path: root/app/test-pmd/csumonly.c

/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2014 Intel Corporation. All rights reserved.
 *   Copyright 2014 6WIND S.A.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * 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.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   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 <stdarg.h>
#include <stdio.h>
#include <errno.h>
#include <stdint.h>
#include <unistd.h>
#include <inttypes.h>

#include <sys/queue.h>
#include <sys/stat.h>

#include <rte_common.h>
#include <rte_byteorder.h>
#include <rte_log.h>
#include <rte_debug.h>
#include <rte_cycles.h>
#include <rte_memory.h>
#include <rte_memcpy.h>
#include <rte_memzone.h>
#include <rte_launch.h>
#include <rte_eal.h>
#include <rte_per_lcore.h>
#include <rte_lcore.h>
#include <rte_atomic.h>
#include <rte_branch_prediction.h>
#include <rte_memory.h>
#include <rte_mempool.h>
#include <rte_mbuf.h>
#include <rte_memcpy.h>
#include <rte_interrupts.h>
#include <rte_pci.h>
#include <rte_ether.h>
#include <rte_ethdev.h>
#include <rte_ip.h>
#include <rte_tcp.h>
#include <rte_udp.h>
#include <rte_sctp.h>
#include <rte_prefetch.h>
#include <rte_string_fns.h>
#include "testpmd.h"

#define IP_DEFTTL  64   /* from RFC 1340. */
#define IP_VERSION 0x40
#define IP_HDRLEN  0x05 /* default IP header length == five 32-bits words. */
#define IP_VHL_DEF (IP_VERSION | IP_HDRLEN)

#define GRE_KEY_PRESENT 0x2000
#define GRE_KEY_LEN     4
#define GRE_SUPPORTED_FIELDS GRE_KEY_PRESENT

/* We cannot use rte_cpu_to_be_16() on a constant in a switch/case */
#if RTE_BYTE_ORDER == RTE_LITTLE_ENDIAN
#define _htons(x) ((uint16_t)((((x) & 0x00ffU) << 8) | (((x) & 0xff00U) >> 8)))
#else
#define _htons(x) (x)
#endif

/* structure that caches offload info for the current packet */
struct testpmd_offload_info {
	uint16_t ethertype;
	uint16_t l2_len;
	uint16_t l3_len;
	uint16_t l4_len;
	uint8_t l4_proto;
	uint8_t is_tunnel;
	uint16_t outer_ethertype;
	uint16_t outer_l2_len;
	uint16_t outer_l3_len;
	uint8_t outer_l4_proto;
	uint16_t tso_segsz;
	uint16_t tunnel_tso_segsz;
	uint32_t pkt_len;
};

/* simplified GRE header */
struct simple_gre_hdr {
	uint16_t flags;
	uint16_t proto;
} __attribute__((__packed__));

static uint16_t
get_psd_sum(void *l3_hdr, uint16_t ethertype, uint64_t ol_flags)
{
	if (ethertype == _htons(ETHER_TYPE_IPv4))
		return rte_ipv4_phdr_cksum(l3_hdr, ol_flags);
	else /* assume ethertype == ETHER_TYPE_IPv6 */
		return rte_ipv6_phdr_cksum(l3_hdr, ol_flags);
}

static uint16_t
get_udptcp_checksum(void *l3_hdr, void *l4_hdr, uint16_t ethertype)
{
	if (ethertype == _htons(ETHER_TYPE_IPv4))
		return rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr);
	else /* assume ethertype == ETHER_TYPE_IPv6 */
		return rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr);
}

/* Parse an IPv4 header to fill l3_len, l4_len, and l4_proto */
static void
parse_ipv4(struct ipv4_hdr *ipv4_hdr, struct testpmd_offload_info *info)
{
	struct tcp_hdr *tcp_hdr;

	info->l3_len = (ipv4_hdr->version_ihl & 0x0f) * 4;
	info->l4_proto = ipv4_hdr->next_proto_id;

	/* only fill l4_len for TCP, it's useful for TSO */
	if (info->l4_proto == IPPROTO_TCP) {
		tcp_hdr = (struct tcp_hdr *)((char *)ipv4_hdr + info->l3_len);
		info->l4_len = (tcp_hdr->data_off & 0xf0) >> 2;
	} else
		info->l4_len = 0;
}

