linux-kernel - Re: [tip:x86/cpu] x86/CPU/AMD: Set the CPB bit unconditionally on F17h

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Date:   Wed, 20 Feb 2019 09:53:34 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     stable <stable@...r.kernel.org>
Cc:     linux-tip-commits@...r.kernel.org, suravee.suthikulpanit@....com,
        jiaxun.yang@...goat.com, tglx@...utronix.de, x86@...nel.org,
        linux-kernel@...r.kernel.org, sherry.hurwitz@....com,
        mingo@...hat.com, mingo@...nel.org, thomas.lendacky@....com,
        hpa@...or.com, Erwan Velu <e.velu@...teo.com>
Subject: Re: [tip:x86/cpu] x86/CPU/AMD: Set the CPB bit unconditionally on
 F17h

On Fri, Jan 18, 2019 at 07:48:59AM -0800, tip-bot for Jiaxun Yang wrote:
> Commit-ID:  0237199186e7a4aa5310741f0a6498a20c820fd7
> Gitweb:     https://git.kernel.org/tip/0237199186e7a4aa5310741f0a6498a20c820fd7
> Author:     Jiaxun Yang <jiaxun.yang@...goat.com>
> AuthorDate: Tue, 20 Nov 2018 11:00:18 +0800
> Committer:  Borislav Petkov <bp@...e.de>
> CommitDate: Fri, 18 Jan 2019 16:44:03 +0100
> 
> x86/CPU/AMD: Set the CPB bit unconditionally on F17h
> 
> Some F17h models do not have CPB set in CPUID even though the CPU
> supports it. Set the feature bit unconditionally on all F17h.
> 
>  [ bp: Rewrite commit message and patch. ]
> 
> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
> Signed-off-by: Borislav Petkov <bp@...e.de>
> Acked-by: Tom Lendacky <thomas.lendacky@....com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Sherry Hurwitz <sherry.hurwitz@....com>
> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: x86-ml <x86@...nel.org>
> Link: https://lkml.kernel.org/r/20181120030018.5185-1-jiaxun.yang@flygoat.com
> ---
>  arch/x86/kernel/cpu/amd.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index 69f6bbb41be0..01004bfb1a1b 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -819,11 +819,9 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
>  static void init_amd_zn(struct cpuinfo_x86 *c)
>  {
>  	set_cpu_cap(c, X86_FEATURE_ZEN);
> -	/*
> -	 * Fix erratum 1076: CPB feature bit not being set in CPUID. It affects
> -	 * all up to and including B1.
> -	 */
> -	if (c->x86_model <= 1 && c->x86_stepping <= 1)
> +
> +	/* Fix erratum 1076: CPB feature bit not being set in CPUID. */
> +	if (!cpu_has(c, X86_FEATURE_CPB))
>  		set_cpu_cap(c, X86_FEATURE_CPB);

Stable folks, please take this one above into those stable trees which
have backported

f7f3dc00f612 ("x86/cpu/AMD: Fix erratum 1076 (CPB bit)")

Thx.

-- 
Regards/Gruss,
    Boris.

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