linux-kernel - Re: [PATCHv2 29/29] Documentation/x86: Document TDX kernel architecture

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Date:   Thu, 24 Feb 2022 17:08:23 +0800
From:   Xiaoyao Li <xiaoyao.li@...el.com>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...el.com, luto@...nel.org, peterz@...radead.org
Cc:     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,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv2 29/29] Documentation/x86: Document TDX kernel
 architecture

On 1/24/2022 11:02 PM, Kirill A. Shutemov wrote:

> +#VE due to CPUID instruction
> +----------------------------
> +
> +In TDX guests, most of CPUID leaf/sub-leaf combinations are virtualized by
> +the TDX module while some trigger #VE. Combinations of CPUID leaf/sub-leaf
> +which triggers #VE are configured by the VMM during the TD initialization
> +time (using TDH.MNG.INIT).
> +

The description is incorrect.

TDH.MNG.INIT does not configure whether the CPUID leaf/sub-leaf triggers 
#VE or not. It configures if some feature bits in specific leaf-subleaf 
are exposed to TD guest or not.

Whether the CPUID(leaf, sub-leaf) causes #VE or not, is defined in TDX 
spec, and not configurable by user or VMM.