sfc_evq *evq;
        struct sfc_txq *txq;
        int rc = 0;
        struct sfc_dp_tx_qcreate_info info;

        sfc_log_init(sa, "TxQ = %u", sw_index);

        rc = sfc_tx_qcheck_conf(sa, nb_tx_desc, tx_conf);
        if (rc != 0)
                goto fail_bad_conf;

        SFC_ASSERT(sw_index < sa->txq_count);
        txq_info = &sa->txq_info[sw_index];

        SFC_ASSERT(nb_tx_desc <= sa->txq_max_entries);
        txq_info->entries = nb_tx_desc;

        rc = sfc_ev_qinit(sa, SFC_EVQ_TYPE_TX, sw_index,
                          txq_info->entries, socket_id, &evq);
        if (rc != 0)
                goto fail_ev_qinit;

        rc = ENOMEM;
        txq = rte_zmalloc_socket("sfc-txq", sizeof(*txq), 0, socket_id);
        if (txq == NULL)
                goto fail_txq_alloc;

        txq_info->txq = txq;

        txq->hw_index = sw_index;
        txq->evq = evq;
        txq->free_thresh =
                (tx_conf->tx_free_thresh) ? tx_conf->tx_free_thresh :
                SFC_TX_DEFAULT_FREE_THRESH;
        txq->flags = tx_conf->txq_flags;

        rc = sfc_dma_alloc(sa, "txq", sw_index, EFX_TXQ_SIZE(txq_info->entries),
                           socket_id, &txq->mem);
        if (rc != 0)
                goto fail_dma_alloc;

        memset(&info, 0, sizeof(info));
        info.free_thresh = txq->free_thresh;
        info.flags = tx_conf->txq_flags;
        info.txq_entries = txq_info->entries;
        info.dma_desc_size_max = encp->enc_tx_dma_desc_size_max;
        info.txq_hw_ring = txq->mem.esm_base;
        info.evq_entries = txq_info->entries;
        info.evq_hw_ring = evq->mem.esm_base;
        info.hw_index = txq->hw_index;
        info.mem_bar = sa->mem_bar.esb_base;

        rc = sa->dp_tx->qcreate(sa->eth_dev->data->port_id, sw_index,
                                &SFC_DEV_TO_PCI(sa->eth_dev)->addr,
                                socket_id, &info, &txq->dp);
        if (rc != 0)
                goto fail_dp_tx_qinit;

        evq->dp_txq = txq->dp;

        txq->state = SFC_TXQ_INITIALIZED;

        txq_info->deferred_start = (tx_conf->tx_deferred_start != 0);

        return 0;

fail_dp_tx_qinit:
        sfc_dma_free(sa, &txq->mem);

fail_dma_alloc:
        txq_info->txq = NULL;
        rte_free(txq);

fail_txq_alloc:
        sfc_ev_qfini(evq);

fail_ev_qinit:
        txq_info->entries = 0;

fail_bad_conf:
        sfc_log_init(sa, "failed (TxQ = %u, rc = %d)", sw_index, rc);
        return rc;
}

void
sfc_tx_qfini(struct sfc_adapter *sa, unsigned int sw_index)
{
        struct sfc_txq_info *txq_info;
        struct sfc_txq *txq;

        sfc_log_init(sa, "TxQ = %u", sw_index);

        SFC_ASSERT(sw_index < sa->txq_count);
        txq_info = &sa->txq_info[sw_index];

        txq = txq_info->txq;
        SFC_ASSERT(txq != NULL);
        SFC_ASSERT(txq->state == SFC_TXQ_INITIALIZED);

        sa->dp_tx->qdestroy(txq->dp);
        txq->dp = NULL;

        txq_info->txq = NULL;
        txq_info->entries = 0;

        sfc_dma_free(sa, &txq->mem);

        sfc_ev_qfini(txq->evq);
        txq->evq = NULL;

        rte_free(txq);
}

static int
sfc_tx_qinit_info(struct sfc_adapter *sa, unsigned int sw_index)
{
        sfc_log_init(sa, "TxQ = %u", sw_index);

        return 0;
}

static int
sfc_tx_check_mode(struct sfc_adapter *sa, const struct rte_eth_txmode *txmode)
{
        int rc = 0;

        switch (txmode->mq_mode) {
        case ETH_MQ_TX_NONE:
                break;
        default:
                sfc_err(sa, "Tx multi-queue mode %u not supported",
                        txmode->mq_mode);
                rc = EINVAL;
        }

