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    Subject[PATCH 4.4 086/107] x86/cpu/AMD: Fix erratum 1076 (CPB bit)
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Borislav Petkov <bp@suse.de>

    commit f7f3dc00f61261cdc9ccd8b886f21bc4dffd6fd9 upstream

    CPUID Fn8000_0007_EDX[CPB] is wrongly 0 on models up to B1. But they do
    support CPB (AMD's Core Performance Boosting cpufreq CPU feature), so fix that.

    Signed-off-by: Borislav Petkov <bp@suse.de>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Sherry Hurwitz <sherry.hurwitz@amd.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/20170907170821.16021-1-bp@alien8.de
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Srivatsa S. Bhat <srivatsa@csail.mit.edu>
    Reviewed-by: Matt Helsley (VMware) <matt.helsley@gmail.com>
    Reviewed-by: Alexey Makhalov <amakhalov@vmware.com>
    Reviewed-by: Bo Gan <ganb@vmware.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---

    arch/x86/kernel/cpu/amd.c | 11 +++++++++++
    1 file changed, 11 insertions(+)

    --- a/arch/x86/kernel/cpu/amd.c
    +++ b/arch/x86/kernel/cpu/amd.c
    @@ -713,6 +713,16 @@ static void init_amd_bd(struct cpuinfo_x
    }
    }

    +static void init_amd_zn(struct cpuinfo_x86 *c)
    +{
    + /*
    + * 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_mask <= 1)
    + set_cpu_cap(c, X86_FEATURE_CPB);
    +}
    +
    static void init_amd(struct cpuinfo_x86 *c)
    {
    u32 dummy;
    @@ -743,6 +753,7 @@ static void init_amd(struct cpuinfo_x86
    case 0x10: init_amd_gh(c); break;
    case 0x12: init_amd_ln(c); break;
    case 0x15: init_amd_bd(c); break;
    + case 0x17: init_amd_zn(c); break;
    }

    /* Enable workaround for FXSAVE leak */

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