[dpdk-dev,v2,08/13] testpmd: rework csum forward engine

  The csum forward engine was becoming too complex to be used and
extended (the next commits want to add the support of TSO):

- no explaination about what the code does
- code is not factorized, lots of code duplicated, especially between
  ipv4/ipv6
- user command line api: use of bitmasks that need to be calculated by
  the user
- the user flags don't have the same semantic:
  - for legacy IP/UDP/TCP/SCTP, it selects software or hardware checksum
  - for other (vxlan), it selects between hardware checksum or no
    checksum
- the code relies too much on flags set by the driver without software
  alternative (ex: PKT_RX_TUNNEL_IPV4_HDR). It is nice to be able to
  compare a software implementation with the hardware offload.

This commit tries to fix these issues, and provide a simple definition
of what is done by the forward engine:

 * Receive a burst of packets, and for supported packet types:
 *  - modify the IPs
 *  - reprocess the checksum in SW or HW, depending on testpmd command line
 *    configuration
 * Then packets are transmitted on the output port.
 *
 * Supported packets are:
 *   Ether / (vlan) / IP|IP6 / UDP|TCP|SCTP .
 *   Ether / (vlan) / IP|IP6 / UDP / VxLAN / Ether / IP|IP6 / UDP|TCP|SCTP
 *
 * The network parser supposes that the packet is contiguous, which may
 * not be the case in real life.

Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
---
 app/test-pmd/cmdline.c  | 151 ++++++++---
 app/test-pmd/config.c   |  11 -
 app/test-pmd/csumonly.c | 668 ++++++++++++++++++++++--------------------------
 app/test-pmd/testpmd.h  |  17 +-
 4 files changed, 423 insertions(+), 424 deletions(-)
  