        /*
         * These features are claimed to be i40e-specific,
         * but it does make sense to double-check their absence
         */
        if (txmode->hw_vlan_reject_tagged) {
                sfc_err(sa, "Rejecting tagged packets not supported");
                rc = EINVAL;
        }

        if (txmode->hw_vlan_reject_untagged) {
                sfc_err(sa, "Rejecting untagged packets not supported");
                rc = EINVAL;
        }

        if (txmode->hw_vlan_insert_pvid) {
                sfc_err(sa, "Port-based VLAN insertion not supported");
                rc = EINVAL;
        }

        return rc;
}

/**
 * Destroy excess queues that are no longer needed after reconfiguration
 * or complete close.
 */
static void
sfc_tx_fini_queues(struct sfc_adapter *sa, unsigned int nb_tx_queues)
{
        int sw_index;

        SFC_ASSERT(nb_tx_queues <= sa->txq_count);

        sw_index = sa->txq_count;
        while (--sw_index >= (int)nb_tx_queues) {
                if (sa->txq_info[sw_index].txq != NULL)
                        sfc_tx_qfini(sa, sw_index);
        }

        sa->txq_count = nb_tx_queues;
}

int
sfc_tx_configure(struct sfc_adapter *sa)
{
        const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
        const struct rte_eth_conf *dev_conf = &sa->eth_dev->data->dev_conf;
        const unsigned int nb_tx_queues = sa->eth_dev->data->nb_tx_queues;
        int rc = 0;

        sfc_log_init(sa, "nb_tx_queues=%u (old %u)",
                     nb_tx_queues, sa->txq_count);

        /*
         * The datapath implementation assumes absence of boundary
         * limits on Tx DMA descriptors. Addition of these checks on
         * datapath would simply make the datapath slower.
         */
        if (encp->enc_tx_dma_desc_boundary != 0) {
                rc = ENOTSUP;
                goto fail_tx_dma_desc_boundary;
        }

        rc = sfc_tx_check_mode(sa, &dev_conf->txmode);
        if (rc != 0)
                goto fail_check_mode;

        if (nb_tx_queues == sa->txq_count)
                goto done;

        if (sa->txq_info == NULL) {
                sa->txq_info = rte_calloc_socket("sfc-txqs", nb_tx_queues,
                                                 sizeof(sa->txq_info[0]), 0,
                                                 sa->socket_id);
                if (sa->txq_info == NULL)
                        goto fail_txqs_alloc;
        } else {
                struct sfc_txq_info *new_txq_info;

                if (nb_tx_queues < sa->txq_count)
                        sfc_tx_fini_queues(sa, nb_tx_queues);

                new_txq_info =
                        rte_realloc(sa->txq_info,
                                    nb_tx_queues * sizeof(sa->txq_info[0]), 0);
                if (new_txq_info == NULL && nb_tx_queues > 0)
                        goto fail_txqs_realloc;

                sa->txq_info = new_txq_info;
                if (nb_tx_queues > sa->txq_count)
                        memset(&sa->txq_info[sa->txq_count], 0,
                               (nb_tx_queues - sa->txq_count) *
                               sizeof(sa->txq_info[0]));
        }

        while (sa->txq_count < nb_tx_queues) {
                rc = sfc_tx_qinit_info(sa, sa->txq_count);
                if (rc != 0)
                        goto fail_tx_qinit_info;

                sa->txq_count++;
        }

done:
        return 0;

fail_tx_qinit_info:
fail_txqs_realloc:
fail_txqs_alloc:
        sfc_tx_close(sa);

fail_check_mode:
fail_tx_dma_desc_boundary:
        sfc_log_init(sa, "failed (rc = %d)", rc);
        return rc;
}

void
sfc_tx_close(struct sfc_adapter *sa)
{
        sfc_tx_fini_queues(sa, 0);

        rte_free(sa->txq_info);
        sa->txq_info = NULL;
}

int
sfc_tx_qstart(struct sfc_adapter *sa, unsigned int sw_index)
{
        struct rte_eth_dev_data *dev_data;
        struct sfc_txq_info *txq_info;
        struct sfc_txq *txq;
        struct sfc_evq *evq;
        uint16_t flags;
        unsigned int desc_index;
        int rc = 0;

        sfc_log_init(sa, "TxQ = %u", sw_index);

