[PATCH V2 4/5] x86/mcheck/AMD: Fix LVT offset configuration for thresholding

[Aravind Gopalakrishnan]

For processor families with  SMCA feature, the LVT offset
for threshold interrupts is configured only in MSR 0xC0000410
and not in each per bank MISC register as was done in earlier
families.

Fixing the code here to obtain the LVT offset from the correct
MSR for those families which have SMCA feature enabled.

Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@xxxxxxx>
---
 arch/x86/kernel/cpu/mcheck/mce_amd.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
index e650fdc..29a7688 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
@@ -49,6 +49,15 @@
 #define DEF_LVT_OFF		0x2
 #define DEF_INT_TYPE_APIC	0x2
 
+/*
+ * SMCA settings:
+ * The following defines provide masks or bit positions of
+ * MSRs that are applicable only to SMCA enabled processors
+ */
+
+/* Threshold LVT offset is at MSR0xC0000410[15:12] */
+#define SMCA_THR_LVT_OFF	0xF000
+
 static const char * const th_names[] = {
 	"load_store",
 	"insn_fetch",
@@ -143,6 +152,15 @@ static int lvt_off_valid(struct threshold_block *b, int apic, u32 lo, u32 hi)
 	}
 
 	if (apic != msr) {
+		/*
+		 * For SMCA enabled processors, LVT offset is programmed at
+		 * different MSR and BIOS provides the value.
+		 * The original field where LVT offset was set is Reserved.
+		 * So, return early here.
+		 */
+		if (mce_flags.smca)
+			return 0;
+
 		pr_err(FW_BUG "cpu %d, invalid threshold interrupt offset %d "
 		       "for bank %d, block %d (MSR%08X=0x%x%08x)\n",
 		       b->cpu, apic, b->bank, b->block, b->address, hi, lo);
@@ -301,7 +319,21 @@ void mce_amd_feature_init(struct cpuinfo_x86 *c)
 				goto init;
 
 			b.interrupt_enable = 1;
-			new	= (high & MASK_LVTOFF_HI) >> 20;
+
+			if (mce_flags.smca) {
+				u32 smca_low = 0, smca_high = 0;
+
+				/* Gather LVT offset for thresholding */
+				if (rdmsr_safe(MSR_CU_DEF_ERR,
+					       &smca_low,
+					       &smca_high))
+					break;
+
+				new = (smca_low & SMCA_THR_LVT_OFF) >> 12;
+			} else {
+				new	= (high & MASK_LVTOFF_HI) >> 20;
+			}
+
 			offset  = setup_APIC_mce_threshold(offset, new);
 
 			if ((offset == new) &&
-- 
2.7.0