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

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commit f7f3dc00f6 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>
This commit is contained in:
Borislav Petkov
2017-09-07 19:08:21 +02:00
committed by Greg Kroah-Hartman
parent f69e91f2c4
commit 5a63725cd1
1 changed files with 11 additions and 0 deletions
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11
arch/x86/kernel/cpu/amd.c
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@@ -749,6 +749,16 @@ static void init_amd_bd(struct cpuinfo_x86 *c)
}
}
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_stepping <= 1)
set_cpu_cap(c, X86_FEATURE_CPB);
}
static void init_amd(struct cpuinfo_x86 *c)
{
u32 dummy;
@@ -779,6 +789,7 @@ static void init_amd(struct cpuinfo_x86 *c)
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 */