linux-kernel - Re: [PATCHv4 10/30] x86/tdx: Handle CPUID via #VE

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Message-ID: <0f558d9b-a4d8-094b-f3d2-4d9fda945cd9@intel.com>
Date:   Mon, 28 Feb 2022 15:37:33 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        luto@...nel.org, peterz@...radead.org,
        sathyanarayanan.kuppuswamy@...ux.intel.com, aarcange@...hat.com,
        ak@...ux.intel.com, dan.j.williams@...el.com, david@...hat.com,
        hpa@...or.com, jgross@...e.com, jmattson@...gle.com,
        joro@...tes.org, jpoimboe@...hat.com, knsathya@...nel.org,
        pbonzini@...hat.com, sdeep@...are.com, seanjc@...gle.com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        thomas.lendacky@....com, brijesh.singh@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 10/30] x86/tdx: Handle CPUID via #VE

On 2/28/22 15:31, Kirill A. Shutemov wrote:
>> Does this, in practice, keep TDX guests from detecting any features that
>> it supports today?
> I scanned through the list of CPUID that probed via #VE during the boot
> and they are related to cache/TLB hierarchy enumeration, thermal and
> topology. Without cache/TLB enumeration we may miss some optimization.
> Topology can be problematic, we may miss ability to communicate the
> configuration, I donno.
> 
> Shouldn't be a show-stopper.

I can live with that for an initial TDX guest series.  Does that bother
anyone else?