-----Original Message-----
From: users [mailto:users-bounces@dpdk.org] On Behalf Of Iain Barker
Sent: Wednesday, October 11, 2017 9:20 PM
To: users@dpdk.org
Cc: dev@dpdk.org
Subject: Re: [dpdk-users] VLAN tags always stripped on i40evf [VMware SR-
IOV]

On Tuesday, October 10, 2017 9:49 AM (EST), Iain Barker wrote:

quoted

I have a problem trying to get VLAN tagged frames to be received at the

i40evf PMD.

With more debugging enabled, I can see that this seems to be a compatibility
problem between DPDK and i40evf related to VLAN hardware stripping.

Specifically, when DPDK requests VLAN stripping to be disabled by VF, but
the PF policy doesn't allow it to be disabled (as is the case for VMware SR-
IOV), an error is returned from the API.

testpmd> vlan set strip off 0
  i40evf_execute_vf_cmd(): No response for 28
  i40evf_disable_vlan_strip(): Failed to execute command of
VIRTCHNL_OP_DISABLE_VLAN_STRIPPING

In that case, received frames with VLAN headers will still be 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 i40e PCI (vlan works):
  PMD: i40e_rxd_to_vlan_tci(): Mbuf vlan_tci: 0, vlan_tci_outer: 0
  Port 0 pkt-len=102 nb-segs=1
    ETH:  src=00:10:E0:8D:A7:52 dst=00:10:E0:8A:86:8A [vlan id=8] type=0x0800
    IPV4: src=8.8.8.102 dst=8.8.8.3 proto=1 (ICMP)
    ICMP: echo request seq id=1

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 DPDK should emulate the
requested behavior by re-add the missing VLAN header in the RX thread,
before it passes the mbuf to the application.  I'm guessing that the native
Linux driver is smart enough to do something like this automatically in
software, but DPDK does not...

Adding a call to rte_vlan_insert() to reinstate the VLAN header using the data
from TCI is sufficient to avoid the problem in a quick test.

--- drivers/net/i40e/i40e_rxtx.c.orig      2016-11-30 04:28:48.000000000 -0500
+++ drivers/net/i40e/i40e_rxtx.c   2017-10-10 15:07:10.851398087 -0400

@@ -93,6 +93,8 @@
                        rte_le_to_cpu_16(rxdp->wb.qword0.lo_dword.l2tag1);
                PMD_RX_LOG(DEBUG, "Descriptor l2tag1: %u",
                           rte_le_to_cpu_16(rxdp->wb.qword0.lo_dword.l2tag1));
+               // vlan got stripped. Re-inject vlan from tci
+               rte_vlan_insert(&mb);
        } else {
                mb->vlan_tci = 0;
        }