/* Parse an IPv6 header to fill l3_len, l4_len, and l4_proto */
static void
parse_ipv6(struct ipv6_hdr *ipv6_hdr, struct testpmd_offload_info *info)
{
	struct tcp_hdr *tcp_hdr;

	info->l3_len = sizeof(struct ipv6_hdr);
	info->l4_proto = ipv6_hdr->proto;

	/* only fill l4_len for TCP, it's useful for TSO */
	if (info->l4_proto == IPPROTO_TCP) {
		tcp_hdr = (struct tcp_hdr *)((char *)ipv6_hdr + info->l3_len);
		info->l4_len = (tcp_hdr->data_off & 0xf0) >> 2;
	} else
		info->l4_len = 0;
}

/*
 * Parse an ethernet header to fill the ethertype, l2_len, l3_len and
 * ipproto. This function is able to recognize IPv4/IPv6 with one optional vlan
 * header. The l4_len argument is only set in case of TCP (useful for TSO).
 */
static void
parse_ethernet(struct ether_hdr *eth_hdr, struct testpmd_offload_info *info)
{
	struct ipv4_hdr *ipv4_hdr;
	struct ipv6_hdr *ipv6_hdr;

	info->l2_len = sizeof(struct ether_hdr);
	info->ethertype = eth_hdr->ether_type;

	if (info->ethertype == _htons(ETHER_TYPE_VLAN)) {
		struct vlan_hdr *vlan_hdr = (struct vlan_hdr *)(eth_hdr + 1);

		info->l2_len  += sizeof(struct vlan_hdr);
		info->ethertype = vlan_hdr->eth_proto;
	}

	switch (info->ethertype) {
	case _htons(ETHER_TYPE_IPv4):
		ipv4_hdr = (struct ipv4_hdr *) ((char *)eth_hdr + info->l2_len);
		parse_ipv4(ipv4_hdr, info);
		break;
	case _htons(ETHER_TYPE_IPv6):
		ipv6_hdr = (struct ipv6_hdr *) ((char *)eth_hdr + info->l2_len);
		parse_ipv6(ipv6_hdr, info);
		break;
	default:
		info->l4_len = 0;
		info->l3_len = 0;
		info->l4_proto = 0;
		break;
	}
}

/* Parse a vxlan header */
static void
parse_vxlan(struct udp_hdr *udp_hdr,
	    struct testpmd_offload_info *info,
	    uint32_t pkt_type)
{
	struct ether_hdr *eth_hdr;

	/* check udp destination port, 4789 is the default vxlan port
	 * (rfc7348) or that the rx offload flag is set (i40e only
	 * currently) */
	if (udp_hdr->dst_port != _htons(4789) &&
		RTE_ETH_IS_TUNNEL_PKT(pkt_type) == 0)
		return;

	info->is_tunnel = 1;
	info->outer_ethertype = info->ethertype;
	info->outer_l2_len = info->l2_len;
	info->outer_l3_len = info->l3_len;
	info->outer_l4_proto = info->l4_proto;

	eth_hdr = (struct ether_hdr *)((char *)udp_hdr +
		sizeof(struct udp_hdr) +
		sizeof(struct vxlan_hdr));

	parse_ethernet(eth_hdr, info);
	info->l2_len += ETHER_VXLAN_HLEN; /* add udp + vxlan */
}

/* Parse a gre header */
static void
parse_gre(struct simple_gre_hdr *gre_hdr, struct testpmd_offload_info *info)
{
	struct ether_hdr *eth_hdr;
	struct ipv4_hdr *ipv4_hdr;
	struct ipv6_hdr *ipv6_hdr;
	uint8_t gre_len = 0;

	/* check which fields are supported */
	if ((gre_hdr->flags & _htons(~GRE_SUPPORTED_FIELDS)) != 0)
		return;

	gre_len += sizeof(struct simple_gre_hdr);

	if (gre_hdr->flags & _htons(GRE_KEY_PRESENT))
		gre_len += GRE_KEY_LEN;

	if (gre_hdr->proto == _htons(ETHER_TYPE_IPv4)) {
		info->is_tunnel = 1;
		info->outer_ethertype = info->ethertype;
		info->outer_l2_len = info->l2_len;
		info->outer_l3_len = info->l3_len;
		info->outer_l4_proto = info->l4_proto;

		ipv4_hdr = (struct ipv4_hdr *)((char *)gre_hdr + gre_len);

		parse_ipv4(ipv4_hdr, info);
		info->ethertype = _htons(ETHER_TYPE_IPv4);
		info->l2_len = 0;