        SFC_ASSERT(sw_index < sa->txq_count);
        txq_info = &sa->txq_info[sw_index];

        txq = txq_info->txq;

        SFC_ASSERT(txq->state == SFC_TXQ_INITIALIZED);

        evq = txq->evq;

        rc = sfc_ev_qstart(evq, sfc_evq_index_by_txq_sw_index(sa, sw_index));
        if (rc != 0)
                goto fail_ev_qstart;

        /*
         * It seems that DPDK has no controls regarding IPv4 offloads,
         * hence, we always enable it here
         */
        if ((txq->flags & ETH_TXQ_FLAGS_NOXSUMTCP) ||
            (txq->flags & ETH_TXQ_FLAGS_NOXSUMUDP)) {
                flags = EFX_TXQ_CKSUM_IPV4;
        } else {
                flags = EFX_TXQ_CKSUM_IPV4 | EFX_TXQ_CKSUM_TCPUDP;

                if (sa->tso)
                        flags |= EFX_TXQ_FATSOV2;
        }

        rc = efx_tx_qcreate(sa->nic, sw_index, 0, &txq->mem,
                            txq_info->entries, 0 /* not used on EF10 */,
                            flags, evq->common,
                            &txq->common, &desc_index);
        if (rc != 0) {
                if (sa->tso && (rc == ENOSPC))
                        sfc_err(sa, "ran out of TSO contexts");

                goto fail_tx_qcreate;
        }

        efx_tx_qenable(txq->common);

        txq->state |= SFC_TXQ_STARTED;

        rc = sa->dp_tx->qstart(txq->dp, evq->read_ptr, desc_index);
        if (rc != 0)
                goto fail_dp_qstart;

        /*
         * It seems to be used by DPDK for debug purposes only ('rte_ether')
         */
        dev_data = sa->eth_dev->data;
        dev_data->tx_queue_state[sw_index] = RTE_ETH_QUEUE_STATE_STARTED;

        return 0;

fail_dp_qstart:
        txq->state = SFC_TXQ_INITIALIZED;
        efx_tx_qdestroy(txq->common);

fail_tx_qcreate:
        sfc_ev_qstop(evq);

fail_ev_qstart:
        return rc;
}

void
sfc_tx_qstop(struct sfc_adapter *sa, unsigned int sw_index)
{
        struct rte_eth_dev_data *dev_data;
        struct sfc_txq_info *txq_info;
        struct sfc_txq *txq;
        unsigned int retry_count;
        unsigned int wait_count;

        sfc_log_init(sa, "TxQ = %u", sw_index);

        SFC_ASSERT(sw_index < sa->txq_count);
        txq_info = &sa->txq_info[sw_index];

        txq = txq_info->txq;

        if (txq->state == SFC_TXQ_INITIALIZED)
                return;

        SFC_ASSERT(txq->state & SFC_TXQ_STARTED);

        sa->dp_tx->qstop(txq->dp, &txq->evq->read_ptr);

        /*
         * Retry TX queue flushing in case of flush failed or
         * timeout; in the worst case it can delay for 6 seconds
         */
        for (retry_count = 0;
             ((txq->state & SFC_TXQ_FLUSHED) == 0) &&
             (retry_count < SFC_TX_QFLUSH_ATTEMPTS);
             ++retry_count) {
                if (efx_tx_qflush(txq->common) != 0) {
                        txq->state |= SFC_TXQ_FLUSHING;
                        break;
                }

