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

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Message-ID: <6978626886a50_1d33100c1@dwillia2-mobl4.notmuch>
Date: Mon, 26 Jan 2026 22:59:52 -0800
From: <dan.j.williams@...el.com>
To: Alexey Kardashevskiy <aik@....com>, <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

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.