	} else if (gre_hdr->proto == _htons(ETHER_TYPE_IPv6)) {
		info->is_tunnel = 1;
		info->outer_ethertype = info->ethertype;
		info->outer_l2_len = info->l2_len;
		info->outer_l3_len = info->l3_len;
		info->outer_l4_proto = info->l4_proto;

		ipv6_hdr = (struct ipv6_hdr *)((char *)gre_hdr + gre_len);

		info->ethertype = _htons(ETHER_TYPE_IPv6);
		parse_ipv6(ipv6_hdr, info);
		info->l2_len = 0;

	} else if (gre_hdr->proto == _htons(ETHER_TYPE_TEB)) {
		info->is_tunnel = 1;
		info->outer_ethertype = info->ethertype;
		info->outer_l2_len = info->l2_len;
		info->outer_l3_len = info->l3_len;
		info->outer_l4_proto = info->l4_proto;

		eth_hdr = (struct ether_hdr *)((char *)gre_hdr + gre_len);

		parse_ethernet(eth_hdr, info);
	} else
		return;

	info->l2_len += gre_len;
}


/* Parse an encapsulated ip or ipv6 header */
static void
parse_encap_ip(void *encap_ip, struct testpmd_offload_info *info)
{
	struct ipv4_hdr *ipv4_hdr = encap_ip;
	struct ipv6_hdr *ipv6_hdr = encap_ip;
	uint8_t ip_version;

	ip_version = (ipv4_hdr->version_ihl & 0xf0) >> 4;

	if (ip_version != 4 && ip_version != 6)
		return;

	info->is_tunnel = 1;
	info->outer_ethertype = info->ethertype;
	info->outer_l2_len = info->l2_len;
	info->outer_l3_len = info->l3_len;

	if (ip_version == 4) {
		parse_ipv4(ipv4_hdr, info);
		info->ethertype = _htons(ETHER_TYPE_IPv4);
	} else {
		parse_ipv6(ipv6_hdr, info);
		info->ethertype = _htons(ETHER_TYPE_IPv6);
	}
	info->l2_len = 0;
}

/* if possible, calculate the checksum of a packet in hw or sw,
 * depending on the testpmd command line configuration */
static uint64_t
process_inner_cksums(void *l3_hdr, const struct testpmd_offload_info *info,
	uint16_t testpmd_ol_flags)
{
	struct ipv4_hdr *ipv4_hdr = l3_hdr;
	struct udp_hdr *udp_hdr;
	struct tcp_hdr *tcp_hdr;
	struct sctp_hdr *sctp_hdr;
	uint64_t ol_flags = 0;
	uint32_t max_pkt_len, tso_segsz = 0;

	/* ensure packet is large enough to require tso */
	if (!info->is_tunnel) {
		max_pkt_len = info->l2_len + info->l3_len + info->l4_len +
			info->tso_segsz;
		if (info->tso_segsz != 0 && info->pkt_len > max_pkt_len)
			tso_segsz = info->tso_segsz;
	} else {
		max_pkt_len = info->outer_l2_len + info->outer_l3_len +
			info->l2_len + info->l3_len + info->l4_len +
			info->tunnel_tso_segsz;
		if (info->tunnel_tso_segsz != 0 && info->pkt_len > max_pkt_len)
			tso_segsz = info->tunnel_tso_segsz;
	}

	if (info->ethertype == _htons(ETHER_TYPE_IPv4)) {
		ipv4_hdr = l3_hdr;
		ipv4_hdr->hdr_checksum = 0;

		ol_flags |= PKT_TX_IPV4;
		if (info->l4_proto == IPPROTO_TCP && tso_segsz) {
			ol_flags |= PKT_TX_IP_CKSUM;
		} else {
			if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_IP_CKSUM)
				ol_flags |= PKT_TX_IP_CKSUM;
			else
				ipv4_hdr->hdr_checksum =
					rte_ipv4_cksum(ipv4_hdr);
		}
	} else if (info->ethertype == _htons(ETHER_TYPE_IPv6))
		ol_flags |= PKT_TX_IPV6;
	else
		return 0; /* packet type not supported, nothing to do */