                /*
                 * Wait for TX queue flush done or flush failed event at least
                 * SFC_TX_QFLUSH_POLL_WAIT_MS milliseconds and not more
                 * than 2 seconds (SFC_TX_QFLUSH_POLL_WAIT_MS multiplied
                 * by SFC_TX_QFLUSH_POLL_ATTEMPTS)
                 */
                wait_count = 0;
                do {
                        rte_delay_ms(SFC_TX_QFLUSH_POLL_WAIT_MS);
                        sfc_ev_qpoll(txq->evq);
                } while ((txq->state & SFC_TXQ_FLUSHING) &&
                         wait_count++ < SFC_TX_QFLUSH_POLL_ATTEMPTS);

                if (txq->state & SFC_TXQ_FLUSHING)
                        sfc_err(sa, "TxQ %u flush timed out", sw_index);

                if (txq->state & SFC_TXQ_FLUSHED)
                        sfc_info(sa, "TxQ %u flushed", sw_index);
        }

        sa->dp_tx->qreap(txq->dp);

        txq->state = SFC_TXQ_INITIALIZED;

        efx_tx_qdestroy(txq->common);

        sfc_ev_qstop(txq->evq);

        /*
         * It seems to be used by DPDK for debug purposes only ('rte_ether')
         */
        dev_data = sa->eth_dev->data;
        dev_data->tx_queue_state[sw_index] = RTE_ETH_QUEUE_STATE_STOPPED;
}

int
sfc_tx_start(struct sfc_adapter *sa)
{
        unsigned int sw_index;
        int rc = 0;

        sfc_log_init(sa, "txq_count = %u", sa->txq_count);

        if (sa->tso) {
                if (!efx_nic_cfg_get(sa->nic)->enc_fw_assisted_tso_v2_enabled) {
                        sfc_warn(sa, "TSO support was unable to be restored");
                        sa->tso = B_FALSE;
                }
        }

        rc = efx_tx_init(sa->nic);
        if (rc != 0)
                goto fail_efx_tx_init;

        for (sw_index = 0; sw_index < sa->txq_count; ++sw_index) {
                if (!(sa->txq_info[sw_index].deferred_start) ||
                    sa->txq_info[sw_index].deferred_started) {
                        rc = sfc_tx_qstart(sa, sw_index);
                        if (rc != 0)
                                goto fail_tx_qstart;
                }
        }

        return 0;

fail_tx_qstart:
        while (sw_index-- > 0)
                sfc_tx_qstop(sa, sw_index);

        efx_tx_fini(sa->nic);

fail_efx_tx_init:
        sfc_log_init(sa, "failed (rc = %d)", rc);
        return rc;
}

void
sfc_tx_stop(struct sfc_adapter *sa)
{
        unsigned int sw_index;

        sfc_log_init(sa, "txq_count = %u", sa->txq_count);

        sw_index = sa->txq_count;
        while (sw_index-- > 0) {
                if (sa->txq_info[sw_index].txq != NULL)
                        sfc_tx_qstop(sa, sw_index);
        }

        efx_tx_fini(sa->nic);
}

static void
sfc_efx_tx_reap(struct sfc_efx_txq *txq)
{
        unsigned int completed;

        sfc_ev_qpoll(txq->evq);

        for (completed = txq->completed;
             completed != txq->pending; completed++) {
                struct sfc_efx_tx_sw_desc *txd;

                txd = &txq->sw_ring[completed & txq->ptr_mask];

                if (txd->mbuf != NULL) {
                        rte_pktmbuf_free(txd->mbuf);
                        txd->mbuf = NULL;
                }
        }

        txq->completed = completed;
}

/*
 * The function is used to insert or update VLAN tag;
 * the firmware has state of the firmware tag to insert per TxQ
 * (controlled by option descriptors), hence, if the tag of the
 * packet to be sent is different from one remembered by the firmware,
 * the function will update it
 */
static unsigned int
sfc_efx_tx_maybe_insert_tag(struct sfc_efx_txq *txq, struct rte_mbuf *m,
                            efx_desc_t **pend)
{
        uint16_t this_tag = ((m->ol_flags & PKT_TX_VLAN_PKT) ?
                             m->vlan_tci : 0);

        if (this_tag == txq->hw_vlan_tci)
                return 0;

