[PATCH 8/8] x86/mce/AMD: Set MCAX Enable bit

[Borislav Petkov]

From: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>

It is required for the 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.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
Cc: linux-edac <linux-edac@xxxxxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: x86-ml <x86@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/1452901836-27632-6-git-send-email-Aravind.Gopalakrishnan@xxxxxxx
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
 arch/x86/include/asm/msr-index.h     |  4 ++++
 arch/x86/kernel/cpu/mcheck/mce_amd.c | 14 ++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index b05402ef3b84..5b1aa4c05c4f 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -264,6 +264,10 @@
 #define MSR_IA32_MC0_CTL2		0x00000280
 #define MSR_IA32_MCx_CTL2(x)		(MSR_IA32_MC0_CTL2 + (x))
 
+/* AMD64 Scalable MCA */
+#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 e5ac583ae915..e1f05e8854d1 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -54,6 +54,14 @@
 /* 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, uncorrectable errors will cause system panic.
+ */
+#define SMCA_MCAX_EN_OFF	0x1
+
 static const char * const th_names[] = {
 	"load_store",
 	"insn_fetch",
@@ -292,6 +300,12 @@ prepare_threshold_block(unsigned int bank, unsigned int block, u32 addr,
 
 	if (mce_flags.smca) {
 		u32 smca_low, smca_high;
+		u32 smca_addr = MSR_AMD64_SMCA_MCx_CONFIG(bank);
+
+		if (!rdmsr_safe(smca_addr, &smca_low, &smca_high)) {
+			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, &smca_low, &smca_high))
-- 
2.3.5