Re: [dpdk-dev] ixgbe and UDP with zero checksum

[Paolo Valerio <pvalerio@redhat.com>]

"Wang, Haiyue" <haiyue.wang@intel.com> writes:

> Hi Paolo,
>
>> -----Original Message-----
>> From: Wang, Haiyue
>> Sent: Friday, January 29, 2021 10:02
>> To: Paolo Valerio <pvalerio@redhat.com>
>> Cc: Guo, Jia <jia.guo@intel.com>; Aaron Conole <aconole@redhat.com>; dev@dpdk.org
>> Subject: RE: ixgbe and UDP with zero checksum
>> 
>> > -----Original Message-----
>> > From: Paolo Valerio <pvalerio@redhat.com>
>> > Sent: Thursday, January 28, 2021 05:35
>> > To: Wang, Haiyue <haiyue.wang@intel.com>
>> > Cc: Guo, Jia <jia.guo@intel.com>; Aaron Conole <aconole@redhat.com>; dev@dpdk.org
>> > Subject: RE: ixgbe and UDP with zero checksum
>> >
>> > "Wang, Haiyue" <haiyue.wang@intel.com> writes:
>> >
>> > > Hi Paolo,
>> > >
>> > >> -----Original Message-----
>> > >> From: Paolo Valerio <pvalerio@redhat.com>
>> > >> Sent: Wednesday, January 27, 2021 21:50
>> > >> To: dev@dpdk.org
>> > >> Cc: Guo, Jia <jia.guo@intel.com>; Wang, Haiyue <haiyue.wang@intel.com>; Aaron Conole
>> > >> <aconole@redhat.com>
>> > >> Subject: ixgbe and UDP with zero checksum
>> > >>
>> > >> Hi,
>> > >>
>> > >> performing some tests, I noticed that on ixgbe when receiving UDP
>> > >> packets with zero checksum (no checksum) over IPv4, the corresponding
>> > >> ol_flag for the l4 checksum is set to PKT_RX_L4_CKSUM_BAD.
>> > >>
>> > >> In particular, this apparently has an impact on OvS using ct() action
>> > >> where UDP packets with zero checksum are not tracked because of that.
>> > >
>> > >
>> > >>
>> > >> [1]
>> > >>
>> >
>> https://patchwork.ozlabs.org/project/netdev/patch/20090724040031.30202.1531.stgit@localhost.localdomai
>> > >> n/
>> > >
>> > > About 12 years old patch, it is hardware errata. For fixing this,
>> > > have to always disable vector Rx path for 82599, it seems not a
>> > > good idea to bring in this workaround. :(
>> > >
>> >
>> > Thanks for the answer.
>> > Yes, as I mentioned, the patch is old although still meaningful.
>> > I linked it mostly because it mentions the hw errata.
>> >
>> 
>> What's your PCI device ID ? My worked ixgbe:
>> 
>
> Sorry, I missed the PKT_RX_L4_CKSUM_BAD information, yes, my NIC have the issue.
>
>> 86:00.0 Ethernet controller [0200]: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection
>> [8086:10fb] (rev 01)
>> 
>> I'm wondering if people will complain that the patch will mark the real bad checksum UDP as
>
> Zero checksum is more popular case, please file a bug on https://bugs.dpdk.org/ to trace the fix.
>
> Thanks for pointing it out.
>

ack, I'm going to file it.

Thanks,
Paolo

>> GOOD. For handling this correctly, looks like driver needs to check the UDP's checksum value,
>> if zero, then skip the error information, but this makes driver do the network stack things ...
>> 
>>