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

From: Borislav Petkov <bp@alien8.de>
To: Kuppuswamy Sathyanarayanan  <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	x86@kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
	David Hildenbrand <david@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Juergen Gross <jgross@suse.com>, Deep Shah <sdeep@vmware.com>,
	VMware Inc <pv-drivers@vmware.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Peter H Anvin <hpa@zytor.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Andi Kleen <ak@linux.intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v10 03/11] x86/cpufeatures: Add TDX Guest CPU feature
Date: Wed, 13 Oct 2021 10:18:18 +0200	[thread overview]
Message-ID: <YWaWSmWn6AZ6OLx+@zn.tnic> (raw)
In-Reply-To: <20211009053747.1694419-4-sathyanarayanan.kuppuswamy@linux.intel.com>

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.

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