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Subject[PATCH 3.16 60/63] x86/cpu/AMD: Fix erratum 1076 (CPB bit)
3.16.58-rc1 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>
[bwh: Backported to 3.16:
- Change the added case into an if-statement
- s/x86_stepping/x86_mask/]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/x86/kernel/cpu/amd.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -533,6 +533,16 @@ static void init_amd_ln(struct cpuinfo_x
msr_set_bit(MSR_AMD64_DE_CFG, 31);
}

+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;
@@ -611,6 +621,9 @@ static void init_amd(struct cpuinfo_x86
clear_cpu_cap(c, X86_FEATURE_MCE);
#endif

+ if (c->x86 == 0x17)
+ init_amd_zn(c);
+
/* Enable workaround for FXSAVE leak */
if (c->x86 >= 6)
set_cpu_cap(c, X86_FEATURE_FXSAVE_LEAK);
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