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Subject[PATCH 4.4 025/118] x86/AMD: Apply erratum 665 on machines without a BIOS fix
Date
4.4-stable review patch.  If anyone has any objections, please let me know.

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

From: Emanuel Czirai <icanrealizeum@gmail.com>

commit d1992996753132e2dafe955cccb2fb0714d3cfc4 upstream.

AMD F12h machines have an erratum which can cause DIV/IDIV to behave
unpredictably. The workaround is to set MSRC001_1029[31] but sometimes
there is no BIOS update containing that workaround so let's do it
ourselves unconditionally. It is simple enough.

[ Borislav: Wrote commit message. ]

Signed-off-by: Emanuel Czirai <icanrealizeum@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Yaowu Xu <yaowu@google.com>
Link: http://lkml.kernel.org/r/20160902053550.18097-1-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/cpu/amd.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -656,6 +656,17 @@ static void init_amd_gh(struct cpuinfo_x
set_cpu_bug(c, X86_BUG_AMD_TLB_MMATCH);
}

+#define MSR_AMD64_DE_CFG 0xC0011029
+
+static void init_amd_ln(struct cpuinfo_x86 *c)
+{
+ /*
+ * Apply erratum 665 fix unconditionally so machines without a BIOS
+ * fix work.
+ */
+ msr_set_bit(MSR_AMD64_DE_CFG, 31);
+}
+
static void init_amd_bd(struct cpuinfo_x86 *c)
{
u64 value;
@@ -713,6 +724,7 @@ static void init_amd(struct cpuinfo_x86
case 6: init_amd_k7(c); break;
case 0xf: init_amd_k8(c); break;
case 0x10: init_amd_gh(c); break;
+ case 0x12: init_amd_ln(c); break;
case 0x15: init_amd_bd(c); break;
}


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