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
> 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;
}
For a proper solution, this would need to be made selective based on whether
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 that 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 paths
for other drivers, if affected by the same shortcoming. I don't have other
combinations available that I could test with, and I guess VMware i40evf SR-IOV
VLAN isn't part of the DPDK release test suite either.
cc: d...@dpdk.org for comment as this is getting beyond my level of knowledge
as a DPDK user
thanks,
Iain