	if (info->l4_proto == IPPROTO_UDP) {
		udp_hdr = (struct udp_hdr *)((char *)l3_hdr + info->l3_len);
		/* do not recalculate udp cksum if it was 0 */
		if (udp_hdr->dgram_cksum != 0) {
			udp_hdr->dgram_cksum = 0;
			if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_UDP_CKSUM) {
				ol_flags |= PKT_TX_UDP_CKSUM;
				udp_hdr->dgram_cksum = get_psd_sum(l3_hdr,
					info->ethertype, ol_flags);
			} else {
				udp_hdr->dgram_cksum =
					get_udptcp_checksum(l3_hdr, udp_hdr,
						info->ethertype);
			}
		}
	} else if (info->l4_proto == IPPROTO_TCP) {
		tcp_hdr = (struct tcp_hdr *)((char *)l3_hdr + info->l3_len);
		tcp_hdr->cksum = 0;
		if (tso_segsz) {
			ol_flags |= PKT_TX_TCP_SEG;
			tcp_hdr->cksum = get_psd_sum(l3_hdr, info->ethertype,
				ol_flags);
		} else if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_TCP_CKSUM) {
			ol_flags |= PKT_TX_TCP_CKSUM;
			tcp_hdr->cksum = get_psd_sum(l3_hdr, info->ethertype,
				ol_flags);
		} else {
			tcp_hdr->cksum =
				get_udptcp_checksum(l3_hdr, tcp_hdr,
					info->ethertype);
		}
	} else if (info->l4_proto == IPPROTO_SCTP) {
		sctp_hdr = (struct sctp_hdr *)((char *)l3_hdr + info->l3_len);
		sctp_hdr->cksum = 0;
		/* sctp payload must be a multiple of 4 to be
		 * offloaded */
		if ((testpmd_ol_flags & TESTPMD_TX_OFFLOAD_SCTP_CKSUM) &&
			((ipv4_hdr->total_length & 0x3) == 0)) {
			ol_flags |= PKT_TX_SCTP_CKSUM;
		} else {
			/* XXX implement CRC32c, example available in
			 * RFC3309 */
		}
	}

	return ol_flags;
}

/* Calculate the checksum of outer header */
static uint64_t
process_outer_cksums(void *outer_l3_hdr, struct testpmd_offload_info *info,
	uint16_t testpmd_ol_flags, int tso_enabled)
{
	struct ipv4_hdr *ipv4_hdr = outer_l3_hdr;
	struct ipv6_hdr *ipv6_hdr = outer_l3_hdr;
	struct udp_hdr *udp_hdr;
	uint64_t ol_flags = 0;

	if (info->outer_ethertype == _htons(ETHER_TYPE_IPv4)) {
		ipv4_hdr->hdr_checksum = 0;
		ol_flags |= PKT_TX_OUTER_IPV4;

		if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_OUTER_IP_CKSUM)
			ol_flags |= PKT_TX_OUTER_IP_CKSUM;
		else
			ipv4_hdr->hdr_checksum = rte_ipv4_cksum(ipv4_hdr);
	} else if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_OUTER_IP_CKSUM)
		ol_flags |= PKT_TX_OUTER_IPV6;

	if (info->outer_l4_proto != IPPROTO_UDP)
		return ol_flags;

	udp_hdr = (struct udp_hdr *)((char *)outer_l3_hdr + info->outer_l3_len);

	/* outer UDP checksum is done in software as we have no hardware
	 * supporting it today, and no API for it. In the other side, for
	 * UDP tunneling, like VXLAN or Geneve, outer UDP checksum can be
	 * set to zero.
	 *
	 * If a packet will be TSOed into small packets by NIC, we cannot
	 * set/calculate a non-zero checksum, because it will be a wrong
	 * value after the packet be split into several small packets.
	 */
	if (tso_enabled)
		udp_hdr->dgram_cksum = 0;

