Re: [PATCH] net/thunderx: fix MTU configuration for jumbo pkts

[Jerin Jacob <jerin.jacob@caviumnetworks.com>]

-----Original Message-----
> Date: Mon, 16 Apr 2018 10:44:47 +0000
> From: Nitin Saxena <nitin.saxena@caviumnetworks.com>
> To: Jerin Jacob <jerin.jacob@caviumnetworks.com>
> Cc: Nitin Saxena <nitin.saxena@caviumnetworks.com>, Narayana Prasad
>  <narayanaprasad.athreya@caviumnetworks.com>, dev@dpdk.org
> Subject: [PATCH] net/thunderx: fix MTU configuration for jumbo pkts
> X-Mailer: git-send-email 2.7.4
> 
> thunderx pmd driver passes dev_info.max_rx_pktlen as
> 9200 (via rte_eth_dev_info_get()) to application.
> But, when application tries to set MTU as
> (9200 - sizeof(ethernet_header_t)) the operation fails
> because of missing CRC and VLAN additions.
> 
> This patch fixes the following for thunderx pmd driver:
>  - Sets NIC_HW_MAX_FRS to 9216 (instead of 9200)
>  - Sets NIC_HW_MAX_MTU to 9190 (NIC_HW_MAX_FRS - ETH_HLEN
>    - ETHER_CRC_LEN - 2*VLAN_HLEN)
>  - Sets dev_info->max_rx_pkt_len to NIC_HW_MAX_MTU +
>    ETH_HLEN (instead of 9200)
>  - Allows rte_eth_dev_set_mtu() to pass if application
>    (like VPP) calls rte_eth_dev_set_mtu() before
>    rte_eth_dev_start() by putting appropriate check for
>    dev->data->dev_started
> 
> Fixes: 65d9804edc05 ("net/thunderx: support MTU configuration")
> 

Cc: stable@dpdk.org

> Signed-off-by: Nitin Saxena <nitin.saxena@caviumnetworks.com>

Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>

> ---
>  drivers/net/thunderx/base/nicvf_hw_defs.h |  5 ++++-
>  drivers/net/thunderx/nicvf_ethdev.c       | 15 +++++++--------
>  2 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/net/thunderx/base/nicvf_hw_defs.h b/drivers/net/thunderx/base/nicvf_hw_defs.h
> index b13c21f..b12c8ec 100644
> --- a/drivers/net/thunderx/base/nicvf_hw_defs.h
> +++ b/drivers/net/thunderx/base/nicvf_hw_defs.h
> @@ -171,7 +171,10 @@
>  
>  /* Min/Max packet size */
>  #define NIC_HW_MIN_FRS                  (64)
> -#define NIC_HW_MAX_FRS                  (9200) /* 9216 max pkt including FCS */
> +/* ETH_HLEN+ETH_FCS_LEN+2*VLAN_HLEN */
> +#define NIC_HW_L2_OVERHEAD              (26)
> +#define NIC_HW_MAX_MTU                  (9190)
> +#define NIC_HW_MAX_FRS                  (NIC_HW_MAX_MTU + NIC_HW_L2_OVERHEAD)
>  #define NIC_HW_MAX_SEGS                 (12)
>  
>  /* Descriptor alignments */
> diff --git a/drivers/net/thunderx/nicvf_ethdev.c b/drivers/net/thunderx/nicvf_ethdev.c
> index 75e9d16..a7931af 100644
> --- a/drivers/net/thunderx/nicvf_ethdev.c
> +++ b/drivers/net/thunderx/nicvf_ethdev.c
> @@ -162,7 +162,7 @@ static int
>  nicvf_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
>  {
>  	struct nicvf *nic = nicvf_pmd_priv(dev);
> -	uint32_t buffsz, frame_size = mtu + ETHER_HDR_LEN + ETHER_CRC_LEN;
> +	uint32_t buffsz, frame_size = mtu + NIC_HW_L2_OVERHEAD;
>  	size_t i;
>  	struct rte_eth_rxmode *rxmode = &dev->data->dev_conf.rxmode;
>  
> @@ -180,7 +180,7 @@ nicvf_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
>  	 * Refuse mtu that requires the support of scattered packets
>  	 * when this feature has not been enabled before.
>  	 */
> -	if (!dev->data->scattered_rx &&
> +	if (dev->data->dev_started && !dev->data->scattered_rx &&
>  		(frame_size + 2 * VLAN_TAG_SIZE > buffsz))
>  		return -EINVAL;
>  
> @@ -194,11 +194,11 @@ nicvf_dev_set_mtu(struct rte_eth_dev *dev, uint16_t mtu)
>  	else
>  		rxmode->offloads &= ~DEV_RX_OFFLOAD_JUMBO_FRAME;
>  
> -	if (nicvf_mbox_update_hw_max_frs(nic, frame_size))
> +	if (nicvf_mbox_update_hw_max_frs(nic, mtu))
>  		return -EINVAL;
>  
> -	/* Update max frame size */
> -	rxmode->max_rx_pkt_len = (uint32_t)frame_size;
> +	/* Update max_rx_pkt_len */
> +	rxmode->max_rx_pkt_len = mtu + ETHER_HDR_LEN;
>  	nic->mtu = mtu;
>  
>  	for (i = 0; i < nic->sqs_count; i++)
> @@ -1408,7 +1408,7 @@ nicvf_dev_info_get(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
>  		dev_info->speed_capa |= ETH_LINK_SPEED_40G;
>  
>  	dev_info->min_rx_bufsize = ETHER_MIN_MTU;
> -	dev_info->max_rx_pktlen = NIC_HW_MAX_FRS;
> +	dev_info->max_rx_pktlen = NIC_HW_MAX_MTU + ETHER_HDR_LEN;
>  	dev_info->max_rx_queues =
>  			(uint16_t)MAX_RCV_QUEUES_PER_QS * (MAX_SQS_PER_VF + 1);
>  	dev_info->max_tx_queues =
> @@ -1741,8 +1741,7 @@ nicvf_dev_start(struct rte_eth_dev *dev)
>  	/* Setup MTU based on max_rx_pkt_len or default */
>  	mtu = dev->data->dev_conf.rxmode.offloads & DEV_RX_OFFLOAD_JUMBO_FRAME ?
>  		dev->data->dev_conf.rxmode.max_rx_pkt_len
> -			-  ETHER_HDR_LEN - ETHER_CRC_LEN
> -		: ETHER_MTU;
> +			-  ETHER_HDR_LEN : ETHER_MTU;
>  
>  	if (nicvf_dev_set_mtu(dev, mtu)) {
>  		PMD_INIT_LOG(ERR, "Failed to set default mtu size");
> -- 
> 2.7.4
>