Patch "x86/AMD: Apply erratum 665 on machines without a BIOS fix" has been added to the 4.7-stable tree

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 4.7-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-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Emanuel Czirai <[email protected]>
Date: Fri, 2 Sep 2016 07:35:50 +0200
Subject: x86/AMD: Apply erratum 665 on machines without a BIOS fix

From: Emanuel Czirai <[email protected]>

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. ]

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

@@ -669,6 +669,17 @@ 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;

@@ -726,6 +737,7 @@ 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 [email protected] are

queue-4.7/x86-amd-apply-erratum-665-on-machines-without-a-bios-fix.patch