Re: [dpdk-dev] [PATCH v2 5/6] ixgbe: support VxLAN & NVGRE TX checksum off-load

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Wenzhuo,

> -----Original Message-----
> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Wenzhuo Lu
> Sent: Thursday, January 14, 2016 1:39 AM
> To: dev@dpdk.org
> Subject: [dpdk-dev] [PATCH v2 5/6] ixgbe: support VxLAN & NVGRE TX checksum off-load
> 
> The patch add VxLAN & NVGRE TX checksum off-load. When the flag of
> outer IP header checksum offload is set, we'll set the context
> descriptor to enable this checksum off-load.
> 
> Signed-off-by: Wenzhuo Lu <wenzhuo.lu@intel.com>
> ---
>  drivers/net/ixgbe/ixgbe_rxtx.c | 52 ++++++++++++++++++++++++++++++++++--------
>  drivers/net/ixgbe/ixgbe_rxtx.h |  6 ++++-
>  lib/librte_mbuf/rte_mbuf.h     |  2 ++
>  3 files changed, 49 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
> index 512ac3a..fea2495 100644
> --- a/drivers/net/ixgbe/ixgbe_rxtx.c
> +++ b/drivers/net/ixgbe/ixgbe_rxtx.c
> @@ -85,7 +85,8 @@
>  		PKT_TX_VLAN_PKT |		 \
>  		PKT_TX_IP_CKSUM |		 \
>  		PKT_TX_L4_MASK |		 \
> -		PKT_TX_TCP_SEG)
> +		PKT_TX_TCP_SEG |		 \
> +		PKT_TX_OUTER_IP_CKSUM)


I think you also need to update dev_info.tx_offload_capa,
couldn't find where you doing it.

> 
>  static inline struct rte_mbuf *
>  rte_rxmbuf_alloc(struct rte_mempool *mp)
> @@ -364,9 +365,11 @@ ixgbe_set_xmit_ctx(struct ixgbe_tx_queue *txq,
>  	uint32_t ctx_idx;
>  	uint32_t vlan_macip_lens;
>  	union ixgbe_tx_offload tx_offload_mask;
> +	uint32_t seqnum_seed = 0;
> 
>  	ctx_idx = txq->ctx_curr;
> -	tx_offload_mask.data = 0;
> +	tx_offload_mask.data[0] = 0;
> +	tx_offload_mask.data[1] = 0;
>  	type_tucmd_mlhl = 0;
> 
>  	/* Specify which HW CTX to upload. */
> @@ -430,9 +433,20 @@ ixgbe_set_xmit_ctx(struct ixgbe_tx_queue *txq,
>  		}
>  	}
> 
> +	if (ol_flags & PKT_TX_OUTER_IP_CKSUM) {
> +		tx_offload_mask.outer_l3_len |= ~0;
> +		tx_offload_mask.outer_l2_len |= ~0;
> +		seqnum_seed |= tx_offload.outer_l3_len
> +			       << IXGBE_ADVTXD_OUTER_IPLEN;
> +		seqnum_seed |= tx_offload.outer_l2_len
> +			       << IXGBE_ADVTXD_TUNNEL_LEN;
> +	}

I don't have an X550 card off-hand, but reading through datasheet - it doesn't seem right.
When OUTER_IP_CKSUM is enabled MACLEN becomes outer_l2_len and 
TUNNEL_LEN should be: outer_l4_len + tunnel_hdr_len + inner_l2_len.
So I think that in our case TUNNEL_LEN should be set to l2_len. 

