x86, mce: Fix MSR_IA32_MCI_CTL2 CMCI threshold setup

It is reported that CMCI is not raised when number of corrected error
reaches preset threshold. After inspection, it is found that
MSR_IA32_MCI_CTL2 threshold field is not setup properly. This patch
fixed it.

Value of MCI_CTL2_CMCI_THRESHOLD_MASK is fixed according to x86_64
Software Developer's Manual too.
Reported-by: Shaohui Zheng <shaohui.zheng@intel.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
LKML-Reference: <1275977350.3444.660.camel@yhuang-dev.sh.intel.com>
Reviewed-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/include/asm/mce.h

@@ -40,7 +40,7 @@
 
 /* CTL2 register defines */
 #define MCI_CTL2_CMCI_EN		(1ULL << 30)
-#define MCI_CTL2_CMCI_THRESHOLD_MASK	0xffffULL
+#define MCI_CTL2_CMCI_THRESHOLD_MASK	0x7fffULL
 
 #define MCJ_CTX_MASK		3
 #define MCJ_CTX(flags)		((flags) & MCJ_CTX_MASK)

arch/x86/kernel/cpu/mcheck/mce_intel.c

@@ -102,6 +102,7 @@ static void cmci_discover(int banks, int boot)
 			continue;
 		}
 
+		val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
 		val |= MCI_CTL2_CMCI_EN | CMCI_THRESHOLD;
 		wrmsrl(MSR_IA32_MCx_CTL2(i), val);
 		rdmsrl(MSR_IA32_MCx_CTL2(i), val);