linux-kernel - Re: [PATCHv6 23/30] x86/boot: Avoid #VE during boot for TDX platforms

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Date:   Thu, 17 Mar 2022 13:48:01 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        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,
        thomas.lendacky@....com, brijesh.singh@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCHv6 23/30] x86/boot: Avoid #VE during boot for TDX platforms

On Wed, Mar 16 2022 at 05:08, Kirill A. Shutemov wrote:
> This theoretically makes the guest boot more fragile. If, for instance,
> EFER was set up incorrectly and a WRMSR was performed, it will trigger
> early exception panic or a triple fault, if it's before early
> exceptions are set up. However, this is likely to trip up the guest
> BIOS long before control reaches the kernel. In any case, these kinds
> of problems are unlikely to occur in production environments, and
> developers have good debug tools to fix them quickly.
>
> Change the common boot code to work on TDX and non-TDX systems.
> This should have no functional effect on non-TDX systems.
>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> Reviewed-by: Andi Kleen <ak@...ux.intel.com>
> Reviewed-by: Dan Williams <dan.j.williams@...el.com>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>