linux-kernel - Re: [RFC][PATCH 12/34] x86/cpu/intel: Actually use "address configuration" infrastructure for MKTME

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Message-ID: <o5axftuoav5b57eu3w2xujur4wumquzpr667jmrq4poxuxxmvf@pvoiyfxyoyen>
Date: Fri, 23 Feb 2024 13:41:01 +0200
From: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
To: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org, pbonzini@...hat.com, tglx@...utronix.de, 
	x86@...nel.org, bp@...en8.de
Subject: Re: [RFC][PATCH 12/34] x86/cpu/intel: Actually use "address
 configuration" infrastructure for MKTME

On Thu, Feb 22, 2024 at 10:39:42AM -0800, Dave Hansen wrote:
> 
> From: Dave Hansen <dave.hansen@...ux.intel.com>
> 
> Now that the TME detection is only called once at boot, stop twiddling
> 'boot_cpu_data' directly and move over to 'bsp_addr_config'.
> 
> Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
> ---
> 
>  b/arch/x86/kernel/cpu/intel.c |    7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
> 
> diff -puN arch/x86/kernel/cpu/intel.c~intel-addr-reduce arch/x86/kernel/cpu/intel.c
> --- a/arch/x86/kernel/cpu/intel.c~intel-addr-reduce	2024-02-22 10:08:54.296682462 -0800
> +++ b/arch/x86/kernel/cpu/intel.c	2024-02-22 10:08:54.296682462 -0800
> @@ -401,11 +401,8 @@ detect_keyid_bits:
>  		mktme_status = MKTME_ENABLED;
>  	}
>  
> -	/*
> -	 * KeyID bits effectively lower the number of physical address
> -	 * bits.  Update cpuinfo_x86::x86_phys_bits accordingly.
> -	 */
> -	c->x86_phys_bits -= keyid_bits;
> +	/* KeyID bits effectively lower the number of physical address bits */
> +	bsp_addr_config.phys_addr_reduction_bits = keyid_bits;

Do we expect reduction_bits to stack? Like can multiple features steal
physical bits? Make use "+= keyid_bits" here?

-- 
  Kiryl Shutsemau / Kirill A. Shutemov