> -----Original Message-----
> From: Olivier Matz [mailto:olivier.matz@6wind.com]
> Sent: Saturday, November 15, 2014 1:03 AM
> To: dev@dpdk.org
> Cc: olivier.matz@6wind.com; Walukiewicz, Miroslaw; Liu, Jijiang; Liu, Yong;
> jigsaw@gmail.com; Richardson, Bruce
> Subject: [PATCH v2 08/13] testpmd: rework csum forward engine
> 
> The csum forward engine was becoming too complex to be used and extended
> (the next commits want to add the support of TSO):
> 
> - no explaination about what the code does
> - code is not factorized, lots of code duplicated, especially between
>   ipv4/ipv6
> - user command line api: use of bitmasks that need to be calculated by
>   the user
> - the user flags don't have the same semantic:
>   - for legacy IP/UDP/TCP/SCTP, it selects software or hardware checksum
>   - for other (vxlan), it selects between hardware checksum or no
>     checksum
> - the code relies too much on flags set by the driver without software
>   alternative (ex: PKT_RX_TUNNEL_IPV4_HDR). It is nice to be able to
>   compare a software implementation with the hardware offload.
> 
> This commit tries to fix these issues, and provide a simple definition of what is
> done by the forward engine:
> 
>  * Receive a burst of packets, and for supported packet types:
>  *  - modify the IPs
>  *  - reprocess the checksum in SW or HW, depending on testpmd command line
>  *    configuration
>  * Then packets are transmitted on the output port.
>  *
>  * Supported packets are:
>  *   Ether / (vlan) / IP|IP6 / UDP|TCP|SCTP .
>  *   Ether / (vlan) / IP|IP6 / UDP / VxLAN / Ether / IP|IP6 / UDP|TCP|SCTP
>  *
>  * The network parser supposes that the packet is contiguous, which may
>  * not be the case in real life.
> 
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>  app/test-pmd/cmdline.c  | 151 ++++++++---
>  app/test-pmd/config.c   |  11 -
>  app/test-pmd/csumonly.c | 668 ++++++++++++++++++++++-------------------------
> -
>  app/test-pmd/testpmd.h  |  17 +-
>  4 files changed, 423 insertions(+), 424 deletions(-)
> 
> diff --git a/app/test-pmd/cmdline.c b/app/test-pmd/cmdline.c index
> 4c3fc76..0361e58 100644
> --- a/app/test-pmd/cmdline.c
> +++ b/app/test-pmd/cmdline.c
> @@ -310,19 +310,14 @@ static void cmd_help_long_parsed(void
> *parsed_result,
>  			"    Disable hardware insertion of a VLAN header in"
>  			" packets sent on a port.\n\n"
> 
> -			"tx_checksum set (mask) (port_id)\n"
> -			"    Enable hardware insertion of checksum offload with"
> -			" the 8-bit mask, 0~0xff, in packets sent on a port.\n"
> -			"        bit 0 - insert ip   checksum offload if set\n"
> -			"        bit 1 - insert udp  checksum offload if set\n"
> -			"        bit 2 - insert tcp  checksum offload if set\n"
> -			"        bit 3 - insert sctp checksum offload if set\n"
> -			"        bit 4 - insert inner ip  checksum offload if set\n"
> -			"        bit 5 - insert inner udp checksum offload if set\n"
> -			"        bit 6 - insert inner tcp checksum offload if set\n"
> -			"        bit 7 - insert inner sctp checksum offload if set\n"
> +			"tx_cksum set (ip|udp|tcp|sctp|vxlan) (hw|sw)
> (port_id)\n"
> +			"    Enable hardware calculation of checksum with when"
> +			" transmitting a packet using 'csum' forward engine.\n"
>  			"    Please check the NIC datasheet for HW limits.\n\n"
> 
> +			"tx_checksum show (port_id)\n"
> +			"    Display tx checksum offload configuration\n\n"
> +
>  			"set fwd (%s)\n"
>  			"    Set packet forwarding mode.\n\n"
> 
> @@ -2738,48 +2733,131 @@ cmdline_parse_inst_t cmd_tx_vlan_reset = {
> 
> 
>  /* *** ENABLE HARDWARE INSERTION OF CHECKSUM IN TX PACKETS *** */ -
> struct cmd_tx_cksum_set_result {
> +struct cmd_tx_cksum_result {
>  	cmdline_fixed_string_t tx_cksum;
> -	cmdline_fixed_string_t set;
> -	uint8_t cksum_mask;
> +	cmdline_fixed_string_t mode;
> +	cmdline_fixed_string_t proto;
> +	cmdline_fixed_string_t hwsw;
>  	uint8_t port_id;
>  };
> 
>  static void
> -cmd_tx_cksum_set_parsed(void *parsed_result,
> +cmd_tx_cksum_parsed(void *parsed_result,
>  		       __attribute__((unused)) struct cmdline *cl,
>  		       __attribute__((unused)) void *data)  {
> -	struct cmd_tx_cksum_set_result *res = parsed_result;
> +	struct cmd_tx_cksum_result *res = parsed_result;
> +	int hw = 0;
> +	uint16_t ol_flags, mask = 0;
> +	struct rte_eth_dev_info dev_info;
> +
> +	if (port_id_is_invalid(res->port_id)) {
> +		printf("invalid port %d\n", res->port_id);
> +		return;
> +	}
> 
> -	tx_cksum_set(res->port_id, res->cksum_mask);
> +	if (!strcmp(res->mode, "set")) {
> +
> +		if (!strcmp(res->hwsw, "hw"))
> +			hw = 1;
> +
> +		if (!strcmp(res->proto, "ip")) {
> +			mask = TESTPMD_TX_OFFLOAD_IP_CKSUM;
> +		} else if (!strcmp(res->proto, "udp")) {
> +			mask = TESTPMD_TX_OFFLOAD_UDP_CKSUM;
> +		} else if (!strcmp(res->proto, "tcp")) {
> +			mask = TESTPMD_TX_OFFLOAD_TCP_CKSUM;
> +		} else if (!strcmp(res->proto, "sctp")) {
> +			mask = TESTPMD_TX_OFFLOAD_SCTP_CKSUM;
> +		} else if (!strcmp(res->proto, "vxlan")) {
> +			mask = TESTPMD_TX_OFFLOAD_VXLAN_CKSUM;
> +		}
> +
> +		if (hw)
> +			ports[res->port_id].tx_ol_flags |= mask;
> +		else
> +			ports[res->port_id].tx_ol_flags &= (~mask);
> +	}
> +
> +	ol_flags = ports[res->port_id].tx_ol_flags;
> +	printf("IP checksum offload is %s\n",
> +		(ol_flags & TESTPMD_TX_OFFLOAD_IP_CKSUM) ? "hw" : "sw");
> +	printf("UDP checksum offload is %s\n",
> +		(ol_flags & TESTPMD_TX_OFFLOAD_UDP_CKSUM) ? "hw" :
> "sw");
> +	printf("TCP checksum offload is %s\n",
> +		(ol_flags & TESTPMD_TX_OFFLOAD_TCP_CKSUM) ? "hw" : "sw");
> +	printf("SCTP checksum offload is %s\n",
