[v2,4/5] net/i40e: fix max mtu size packets with vlan tag cannot be received by default

  testpmd will initialize default max packet length to 1518 which doesn't
include vlan tag size in ether overheader. Once, send the max mtu length
packet with vlan tag, the max packet length will exceed 1518 that will
cause packets dropped directly from NIC hw side. But for i40e/i40evf,
they should support dual vlan tags that need more 8 bytes for max packet
size, so, configure the correct max packet size in dev_config ops.

Fixes: ff8282f4bbcd ("net/i40e: consider QinQ when setting MTU")

Signed-off-by: SteveX Yang <stevex.yang@intel.com>
---
 drivers/net/i40e/i40e_ethdev.c    |  5 +++++
 drivers/net/i40e/i40e_ethdev_vf.c | 11 +++++++++++
 2 files changed, 16 insertions(+)
  

> -----Original Message-----
> From: Yang, SteveX <stevex.yang@intel.com>
> Sent: Tuesday, September 22, 2020 2:24 AM
> To: dev@dpdk.org
> Cc: Zhao1, Wei <wei.zhao1@intel.com>; Guo, Jia <jia.guo@intel.com>; Yang, Qiming <qiming.yang@intel.com>; Zhang, Qi Z
> <qi.z.zhang@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>; Xing, Beilei <beilei.xing@intel.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.com>; Yang, SteveX <stevex.yang@intel.com>
> Subject: [PATCH v2 4/5] net/i40e: fix max mtu size packets with vlan tag cannot be received by default
> 
> testpmd will initialize default max packet length to 1518 which doesn't
> include vlan tag size in ether overheader. Once, send the max mtu length
> packet with vlan tag, the max packet length will exceed 1518 that will
> cause packets dropped directly from NIC hw side. But for i40e/i40evf,
> they should support dual vlan tags that need more 8 bytes for max packet
> size, so, configure the correct max packet size in dev_config ops.
> 
> Fixes: ff8282f4bbcd ("net/i40e: consider QinQ when setting MTU")
> 
> Signed-off-by: SteveX Yang <stevex.yang@intel.com>
> ---
>  drivers/net/i40e/i40e_ethdev.c    |  5 +++++
>  drivers/net/i40e/i40e_ethdev_vf.c | 11 +++++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/drivers/net/i40e/i40e_ethdev.c b/drivers/net/i40e/i40e_ethdev.c
> index 563f21d9d..023c86d66 100644
> --- a/drivers/net/i40e/i40e_ethdev.c
> +++ b/drivers/net/i40e/i40e_ethdev.c
> @@ -1930,6 +1930,11 @@ i40e_dev_configure(struct rte_eth_dev *dev)
>  	ad->tx_simple_allowed = true;
>  	ad->tx_vec_allowed = true;
> 
> +	/* Considering QinQ packet, max frame size should be MTU and
> +	 * corresponding ether overhead.
> +	 */
> +	i40e_dev_mtu_set(dev, dev->data->mtu);
> +
>  	if (dev->data->dev_conf.rxmode.mq_mode & ETH_MQ_RX_RSS_FLAG)
>  		dev->data->dev_conf.rxmode.offloads |= DEV_RX_OFFLOAD_RSS_HASH;
> 
> diff --git a/drivers/net/i40e/i40e_ethdev_vf.c b/drivers/net/i40e/i40e_ethdev_vf.c
> index 8531cf6b1..b268b3d00 100644
> --- a/drivers/net/i40e/i40e_ethdev_vf.c
> +++ b/drivers/net/i40e/i40e_ethdev_vf.c
> @@ -1669,6 +1669,7 @@ i40evf_dev_configure(struct rte_eth_dev *dev)
>  		I40E_DEV_PRIVATE_TO_ADAPTER(dev->data->dev_private);
>  	uint16_t num_queue_pairs = RTE_MAX(dev->data->nb_rx_queues,
>  				dev->data->nb_tx_queues);
> +	struct rte_eth_rxmode *rxmode = &dev->data->dev_conf.rxmode;
> 
>  	/* Initialize to TRUE. If any of Rx queues doesn't meet the bulk
>  	 * allocation or vector Rx preconditions we will reset it.
> @@ -1681,6 +1682,16 @@ i40evf_dev_configure(struct rte_eth_dev *dev)
>  	dev->data->dev_conf.intr_conf.lsc =
>  		!!(dev->data->dev_flags & RTE_ETH_DEV_INTR_LSC);
> 
> +
> +	/* Considering QinQ packet, max frame size should be MTU and
> +	 * corresponding ether overhead.
> +	 */
> +	if (dev->data->mtu == RTE_ETHER_MTU &&
> +		rxmode->max_rx_pkt_len == RTE_ETHER_MAX_LEN) {
> +		rxmode->max_rx_pkt_len = RTE_ETHER_MTU + I40E_ETH_OVERHEAD;
> +		rxmode->offloads |= DEV_RX_OFFLOAD_JUMBO_FRAME;
> +	}

Wonder why vf code-path is different here?
Can't we also do mtu_set() here?

> +
>  	if (num_queue_pairs > vf->vsi_res->num_queue_pairs) {
>  		struct i40e_hw *hw;
>  		int ret;
> --
> 2.17.1