linux-kernel - Re: [PATCH v15 22/23] x86/mce: Improve error log of kernel space TDX #MC due to erratum

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Message-ID: <20231205202927.GJZW+IJ0NelvVmEum/@fat_crate.local>
Date:   Tue, 5 Dec 2023 21:29:27 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Huang, Kai" <kai.huang@...el.com>
Cc:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "david@...hat.com" <david@...hat.com>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "seanjc@...gle.com" <seanjc@...gle.com>,
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        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
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        "Luck, Tony" <tony.luck@...el.com>,
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        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        "Huang, Ying" <ying.huang@...el.com>,
        "Brown, Len" <len.brown@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH v15 22/23] x86/mce: Improve error log of kernel space TDX
 #MC due to erratum

On Tue, Dec 05, 2023 at 08:08:34PM +0000, Huang, Kai wrote:
> The difference is for TDX host the kernel needs to initialize the TDX module
> first before TDX can be used.  The module initialization is done at runtime, and
> the platform_tdx_enabled() here only returns whether the BIOS has enabled TDX.
> 
> IIUC the X86_FEATURE_ flag doesn't suit this purpose because based on my
> understanding the flag being present means the kernel has done some enabling
> work and the feature is ready to use.

Which flag do you mean? X86_FEATURE_TDX_GUEST?

I mean, you would set a separate X86_FEATURE_TDX or so flag to denote
that the BIOS has enabled it, at the end of that tdx_init() in the first
patch.

-- 
Regards/Gruss,
    Boris.

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