> +		(ol_flags & TESTPMD_TX_OFFLOAD_SCTP_CKSUM) ? "hw" :
> "sw");
> +	printf("VxLAN checksum offload is %s\n",
> +		(ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM) ? "hw" :
> "sw");
> +
> +	/* display warnings if configuration is not supported by the NIC */
> +	rte_eth_dev_info_get(res->port_id, &dev_info);
> +	if ((ol_flags & TESTPMD_TX_OFFLOAD_IP_CKSUM) &&
> +		(dev_info.tx_offload_capa & DEV_TX_OFFLOAD_IPV4_CKSUM)
> == 0) {
> +		printf("Warning: hardware IP checksum enabled but not "
> +			"supported by port %d\n", res->port_id);
> +	}
> +	if ((ol_flags & TESTPMD_TX_OFFLOAD_UDP_CKSUM) &&
> +		(dev_info.tx_offload_capa & DEV_TX_OFFLOAD_UDP_CKSUM)
> == 0) {
> +		printf("Warning: hardware UDP checksum enabled but not "
> +			"supported by port %d\n", res->port_id);
> +	}
> +	if ((ol_flags & TESTPMD_TX_OFFLOAD_TCP_CKSUM) &&
> +		(dev_info.tx_offload_capa & DEV_TX_OFFLOAD_TCP_CKSUM) ==
> 0) {
> +		printf("Warning: hardware TCP checksum enabled but not "
> +			"supported by port %d\n", res->port_id);
> +	}
> +	if ((ol_flags & TESTPMD_TX_OFFLOAD_SCTP_CKSUM) &&
> +		(dev_info.tx_offload_capa & DEV_TX_OFFLOAD_SCTP_CKSUM)
> == 0) {
> +		printf("Warning: hardware SCTP checksum enabled but not "
> +			"supported by port %d\n", res->port_id);
> +	}
>  }
> 
> -cmdline_parse_token_string_t cmd_tx_cksum_set_tx_cksum =
> -	TOKEN_STRING_INITIALIZER(struct cmd_tx_cksum_set_result,
> +cmdline_parse_token_string_t cmd_tx_cksum_tx_cksum =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_cksum_result,
>  				tx_cksum, "tx_checksum");
> -cmdline_parse_token_string_t cmd_tx_cksum_set_set =
> -	TOKEN_STRING_INITIALIZER(struct cmd_tx_cksum_set_result,
> -				set, "set");
> -cmdline_parse_token_num_t cmd_tx_cksum_set_cksum_mask =
> -	TOKEN_NUM_INITIALIZER(struct cmd_tx_cksum_set_result,
> -				cksum_mask, UINT8);
> -cmdline_parse_token_num_t cmd_tx_cksum_set_portid =
> -	TOKEN_NUM_INITIALIZER(struct cmd_tx_cksum_set_result,
> +cmdline_parse_token_string_t cmd_tx_cksum_mode =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_cksum_result,
> +				mode, "set");
> +cmdline_parse_token_string_t cmd_tx_cksum_proto =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_cksum_result,
> +				proto, "ip#tcp#udp#sctp#vxlan");
> +cmdline_parse_token_string_t cmd_tx_cksum_hwsw =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_cksum_result,
> +				hwsw, "hw#sw");
> +cmdline_parse_token_num_t cmd_tx_cksum_portid =
> +	TOKEN_NUM_INITIALIZER(struct cmd_tx_cksum_result,
>  				port_id, UINT8);
> 
>  cmdline_parse_inst_t cmd_tx_cksum_set = {
> -	.f = cmd_tx_cksum_set_parsed,
> +	.f = cmd_tx_cksum_parsed,
> +	.data = NULL,
> +	.help_str = "enable/disable hardware calculation of L3/L4 checksum
> when "
> +		"using csum forward engine: tx_cksum set
> ip|tcp|udp|sctp|vxlan hw|sw <port>",
> +	.tokens = {
> +		(void *)&cmd_tx_cksum_tx_cksum,
> +		(void *)&cmd_tx_cksum_mode,
> +		(void *)&cmd_tx_cksum_proto,
> +		(void *)&cmd_tx_cksum_hwsw,
> +		(void *)&cmd_tx_cksum_portid,
> +		NULL,
> +	},
> +};
> +
> +cmdline_parse_token_string_t cmd_tx_cksum_mode_show =
> +	TOKEN_STRING_INITIALIZER(struct cmd_tx_cksum_result,
> +				mode, "show");
> +
> +cmdline_parse_inst_t cmd_tx_cksum_show = {
> +	.f = cmd_tx_cksum_parsed,
>  	.data = NULL,
> -	.help_str = "enable hardware insertion of L3/L4checksum with a given "
> -	"mask in packets sent on a port, the bit mapping is given as, Bit 0 for ip, "
> -	"Bit 1 for UDP, Bit 2 for TCP, Bit 3 for SCTP, Bit 4 for inner ip, "
> -	"Bit 5 for inner UDP, Bit 6 for inner TCP, Bit 7 for inner SCTP",
> +	.help_str = "show checksum offload configuration: tx_cksum show
> +<port>",
>  	.tokens = {
> -		(void *)&cmd_tx_cksum_set_tx_cksum,
> -		(void *)&cmd_tx_cksum_set_set,
> -		(void *)&cmd_tx_cksum_set_cksum_mask,
> -		(void *)&cmd_tx_cksum_set_portid,
> +		(void *)&cmd_tx_cksum_tx_cksum,
> +		(void *)&cmd_tx_cksum_mode_show,
> +		(void *)&cmd_tx_cksum_portid,
>  		NULL,
>  	},
>  };
> @@ -7796,6 +7874,7 @@ cmdline_parse_ctx_t main_ctx[] = {
>  	(cmdline_parse_inst_t *)&cmd_tx_vlan_reset,
>  	(cmdline_parse_inst_t *)&cmd_tx_vlan_set_pvid,
>  	(cmdline_parse_inst_t *)&cmd_tx_cksum_set,
> +	(cmdline_parse_inst_t *)&cmd_tx_cksum_show,
>  	(cmdline_parse_inst_t *)&cmd_link_flow_control_set,
>  	(cmdline_parse_inst_t *)&cmd_link_flow_control_set_rx,
>  	(cmdline_parse_inst_t *)&cmd_link_flow_control_set_tx, diff --git
> a/app/test-pmd/config.c b/app/test-pmd/config.c index 34b6fdb..16d62ab
> 100644
> --- a/app/test-pmd/config.c
> +++ b/app/test-pmd/config.c
> @@ -1744,17 +1744,6 @@ set_qmap(portid_t port_id, uint8_t is_rx, uint16_t
> queue_id, uint8_t map_value)  }
> 
>  void
> -tx_cksum_set(portid_t port_id, uint64_t ol_flags) -{
> -	uint64_t tx_ol_flags;
> -	if (port_id_is_invalid(port_id))
> -		return;
> -	/* Clear last 8 bits and then set L3/4 checksum mask again */
> -	tx_ol_flags = ports[port_id].tx_ol_flags & (~0x0FFull);
> -	ports[port_id].tx_ol_flags = ((ol_flags & 0xff) | tx_ol_flags);
> -}
> -
> -void
>  fdir_add_signature_filter(portid_t port_id, uint8_t queue_id,
>  			  struct rte_fdir_filter *fdir_filter)  { diff --git a/app/test-
> pmd/csumonly.c b/app/test-pmd/csumonly.c index 743094a..dda5d9e 100644
> --- a/app/test-pmd/csumonly.c
> +++ b/app/test-pmd/csumonly.c
> @@ -73,13 +73,19 @@
>  #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)
> 
> +/* we cannot use htons() from arpa/inet.h due to name conflicts, and we
> + * cannot use rte_cpu_to_be_16() on a constant in a switch/case */ #if
> +__BYTE_ORDER == __LITTLE_ENDIAN #define _htons(x) ((uint16_t)((((x) &
