linux-kernel - Re: [PATCH v6 01/16] x86/mtrr: remove physical address size calculation

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Date:   Thu, 4 May 2023 09:47:33 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Juergen Gross <jgross@...e.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        mikelley@...rosoft.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v6 01/16] x86/mtrr: remove physical address size
 calculation

On Tue, May 02, 2023 at 02:09:16PM +0200, Juergen Gross wrote:
> diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
> index ee09d359e08f..3922552340b1 100644
> --- a/arch/x86/kernel/cpu/mtrr/generic.c
> +++ b/arch/x86/kernel/cpu/mtrr/generic.c
> @@ -38,6 +38,16 @@ u64 mtrr_tom2;
>  struct mtrr_state_type mtrr_state;
>  EXPORT_SYMBOL_GPL(mtrr_state);
>  
> +static u64 size_or_mask, size_and_mask;
> +
> +void __init mtrr_set_mask(void)
> +{
> +	unsigned int phys_addr = boot_cpu_data.x86_phys_bits;
> +
> +	size_or_mask = ~GENMASK_ULL(phys_addr - PAGE_SHIFT - 1, 0);
> +	size_and_mask = ~size_or_mask & GENMASK_ULL(39, 20);

What happened to getting rid of those:

https://lore.kernel.org/r/20230405202633.GFZC3ZeVWtmjkODYW7@fat_crate.local

and using the reserved bitfield masks as they're defined for the MSRs?

-- 
Regards/Gruss,
    Boris.

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