linux-kernel - Re: [PATCH v10 03/11] x86/cpufeatures: Add TDX Guest CPU feature

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Date:   Wed, 13 Oct 2021 10:18:18 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Juergen Gross <jgross@...e.com>, Deep Shah <sdeep@...are.com>,
        VMware Inc <pv-drivers@...are.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Peter H Anvin <hpa@...or.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v10 03/11] x86/cpufeatures: Add TDX Guest CPU feature

On Fri, Oct 08, 2021 at 10:37:39PM -0700, Kuppuswamy Sathyanarayanan wrote:
> @@ -500,6 +501,14 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
>  
>  	copy_bootdata(__va(real_mode_data));
>  
> +	/*
> +	 * A future dependency on cmdline parameters is expected (for
> +	 * adding debug options). So the order of calling it should be
> +	 * after copy_bootdata() (in which command line parameter is
> +	 * initialized).
> +	 */

Plain and simple:

        /*
         * Keep this after copy_bootdata() so that TDX cmdline options can take
         * effect.
         */


> +	tdx_early_init();
> +
>  	/*
>  	 * Load microcode early on BSP.
>  	 */
> diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
> new file mode 100644
> index 000000000000..88bf12788684
> --- /dev/null
> +++ b/arch/x86/kernel/tdx.c
> @@ -0,0 +1,38 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (C) 2020 Intel Corporation */
> +
> +#undef pr_fmt
> +#define pr_fmt(fmt)     "tdx: " fmt
> +
> +#include <asm/tdx.h>
> +
> +bool is_tdx_guest(void)
> +{
> +	static int tdx_guest = -1;

Put that one at the top of the file because such static variables do not
belong among the automatic function vars.

Thx.

-- 
Regards/Gruss,
    Boris.

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