linux-kernel - Re: [PATCH v2] x86/mce: work around an erratum on fast string copy instructions.

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Message-ID: <Yg/FyrvLWhZHB/UC@zn.tnic>
Date:   Fri, 18 Feb 2022 17:14:02 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Jue Wang <juew@...gle.com>
Cc:     Tony Luck <tony.luck@...el.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, patches@...ts.linux.dev
Subject: Re: [PATCH v2] x86/mce: work around an erratum on fast string copy
 instructions.

On Fri, Feb 18, 2022 at 08:03:24AM -0800, Jue Wang wrote:
> Since MSR_IA32_MISC_ENABLE is not a MCA register, I wonder if we want
> to mix its read/write with the injected MCE code.
>
> I was a bit concerned about potential race with mce-inject and the
> read/write to MSR_IA32_MISC_ENABLE.

It won't inject anything:

                offset = msr_to_offset(msr);
                if (offset < 0)
                        ret = 0;


Besides, you need to use those routines due to EX_TYPE_{RD,WR}MSR_IN_MCE

-- 
Regards/Gruss,
    Boris.

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