        /*
         * The expression inside SFC_ASSERT() is not desired to be checked in
         * a non-debug build because it might be too expensive on the data path
         */
        SFC_ASSERT(efx_nic_cfg_get(txq->evq->sa->nic)->enc_hw_tx_insert_vlan_enabled);

        efx_tx_qdesc_vlantci_create(txq->common, rte_cpu_to_be_16(this_tag),
                                    *pend);
        (*pend)++;
        txq->hw_vlan_tci = this_tag;

        return 1;
}

static uint16_t
sfc_efx_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
{
        struct sfc_dp_txq *dp_txq = (struct sfc_dp_txq *)tx_queue;
        struct sfc_efx_txq *txq = sfc_efx_txq_by_dp_txq(dp_txq);
        unsigned int added = txq->added;
        unsigned int pushed = added;
        unsigned int pkts_sent = 0;
        efx_desc_t *pend = &txq->pend_desc[0];
        const unsigned int hard_max_fill = EFX_TXQ_LIMIT(txq->ptr_mask + 1);
        const unsigned int soft_max_fill = hard_max_fill - txq->free_thresh;
        unsigned int fill_level = added - txq->completed;
        boolean_t reap_done;
        int rc __rte_unused;
        struct rte_mbuf **pktp;

        if (unlikely((txq->flags & SFC_EFX_TXQ_FLAG_RUNNING) == 0))
                goto done;

        /*
         * If insufficient space for a single packet is present,
         * we should reap; otherwise, we shouldn't do that all the time
         * to avoid latency increase
         */
        reap_done = (fill_level > soft_max_fill);

        if (reap_done) {
                sfc_efx_tx_reap(txq);
                /*
                 * Recalculate fill level since 'txq->completed'
                 * might have changed on reap
                 */
                fill_level = added - txq->completed;
        }

        for (pkts_sent = 0, pktp = &tx_pkts[0];
             (pkts_sent < nb_pkts) && (fill_level <= soft_max_fill);
             pkts_sent++, pktp++) {
                struct rte_mbuf         *m_seg = *pktp;
                size_t                  pkt_len = m_seg->pkt_len;
                unsigned int            pkt_descs = 0;
                size_t                  in_off = 0;

                /*
                 * Here VLAN TCI is expected to be zero in case if no
                 * DEV_TX_VLAN_OFFLOAD capability is advertised;
                 * if the calling app ignores the absence of
                 * DEV_TX_VLAN_OFFLOAD and pushes VLAN TCI, then
                 * TX_ERROR will occur
                 */
                pkt_descs += sfc_efx_tx_maybe_insert_tag(txq, m_seg, &pend);

                if (m_seg->ol_flags & PKT_TX_TCP_SEG) {
                        /*
                         * We expect correct 'pkt->l[2, 3, 4]_len' values
                         * to be set correctly by the caller
                         */
                        if (sfc_efx_tso_do(txq, added, &m_seg, &in_off, &pend,
                                           &pkt_descs, &pkt_len) != 0) {
                                /* We may have reached this place for
                                 * one of the following reasons:
                                 *
                                 * 1) Packet header length is greater
                                 *    than SFC_TSOH_STD_LEN
                                 * 2) TCP header starts at more then
                                 *    208 bytes into the frame
                                 *
                                 * We will deceive RTE saying that we have sent
                                 * the packet, but we will actually drop it.
                                 * Hence, we should revert 'pend' to the
                                 * previous state (in case we have added
                                 * VLAN descriptor) and start processing
                                 * another one packet. But the original
                                 * mbuf shouldn't be orphaned
                                 */
                                pend -= pkt_descs;

                                rte_pktmbuf_free(*pktp);

                                continue;
                        }

                        /*
                         * We've only added 2 FATSOv2 option descriptors
                         * and 1 descriptor for the linearized packet header.
                         * The outstanding work will be done in the same manner
                         * as for the usual non-TSO path
                         */
                }

                for (; m_seg != NULL; m_seg = m_seg->next) {
                        efsys_dma_addr_t        next_frag;
                        size_t                  seg_len;

                        seg_len = m_seg->data_len;
                        next_frag = rte_mbuf_data_dma_addr(m_seg);

                        /*
                         * If we've started TSO transaction few steps earlier,
                         * we'll skip packet header using an offset in the
                         * current segment (which has been set to the
                         * first one containing payload)
                         */
                        seg_len -= in_off;
                        next_frag += in_off;
                        in_off = 0;

                        do {
                                efsys_dma_addr_t        frag_addr = next_frag;
                                size_t                  frag_len;

