linux-kernel - Re: [PATCH 02/22] x86/srso: Set CPUID feature bits independently of bug or mitigation status

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Message-ID: <20230824042420.GAZObbdNb38eKaCPAm@fat_crate.local>
Date:   Thu, 24 Aug 2023 06:24:20 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Andrew Cooper <andrew.cooper3@...rix.com>
Cc:     Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Babu Moger <babu.moger@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>, David.Kaplan@....com,
        Nikolay Borisov <nik.borisov@...e.com>,
        gregkh@...uxfoundation.org, Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 02/22] x86/srso: Set CPUID feature bits independently of
 bug or mitigation status

On Wed, Aug 23, 2023 at 01:22:34PM +0100, Andrew Cooper wrote:
> In my previous reply, I explained why this goes wrong when Linux ignores
> the CPUID bit provided by the hypervisor and decides to probe manually.

Send a patch and explain in its commit message *why* this is needed.

> No.

Hell yeah!

How do you expect us to support use cases we don't know about?!

> You don't get to take my code, break it when integrating it into Linux,
> then dismiss the bug as something hypothetical that you don't want to fix.

I have no clue what you're talking about but it sounds like
a misunderstanding. All I'm saying is, the live migration use cases the
kernel should support, should be documented first. If there's no
documentation for them, *then* you have hypothetical.

So patches explaining what we're supporting are welcome.

-- 
Regards/Gruss,
    Boris.

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