	/* do not recalculate udp cksum if it was 0 */
	if (udp_hdr->dgram_cksum != 0) {
		udp_hdr->dgram_cksum = 0;
		if (info->outer_ethertype == _htons(ETHER_TYPE_IPv4))
			udp_hdr->dgram_cksum =
				rte_ipv4_udptcp_cksum(ipv4_hdr, udp_hdr);
		else
			udp_hdr->dgram_cksum =
				rte_ipv6_udptcp_cksum(ipv6_hdr, udp_hdr);
	}

	return ol_flags;
}

/*
 * Helper function.
 * Performs actual copying.
 * Returns number of segments in the destination mbuf on success,
 * or negative error code on failure.
 */
static int
mbuf_copy_split(const struct rte_mbuf *ms, struct rte_mbuf *md[],
	uint16_t seglen[], uint8_t nb_seg)
{
	uint32_t dlen, slen, tlen;
	uint32_t i, len;
	const struct rte_mbuf *m;
	const uint8_t *src;
	uint8_t *dst;

	dlen = 0;
	slen = 0;
	tlen = 0;

	dst = NULL;
	src = NULL;

	m = ms;
	i = 0;
	while (ms != NULL && i != nb_seg) {

		if (slen == 0) {
			slen = rte_pktmbuf_data_len(ms);
			src = rte_pktmbuf_mtod(ms, const uint8_t *);
		}

		if (dlen == 0) {
			dlen = RTE_MIN(seglen[i], slen);
			md[i]->data_len = dlen;
			md[i]->next = (i + 1 == nb_seg) ? NULL : md[i + 1];
			dst = rte_pktmbuf_mtod(md[i], uint8_t *);
		}

		len = RTE_MIN(slen, dlen);
		memcpy(dst, src, len);
		tlen += len;
		slen -= len;
		dlen -= len;
		src += len;
		dst += len;

		if (slen == 0)
			ms = ms->next;
		if (dlen == 0)
			i++;
	}

	if (ms != NULL)
		return -ENOBUFS;
	else if (tlen != m->pkt_len)
		return -EINVAL;

	md[0]->nb_segs = nb_seg;
	md[0]->pkt_len = tlen;
	md[0]->vlan_tci = m->vlan_tci;
	md[0]->vlan_tci_outer = m->vlan_tci_outer;
	md[0]->ol_flags = m->ol_flags;
	md[0]->tx_offload = m->tx_offload;

	return nb_seg;
}

/*
 * Allocate a new mbuf with up to tx_pkt_nb_segs segments.
 * Copy packet contents and offload information into then new segmented mbuf.
 */
static struct rte_mbuf *
pkt_copy_split(const struct rte_mbuf *pkt)
{
	int32_t n, rc;
	uint32_t i, len, nb_seg;
	struct rte_mempool *mp;
	uint16_t seglen[RTE_MAX_SEGS_PER_PKT];
	struct rte_mbuf *p, *md[RTE_MAX_SEGS_PER_PKT];

	mp = current_fwd_lcore()->mbp;

	if (tx_pkt_split == TX_PKT_SPLIT_RND)
		nb_seg = random() % tx_pkt_nb_segs + 1;
	else
		nb_seg = tx_pkt_nb_segs;

	memcpy(seglen, tx_pkt_seg_lengths, nb_seg * sizeof(seglen[0]));

	/* calculate number of segments to use and their length. */
	len = 0;
	for (i = 0; i != nb_seg && len < pkt->pkt_len; i++) {
		len += seglen[i];
		md[i] = NULL;
	}

	n = pkt->pkt_len - len;

	/* update size of the last segment to fit rest of the packet */
	if (n >= 0) {
		seglen[i - 1] += n;
		len += n;
	}

	nb_seg = i;
	while (i != 0) {
		p = rte_pktmbuf_alloc(mp);
		if (p == NULL) {
			RTE_LOG(ERR, USER1,
				"failed to allocate %u-th of %u mbuf "
				"from mempool: %s\n",
				nb_seg - i, nb_seg, mp->name);
			break;
		}

		md[--i] = p;
		if (rte_pktmbuf_tailroom(md[i]) < seglen[i]) {
			RTE_LOG(ERR, USER1, "mempool %s, %u-th segment: "
				"expected seglen: %u, "
				"actual mbuf tailroom: %u\n",
				mp->name, i, seglen[i],
				rte_pktmbuf_tailroom(md[i]));
			break;
		}
	}

	/* all mbufs successfully allocated, do copy */
	if (i == 0) {
		rc = mbuf_copy_split(pkt, md, seglen, nb_seg);
		if (rc < 0)
			RTE_LOG(ERR, USER1,
				"mbuf_copy_split for %p(len=%u, nb_seg=%hhu) "
				"into %u segments failed with error code: %d\n",
				pkt, pkt->pkt_len, pkt->nb_segs, nb_seg, rc);

		/* figure out how many mbufs to free. */
		i = RTE_MAX(rc, 0);
	}

	/* free unused mbufs */
	for (; i != nb_seg; i++) {
		rte_pktmbuf_free_seg(md[i]);
		md[i] = NULL;
	}

	return md[0];
}

/*
 * Receive a burst of packets, and for each packet:
 *  - parse packet, and try to recognize a supported packet type (1)
 *  - if it's not a supported packet type, don't touch the packet, else:
 *  - reprocess the checksum of all supported layers. This is done in SW
 *    or HW, depending on testpmd command line configuration
 *  - if TSO is enabled in testpmd command line, also flag the mbuf for TCP
 *    segmentation offload (this implies HW TCP checksum)
 * Then transmit packets on the output port.
 *
 * (1) Supported packets are:
 *   Ether / (vlan) / IP|IP6 / UDP|TCP|SCTP .
 *   Ether / (vlan) / outer IP|IP6 / outer UDP / VxLAN / Ether / IP|IP6 /
 *           UDP|TCP|SCTP
 *   Ether / (vlan) / outer IP|IP6 / GRE / Ether / IP|IP6 / UDP|TCP|SCTP
 *   Ether / (vlan) / outer IP|IP6 / GRE / IP|IP6 / UDP|TCP|SCTP
 *   Ether / (vlan) / outer IP|IP6 / IP|IP6 / UDP|TCP|SCTP
 *
 * The testpmd command line for this forward engine sets the flags
 * TESTPMD_TX_OFFLOAD_* in ports[tx_port].tx_ol_flags. They control
 * wether a checksum must be calculated in software or in hardware. The
 * IP, UDP, TCP and SCTP flags always concern the inner layer. The
 * OUTER_IP is only useful for tunnel packets.
 */
static void
pkt_burst_checksum_forward(struct fwd_stream *fs)
{
	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
	struct rte_port *txp;
	struct rte_mbuf *m, *p;
	struct ether_hdr *eth_hdr;
	void *l3_hdr = NULL, *outer_l3_hdr = NULL; /* can be IPv4 or IPv6 */
	uint16_t nb_rx;
	uint16_t nb_tx;
	uint16_t i;
	uint64_t rx_ol_flags, tx_ol_flags;
	uint16_t testpmd_ol_flags;
	uint32_t retry;
	uint32_t rx_bad_ip_csum;
	uint32_t rx_bad_l4_csum;
	struct testpmd_offload_info info;

#ifdef RTE_TEST_PMD_RECORD_CORE_CYCLES
	uint64_t start_tsc;
	uint64_t end_tsc;
	uint64_t core_cycles;
#endif

#ifdef RTE_TEST_PMD_RECORD_CORE_CYCLES
	start_tsc = rte_rdtsc();
#endif

	/* receive a burst of packet */
	nb_rx = rte_eth_rx_burst(fs->rx_port, fs->rx_queue, pkts_burst,
				 nb_pkt_per_burst);
	if (unlikely(nb_rx == 0))
		return;

#ifdef RTE_TEST_PMD_RECORD_BURST_STATS
	fs->rx_burst_stats.pkt_burst_spread[nb_rx]++;
#endif
	fs->rx_packets += nb_rx;
	rx_bad_ip_csum = 0;
	rx_bad_l4_csum = 0;

	txp = &ports[fs->tx_port];
	testpmd_ol_flags = txp->tx_ol_flags;
	memset(&info, 0, sizeof(info));
	info.tso_segsz = txp->tso_segsz;
	info.tunnel_tso_segsz = txp->tunnel_tso_segsz;

	for (i = 0; i < nb_rx; i++) {
		if (likely(i < nb_rx - 1))
			rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[i + 1],
						       void *));

		m = pkts_burst[i];
		info.is_tunnel = 0;
		info.pkt_len = rte_pktmbuf_pkt_len(m);
		tx_ol_flags = 0;
		rx_ol_flags = m->ol_flags;

		/* Update the L3/L4 checksum error packet statistics */
		if ((rx_ol_flags & PKT_RX_IP_CKSUM_MASK) == PKT_RX_IP_CKSUM_BAD)
			rx_bad_ip_csum += 1;
		if ((rx_ol_flags & PKT_RX_L4_CKSUM_MASK) == PKT_RX_L4_CKSUM_BAD)
			rx_bad_l4_csum += 1;

