This is a note to let you know that I've just added the patch titled
x86/AMD: Apply erratum 665 on machines without a BIOS fix
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-amd-apply-erratum-665-on-machines-without-a-bios-fix.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d1992996753132e2dafe955cccb2fb0714d3cfc4 Mon Sep 17 00:00:00 2001
From: Emanuel Czirai <icanrealizeum@xxxxxxxxx>
Date: Fri, 2 Sep 2016 07:35:50 +0200
Subject: x86/AMD: Apply erratum 665 on machines without a BIOS fix
From: Emanuel Czirai <icanrealizeum@xxxxxxxxx>
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@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: Yaowu Xu <yaowu@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20160902053550.18097-1-bp@xxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
}
Patches currently in stable-queue which might be from icanrealizeum@xxxxxxxxx are
queue-4.4/x86-amd-apply-erratum-665-on-machines-without-a-bios-fix.patch
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