netdev - Re: [RFC PATCH 4/5] bnxt: Add support for segmentation of tunnels with outer checksums

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Message-ID: <CACKFLinpYTDTxzBaijdSTE9q+5Ln4Sbo5fGxRbY+wv6bwP=vOQ@mail.gmail.com>
Date:	Fri, 29 Apr 2016 14:29:24 -0700
From:	Michael Chan <michael.chan@...adcom.com>
To:	Alexander Duyck <alexander.duyck@...il.com>
Cc:	Alexander Duyck <aduyck@...antis.com>,
	Eugenia Emantayev <eugenia@...lanox.com>,
	Bruce W Allan <bruce.w.allan@...el.com>,
	Saeed Mahameed <saeedm@...lanox.com>,
	Netdev <netdev@...r.kernel.org>,
	intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
	Ariel Elior <ariel.elior@...gic.com>,
	Michael Chan <mchan@...adcom.com>
Subject: Re: [RFC PATCH 4/5] bnxt: Add support for segmentation of tunnels
 with outer checksums

On Fri, Apr 29, 2016 at 2:17 PM, Alexander Duyck
<alexander.duyck@...il.com> wrote:
> On Wed, Apr 27, 2016 at 9:32 PM, Michael Chan <michael.chan@...adcom.com> wrote:
>> On Wed, Apr 27, 2016 at 8:21 AM, Alexander Duyck
>> <alexander.duyck@...il.com> wrote:
>>> On Tue, Apr 26, 2016 at 10:55 PM, Michael Chan
>>> <michael.chan@...adcom.com> wrote:
>>>> On Tue, Apr 19, 2016 at 12:06 PM, Alexander Duyck <aduyck@...antis.com> wrote:
>>>>> This patch assumes that the bnxt hardware will ignore existing IPv4/v6
>>>>> header fields for length and checksum as well as the length and checksum
>>>>> fields for outer UDP and GRE headers.
>>>>>
>>>>> I have no means of testing this as I do not have any bnx2x hardware but
>>>>> thought I would submit it as an RFC to see if anyone out there wants to
>>>>> test this and see if this does in fact enable this functionality allowing
>>>>> us to to segment tunneled frames that have an outer checksum.
>>>>>
>>>>> Signed-off-by: Alexander Duyck <aduyck@...antis.com>
>>>>
>>>> Hi Alex, I just did a very quick test of this patch on our bnxt
>>>> hardware and it seemed to work.
>>>>
>>>> I created a vxlan endpoint with udpcsum enabled and I saw TSO packets
>>>> getting through.  I've verified that our hardware can be programmed to
>>>> either ignore outer UDP checksum or to calculate it.  Current default
>>>> is to ignore ipv4 UDP checksum and calculate ipv6 UDP checksum.
>>>> Thanks.
>>>
>>> Are you saying you can natively support UDP tunnel with outer checksum
>>> offload then?
>>
>> Yes.  Calculate or ignore the outer UDP checksum.
>
> I was just thinking about this.  When you say you compute the IPv6
> checksum how is it you are specifying to the hardware that you want to
> do that?  Is it something you can configure per packet or is it
> something that is configured for the VXLAN flow?

In the current version of the hardware, it is a global (chip-wide)
setting.  1 bit to control outer ipv4 vxlan and 1 bit for outer ipv6
vxlan.

>
> I just want to make sure you aren't adding checksums to IPv6 tunnels
> that specify that they don't want a checksum, or stripping them from
> v4 tunnels that do want a checksum.

If the global setting has outer UDP checksum enabled, it will be
calculated no matter what.  If the setting is disabled, it will just
ignore it without overwriting it.

Thanks.