netdev - Re: [Intel-wired-lan] [PATCH next-queue 0/8] ixgbe/ixgbevf: IPsec offload support for VFs

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Date:   Thu, 16 Aug 2018 14:36:15 -0700
From:   Shannon Nelson <shannon.nelson@...cle.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Netdev <netdev@...r.kernel.org>
Subject: Re: [Intel-wired-lan] [PATCH next-queue 0/8] ixgbe/ixgbevf: IPsec
 offload support for VFs

On 8/16/2018 2:15 PM, Alexander Duyck wrote:
> On Tue, Aug 14, 2018 at 10:10 AM Shannon Nelson
> <shannon.nelson@...cle.com> wrote:
>>
>> On 8/14/2018 8:30 AM, Alexander Duyck wrote:
>>> On Mon, Aug 13, 2018 at 11:43 AM Shannon Nelson
>>> <shannon.nelson@...cle.com> wrote:
>>>>
>>>> This set of patches implements IPsec hardware offload for VF devices in
>>>> Intel's 10Gbe x540 family of Ethernet devices.
>>
>> [...]
>>
>>>
>>> So the one question I would have about this patch set is what happens
>>> if you are setting up a ipsec connection between the PF and one of the
>>> VFs on the same port/function? Do the ipsec offloads get translated
>>> across the Tx loopback or do they end up causing issues? Specifically
>>> I would be interested in seeing the results of a test either between
>>> two VFs, or the PF and one of the VFs on the same port.
>>>
>>> - Alex
>>>
>>
>> There is definitely something funky in the internal switch connection,
>> as messages going from PF to VF with an offloaded encryption don't seem
>> to get received by the VF, at least when in a VEB setup.  If I only set
>> up offloads on the Rx on both PF and VF, and don't offload the Tx, then
>> things work.
>>
>> I don't have a setup to test this, but I suspect that in a VEPA
>> configuration, with packets going out to the switch and turned around
>> back in, the Tx encryption offload would happen as expected.
>>
>> sln
> 
> We should probably look at adding at least one patch to the set then
> that disables IPsec Tx offload if SR-IOV is enabled with VEB so that
> we don't end up breaking connections should a VF be migrated from a
> remote system to a local one that it is connected to.
> 
> - Alex
> 

The problem with this is that someone could set up an IPsec connection 
on the PF for Tx and Rx use, then set num_vfs, start some VFs, and we 
still can end up in the same place.  I don't think we want to disallow 
all Tx IPsec offload.

Maybe we can catch it in ixgbe_ipsec_offload_ok()?  If it can find that 
the dest mac is on the internal switch, perhaps it can NAK the Tx 
offload?  That would force the XFRM xmit code to do a regular SW encrypt 
before sending the packet.  I'll look into this.

sln