x86/mce: Create helper function to save addr/misc when needed

The MCI_STATUS_MISCV and MCI_STATUS_ADDRV bits in the bank status
registers define whether the MISC and ADDR registers respectively
contain valid data - provide a helper function to check these bits
and read the registers when needed.

In addition, processors that support software error recovery (as
indicated by the MCG_SER_P bit in the MCG_CAP register) may include
some undefined bits in the ADDR register - mask these out.
Acked-by: NBorislav Petkov <bp@amd64.org>
Signed-off-by: NTony Luck <tony.luck@intel.com>

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

@@ -492,6 +492,27 @@ static void mce_report_event(struct pt_regs *regs)
 	irq_work_queue(&__get_cpu_var(mce_irq_work));
 }
 
+/*
+ * Read ADDR and MISC registers.
+ */
+static void mce_read_aux(struct mce *m, int i)
+{
+	if (m->status & MCI_STATUS_MISCV)
+		m->misc = mce_rdmsrl(MSR_IA32_MCx_MISC(i));
+	if (m->status & MCI_STATUS_ADDRV) {
+		m->addr = mce_rdmsrl(MSR_IA32_MCx_ADDR(i));
+
+		/*
+		 * Mask the reported address by the reported granularity.
+		 */
+		if (mce_ser && (m->status & MCI_STATUS_MISCV)) {
+			u8 shift = MCI_MISC_ADDR_LSB(m->misc);
+			m->addr >>= shift;
+			m->addr <<= shift;
+		}
+	}
+}
+
 DEFINE_PER_CPU(unsigned, mce_poll_count);
 
 /*
@@ -542,10 +563,7 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
 		    (m.status & (mce_ser ? MCI_STATUS_S : MCI_STATUS_UC)))
 			continue;
 
-		if (m.status & MCI_STATUS_MISCV)
-			m.misc = mce_rdmsrl(MSR_IA32_MCx_MISC(i));
-		if (m.status & MCI_STATUS_ADDRV)
-			m.addr = mce_rdmsrl(MSR_IA32_MCx_ADDR(i));
+		mce_read_aux(&m, i);
 
 		if (!(flags & MCP_TIMESTAMP))
 			m.tsc = 0;
@@ -981,10 +999,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 		if (severity == MCE_AR_SEVERITY)
 			kill_it = 1;
 
-		if (m.status & MCI_STATUS_MISCV)
-			m.misc = mce_rdmsrl(MSR_IA32_MCx_MISC(i));
-		if (m.status & MCI_STATUS_ADDRV)
-			m.addr = mce_rdmsrl(MSR_IA32_MCx_ADDR(i));
+		mce_read_aux(&m, i);
 
 		/*
 		 * Action optional error. Queue address for later processing.