Patch "x86/AMD: Apply erratum 665 on machines without a BIOS fix" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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@vger.kernel.org> know about it.


>From d1992996753132e2dafe955cccb2fb0714d3cfc4 Mon Sep 17 00:00:00 2001
From: Emanuel Czirai <icanrealizeum@gmail.com>
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@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;
 	}
 


Patches currently in stable-queue which might be from icanrealizeum@gmail.com are

queue-4.4/x86-amd-apply-erratum-665-on-machines-without-a-bios-fix.patch