linux-kernel - Re: [PATCH v4 1/2] x86/mce: Check for writes ignored in MCA

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Message-ID: <Yl/PupT3bAfc4IBW@zn.tnic>
Date:   Wed, 20 Apr 2022 11:17:46 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
Cc:     x86@...nel.org, linux-edac@...r.kernel.org,
        linux-kernel@...r.kernel.org, Tony Luck <tony.luck@...el.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Yazen Ghannam <yazen.ghannam@....com>
Subject: Re: [PATCH v4 1/2] x86/mce: Check for writes ignored in MCA_STATUS
 register

On Mon, Apr 18, 2022 at 08:24:35PM -0700, Smita Koralahalli wrote:
> Why are we checking this here? This flag (hw_injection_possible)
> is set to false inside prepare_msrs() called from
> smp_call_function_single().
> Should this check be done after the call to smp_call_function_single()?

Why would you do that then?

Is any of the code after

        if (inj_type == SW_INJ) {
                mce_log(m);
                return 0;
        }

worth running if hardware injection is not possible?

> Also, we already have inj_desc.err which returns error code to userspace
> when WRIG in status registers. Why is this flag needed?

To not do unnecessary work when you *know* hardware injection won't
work.

:-)

Btw, please trim your mails when you reply, just like I did.

Thx.

-- 
Regards/Gruss,
    Boris.

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