		/* step 1: dissect packet, parsing optional vlan, ip4/ip6, vxlan
		 * and inner headers */

		eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
		ether_addr_copy(&peer_eth_addrs[fs->peer_addr],
				&eth_hdr->d_addr);
		ether_addr_copy(&ports[fs->tx_port].eth_addr,
				&eth_hdr->s_addr);
		parse_ethernet(eth_hdr, &info);
		l3_hdr = (char *)eth_hdr + info.l2_len;

		/* check if it's a supported tunnel */
		if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_PARSE_TUNNEL) {
			if (info.l4_proto == IPPROTO_UDP) {
				struct udp_hdr *udp_hdr;

				udp_hdr = (struct udp_hdr *)((char *)l3_hdr +
					info.l3_len);
				parse_vxlan(udp_hdr, &info, m->packet_type);
				if (info.is_tunnel)
					tx_ol_flags |= PKT_TX_TUNNEL_VXLAN;
			} else if (info.l4_proto == IPPROTO_GRE) {
				struct simple_gre_hdr *gre_hdr;

				gre_hdr = (struct simple_gre_hdr *)
					((char *)l3_hdr + info.l3_len);
				parse_gre(gre_hdr, &info);
				if (info.is_tunnel)
					tx_ol_flags |= PKT_TX_TUNNEL_GRE;
			} else if (info.l4_proto == IPPROTO_IPIP) {
				void *encap_ip_hdr;

				encap_ip_hdr = (char *)l3_hdr + info.l3_len;
				parse_encap_ip(encap_ip_hdr, &info);
				if (info.is_tunnel)
					tx_ol_flags |= PKT_TX_TUNNEL_IPIP;
			}
		}

		/* update l3_hdr and outer_l3_hdr if a tunnel was parsed */
		if (info.is_tunnel) {
			outer_l3_hdr = l3_hdr;
			l3_hdr = (char *)l3_hdr + info.outer_l3_len + info.l2_len;
		}

		/* step 2: depending on user command line configuration,
		 * recompute checksum either in software or flag the
		 * mbuf to offload the calculation to the NIC. If TSO
		 * is configured, prepare the mbuf for TCP segmentation. */

		/* process checksums of inner headers first */
		tx_ol_flags |= process_inner_cksums(l3_hdr, &info,
			testpmd_ol_flags);

		/* Then process outer headers if any. Note that the software
		 * checksum will be wrong if one of the inner checksums is
		 * processed in hardware. */
		if (info.is_tunnel == 1) {
			tx_ol_flags |= process_outer_cksums(outer_l3_hdr, &info,
					testpmd_ol_flags,
					!!(tx_ol_flags & PKT_TX_TCP_SEG));
		}

		/* step 3: fill the mbuf meta data (flags and header lengths) */

		if (info.is_tunnel == 1) {
			if (info.tunnel_tso_segsz ||
			    testpmd_ol_flags & TESTPMD_TX_OFFLOAD_OUTER_IP_CKSUM) {
				m->outer_l2_len = info.outer_l2_len;
				m->outer_l3_len = info.outer_l3_len;
				m->l2_len = info.l2_len;
				m->l3_len = info.l3_len;
				m->l4_len = info.l4_len;
				m->tso_segsz = info.tunnel_tso_segsz;
			}
			else {
				/* if there is a outer UDP cksum
				   processed in sw and the inner in hw,
				   the outer checksum will be wrong as
				   the payload will be modified by the
				   hardware */
				m->l2_len = info.outer_l2_len +
					info.outer_l3_len + info.l2_len;
				m->l3_len = info.l3_len;
				m->l4_len = info.l4_len;
			}
		} else {
			/* this is only useful if an offload flag is
			 * set, but it does not hurt to fill it in any
			 * case */
			m->l2_len = info.l2_len;
			m->l3_len = info.l3_len;
			m->l4_len = info.l4_len;
			m->tso_segsz = info.tso_segsz;
		}
		m->ol_flags = tx_ol_flags;

		/* Do split & copy for the packet. */
		if (tx_pkt_split != TX_PKT_SPLIT_OFF) {
			p = pkt_copy_split(m);
			if (p != NULL) {
				rte_pktmbuf_free(m);
				m = p;
				pkts_burst[i] = m;
			}
		}