> +0x00ffU) << 8) | (((x) & 0xff00U) >> 8))) #else #define _htons(x) (x)
> +#endif
> +
>  static inline uint16_t
>  get_16b_sum(uint16_t *ptr16, uint32_t nr)  { @@ -112,7 +118,7 @@
> get_ipv4_cksum(struct ipv4_hdr *ipv4_hdr)
> 
> 
>  static inline uint16_t
> -get_ipv4_psd_sum (struct ipv4_hdr * ip_hdr)
> +get_ipv4_psd_sum(struct ipv4_hdr *ip_hdr)
>  {
>  	/* Pseudo Header for IPv4/UDP/TCP checksum */
>  	union ipv4_psd_header {
> @@ -136,7 +142,7 @@ get_ipv4_psd_sum (struct ipv4_hdr * ip_hdr)  }
> 
>  static inline uint16_t
> -get_ipv6_psd_sum (struct ipv6_hdr * ip_hdr)
> +get_ipv6_psd_sum(struct ipv6_hdr *ip_hdr)
>  {
>  	/* Pseudo Header for IPv6/UDP/TCP checksum */
>  	union ipv6_psd_header {
> @@ -158,6 +164,15 @@ get_ipv6_psd_sum (struct ipv6_hdr * ip_hdr)
>  	return get_16b_sum(psd_hdr.u16_arr, sizeof(psd_hdr));  }
> 
> +static uint16_t
> +get_psd_sum(void *l3_hdr, uint16_t ethertype) {
> +	if (ethertype == _htons(ETHER_TYPE_IPv4))
> +		return get_ipv4_psd_sum(l3_hdr);
> +	else /* assume ethertype == ETHER_TYPE_IPv6 */
> +		return get_ipv6_psd_sum(l3_hdr);
> +}
> +
>  static inline uint16_t
>  get_ipv4_udptcp_checksum(struct ipv4_hdr *ipv4_hdr, uint16_t *l4_hdr)  { @@ -
> 174,7 +189,6 @@ get_ipv4_udptcp_checksum(struct ipv4_hdr *ipv4_hdr,
> uint16_t *l4_hdr)
>  	if (cksum == 0)
>  		cksum = 0xffff;
>  	return (uint16_t)cksum;
> -
>  }
> 
>  static inline uint16_t
> @@ -196,48 +210,218 @@ get_ipv6_udptcp_checksum(struct ipv6_hdr
> *ipv6_hdr, uint16_t *l4_hdr)
>  	return (uint16_t)cksum;
>  }
> 
> +static uint16_t
> +get_udptcp_checksum(void *l3_hdr, void *l4_hdr, uint16_t ethertype) {
> +	if (ethertype == _htons(ETHER_TYPE_IPv4))
> +		return get_ipv4_udptcp_checksum(l3_hdr, l4_hdr);
> +	else /* assume ethertype == ETHER_TYPE_IPv6 */
> +		return get_ipv6_udptcp_checksum(l3_hdr, l4_hdr); }
> 
>  /*
> - * Forwarding of packets. Change the checksum field with HW or SW methods
> - * The HW/SW method selection depends on the ol_flags on every packet
> + * 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.
> + */
> +static void
> +parse_ethernet(struct ether_hdr *eth_hdr, uint16_t *ethertype, uint16_t
> *l2_len,
> +	uint16_t *l3_len, uint8_t *l4_proto)
> +{
> +	struct ipv4_hdr *ipv4_hdr;
> +	struct ipv6_hdr *ipv6_hdr;
> +
> +	*l2_len = sizeof(struct ether_hdr);
> +	*ethertype = eth_hdr->ether_type;
> +
> +	if (*ethertype == _htons(ETHER_TYPE_VLAN)) {
> +		struct vlan_hdr *vlan_hdr = (struct vlan_hdr *)(eth_hdr + 1);
> +
> +		*l2_len  += sizeof(struct vlan_hdr);
> +		*ethertype = vlan_hdr->eth_proto;
> +	}
> +
> +	switch (*ethertype) {
> +	case _htons(ETHER_TYPE_IPv4):
> +		ipv4_hdr = (struct ipv4_hdr *) ((char *)eth_hdr + *l2_len);
> +		*l3_len = (ipv4_hdr->version_ihl & 0x0f) * 4;
> +		*l4_proto = ipv4_hdr->next_proto_id;
> +		break;
> +	case _htons(ETHER_TYPE_IPv6):
> +		ipv6_hdr = (struct ipv6_hdr *) ((char *)eth_hdr + *l2_len);
> +		*l3_len = sizeof(struct ipv6_hdr) ;
> +		*l4_proto = ipv6_hdr->proto;
> +		break;
> +	default:
> +		*l3_len = 0;
> +		*l4_proto = 0;
> +		break;
> +	}
> +}
> +
> +/* modify the IPv4 or IPv4 source address of a packet */ static void
> +change_ip_addresses(void *l3_hdr, uint16_t ethertype) {
> +	struct ipv4_hdr *ipv4_hdr = l3_hdr;
> +	struct ipv6_hdr *ipv6_hdr = l3_hdr;
> +
> +	if (ethertype == _htons(ETHER_TYPE_IPv4)) {
> +		ipv4_hdr->src_addr =
> +			rte_cpu_to_be_32(rte_be_to_cpu_32(ipv4_hdr-
> >src_addr) + 1);
> +	}
> +	else if (ethertype == _htons(ETHER_TYPE_IPv6)) {
> +		ipv6_hdr->src_addr[15] = ipv6_hdr->src_addr[15] + 1;
> +	}
> +}
> +
> +/* 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, uint16_t ethertype,
> +uint16_t l3_len,
> +	uint8_t l4_proto, 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;
> +
> +	if (ethertype == _htons(ETHER_TYPE_IPv4)) {
> +		ipv4_hdr = l3_hdr;
> +		ipv4_hdr->hdr_checksum = 0;
> +
> +		if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_IP_CKSUM)
> +			ol_flags |= PKT_TX_IP_CKSUM;
> +		else
> +			ipv4_hdr->hdr_checksum = get_ipv4_cksum(ipv4_hdr);
> +
> +	}
> +	else if (ethertype != _htons(ETHER_TYPE_IPv6))
> +		return 0; /* packet type not supported nothing to do */
> +
> +	if (l4_proto == IPPROTO_UDP) {
> +		udp_hdr = (struct udp_hdr *)((char *)l3_hdr + 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,
> +					ethertype);
> +			}
> +			else {
> +				udp_hdr->dgram_cksum =
> +					get_udptcp_checksum(l3_hdr, udp_hdr,
> +						ethertype);
> +			}
> +		}
> +	}
> +	else if (l4_proto == IPPROTO_TCP) {
> +		tcp_hdr = (struct tcp_hdr *)((char *)l3_hdr + l3_len);
> +		tcp_hdr->cksum = 0;
> +		if (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_TCP_CKSUM) {
> +			ol_flags |= PKT_TX_TCP_CKSUM;
> +			tcp_hdr->cksum = get_psd_sum(l3_hdr, ethertype);
> +		}
> +		else {
> +			tcp_hdr->cksum =
> +				get_udptcp_checksum(l3_hdr, tcp_hdr,
> ethertype);
> +		}
> +	}
> +	else if (l4_proto == IPPROTO_SCTP) {
> +		sctp_hdr = (struct sctp_hdr *)((char *)l3_hdr + 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 (only vxlan is supported,
> + * meaning IP + UDP). The caller already checked that it's a vxlan
> + * packet */
> +static uint64_t
> +process_outer_cksums(void *outer_l3_hdr, uint16_t outer_ethertype,
> +	uint16_t outer_l3_len, uint16_t testpmd_ol_flags) {
> +	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 (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM)
> +		ol_flags |= PKT_TX_VXLAN_CKSUM;
> +
> +	if (outer_ethertype == _htons(ETHER_TYPE_IPv4)) {
> +		ipv4_hdr->hdr_checksum = 0;
> +
> +		if ((testpmd_ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM)
> == 0)
> +			ipv4_hdr->hdr_checksum = get_ipv4_cksum(ipv4_hdr);
> +	}

As I mentioned, we should use TESTPMD_TX_OFFLOAD_IP_CKSUM instead of using TESTPMD_TX_OFFLOAD_VXLAN_CKSUM flag to check if we need to set outer IP checksum offload.
In other words, even if VXLAN packet, outer IP TX checksum offload is also needed if  TESTPMD_TX_OFFLOAD_IP_CKSUM is set.

> +	udp_hdr = (struct udp_hdr *)((char *)outer_l3_hdr + outer_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_VXLAN_CKSUM)
> == 0) {
> +			if (outer_ethertype == _htons(ETHER_TYPE_IPv4))
> +				udp_hdr->dgram_cksum =
> +					get_ipv4_udptcp_checksum(ipv4_hdr,
> +						(uint16_t *)udp_hdr);
> +			else
> +				udp_hdr->dgram_cksum =
> +					get_ipv6_udptcp_checksum(ipv6_hdr,
> +						(uint16_t *)udp_hdr);
> +		}
> +	}
> +
> +	return ol_flags;
> +}
> +
> +/*
> + * Receive a burst of packets, and for supported packet types:
> + *  - modify the IPs
> + *  - reprocess the checksum in SW or HW, depending on testpmd command line
> + *    configuration
> + * Then packets are transmitted on the output port.
> + *
> + * Supported packets are:
> + *   Ether / (vlan) / IP|IP6 / UDP|TCP|SCTP .
> + *   Ether / (vlan) / IP|IP6 / UDP / VxLAN / Ether / IP|IP6 / UDP|TCP|SCTP
> + *
> + * The network parser supposes that the packet is contiguous, which may
> + * not be the case in real life.
>   */
>  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  *mb;
> +	struct rte_mbuf *pkts_burst[MAX_PKT_BURST];
> +	struct rte_port *txp;
> +	struct rte_mbuf *m;
>  	struct ether_hdr *eth_hdr;
> -	struct ipv4_hdr  *ipv4_hdr;
> -	struct ether_hdr *inner_eth_hdr;
> -	struct ipv4_hdr  *inner_ipv4_hdr = NULL;
> -	struct ipv6_hdr  *ipv6_hdr;
> -	struct ipv6_hdr  *inner_ipv6_hdr = NULL;
> -	struct udp_hdr   *udp_hdr;
> -	struct udp_hdr   *inner_udp_hdr;
> -	struct tcp_hdr   *tcp_hdr;
> -	struct tcp_hdr   *inner_tcp_hdr;
> -	struct sctp_hdr  *sctp_hdr;
> -	struct sctp_hdr  *inner_sctp_hdr;
> -
> +	void *l3_hdr = NULL, *outer_l3_hdr = NULL; /* can be IPv4 or IPv6 */
> +	struct udp_hdr *udp_hdr;
>  	uint16_t nb_rx;
>  	uint16_t nb_tx;
>  	uint16_t i;
>  	uint64_t ol_flags;
> -	uint64_t pkt_ol_flags;
> -	uint64_t tx_ol_flags;
> -	uint16_t l4_proto;
> -	uint16_t inner_l4_proto = 0;
> -	uint16_t eth_type;
> -	uint8_t  l2_len;
> -	uint8_t  l3_len;
> -	uint8_t  inner_l2_len = 0;
> -	uint8_t  inner_l3_len = 0;
> -
> +	uint16_t testpmd_ol_flags;
> +	uint8_t l4_proto;
> +	uint16_t ethertype = 0, outer_ethertype = 0;
> +	uint16_t  l2_len = 0, l3_len = 0, outer_l2_len = 0, outer_l3_len = 0;
> +	int tunnel = 0;
>  	uint32_t rx_bad_ip_csum;
>  	uint32_t rx_bad_l4_csum;
> -	uint8_t  ipv4_tunnel;
> -	uint8_t  ipv6_tunnel;
> 
>  #ifdef RTE_TEST_PMD_RECORD_CORE_CYCLES
>  	uint64_t start_tsc;
> @@ -249,9 +433,7 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
>  	start_tsc = rte_rdtsc();
>  #endif
> 
> -	/*
> -	 * Receive a burst of packets and forward them.
> -	 */
> +	/* 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))
> @@ -265,348 +447,107 @@ pkt_burst_checksum_forward(struct fwd_stream
> *fs)
>  	rx_bad_l4_csum = 0;
> 
>  	txp = &ports[fs->tx_port];
> -	tx_ol_flags = txp->tx_ol_flags;
> +	testpmd_ol_flags = txp->tx_ol_flags;
> 
>  	for (i = 0; i < nb_rx; i++) {
> 
> -		mb = pkts_burst[i];
> -		l2_len  = sizeof(struct ether_hdr);
> -		pkt_ol_flags = mb->ol_flags;
> -		ol_flags = (pkt_ol_flags & (~PKT_TX_L4_MASK));
> -		ipv4_tunnel = (pkt_ol_flags & PKT_RX_TUNNEL_IPV4_HDR) ?
> -				1 : 0;
> -		ipv6_tunnel = (pkt_ol_flags & PKT_RX_TUNNEL_IPV6_HDR) ?
> -				1 : 0;
> -		eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *);
> -		eth_type = rte_be_to_cpu_16(eth_hdr->ether_type);
> -		if (eth_type == ETHER_TYPE_VLAN) {
> -			/* Only allow single VLAN label here */
> -			l2_len  += sizeof(struct vlan_hdr);
> -			 eth_type = rte_be_to_cpu_16(*(uint16_t *)
> -				((uintptr_t)&eth_hdr->ether_type +
> -				sizeof(struct vlan_hdr)));
> +		ol_flags = 0;
> +		tunnel = 0;
> +		m = pkts_burst[i];
> +
> +		/* Update the L3/L4 checksum error packet statistics */
> +		rx_bad_ip_csum += ((m->ol_flags & PKT_RX_IP_CKSUM_BAD) !=
> 0);
> +		rx_bad_l4_csum += ((m->ol_flags & PKT_RX_L4_CKSUM_BAD) !=
> 0);
> +
> +		/* step 1: dissect packet, parsing optional vlan, ip4/ip6, vxlan
> +		 * and inner headers */
> +
> +		eth_hdr = rte_pktmbuf_mtod(m, struct ether_hdr *);
> +		parse_ethernet(eth_hdr, &ethertype, &l2_len, &l3_len,
> &l4_proto);
> +		l3_hdr = (char *)eth_hdr + l2_len;
> +
> +		/* check if it's a supported tunnel (only vxlan for now) */
> +		if (l4_proto == IPPROTO_UDP) {
> +			udp_hdr = (struct udp_hdr *)((char *)l3_hdr + l3_len);
> +
> +			/* currently, this flag is set by i40e only if the
> +			 * packet is vxlan */
> +			if (((m->ol_flags & PKT_RX_TUNNEL_IPV4_HDR) ||
> +					(m->ol_flags &
> PKT_RX_TUNNEL_IPV6_HDR)))
> +				tunnel = 1;
> +			/* else check udp destination port, 4789 is the default
> +			 * vxlan port (rfc7348) */
> +			else if (udp_hdr->dst_port == _htons(4789))
> +				tunnel = 1;
> +
> +			if (tunnel == 1) {
> +				outer_ethertype = ethertype;
> +				outer_l2_len = l2_len;
> +				outer_l3_len = l3_len;
> +				outer_l3_hdr = l3_hdr;
> +
> +				eth_hdr = (struct ether_hdr *)((char *)udp_hdr +
> +					sizeof(struct udp_hdr) +
> +					sizeof(struct vxlan_hdr));
> +
> +				parse_ethernet(eth_hdr, &ethertype, &l2_len,
> +					&l3_len, &l4_proto);
> +				l3_hdr = (char *)eth_hdr + l2_len;
> +			}
>  		}
> 
> -		/* Update the L3/L4 checksum error packet count  */
> -		rx_bad_ip_csum += (uint16_t) ((pkt_ol_flags &
> PKT_RX_IP_CKSUM_BAD) != 0);
> -		rx_bad_l4_csum += (uint16_t) ((pkt_ol_flags &
> PKT_RX_L4_CKSUM_BAD) != 0);
> -
> -		/*
> -		 * Try to figure out L3 packet type by SW.
> -		 */
> -		if ((pkt_ol_flags & (PKT_RX_IPV4_HDR | PKT_RX_IPV4_HDR_EXT
> |
> -				PKT_RX_IPV6_HDR | PKT_RX_IPV6_HDR_EXT))
> == 0) {
> -			if (eth_type == ETHER_TYPE_IPv4)
> -				pkt_ol_flags |= PKT_RX_IPV4_HDR;
> -			else if (eth_type == ETHER_TYPE_IPv6)
> -				pkt_ol_flags |= PKT_RX_IPV6_HDR;
> -		}
> +		/* step 2: change all source IPs (v4 or v6) so we need
> +		 * to recompute the chksums even if they were correct */
> 
> -		/*
> -		 * Simplify the protocol parsing
> -		 * Assuming the incoming packets format as
> -		 *      Ethernet2 + optional single VLAN
> -		 *      + ipv4 or ipv6
> -		 *      + udp or tcp or sctp or others
> -		 */
> -		if (pkt_ol_flags & (PKT_RX_IPV4_HDR |
> PKT_RX_TUNNEL_IPV4_HDR)) {
> +		change_ip_addresses(l3_hdr, ethertype);
> +		if (tunnel == 1)
> +			change_ip_addresses(outer_l3_hdr, outer_ethertype);
> 
> -			/* Do not support ipv4 option field */
> -			l3_len = sizeof(struct ipv4_hdr) ;
> +		/* step 3: depending on user command line configuration,
> +		 * recompute checksum either in software or flag the
> +		 * mbuf to offload the calculation to the NIC */
> 
> -			ipv4_hdr = (struct ipv4_hdr *) (rte_pktmbuf_mtod(mb,
> -					unsigned char *) + l2_len);
> +		/* process checksums of inner headers first */
> +		ol_flags |= process_inner_cksums(l3_hdr, ethertype,
> +			l3_len, l4_proto, testpmd_ol_flags);
> -			l4_proto = ipv4_hdr->next_proto_id;
