Merge tag 'x86-mce-merge' of git://git.kernel.org/pub/scm/linux/kerne…

…l/git/ras/ras

Pull x86/mce merge window patches from Tony Luck:
 "Including two that make error_context() checks less sucky"

* tag 'x86-mce-merge' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras:
  x86/mce: Add instruction recovery signatures to mce-severity table
  x86/mce: Fix check for processor context when machine check was taken.
  MCE: Fix vm86 handling for 32bit mce handler
  x86/mce Add validation check before GHES error is recorded
  x86/mce: Avoid reading every machine check bank register twice.

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

@@ -42,7 +42,8 @@ void apei_mce_report_mem_error(int corrected, struct cper_sec_mem_err *mem_err)
 	struct mce m;
 
 	/* Only corrected MC is reported */
-	if (!corrected)
+	if (!corrected || !(mem_err->validation_bits &
+				CPER_MEM_VALID_PHYSICAL_ADDRESS))
 		return;
 
 	mce_setup(&m);

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

@@ -126,6 +126,16 @@ static struct severity {
 		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
 		USER
 		),
+	MCESEV(
+		KEEP, "HT thread notices Action required: instruction fetch error",
+		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_INSTR),
+		MCGMASK(MCG_STATUS_EIPV, 0)
+		),
+	MCESEV(
+		AR, "Action required: instruction fetch error",
+		SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_INSTR),
+		USER
+		),
 #endif
 	MCESEV(
 		PANIC, "Action required: unknown MCACOD",
@@ -165,15 +175,19 @@ static struct severity {
 };
 
 /*
- * If the EIPV bit is set, it means the saved IP is the
- * instruction which caused the MCE.
+ * If mcgstatus indicated that ip/cs on the stack were
+ * no good, then "m->cs" will be zero and we will have
+ * to assume the worst case (IN_KERNEL) as we actually
+ * have no idea what we were executing when the machine
+ * check hit.
+ * If we do have a good "m->cs" (or a faked one in the
+ * case we were executing in VM86 mode) we can use it to
+ * distinguish an exception taken in user from from one
+ * taken in the kernel.
  */
 static int error_context(struct mce *m)
 {
-	if (m->mcgstatus & MCG_STATUS_EIPV)
-		return (m->ip && (m->cs & 3) == 3) ? IN_USER : IN_KERNEL;
-	/* Unknown, assume kernel */
-	return IN_KERNEL;
+	return ((m->cs & 3) == 3) ? IN_USER : IN_KERNEL;
 }
 
 int mce_severity(struct mce *m, int tolerant, char **msg)

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

@@ -437,6 +437,14 @@ static inline void mce_gather_info(struct mce *m, struct pt_regs *regs)
 		if (m->mcgstatus & (MCG_STATUS_RIPV|MCG_STATUS_EIPV)) {
 			m->ip = regs->ip;
 			m->cs = regs->cs;
+
+			/*
+			 * When in VM86 mode make the cs look like ring 3
+			 * always. This is a lie, but it's better than passing
+			 * the additional vm86 bit around everywhere.
+			 */
+			if (v8086_mode(regs))
+				m->cs |= 3;
 		}
 		/* Use accurate RIP reporting if available. */
 		if (rip_msr)
@@ -641,16 +649,18 @@ EXPORT_SYMBOL_GPL(machine_check_poll);
  * Do a quick check if any of the events requires a panic.
  * This decides if we keep the events around or clear them.
  */
-static int mce_no_way_out(struct mce *m, char **msg)
+static int mce_no_way_out(struct mce *m, char **msg, unsigned long *validp)
 {
-	int i;
+	int i, ret = 0;
 
 	for (i = 0; i < banks; i++) {
 		m->status = mce_rdmsrl(MSR_IA32_MCx_STATUS(i));
+		if (m->status & MCI_STATUS_VAL)
+			__set_bit(i, validp);
 		if (mce_severity(m, tolerant, msg) >= MCE_PANIC_SEVERITY)
-			return 1;
+			ret = 1;
 	}
-	return 0;
+	return ret;
 }
 
 /*
@@ -1013,6 +1023,7 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 	 */
 	int kill_it = 0;
 	DECLARE_BITMAP(toclear, MAX_NR_BANKS);
+	DECLARE_BITMAP(valid_banks, MAX_NR_BANKS);
 	char *msg = "Unknown";
 
 	atomic_inc(&mce_entry);
@@ -1027,7 +1038,8 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 	final = &__get_cpu_var(mces_seen);
 	*final = m;
 
-	no_way_out = mce_no_way_out(&m, &msg);
+	memset(valid_banks, 0, sizeof(valid_banks));
+	no_way_out = mce_no_way_out(&m, &msg, valid_banks);
 
 	barrier();
 
@@ -1047,6 +1059,8 @@ void do_machine_check(struct pt_regs *regs, long error_code)
 	order = mce_start(&no_way_out);
 	for (i = 0; i < banks; i++) {
 		__clear_bit(i, toclear);
+		if (!test_bit(i, valid_banks))
+			continue;
 		if (!mce_banks[i].ctl)
 			continue;