linux-kernel - Re: [PATCH v2] x86/bugs: Explicitly clear speculative MSR bits

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Message-ID: <Y4VFmvTOkRgVmxtc@zn.tnic>
Date:   Tue, 29 Nov 2022 00:34:50 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Cc:     Breno Leitao <leitao@...ian.org>, tglx@...utronix.de,
        mingo@...hat.com, dave.hansen@...ux.intel.com, hpa@...or.com,
        jpoimboe@...nel.org, peterz@...radead.org, x86@...nel.org,
        cascardo@...onical.com, leit@...a.com, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] x86/bugs: Explicitly clear speculative MSR bits

On Mon, Nov 28, 2022 at 03:02:19PM -0800, Pawan Gupta wrote:
> Yes thats a cleaner approach, except that the late microcode load will
> ruin the MSR:
> 
> microcode_reload_late()
>   microcode_check()
>     get_cpu_cap()
>       init_speculation_control()

Microcode late loading ruins a lot of crap already anyway.

Then I guess we'll have to look for a better place for this on the init
path - I don't want any more hackery in the hw vuln nightmare code.

-- 
Regards/Gruss,
    Boris.

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