> +		/* 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 (tunnel == 1) {
> +			ol_flags |= process_outer_cksums(outer_l3_hdr,
> +				outer_ethertype, outer_l3_len,
> testpmd_ol_flags);
> +		}
> 
> -			/* Do not delete, this is required by HW*/
> -			ipv4_hdr->hdr_checksum = 0;
> +		/* step 4: fill the mbuf meta data (flags and header lengths) */
> 
> -			if (tx_ol_flags & TESTPMD_TX_OFFLOAD_IP_CKSUM) {
> -				/* HW checksum */
> -				ol_flags |= PKT_TX_IP_CKSUM;
> +		if (tunnel == 1) {
> +			if (testpmd_ol_flags &
> TESTPMD_TX_OFFLOAD_VXLAN_CKSUM) {
> +				m->l2_len = outer_l2_len;
> +				m->l3_len = outer_l3_len;
> +				m->inner_l2_len = l2_len;
> +				m->inner_l3_len = l3_len;
>  			}
>  			else {
> -				ol_flags |= PKT_TX_IPV4;
> -				/* SW checksum calculation */
> -				ipv4_hdr->src_addr++;
> -				ipv4_hdr->hdr_checksum =
> get_ipv4_cksum(ipv4_hdr);
> +				/* if we don't do vxlan cksum in hw,
> +				   outer checksum will be wrong because
> +				   we changed the ip, but it shows that
> +				   we can process the inner header cksum
> +				   in the nic */
> +				m->l2_len = outer_l2_len + outer_l3_len +
> +					sizeof(struct udp_hdr) +
> +					sizeof(struct vxlan_hdr) + l2_len;
> +				m->l3_len = l3_len;
>  			}
> -
> -			if (l4_proto == IPPROTO_UDP) {
> -				udp_hdr = (struct udp_hdr*)
> (rte_pktmbuf_mtod(mb,
> -						unsigned char *) + l2_len +
> l3_len);
> -				if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_UDP_CKSUM) {
> -					/* HW Offload */
> -					ol_flags |= PKT_TX_UDP_CKSUM;
> -					if (ipv4_tunnel)
> -						udp_hdr->dgram_cksum = 0;
> -					else
> -						/* Pseudo header sum need be
> set properly */
> -						udp_hdr->dgram_cksum =
> -
> 	get_ipv4_psd_sum(ipv4_hdr);
> -				}
> -				else {
> -					/* SW Implementation, clear checksum
> field first */
> -					udp_hdr->dgram_cksum = 0;
> -					udp_hdr->dgram_cksum =
> get_ipv4_udptcp_checksum(ipv4_hdr,
> -
> 	(uint16_t *)udp_hdr);
> -				}
> -
> -				if (ipv4_tunnel) {
> -
> -					uint16_t len;
> -
> -					/* Check if inner L3/L4 checkum flag is
> set */
> -					if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_CKSUM_MASK)
> -						ol_flags |=
> PKT_TX_VXLAN_CKSUM;
> -
> -					inner_l2_len  = sizeof(struct ether_hdr);
> -					inner_eth_hdr = (struct ether_hdr *)
> (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + l2_len + l3_len
> -								 +
> ETHER_VXLAN_HLEN);
> -
> -					eth_type =
> rte_be_to_cpu_16(inner_eth_hdr->ether_type);
> -					if (eth_type == ETHER_TYPE_VLAN) {
> -						inner_l2_len += sizeof(struct
> vlan_hdr);
> -						eth_type =
> rte_be_to_cpu_16(*(uint16_t *)
> -							((uintptr_t)&eth_hdr-
> >ether_type +
> -								sizeof(struct
> vlan_hdr)));
> -					}
> -
> -					len = l2_len + l3_len +
> ETHER_VXLAN_HLEN + inner_l2_len;
> -					if (eth_type == ETHER_TYPE_IPv4) {
> -						inner_l3_len = sizeof(struct
> ipv4_hdr);
> -						inner_ipv4_hdr = (struct
> ipv4_hdr *) (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + len);
> -						inner_l4_proto =
> inner_ipv4_hdr->next_proto_id;
> -
> -						if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_IP_CKSUM) {
> -
> -							/* Do not delete, this is
> required by HW*/
> -							inner_ipv4_hdr-
> >hdr_checksum = 0;
> -							ol_flags |=
> PKT_TX_IPV4_CSUM;
> -						}
> -
> -					} else if (eth_type ==
> ETHER_TYPE_IPv6) {
> -						inner_l3_len = sizeof(struct
> ipv6_hdr);
> -						inner_ipv6_hdr = (struct
> ipv6_hdr *) (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + len);
> -						inner_l4_proto =
> inner_ipv6_hdr->proto;
> -					}
> -					if ((inner_l4_proto == IPPROTO_UDP)
> &&
> -						(tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_UDP_CKSUM)) {
> -
> -						/* HW Offload */
> -						ol_flags |=
> PKT_TX_UDP_CKSUM;
> -						inner_udp_hdr = (struct
> udp_hdr *) (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + len + inner_l3_len);
> -						if (eth_type ==
> ETHER_TYPE_IPv4)
> -							inner_udp_hdr-
> >dgram_cksum = get_ipv4_psd_sum(inner_ipv4_hdr);
> -						else if (eth_type ==
> ETHER_TYPE_IPv6)
> -							inner_udp_hdr-
> >dgram_cksum = get_ipv6_psd_sum(inner_ipv6_hdr);
> -
> -					} else if ((inner_l4_proto ==
> IPPROTO_TCP) &&
> -						(tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_TCP_CKSUM)) {
> -						/* HW Offload */
> -						ol_flags |=
> PKT_TX_TCP_CKSUM;
> -						inner_tcp_hdr = (struct tcp_hdr
> *) (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + len + inner_l3_len);
> -						if (eth_type ==
> ETHER_TYPE_IPv4)
> -							inner_tcp_hdr->cksum
> = get_ipv4_psd_sum(inner_ipv4_hdr);
> -						else if (eth_type ==
> ETHER_TYPE_IPv6)
> -							inner_tcp_hdr->cksum
> = get_ipv6_psd_sum(inner_ipv6_hdr);
> -					} else if ((inner_l4_proto ==
> IPPROTO_SCTP) &&
> -						(tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_SCTP_CKSUM)) {
> -						/* HW Offload */
> -						ol_flags |=
> PKT_TX_SCTP_CKSUM;
> -						inner_sctp_hdr = (struct
> sctp_hdr *) (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + len + inner_l3_len);
> -						inner_sctp_hdr->cksum = 0;
> -					}
> -
> -				}
> -
> -			} else if (l4_proto == IPPROTO_TCP) {
> -				tcp_hdr = (struct tcp_hdr*)
> (rte_pktmbuf_mtod(mb,
> -						unsigned char *) + l2_len +
> l3_len);
> -				if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_TCP_CKSUM) {
> -					ol_flags |= PKT_TX_TCP_CKSUM;
> -					tcp_hdr->cksum =
> get_ipv4_psd_sum(ipv4_hdr);
> -				}
> -				else {
> -					tcp_hdr->cksum = 0;
> -					tcp_hdr->cksum =
> get_ipv4_udptcp_checksum(ipv4_hdr,
> -							(uint16_t*)tcp_hdr);
> -				}
> -			} else if (l4_proto == IPPROTO_SCTP) {
> -				sctp_hdr = (struct sctp_hdr*)
> (rte_pktmbuf_mtod(mb,
> -						unsigned char *) + l2_len +
> l3_len);
> -
> -				if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_SCTP_CKSUM) {
> -					ol_flags |= PKT_TX_SCTP_CKSUM;
> -					sctp_hdr->cksum = 0;
> -
> -					/* Sanity check, only number of 4 bytes
> supported */
> -					if ((rte_be_to_cpu_16(ipv4_hdr-
> >total_length) % 4) != 0)
> -						printf("sctp payload must be a
> multiple "
> -							"of 4 bytes for
> checksum offload");
> -				}
> -				else {
> -					sctp_hdr->cksum = 0;
> -					/* CRC32c sample code available in
> RFC3309 */
> -				}
> -			}
> -			/* End of L4 Handling*/
> -		} else if (pkt_ol_flags & (PKT_RX_IPV6_HDR |
> PKT_RX_TUNNEL_IPV6_HDR)) {
> -			ipv6_hdr = (struct ipv6_hdr *) (rte_pktmbuf_mtod(mb,
> -					unsigned char *) + l2_len);
> -			l3_len = sizeof(struct ipv6_hdr) ;
> -			l4_proto = ipv6_hdr->proto;
> -			ol_flags |= PKT_TX_IPV6;
> -
> -			if (l4_proto == IPPROTO_UDP) {
> -				udp_hdr = (struct udp_hdr*)
> (rte_pktmbuf_mtod(mb,
> -						unsigned char *) + l2_len +
> l3_len);
> -				if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_UDP_CKSUM) {
> -					/* HW Offload */
> -					ol_flags |= PKT_TX_UDP_CKSUM;
> -					if (ipv6_tunnel)
> -						udp_hdr->dgram_cksum = 0;
> -					else
> -						udp_hdr->dgram_cksum =
> -
> 	get_ipv6_psd_sum(ipv6_hdr);
> -				}
> -				else {
> -					/* SW Implementation */
