linux-kernel - Re: [PATCH v2 7/8] x86/mm: only check uniform after calling mtrr_type

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Message-ID: <92a63877e054775884d9c7a7d15ed613cc3059bc.camel@intel.com>
Date:   Sat, 11 Feb 2023 00:06:05 +0000
From:   "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Gross, Jurgen" <jgross@...e.com>,
        "x86@...nel.org" <x86@...nel.org>
CC:     "peterz@...radead.org" <peterz@...radead.org>,
        "Torvalds, Linus" <torvalds@...ux-foundation.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "lists@...dbynature.de" <lists@...dbynature.de>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "hpa@...or.com" <hpa@...or.com>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "Lutomirski, Andy" <luto@...nel.org>,
        "bp@...en8.de" <bp@...en8.de>,
        "mikelley@...rosoft.com" <mikelley@...rosoft.com>
Subject: Re: [PATCH v2 7/8] x86/mm: only check uniform after calling
 mtrr_type_lookup()

On Thu, 2023-02-09 at 08:22 +0100, Juergen Gross wrote:
> diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
> index e4f499eb0f29..7b9c5443d176 100644
> --- a/arch/x86/mm/pgtable.c
> +++ b/arch/x86/mm/pgtable.c
> @@ -721,8 +721,7 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr,
> pgprot_t prot)
>         u8 mtrr, uniform;

'mtrr' is now unused. Can it be dropped? Same for the pmd_set_huge().

>  
>         mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE, &uniform);
> -       if ((mtrr != MTRR_TYPE_INVALID) && (!uniform) &&
> -           (mtrr != MTRR_TYPE_WRBACK))
> +       if (!uniform)
>                 return 0;