linux-kernel - [PATCH V2 5/5] x86/mcheck/AMD: Set MCAX Enable bit

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Date:	Fri, 15 Jan 2016 17:50:36 -0600
From:	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
To:	<tony.luck@...el.com>, <bp@...en8.de>, <tglx@...utronix.de>,
	<mingo@...hat.com>, <hpa@...or.com>
CC:	<x86@...nel.org>, <linux-edac@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH V2 5/5] x86/mcheck/AMD: Set MCAX Enable bit

It is required for OS to acknowledge that it is using
the MCAX register set and its associated fields by setting
the 'McaXEnable' bit in each bank's MCi_CONFIG register. If
it is not set, then all UC errors will cause a system panic.

So setting the bit here and also defining the new MSR range for
SMCA enabled proccessors in msr-index

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
---
 arch/x86/include/asm/msr-index.h     |  5 +++++
 arch/x86/kernel/cpu/mcheck/mce_amd.c | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index b05402e..088b5a7 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -264,6 +264,11 @@
 #define MSR_IA32_MC0_CTL2		0x00000280
 #define MSR_IA32_MCx_CTL2(x)		(MSR_IA32_MC0_CTL2 + (x))
 
+/* SMCA defined MSR register set for AMD64 */
+#define MSR_AMD64_SMCA_MC0_CONFIG	0xc0002004
+
+#define MSR_AMD64_SMCA_MCx_CONFIG(x)	(MSR_AMD64_SMCA_MC0_CONFIG + 0x10*(x))
+
 #define MSR_P6_PERFCTR0			0x000000c1
 #define MSR_P6_PERFCTR1			0x000000c2
 #define MSR_P6_EVNTSEL0			0x00000186
diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
index 29a7688..158ea86 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -57,6 +57,14 @@
 
 /* Threshold LVT offset is at MSR0xC0000410[15:12] */
 #define SMCA_THR_LVT_OFF	0xF000
+/*
+ * OS is required to set the MCAX bit to acknowledge
+ * that it is now using the new MSR ranges and new registers
+ * under each bank. It also means that OS will configure
+ * Deferred errors in the new MCx_CONFIG register.
+ * If the bit is not set, UC errors will cause a system panic
+ */
+#define SMCA_MCAX_EN_OFF	0x1
 
 static const char * const th_names[] = {
 	"load_store",
@@ -322,6 +330,17 @@ void mce_amd_feature_init(struct cpuinfo_x86 *c)
 
 			if (mce_flags.smca) {
 				u32 smca_low = 0, smca_high = 0;
+				u32 smca_addr = 0;
+
+				/* Set MCAXEnable bit for each bank */
+				smca_addr = MSR_AMD64_SMCA_MCx_CONFIG(bank);
+				if (rdmsr_safe(smca_addr,
+					       &smca_low,
+					       &smca_high))
+					continue;
+
+				smca_high |= SMCA_MCAX_EN_OFF;
+				wrmsr(smca_addr, smca_low, smca_high);
 
 				/* Gather LVT offset for thresholding */
 				if (rdmsr_safe(MSR_CU_DEF_ERR,
-- 
2.7.0