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

From: Borislav Petkov
Date: Wed Feb 20 2019 - 03:53:52 EST


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@xxxxxxxxxxx>
> AuthorDate: Tue, 20 Nov 2018 11:00:18 +0800
> Committer: Borislav Petkov <bp@xxxxxxx>
> 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@xxxxxxxxxxx>
> Signed-off-by: Borislav Petkov <bp@xxxxxxx>
> Acked-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Sherry Hurwitz <sherry.hurwitz@xxxxxxx>
> Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: x86-ml <x86@xxxxxxxxxx>
> Link: https://lkml.kernel.org/r/20181120030018.5185-1-jiaxun.yang@xxxxxxxxxxx
> ---
> 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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