[virtio-dev] Re: [virtio-comment] RE: [PATCH v13] virtio-net: support inner header hash

[Heng Qi <hengqi@linux.alibaba.com>]

在 2023/4/26 下午9:47, Parav Pandit 写道:
>
>> From: Heng Qi <hengqi@linux.alibaba.com>
>> Sent: Wednesday, April 26, 2023 9:43 AM
>>> "With that no need to define two fields at two different places in
>>> config area and also in cvq."
>> I'm not sure if this is sufficiently motivated, RSS also has supports_hash_types
>> in config space.
>>
> There are many fields grown to MMIO config space because 0.9.5 has config space there.
> These are usually one time read or rarely used; hence it doesn’t need to come from this area of the device to be _always_ available.

Yes.

supported_tunnel_hash_types If in cvq, each GET command needs to return 
supported_tunnel_hash_types and hash_tunnel_types,
but users may only need the hash_tunnel_types "SET" by themselves.

>   
>> We don't actually need cvq and config to sync on
>> supported_tunnel_hash_types, since it doesn't need to change (meaning
>> supported_tunnel_hash_types doesn't send configuration change
>> notifications).
>>
> It doesn’t but device is expected to publish the value at two places.

Yes, but that seems like a tiny cost, and the cvq command-related 
structure is much simpler.

>
>>>> +For scenarios with sufficient external entropy or no internal
>>>> hashing requirements, inner header hash may not be needed:
>>>> +A tunnel is often expected to isolate the external network from the
>>>> internal one. By completely ignoring entropy
>>>> +in the external header and replacing it with entropy from the
>>>> internal header, for hash calculations, this expectation
>>> You wanted to say inner here like rest of the places.
>>>
>>> s/internal header/inner header
>> I want to make the 'external' and 'internal' correspond, but avoid the internal
>> header, and use a unified 'inner header' is also reasonable.:)
>>
> Since in rest of other description, we refer to it as "outer", it is better to keep it consistent as outer instead of external here.

Totally agree.

Thanks.



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