> -					/* checksum field need be clear first */
> -					udp_hdr->dgram_cksum = 0;
> -					udp_hdr->dgram_cksum =
> get_ipv6_udptcp_checksum(ipv6_hdr,
> -								(uint16_t
> *)udp_hdr);
> -				}
> -
> -				if (ipv6_tunnel) {
> -
> -					uint16_t len;
> -
> -					/* Check if inner L3/L4 checksum flag is
> set */
> -					if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_CKSUM_MASK)
> -						ol_flags |=
> PKT_TX_VXLAN_CKSUM;
> -
> -					inner_l2_len  = sizeof(struct ether_hdr);
> -					inner_eth_hdr = (struct ether_hdr *)
> (rte_pktmbuf_mtod(mb,
> -						unsigned char *) + l2_len +
> l3_len + ETHER_VXLAN_HLEN);
> -					eth_type =
> rte_be_to_cpu_16(inner_eth_hdr->ether_type);
> -
> -					if (eth_type == ETHER_TYPE_VLAN) {
> -						inner_l2_len += sizeof(struct
> vlan_hdr);
> -						eth_type =
> rte_be_to_cpu_16(*(uint16_t *)
> -							((uintptr_t)&eth_hdr-
> >ether_type +
> -							sizeof(struct
> vlan_hdr)));
> -					}
> -
> -					len = l2_len + l3_len +
> ETHER_VXLAN_HLEN + inner_l2_len;
> -
> -					if (eth_type == ETHER_TYPE_IPv4) {
> -						inner_l3_len = sizeof(struct
> ipv4_hdr);
> -						inner_ipv4_hdr = (struct
> ipv4_hdr *) (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + len);
> -						inner_l4_proto =
> inner_ipv4_hdr->next_proto_id;
> -
> -						/* HW offload */
> -						if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_IP_CKSUM) {
> -
> -							/* Do not delete, this is
> required by HW*/
> -							inner_ipv4_hdr-
> >hdr_checksum = 0;
> -							ol_flags |=
> PKT_TX_IPV4_CSUM;
> -						}
> -					} else if (eth_type ==
> ETHER_TYPE_IPv6) {
> -						inner_l3_len = sizeof(struct
> ipv6_hdr);
> -						inner_ipv6_hdr = (struct
> ipv6_hdr *) (rte_pktmbuf_mtod(mb,
> -							unsigned char *) + len);
> -						inner_l4_proto =
> inner_ipv6_hdr->proto;
> -					}
> -
> -					if ((inner_l4_proto == IPPROTO_UDP)
> &&
> -						(tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_UDP_CKSUM)) {
> -						inner_udp_hdr = (struct
> udp_hdr *) (rte_pktmbuf_mtod(mb,
> -							unsigned char *) + len
> + inner_l3_len);
> -						/* HW offload */
> -						ol_flags |=
> PKT_TX_UDP_CKSUM;
> -						inner_udp_hdr->dgram_cksum
> = 0;
> -						if (eth_type ==
> ETHER_TYPE_IPv4)
> -							inner_udp_hdr-
> >dgram_cksum = get_ipv4_psd_sum(inner_ipv4_hdr);
> -						else if (eth_type ==
> ETHER_TYPE_IPv6)
> -							inner_udp_hdr-
> >dgram_cksum = get_ipv6_psd_sum(inner_ipv6_hdr);
> -					} else if ((inner_l4_proto ==
> IPPROTO_TCP) &&
> -						(tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_TCP_CKSUM)) {
> -						/* HW offload */
> -						ol_flags |=
> PKT_TX_TCP_CKSUM;
> -						inner_tcp_hdr = (struct tcp_hdr
> *) (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + len + inner_l3_len);
> -
> -						if (eth_type ==
> ETHER_TYPE_IPv4)
> -							inner_tcp_hdr->cksum
> = get_ipv4_psd_sum(inner_ipv4_hdr);
> -						else if (eth_type ==
> ETHER_TYPE_IPv6)
> -							inner_tcp_hdr->cksum
> = get_ipv6_psd_sum(inner_ipv6_hdr);
> -
> -					} else if ((inner_l4_proto ==
> IPPROTO_SCTP) &&
> -						(tx_ol_flags &
> TESTPMD_TX_OFFLOAD_INNER_SCTP_CKSUM)) {
> -						/* HW offload */
> -						ol_flags |=
> PKT_TX_SCTP_CKSUM;
> -						inner_sctp_hdr = (struct
> sctp_hdr *) (rte_pktmbuf_mtod(mb,
> -								unsigned char
> *) + len + inner_l3_len);
> -						inner_sctp_hdr->cksum = 0;
> -					}
> -
> -				}
> -
> -			}
> -			else if (l4_proto == IPPROTO_TCP) {
> -				tcp_hdr = (struct tcp_hdr*)
> (rte_pktmbuf_mtod(mb,
> -						unsigned char *) + l2_len +
> l3_len);
> -				if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_TCP_CKSUM) {
> -					ol_flags |= PKT_TX_TCP_CKSUM;
> -					tcp_hdr->cksum =
> get_ipv6_psd_sum(ipv6_hdr);
> -				}
> -				else {
> -					tcp_hdr->cksum = 0;
> -					tcp_hdr->cksum =
> get_ipv6_udptcp_checksum(ipv6_hdr,
> -							(uint16_t*)tcp_hdr);
> -				}
> -			}
> -			else if (l4_proto == IPPROTO_SCTP) {
> -				sctp_hdr = (struct sctp_hdr*)
> (rte_pktmbuf_mtod(mb,
> -						unsigned char *) + l2_len +
> l3_len);
> -
> -				if (tx_ol_flags &
> TESTPMD_TX_OFFLOAD_SCTP_CKSUM) {
> -					ol_flags |= PKT_TX_SCTP_CKSUM;
> -					sctp_hdr->cksum = 0;
> -					/* Sanity check, only number of 4 bytes
> supported by HW */
> -					if ((rte_be_to_cpu_16(ipv6_hdr-
> >payload_len) % 4) != 0)
> -						printf("sctp payload must be a
> multiple "
> -							"of 4 bytes for
> checksum offload");
> -				}
> -				else {
> -					/* CRC32c sample code available in
> RFC3309 */
> -					sctp_hdr->cksum = 0;
> -				}
> -			} else {
> -				printf("Test flow control for 1G PMD \n");
> -			}
> -			/* End of L6 Handling*/
> -		}
> -		else {
> -			l3_len = 0;
> -			printf("Unhandled packet type: %#hx\n", eth_type);
> +		} 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 = l2_len;
> +			m->l3_len = l3_len;
>  		}
> +		m->ol_flags = ol_flags;
> 
> -		/* Combine the packet header write. VLAN is not consider here
> */
> -		mb->l2_len = l2_len;
> -		mb->l3_len = l3_len;
> -		mb->inner_l2_len = inner_l2_len;
> -		mb->inner_l3_len = inner_l3_len;
> -		mb->ol_flags = ol_flags;
>  	}
>  	nb_tx = rte_eth_tx_burst(fs->tx_port, fs->tx_queue, pkts_burst, nb_rx);
>  	fs->tx_packets += nb_tx;
> @@ -629,7 +570,6 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
> #endif  }
> 
> -
>  struct fwd_engine csum_fwd_engine = {
>  	.fwd_mode_name  = "csum",
>  	.port_fwd_begin = NULL,
> diff --git a/app/test-pmd/testpmd.h b/app/test-pmd/testpmd.h index
> 82af2bd..c753d37 100644
> --- a/app/test-pmd/testpmd.h
> +++ b/app/test-pmd/testpmd.h
> @@ -131,18 +131,11 @@ struct fwd_stream {
>  #define TESTPMD_TX_OFFLOAD_TCP_CKSUM         0x0004
>  /** Offload SCTP checksum in csum forward engine */
>  #define TESTPMD_TX_OFFLOAD_SCTP_CKSUM        0x0008
> -/** Offload inner IP checksum in csum forward engine */
> -#define TESTPMD_TX_OFFLOAD_INNER_IP_CKSUM    0x0010
> -/** Offload inner UDP checksum in csum forward engine */
> -#define TESTPMD_TX_OFFLOAD_INNER_UDP_CKSUM   0x0020
> -/** Offload inner TCP checksum in csum forward engine */
> -#define TESTPMD_TX_OFFLOAD_INNER_TCP_CKSUM   0x0040
> -/** Offload inner SCTP checksum in csum forward engine */ -#define
> TESTPMD_TX_OFFLOAD_INNER_SCTP_CKSUM  0x0080
> -/** Offload inner IP checksum mask */
> -#define TESTPMD_TX_OFFLOAD_INNER_CKSUM_MASK  0x00F0
> +/** Offload VxLAN checksum in csum forward engine */
> +#define TESTPMD_TX_OFFLOAD_VXLAN_CKSUM       0x0010
>  /** Insert VLAN header in forward engine */
> -#define TESTPMD_TX_OFFLOAD_INSERT_VLAN       0x0100
> +#define TESTPMD_TX_OFFLOAD_INSERT_VLAN       0x0020
> +
>  /**
>   * The data structure associated with each port.
>   */
> @@ -510,8 +503,6 @@ void tx_vlan_pvid_set(portid_t port_id, uint16_t vlan_id,
> int on);
> 
>  void set_qmap(portid_t port_id, uint8_t is_rx, uint16_t queue_id, uint8_t
> map_value);
> 
> -void tx_cksum_set(portid_t port_id, uint64_t ol_flags);
> -
>  void set_verbose_level(uint16_t vb_level);  void set_tx_pkt_segments(unsigned
> *seg_lengths, unsigned nb_segs);  void set_nb_pkt_per_burst(uint16_t
> pkt_burst);
> --
> 2.1.0
  