                                /*
                                 * It is assumed here that there is no
                                 * limitation on address boundary
                                 * crossing by DMA descriptor.
                                 */
                                frag_len = MIN(seg_len, txq->dma_desc_size_max);
                                next_frag += frag_len;
                                seg_len -= frag_len;
                                pkt_len -= frag_len;

                                efx_tx_qdesc_dma_create(txq->common,
                                                        frag_addr, frag_len,
                                                        (pkt_len == 0),
                                                        pend++);

                                pkt_descs++;
                        } while (seg_len != 0);
                }

                added += pkt_descs;

                fill_level += pkt_descs;
                if (unlikely(fill_level > hard_max_fill)) {
                        /*
                         * Our estimation for maximum number of descriptors
                         * required to send a packet seems to be wrong.
                         * Try to reap (if we haven't yet).
                         */
                        if (!reap_done) {
                                sfc_efx_tx_reap(txq);
                                reap_done = B_TRUE;
                                fill_level = added - txq->completed;
                                if (fill_level > hard_max_fill) {
                                        pend -= pkt_descs;
                                        break;
                                }
                        } else {
                                pend -= pkt_descs;
                                break;
                        }
                }

                /* Assign mbuf to the last used desc */
                txq->sw_ring[(added - 1) & txq->ptr_mask].mbuf = *pktp;
        }

        if (likely(pkts_sent > 0)) {
                rc = efx_tx_qdesc_post(txq->common, txq->pend_desc,
                                       pend - &txq->pend_desc[0],
                                       txq->completed, &txq->added);
                SFC_ASSERT(rc == 0);

                if (likely(pushed != txq->added))
                        efx_tx_qpush(txq->common, txq->added, pushed);
        }

#if SFC_TX_XMIT_PKTS_REAP_AT_LEAST_ONCE
        if (!reap_done)
                sfc_efx_tx_reap(txq);
#endif

done:
        return pkts_sent;
}

struct sfc_txq *
sfc_txq_by_dp_txq(const struct sfc_dp_txq *dp_txq)
{
        const struct sfc_dp_queue *dpq = &dp_txq->dpq;
        struct rte_eth_dev *eth_dev;
        struct sfc_adapter *sa;
        struct sfc_txq *txq;

        SFC_ASSERT(rte_eth_dev_is_valid_port(dpq->port_id));
        eth_dev = &rte_eth_devices[dpq->port_id];

        sa = eth_dev->data->dev_private;

        SFC_ASSERT(dpq->queue_id < sa->txq_count);
        txq = sa->txq_info[dpq->queue_id].txq;

        SFC_ASSERT(txq != NULL);
        return txq;
}

static sfc_dp_tx_qcreate_t sfc_efx_tx_qcreate;
static int
sfc_efx_tx_qcreate(uint16_t port_id, uint16_t queue_id,
                   const struct rte_pci_addr *pci_addr,
                   int socket_id,
                   const struct sfc_dp_tx_qcreate_info *info,
                   struct sfc_dp_txq **dp_txqp)
{
        struct sfc_efx_txq *txq;
        struct sfc_txq *ctrl_txq;
        int rc;

        rc = ENOMEM;
        txq = rte_zmalloc_socket("sfc-efx-txq", sizeof(*txq),
                                 RTE_CACHE_LINE_SIZE, socket_id);
        if (txq == NULL)
                goto fail_txq_alloc;

        sfc_dp_queue_init(&txq->dp.dpq, port_id, queue_id, pci_addr);

        rc = ENOMEM;
        txq->pend_desc = rte_calloc_socket("sfc-efx-txq-pend-desc",
                                           EFX_TXQ_LIMIT(info->txq_entries),
                                           sizeof(*txq->pend_desc), 0,
                                           socket_id);
        if (txq->pend_desc == NULL)
                goto fail_pend_desc_alloc;

        rc = ENOMEM;
        txq->sw_ring = rte_calloc_socket("sfc-efx-txq-sw_ring",
                                         info->txq_entries,
                                         sizeof(*txq->sw_ring),
                                         RTE_CACHE_LINE_SIZE, socket_id);
        if (txq->sw_ring == NULL)
                goto fail_sw_ring_alloc;

        ctrl_txq = sfc_txq_by_dp_txq(&txq->dp);
        if (ctrl_txq->evq->sa->tso) {
                rc = sfc_efx_tso_alloc_tsoh_objs(txq->sw_ring,
                                                 info->txq_entries, socket_id);
                if (rc != 0)
                        goto fail_alloc_tsoh_objs;
        }

        txq->evq = ctrl_txq->evq;
        txq->ptr_mask = info->txq_entries - 1;
        txq->free_thresh = info->free_thresh;
        txq->dma_desc_size_max = info->dma_desc_size_max;