		/* if verbose mode is enabled, dump debug info */
		if (verbose_level > 0) {
			char buf[256];

			printf("-----------------\n");
			printf("port=%u, mbuf=%p, pkt_len=%u, nb_segs=%hhu:\n",
				fs->rx_port, m, m->pkt_len, m->nb_segs);
			/* dump rx parsed packet info */
			rte_get_rx_ol_flag_list(rx_ol_flags, buf, sizeof(buf));
			printf("rx: l2_len=%d ethertype=%x l3_len=%d "
				"l4_proto=%d l4_len=%d flags=%s\n",
				info.l2_len, rte_be_to_cpu_16(info.ethertype),
				info.l3_len, info.l4_proto, info.l4_len, buf);
			if (rx_ol_flags & PKT_RX_LRO)
				printf("rx: m->lro_segsz=%u\n", m->tso_segsz);
			if (info.is_tunnel == 1)
				printf("rx: outer_l2_len=%d outer_ethertype=%x "
					"outer_l3_len=%d\n", info.outer_l2_len,
					rte_be_to_cpu_16(info.outer_ethertype),
					info.outer_l3_len);
			/* dump tx packet info */
			if ((testpmd_ol_flags & (TESTPMD_TX_OFFLOAD_IP_CKSUM |
						TESTPMD_TX_OFFLOAD_UDP_CKSUM |
						TESTPMD_TX_OFFLOAD_TCP_CKSUM |
						TESTPMD_TX_OFFLOAD_SCTP_CKSUM)) ||
				info.tso_segsz != 0)
				printf("tx: m->l2_len=%d m->l3_len=%d "
					"m->l4_len=%d\n",
					m->l2_len, m->l3_len, m->l4_len);
			if (info.is_tunnel == 1) {
				if (testpmd_ol_flags &
				    TESTPMD_TX_OFFLOAD_OUTER_IP_CKSUM)
					printf("tx: m->outer_l2_len=%d "
						"m->outer_l3_len=%d\n",
						m->outer_l2_len,
						m->outer_l3_len);
				if (info.tunnel_tso_segsz != 0 &&
						(m->ol_flags & PKT_TX_TCP_SEG))
					printf("tx: m->tso_segsz=%d\n",
						m->tso_segsz);
			} else if (info.tso_segsz != 0 &&
					(m->ol_flags & PKT_TX_TCP_SEG))
				printf("tx: m->tso_segsz=%d\n", m->tso_segsz);
			rte_get_tx_ol_flag_list(m->ol_flags, buf, sizeof(buf));
			printf("tx: flags=%s", buf);
			printf("\n");
		}
	}
	nb_tx = rte_eth_tx_burst(fs->tx_port, fs->tx_queue, pkts_burst, nb_rx);
	/*
	 * Retry if necessary
	 */
	if (unlikely(nb_tx < nb_rx) && fs->retry_enabled) {
		retry = 0;
		while (nb_tx < nb_rx && retry++ < burst_tx_retry_num) {
			rte_delay_us(burst_tx_delay_time);
			nb_tx += rte_eth_tx_burst(fs->tx_port, fs->tx_queue,
					&pkts_burst[nb_tx], nb_rx - nb_tx);
		}
	}
	fs->tx_packets += nb_tx;
	fs->rx_bad_ip_csum += rx_bad_ip_csum;
	fs->rx_bad_l4_csum += rx_bad_l4_csum;

#ifdef RTE_TEST_PMD_RECORD_BURST_STATS
	fs->tx_burst_stats.pkt_burst_spread[nb_tx]++;
#endif
	if (unlikely(nb_tx < nb_rx)) {
		fs->fwd_dropped += (nb_rx - nb_tx);
		do {
			rte_pktmbuf_free(pkts_burst[nb_tx]);
		} while (++nb_tx < nb_rx);
	}
#ifdef RTE_TEST_PMD_RECORD_CORE_CYCLES
	end_tsc = rte_rdtsc();
	core_cycles = (end_tsc - start_tsc);
	fs->core_cycles = (uint64_t) (fs->core_cycles + core_cycles);
#endif
}

struct fwd_engine csum_fwd_engine = {
	.fwd_mode_name  = "csum",
	.port_fwd_begin = NULL,
	.port_fwd_end   = NULL,
	.packet_fwd     = pkt_burst_checksum_forward,
};