Hi Jijiang,

On 11/17/2014 09:11 AM, Liu, Jijiang wrote:
>> +/* Calculate the checksum of outer header (only vxlan is supported,
>> + * meaning IP + UDP). The caller already checked that it's a vxlan
>> + * packet */
>> +static uint64_t
>> +process_outer_cksums(void *outer_l3_hdr, uint16_t outer_ethertype,
>> +	uint16_t outer_l3_len, uint16_t testpmd_ol_flags) {
>> +	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 (testpmd_ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM)
>> +		ol_flags |= PKT_TX_VXLAN_CKSUM;
>> +
>> +	if (outer_ethertype == _htons(ETHER_TYPE_IPv4)) {
>> +		ipv4_hdr->hdr_checksum = 0;
>> +
>> +		if ((testpmd_ol_flags & TESTPMD_TX_OFFLOAD_VXLAN_CKSUM)
>> == 0)
>> +			ipv4_hdr->hdr_checksum = get_ipv4_cksum(ipv4_hdr);
>> +	}
> 
> As I mentioned, we should use TESTPMD_TX_OFFLOAD_IP_CKSUM instead of using TESTPMD_TX_OFFLOAD_VXLAN_CKSUM flag to check if we need to set outer IP checksum offload.
> In other words, even if VXLAN packet, outer IP TX checksum offload is also needed if  TESTPMD_TX_OFFLOAD_IP_CKSUM is set.

The csum forward engine works as follow after the rework. I can add
some more comments in the patch or testpmd help to describe it more
clearly.

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:
 - modify the IPs in inner headers and in outer headers if any
 - 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

The testpmd command line for csum takes the following arguments:
  tx_cksum set (ip|udp|tcp|sctp|vxlan) (hw|sw) (port_id)

- "ip|udp|tcp|sctp" always concern the inner layer
- "vxlan" concerns the outer IP and UDP layer (if packet is recognized
  as a vxlan packet)

Hope it's enough precisely described to be able to predict the output
of testpmd without reading the code or the i40e datasheets. This was
not so clear before.

So, following this description, there is not reason to check the
TESTPMD_TX_OFFLOAD_IP_CKSUM when scheduling the hardware VxLAN checksum.
One thing may be wrong however, it's the mbuf flags set in the packet.
But we cannot say it's wrong today because the API is not documented.
But the VXLAN feature is not enough documented to be sure it's wrong.


Regards,
Olivier