linux-kernel - Re: [PATCH kernel 2/2] crypto/ccp: Allow multiple streams on the same root bridge

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Message-ID: <ae86149a-8590-46cb-bdbb-726963f39455@amd.com>
Date: Fri, 30 Jan 2026 09:29:51 +1100
From: Alexey Kardashevskiy <aik@....com>
To: dan.j.williams@...el.com, linux-crypto@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Ashish Kalra <ashish.kalra@....com>,
 Tom Lendacky <thomas.lendacky@....com>, John Allen <john.allen@....com>,
 Herbert Xu <herbert@...dor.apana.org.au>,
 "David S. Miller" <davem@...emloft.net>, x86@...nel.org,
 linux-coco@...ts.linux.dev, "Pratik R . Sampat" <prsampat@....com>
Subject: Re: [PATCH kernel 2/2] crypto/ccp: Allow multiple streams on the same
 root bridge



On 27/1/26 17:59, dan.j.williams@...el.com wrote:
> Alexey Kardashevskiy wrote:
>> On 24/1/26 09:59, dan.j.williams@...el.com wrote:
>>> Alexey Kardashevskiy wrote:
>>>> IDE stream IDs are responsibility of a platform and in some cases
>>>> TSM allocates the numbers. AMD SEV TIO though leaves it to the host
>>>> OS.  Mistakenly stream ID is hard coded to be the same as a traffic
>>>> class.
>>>
>>> I scratched my head at this comment, but now realize that you are
>>> saying the existing code used the local @tc, not that the hardware
>>> stream ID is in any way related to traffic class, right?
>>
>> When I did that in the first place, I also wanted to try different
>> traffic classes so I just took a shortcut here.
>>
>>> It would help to detail what the end user visible effects of this
>>> bug are. The TSM framework does not allow for multiple streams per
>>> PF, so I wonder what scenario is being fixed?
>>
>> There is no way in the current upstream code to specify this TC so the
>> only visible effect is that 2 devices under the same bridge can work
>> now, previously the second device would fail to allocate a stream.
>>
>>> Lastly, are you expecting tsm.git#fixes to pick this up? I am
>>> assuming that this goes through crypto.git and tsm.git can just stay
>>> focused on core fixes.
>>
>> I was kinda hoping that Tom acks these (as he did) and you could take
>> them. Thanks,
> 
> Ok, so can you refresh the changelog to call out the user visible
> effects?  Something like:
> 
> ---
> With SEV-TIO the low-level TSM driver is responsible for allocating a
> Stream ID. The Stream ID needs to be unique within each IDE partner
> port. Fix the Stream ID selection to reuse the host bridge stream
> resource id which is a pool of 256 ids per host bridge on AMD platforms.
> Otherwise, only one device per-host bridge can establish Selective
> Stream IDE.
> ---
> 
> Send a v2, and I will pick it up.

Please squash it in the v1, if possible.

Acked-by: Alexey Kardashevskiy <aik@....com>

thanks!

ps sorry missed that on time, I do suck at multitasking :(


-- 
Alexey