Re: [dpdk-dev] [PATCH v3] i40: fix the VXLAN TSO issue

["Tan, Jianfeng" <jianfeng.tan@intel.com>]

Hi,

On 7/18/2016 7:56 PM, Zhe Tao wrote:
> Problem:
> When using the TSO + VXLAN feature in i40e, the outer UDP length fields in
> the multiple UDP segments which are TSOed by the i40e will have a
> wrong value.
>
> Fix this problem by adding the tunnel type field in the i40e descriptor
> which was missed before.
>
> Fixes: 77b8301733c3 ("i40e: VXLAN Tx checksum offload")
>
> Signed-off-by: Zhe Tao <zhe.tao@intel.com>
> ---
> v2: edited the comments
> v3: added external IP offload flag when TSO is enabled for tunnelling packets
>
>   app/test-pmd/csumonly.c      | 29 +++++++++++++++++++++--------
>   drivers/net/i40e/i40e_rxtx.c | 12 +++++++++---
>   lib/librte_mbuf/rte_mbuf.h   | 16 +++++++++++++++-
>   3 files changed, 45 insertions(+), 12 deletions(-)
>
...
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index 15e3a10..90812ea 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -133,6 +133,17 @@ extern "C" {
>   /* add new TX flags here */
>   
>   /**
> + * Bits 45:48 used for the tunnel type.
> + * When doing Tx offload like TSO or checksum, the HW needs to configure the
> + * tunnel type into the HW descriptors.
> + */
> +#define PKT_TX_TUNNEL_VXLAN   (1ULL << 45)
> +#define PKT_TX_TUNNEL_GRE   (2ULL << 45)
> +#define PKT_TX_TUNNEL_IPIP    (3ULL << 45)
> +/* add new TX TUNNEL type here */
> +#define PKT_TX_TUNNEL_MASK    (0xFULL << 45)
> +

Above flag bits are added so that i40e driver can tell tunnel type of 
this packet (udp or gre or ipip), just interested to know how about just 
do a simple analysis like below without introducing these flags?

if outer_ether.proto == ipv4
     l4_proto = ipv4_hdr->next_proto;
else outer_ether.proto == ipv6
     l4_proto = ipv6_hdr->next_proto;

switch (l4_proto)
     case ipv4:
     case ipv6:
         tunnel_type = ipip;
         break;
     case udp:
         tunnel_type = udp;
         break;
     case gre:
         tunnel_type = gre;
         break;
     default:
          error;

Thanks,
Jianfeng


> +/**
>    * Second VLAN insertion (QinQ) flag.
>    */
>   #define PKT_TX_QINQ_PKT    (1ULL << 49)   /**< TX packet with double VLAN inserted. */
> @@ -867,7 +878,10 @@ struct rte_mbuf {
>   	union {
>   		uint64_t tx_offload;       /**< combined for easy fetch */
>   		struct {
> -			uint64_t l2_len:7; /**< L2 (MAC) Header Length. */
> +			uint64_t l2_len:7;
> +			/**< L2 (MAC) Header Length if it isn't a tunneling pkt.
> +			 * for tunnel it is outer L4 len+tunnel len+inner L2 len
> +			 */
>   			uint64_t l3_len:9; /**< L3 (IP) Header Length. */
>   			uint64_t l4_len:8; /**< L4 (TCP/UDP) Header Length. */
>   			uint64_t tso_segsz:16; /**< TCP TSO segment size */