linux-kernel - Re: [PATCHv5.1 01/30] x86/tdx: Detect running as a TDX guest in early boot

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Message-ID: <YijwSjP2rlvwi0mi@zn.tnic>
Date:   Wed, 9 Mar 2022 19:22:02 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc:     aarcange@...hat.com, ak@...ux.intel.com, brijesh.singh@....com,
        dan.j.williams@...el.com, dave.hansen@...el.com,
        dave.hansen@...ux.intel.com, david@...hat.com, hpa@...or.com,
        jgross@...e.com, jmattson@...gle.com, joro@...tes.org,
        jpoimboe@...hat.com, knsathya@...nel.org,
        linux-kernel@...r.kernel.org, luto@...nel.org, mingo@...hat.com,
        pbonzini@...hat.com, peterz@...radead.org,
        sathyanarayanan.kuppuswamy@...ux.intel.com, sdeep@...are.com,
        seanjc@...gle.com, tglx@...utronix.de, thomas.lendacky@....com,
        tony.luck@...el.com, vkuznets@...hat.com, wanpengli@...cent.com,
        x86@...nel.org
Subject: Re: [PATCHv5.1 01/30] x86/tdx: Detect running as a TDX guest in
 early boot

On Tue, Mar 08, 2022 at 01:24:56AM +0300, Kirill A. Shutemov wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> 
> In preparation of extending cc_platform_has() API to support TDX guest,
> use CPUID instruction to detect support for TDX guests in the early
> boot code (via tdx_early_init()). Since copy_bootdata() is the first
> user of cc_platform_has() API, detect the TDX guest status before it.
> 
> Define a synthetic feature flag (X86_FEATURE_TDX_GUEST) and set this
> bit in a valid TDX guest platform.
> 
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> Reviewed-by: Andi Kleen <ak@...ux.intel.com>
> Reviewed-by: Tony Luck <tony.luck@...el.com>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Acked-by: Dave Hansen <dave.hansen@...ux.intel.com>
> ---
>  v5.1:
>    - Drop BUILD_BUG_ON()
> ---
>  arch/x86/Kconfig                         | 12 ++++++++++++
>  arch/x86/coco/Makefile                   |  2 ++
>  arch/x86/coco/tdx.c                      | 22 ++++++++++++++++++++++
>  arch/x86/include/asm/cpufeatures.h       |  1 +
>  arch/x86/include/asm/disabled-features.h |  8 +++++++-
>  arch/x86/include/asm/tdx.h               | 21 +++++++++++++++++++++
>  arch/x86/kernel/head64.c                 |  4 ++++
>  7 files changed, 69 insertions(+), 1 deletion(-)
>  create mode 100644 arch/x86/coco/tdx.c
>  create mode 100644 arch/x86/include/asm/tdx.h

I don't know how many versions of this patch I've reviewed by now. Oh
well, finally:

Reviewed-by: Borislav Petkov <bp@...e.de>

:-)

-- 
Regards/Gruss,
    Boris.

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