        *dp_txqp = &txq->dp;
        return 0;

fail_alloc_tsoh_objs:
        rte_free(txq->sw_ring);

fail_sw_ring_alloc:
        rte_free(txq->pend_desc);

fail_pend_desc_alloc:
        rte_free(txq);

fail_txq_alloc:
        return rc;
}

static sfc_dp_tx_qdestroy_t sfc_efx_tx_qdestroy;
static void
sfc_efx_tx_qdestroy(struct sfc_dp_txq *dp_txq)
{
        struct sfc_efx_txq *txq = sfc_efx_txq_by_dp_txq(dp_txq);

        sfc_efx_tso_free_tsoh_objs(txq->sw_ring, txq->ptr_mask + 1);
        rte_free(txq->sw_ring);
        rte_free(txq->pend_desc);
        rte_free(txq);
}

static sfc_dp_tx_qstart_t sfc_efx_tx_qstart;
static int
sfc_efx_tx_qstart(struct sfc_dp_txq *dp_txq,
                  __rte_unused unsigned int evq_read_ptr,
                  unsigned int txq_desc_index)
{
        /* libefx-based datapath is specific to libefx-based PMD */
        struct sfc_efx_txq *txq = sfc_efx_txq_by_dp_txq(dp_txq);
        struct sfc_txq *ctrl_txq = sfc_txq_by_dp_txq(dp_txq);

        txq->common = ctrl_txq->common;

        txq->pending = txq->completed = txq->added = txq_desc_index;
        txq->hw_vlan_tci = 0;

        txq->flags |= (SFC_EFX_TXQ_FLAG_STARTED | SFC_EFX_TXQ_FLAG_RUNNING);

        return 0;
}

static sfc_dp_tx_qstop_t sfc_efx_tx_qstop;
static void
sfc_efx_tx_qstop(struct sfc_dp_txq *dp_txq,
                 __rte_unused unsigned int *evq_read_ptr)
{
        struct sfc_efx_txq *txq = sfc_efx_txq_by_dp_txq(dp_txq);

        txq->flags &= ~SFC_EFX_TXQ_FLAG_RUNNING;
}

static sfc_dp_tx_qreap_t sfc_efx_tx_qreap;
static void
sfc_efx_tx_qreap(struct sfc_dp_txq *dp_txq)
{
        struct sfc_efx_txq *txq = sfc_efx_txq_by_dp_txq(dp_txq);
        unsigned int txds;

        sfc_efx_tx_reap(txq);

        for (txds = 0; txds <= txq->ptr_mask; txds++) {
                if (txq->sw_ring[txds].mbuf != NULL) {
                        rte_pktmbuf_free(txq->sw_ring[txds].mbuf);
                        txq->sw_ring[txds].mbuf = NULL;
                }
        }

        txq->flags &= ~SFC_EFX_TXQ_FLAG_STARTED;
}

struct sfc_dp_tx sfc_efx_tx = {
        .dp = {
                .name           = SFC_KVARG_DATAPATH_EFX,
                .type           = SFC_DP_TX,
                .hw_fw_caps     = 0,
        },
        .features               = SFC_DP_TX_FEAT_VLAN_INSERT |
                                  SFC_DP_TX_FEAT_TSO |
                                  SFC_DP_TX_FEAT_MULTI_SEG,
        .qcreate                = sfc_efx_tx_qcreate,
        .qdestroy               = sfc_efx_tx_qdestroy,
        .qstart                 = sfc_efx_tx_qstart,
        .qstop                  = sfc_efx_tx_qstop,
        .qreap                  = sfc_efx_tx_qreap,
        .pkt_burst              = sfc_efx_xmit_pkts,
};