[dpdk-dev] i40eVF pmd vlan id handling

["Dey, Souvik" <sodey@rbbn.com>]

Hi All,
        I am using DPDK 18.11.2 and i40e PF linux driver on the host 2.4.6. I see there, when I enable DEV_RX_OFFLOAD_VLAN_FILTER from the DPDK app, and then configure the specific vlan id using rte_eth_dev_vlan_filter(). As per DPDK code by default when we do dev_configure, we call i40evf_init_vlan() and if we don't enable rxmode.offloads with DEV_RX_OFFLOAD_VLAN_STRIP, then we should send VIRTCHNL_OP_DISABLE_VLAN_STRIPPING command to the PF from the guest.

With more debugging enabled, when DPDK requests VLAN filtering by sending VIRTCHNL_OP_ADD_VLAN to the PF, then we see that the VF stripping is enabled also on Linux. If we don't add VLAN ID and send VIRTCHNL_OP_ADD_VLAN message down to the PF , then we do receive packets with VLAN ID set.
The same works fine in VmWare drivers, where we do receive VALN id in the packets if STRIP is disabled.

In the linux case, when we receive frames with VLAN headers, the vlan id is stripped at the PF, and the TCI will record the missing VLAN details when handed up to the DPDK driver.

With i40e debug enabled, it's clear to see the difference being reported in i40e_rxd_to_vlan_tci:


Example using VLAN on i40evf SR-IOV (vlan fails):
  PMD: i40e_rxd_to_vlan_tci(): Mbuf vlan_tci: 8, vlan_tci_outer: 0
  Port 0 pkt-len=60 nb-segs=1
    ETH:  src=00:10:E0:8D:A7:52 dst=FF:FF:FF:FF:FF:FF type=0x0806
    ARP:  hrd=1 proto=0x0800 hln=6 pln=4 op=1 (ARP Request)
          sha=00:10:E0:8D:A7:52 sip=8.8.8.102
          tha=00:00:00:00:00:00 tip=8.8.8.3

As the application requested tagging not be stripped, and the hardware driver was not able to disable strip, in my opinion either DPDK or linux driver should have a bug in handing this. Also as we see VmWare i40e driver working it could be either a extra config required for linux driver or a bug in linux driver.
I also tried to add a call to rte_vlan_insert() to reinstate the VLAN header using the data from TCI in i40e_rxd_to_vlan_tci(), but it is having performance impacts as expected. Also as rte_vlan_insert() does not support QINQ, it will have other issues too.

Can you please clarify if this is working for i40e vlan filter test and if we are missing something in the DPDK, like sending VIRTCHNL_OP_DISABLE_VLAN_STRIPPING after every VIRTCHNL_OP_ADD_VLAN if DEV_RX_OFFLOAD_VLAN_STRIP is not set by the DPDk app.

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Regards,
Souvik