linux-kernel - Re: [PATCH v2 0/4] x86, fpu/kvm: fix crash with AMX

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Message-ID: <20260123132323.GAaXN2S0WQxm9o6EBG@fat_crate.local>
Date: Fri, 23 Jan 2026 14:23:23 +0100
From: Borislav Petkov <bp@...en8.de>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: "Kernel Mailing List, Linux" <linux-kernel@...r.kernel.org>,
	kvm <kvm@...r.kernel.org>, Sean Christopherson <seanjc@...gle.com>,
	the arch/x86 maintainers <x86@...nel.org>
Subject: Re: [PATCH v2 0/4] x86, fpu/kvm: fix crash with AMX

On Thu, Jan 22, 2026 at 01:00:27PM +0100, Paolo Bonzini wrote:
> I agree - as I wrote below, I judged that this was _not_ solo
> considering that (while not including any x86 maintainers) there were
> multiple people intervening and building on each other's analysis.
> Yes, there was no x86 maintainer, I obviously knew that, but my
> judgment call was that all these people together had looked at the
> code more than it deserved. In the previous mail I said the
> probability of a disagreement was small, it was even practically
> nonexistent.

This all doesn't matter. Because when it comes down to cleaning up the mess
people have left behind, it is always we who end up mopping after everyone.
And everyone esle skedaddles into their next feature enablement.

And I do appreciate more than anyone when people make an effort to review
patches. You still need a maintainer ack though.

And it is not hard - you just need to ping us/send us a private mail even call
us if you want. :-)

> I don't think you can say that this is routine, for example in commit
> eb4441864e03 ("KVM: SEV: sync FPU and AVX state at LAUNCH_UPDATE_VMSA
> time", 2024-04-11) I explicitly sought an ack for just an
> EXPORT_SYMBOL change. Knowing that x86 maintainers want to tightly
> control the API boundary of arch/x86/kernel/fpu, I considered that to
> require the attention of you guys *even more* than a code change!

Much appreciated, this is how it should always work. So let's make that the
default workflow please.

> I appreciate a lot the support that Thomas and other arch/x86/ people
> put in to help Linux run well and without hacks as a hypervisor. At
> the same time I think it's fine for both sides to acknowledge that in
> extremely rare cases the lines can be blurred.

If we don't reply for a week or so, sure. But if you really need an x86
maintainer ack, I'm sure you'll get one in time.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette