linux-kernel - Re: [PATCH 1/1] x86/mce/amd: Add PPIN support for AMD MCE

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Message-ID: <CY4PR12MB1352F7AED37C67DAECC063E6CFF40@CY4PR12MB1352.namprd12.prod.outlook.com>
Date:   Thu, 19 Mar 2020 20:58:17 +0000
From:   "Huang2, Wei" <Wei.Huang2@....com>
To:     Borislav Petkov <bp@...en8.de>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "Ghannam, Yazen" <Yazen.Ghannam@....com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "Koralahalli Channabasappa, Smita" 
        <Smita.KoralahalliChannabasappa@....com>
Subject: Re: [PATCH 1/1] x86/mce/amd: Add PPIN support for AMD MCE

[AMD Official Use Only - Internal Distribution Only]

From: linux-kernel-owner@...r.kernel.org <linux-kernel-owner@...r.kernel.org> on behalf of Borislav Petkov <bp@...en8.de>

Sent: Thursday, March 19, 2020 3:21 PM

> You can add it to arch/x86/kernel/cpu/mce/amd.c just like
> intel_ppin_init() is respectively in .../mce/intel.c, as mce/ is where
> this thing is used only. We can move it to kernel/cpu/ later if it turns
> out that it is needed for something else.

To use this approach, I have to clear X86_FEATURE_AMD_PPIN if MSR_AMD_PPIN_CTL is locked and disabled.

However, there is a small problem: during boot, mce_setup() is called once before mce_amd_ppin_init() is invoked. As a result, mce_setup() might read X86_FEATURE_AMD_PPIN incorrectly. This concerns me.

Thanks,
-Wei