> +
>  	txq->ctx_cache[ctx_idx].flags = ol_flags;
> -	txq->ctx_cache[ctx_idx].tx_offload.data  =
> -		tx_offload_mask.data & tx_offload.data;
> +	txq->ctx_cache[ctx_idx].tx_offload.data[0]  =
> +		tx_offload_mask.data[0] & tx_offload.data[0];
> +	txq->ctx_cache[ctx_idx].tx_offload.data[1]  =
> +		tx_offload_mask.data[1] & tx_offload.data[1];
>  	txq->ctx_cache[ctx_idx].tx_offload_mask    = tx_offload_mask;
> 
>  	ctx_txd->type_tucmd_mlhl = rte_cpu_to_le_32(type_tucmd_mlhl);
> @@ -441,7 +455,7 @@ ixgbe_set_xmit_ctx(struct ixgbe_tx_queue *txq,
>  	vlan_macip_lens |= ((uint32_t)tx_offload.vlan_tci << IXGBE_ADVTXD_VLAN_SHIFT);
>  	ctx_txd->vlan_macip_lens = rte_cpu_to_le_32(vlan_macip_lens);
>  	ctx_txd->mss_l4len_idx   = rte_cpu_to_le_32(mss_l4len_idx);
> -	ctx_txd->seqnum_seed     = 0;
> +	ctx_txd->seqnum_seed     = seqnum_seed;
>  }
> 
>  /*
> @@ -454,16 +468,24 @@ what_advctx_update(struct ixgbe_tx_queue *txq, uint64_t flags,
>  {
>  	/* If match with the current used context */
>  	if (likely((txq->ctx_cache[txq->ctx_curr].flags == flags) &&
> -		(txq->ctx_cache[txq->ctx_curr].tx_offload.data ==
> -		(txq->ctx_cache[txq->ctx_curr].tx_offload_mask.data & tx_offload.data)))) {
> +		(txq->ctx_cache[txq->ctx_curr].tx_offload.data[0] ==
> +		(txq->ctx_cache[txq->ctx_curr].tx_offload_mask.data[0]
> +		 & tx_offload.data[0])) &&
> +		(txq->ctx_cache[txq->ctx_curr].tx_offload.data[1] ==
> +		(txq->ctx_cache[txq->ctx_curr].tx_offload_mask.data[1]
> +		 & tx_offload.data[1])))) {
>  			return txq->ctx_curr;
>  	}
> 
>  	/* What if match with the next context  */
>  	txq->ctx_curr ^= 1;
>  	if (likely((txq->ctx_cache[txq->ctx_curr].flags == flags) &&
> -		(txq->ctx_cache[txq->ctx_curr].tx_offload.data ==
> -		(txq->ctx_cache[txq->ctx_curr].tx_offload_mask.data & tx_offload.data)))) {
> +		(txq->ctx_cache[txq->ctx_curr].tx_offload.data[0] ==
> +		(txq->ctx_cache[txq->ctx_curr].tx_offload_mask.data[0]
> +		 & tx_offload.data[0])) &&
> +		(txq->ctx_cache[txq->ctx_curr].tx_offload.data[1] ==
> +		(txq->ctx_cache[txq->ctx_curr].tx_offload_mask.data[1]
> +		 & tx_offload.data[1])))) {
>  			return txq->ctx_curr;
>  	}
> 
> @@ -492,6 +514,12 @@ tx_desc_ol_flags_to_cmdtype(uint64_t ol_flags)
>  		cmdtype |= IXGBE_ADVTXD_DCMD_VLE;
>  	if (ol_flags & PKT_TX_TCP_SEG)
>  		cmdtype |= IXGBE_ADVTXD_DCMD_TSE;
> +	if (ol_flags & PKT_TX_OUTER_IP_CKSUM)
> +		cmdtype |= (1 << IXGBE_ADVTXD_OUTERIPCS_SHIFT);
> +	if (ol_flags & PKT_TX_VXLAN_PKT)
> +		cmdtype &= ~(1 << IXGBE_ADVTXD_TUNNEL_TYPE_NVGRE);
> +	else
> +		cmdtype |= (1 << IXGBE_ADVTXD_TUNNEL_TYPE_NVGRE);
>  	return cmdtype;
>  }
> 
> @@ -588,8 +616,10 @@ ixgbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
>  	uint64_t tx_ol_req;
>  	uint32_t ctx = 0;
>  	uint32_t new_ctx;
> -	union ixgbe_tx_offload tx_offload = {0};
> +	union ixgbe_tx_offload tx_offload;
> 
> +	tx_offload.data[0] = 0;
> +	tx_offload.data[1] = 0;
>  	txq = tx_queue;
>  	sw_ring = txq->sw_ring;
>  	txr     = txq->tx_ring;
> @@ -623,6 +653,8 @@ ixgbe_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
>  			tx_offload.l4_len = tx_pkt->l4_len;
>  			tx_offload.vlan_tci = tx_pkt->vlan_tci;
>  			tx_offload.tso_segsz = tx_pkt->tso_segsz;
> +			tx_offload.outer_l2_len = tx_pkt->outer_l2_len;
> +			tx_offload.outer_l3_len = tx_pkt->outer_l3_len;
> 
>  			/* If new context need be built or reuse the exist ctx. */
>  			ctx = what_advctx_update(txq, tx_ol_req,
> diff --git a/drivers/net/ixgbe/ixgbe_rxtx.h b/drivers/net/ixgbe/ixgbe_rxtx.h
> index 475a800..c15f9fa 100644
> --- a/drivers/net/ixgbe/ixgbe_rxtx.h
> +++ b/drivers/net/ixgbe/ixgbe_rxtx.h
> @@ -163,7 +163,7 @@ enum ixgbe_advctx_num {
> 
>  /** Offload features */
>  union ixgbe_tx_offload {
> -	uint64_t data;
> +	uint64_t data[2];

I wonder what is there any performance impact of increasing size of tx_offload?

>  	struct {
>  		uint64_t l2_len:7; /**< L2 (MAC) Header Length. */
>  		uint64_t l3_len:9; /**< L3 (IP) Header Length. */
> @@ -171,6 +171,10 @@ union ixgbe_tx_offload {
>  		uint64_t tso_segsz:16; /**< TCP TSO segment size */
>  		uint64_t vlan_tci:16;
>  		/**< VLAN Tag Control Identifier (CPU order). */
> +
> +		/* fields for TX offloading of tunnels */
> +		uint64_t outer_l3_len:8; /**< Outer L3 (IP) Hdr Length. */
> +		uint64_t outer_l2_len:8; /**< Outer L2 (MAC) Hdr Length. */
>  	};
>  };
> 
> diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
> index 5ad5e59..1bda00e 100644
> --- a/lib/librte_mbuf/rte_mbuf.h
> +++ b/lib/librte_mbuf/rte_mbuf.h
> @@ -103,6 +103,8 @@ extern "C" {
> 
>  /* add new TX flags here */
> 
> +#define PKT_TX_VXLAN_PKT      (1ULL << 48) /**< TX packet is a VxLAN packet. */
> +

>From reading X550 spec, I don't really understand what for we need to specify is it
GRE or VXLAN packet, so probably we don't need that flag for now at all?
If we really do, might bw worth to organise it like KT_TX_L4_CKSUM (as enum)
and reserve few values for future expansion (2 or 3 bits?).

Konstantin