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x86/AMD: Apply erratum 665 on machines without a BIOS fix

PATCH New Borislav Petkov 2 participants 2 messages Sep 2, 2016 x86

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Borislav Petkov

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#0 lore raw

PATCH 1/1 x86/AMD: Apply erratum 665 on machines without a BIOS fix

From: Emanuel Czirai <[email protected]>

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 in that case. It is simple enough.

Signed-off-by Emanuel Czirai <[email protected]>
Cc Yaowu Xu <[email protected]>
[ Write commit message. ]
Signed-off-by Borislav Petkov <[email protected]>
---
 arch/x86/kernel/cpu/amd.c | 9 +++++++++
 1 file changed, 9 insertions(+)
arch/x86/kernel/cpu/amd.c +9 -0
index f5c69d8974e1..eaf938e9df88 100644
@@ -669,6 +669,14 @@ static void init_amd_gh(struct cpuinfo_x86 *c)
 		set_cpu_bug(c, X86_BUG_AMD_TLB_MMATCH);
 }
 
+static void init_amd_ln(struct cpuinfo_x86 *c)
+{
+#define MSR_AMD64_DE_CFG		0xC0011029
+
+	/* Apply erratum 665 fix to machines without a BIOS fix.  */
+	msr_set_bit(MSR_AMD64_DE_CFG, 31);
+}
+
 static void init_amd_bd(struct cpuinfo_x86 *c)
 {
 	u64 value;

@@ -726,6 +734,7 @@ static void init_amd(struct cpuinfo_x86 *c)
 	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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#1 lore raw
x86/AMD: Apply erratum 665 on machines without a BIOS fix
Commit-ID:  d1992996753132e2dafe955cccb2fb0714d3cfc4
Gitweb:     http://git.kernel.org/tip/d1992996753132e2dafe955cccb2fb0714d3cfc4
Author:     Emanuel Czirai <[email protected]>
AuthorDate: Fri, 2 Sep 2016 07:35:50 +0200
Committer:  Thomas Gleixner <[email protected]>
CommitDate: Fri, 2 Sep 2016 20:42:28 +0200

x86/AMD: Apply erratum 665 on machines without a BIOS fix

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 <[email protected]>
Signed-off-by Borislav Petkov <[email protected]>
Cc Yaowu Xu <[email protected]>
Cc [email protected]
Link http://lkml.kernel.org/r/[email protected] open here
Signed-off-by Thomas Gleixner <[email protected]>
---
 arch/x86/kernel/cpu/amd.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
arch/x86/kernel/cpu/amd.c +12 -0
index f5c69d8..b81fe2d 100644
@@ -669,6 +669,17 @@ static void init_amd_gh(struct cpuinfo_x86 *c)
 		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 *c)
 	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;
 	}