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Date: Wed, 11 Oct 2017 06:19:41 -0700 (PDT)
From: Iain Barker <iain.barker@oracle.com>
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Subject: Re: [dpdk-dev] [dpdk-users] VLAN tags always stripped on i40evf
[VMware SR-IOV]
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On Tuesday, October 10, 2017 9:49 AM (EST), Iain Barker wrote:
> I have a problem trying to get VLAN tagged frames to be received at the i=
40evf PMD. =20
With more debugging enabled, I can see that this seems to be a compatibilit=
y problem between DPDK and i40evf related to VLAN hardware stripping.
Specifically, when DPDK requests VLAN stripping to be disabled by VF, but t=
he 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_DIS=
ABLE_VLAN_STRIPPING
In that case, received frames with VLAN headers will still be stripped at t=
he PF, and the TCI will record the missing VLAN details when handed up to t=
he 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=3D102 nb-segs=3D1
ETH: src=3D00:10:E0:8D:A7:52 dst=3D00:10:E0:8A:86:8A [vlan id=3D8] typ=
e=3D0x0800
IPV4: src=3D8.8.8.102 dst=3D8.8.8.3 proto=3D1 (ICMP)
ICMP: echo request seq id=3D1
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=3D60 nb-segs=3D1
ETH: src=3D00:10:E0:8D:A7:52 dst=3DFF:FF:FF:FF:FF:FF type=3D0x0806
ARP: hrd=3D1 proto=3D0x0800 hln=3D6 pln=3D4 op=3D1 (ARP Request)
sha=3D00:10:E0:8D:A7:52 sip=3D8.8.8.102
tha=3D00:00:00:00:00:00 tip=3D8.8.8.3
As the application requested tagging not be stripped, and the hardware driv=
er was not able to disable strip, in my opinion DPDK should emulate the req=
uested 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 d=
ata 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 -0=
500
+++ 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 =3D 0;
}
For a proper solution, this would need to be made selective based on whethe=
r the port config originally asked for VLANs to be stripped or not. But I'=
m not sure that rte_vlan_insert() has enough context to be able to access t=
hat data, as it's stored in the driver/hw struct not the rx buffer.
Obviously the same would be required in the vector rxtx and similar data pa=
ths for other drivers, if affected by the same shortcoming. I don't have o=
ther combinations available that I could test with, and I guess VMware i40e=
vf SR-IOV VLAN isn't part of the DPDK release test suite either.
cc: dev@dpdk.org for comment as this is getting beyond my level of knowledg=
e as a DPDK user
thanks,
Iain