x86/mce: Remove the tolerance level control

This is pretty much unused and not really useful. What is more, all
relevant MCA hardware has recoverable machine checks support so there's
no real need to tweak MCA tolerance levels in order to *maybe* extend
machine lifetime.

So rip it out.

Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/YcDq8PxvKtTENl/e@zn.tnic

1 files changed, 20 insertions, 33 deletions

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 3d766e6247bc..6c9b5dac38fd 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -86,14 +86,6 @@ struct mce_vendor_flags mce_flags __read_mostly;
 
 struct mca_config mca_cfg __read_mostly = {
 	.bootlog  = -1,
-	/*
-	 * Tolerant levels:
-	 * 0: always panic on uncorrected errors, log corrected errors
-	 * 1: panic or SIGBUS on uncorrected errors, log corrected errors
-	 * 2: SIGBUS or log uncorrected errors (if possible), log corr. errors
-	 * 3: never panic or SIGBUS, log all errors (for testing only)
-	 */
-	.tolerant = 1,
 	.monarch_timeout = -1
 };
 
@@ -753,7 +745,7 @@ log_it:
 			goto clear_it;
 
 		mce_read_aux(&m, i);
-		m.severity = mce_severity(&m, NULL, mca_cfg.tolerant, NULL, false);
+		m.severity = mce_severity(&m, NULL, NULL, false);
 		/*
 		 * Don't get the IP here because it's unlikely to
 		 * have anything to do with the actual error location.
@@ -887,7 +879,7 @@ static __always_inline int mce_no_way_out(struct mce *m, char **msg, unsigned lo
 			quirk_sandybridge_ifu(i, m, regs);
 
 		m->bank = i;
-		if (mce_severity(m, regs, mca_cfg.tolerant, &tmp, true) >= MCE_PANIC_SEVERITY) {
+		if (mce_severity(m, regs, &tmp, true) >= MCE_PANIC_SEVERITY) {
 			mce_read_aux(m, i);
 			*msg = tmp;
 			return 1;
@@ -935,12 +927,11 @@ static noinstr int mce_timed_out(u64 *t, const char *msg)
 	if (!mca_cfg.monarch_timeout)
 		goto out;
 	if ((s64)*t < SPINUNIT) {
-		if (mca_cfg.tolerant <= 1) {
-			if (cpumask_and(&mce_missing_cpus, cpu_online_mask, &mce_missing_cpus))
-				pr_emerg("CPUs not responding to MCE broadcast (may include false positives): %*pbl\n",
-					 cpumask_pr_args(&mce_missing_cpus));
-			mce_panic(msg, NULL, NULL);
-		}
+		if (cpumask_and(&mce_missing_cpus, cpu_online_mask, &mce_missing_cpus))
+			pr_emerg("CPUs not responding to MCE broadcast (may include false positives): %*pbl\n",
+				 cpumask_pr_args(&mce_missing_cpus));
+		mce_panic(msg, NULL, NULL);
+
 		ret = 1;
 		goto out;
 	}
@@ -1004,9 +995,9 @@ static void mce_reign(void)
 	 * This dumps all the mces in the log buffer and stops the
 	 * other CPUs.
 	 */
-	if (m && global_worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3) {
+	if (m && global_worst >= MCE_PANIC_SEVERITY) {
 		/* call mce_severity() to get "msg" for panic */
-		mce_severity(m, NULL, mca_cfg.tolerant, &msg, true);
+		mce_severity(m, NULL, &msg, true);
 		mce_panic("Fatal machine check", m, msg);
 	}
 
@@ -1020,7 +1011,7 @@ static void mce_reign(void)
 	 * No machine check event found. Must be some external
 	 * source or one CPU is hung. Panic.
 	 */
-	if (global_worst <= MCE_KEEP_SEVERITY && mca_cfg.tolerant < 3)
+	if (global_worst <= MCE_KEEP_SEVERITY)
 		mce_panic("Fatal machine check from unknown source", NULL, NULL);
 
 	/*
@@ -1267,7 +1258,7 @@ __mc_scan_banks(struct mce *m, struct pt_regs *regs, struct mce *final,
 		/* Set taint even when machine check was not enabled. */
 		taint++;
 
-		severity = mce_severity(m, regs, cfg->tolerant, NULL, true);
+		severity = mce_severity(m, regs, NULL, true);
 
 		/*
 		 * When machine check was for corrected/deferred handler don't
@@ -1425,7 +1416,6 @@ noinstr void do_machine_check(struct pt_regs *regs)
 	int worst = 0, order, no_way_out, kill_current_task, lmce, taint = 0;
 	DECLARE_BITMAP(valid_banks, MAX_NR_BANKS) = { 0 };
 	DECLARE_BITMAP(toclear, MAX_NR_BANKS) = { 0 };
-	struct mca_config *cfg = &mca_cfg;
 	struct mce m, *final;
 	char *msg = NULL;
 
@@ -1447,7 +1437,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
 
 	/*
 	 * If no_way_out gets set, there is no safe way to recover from this
-	 * MCE.  If mca_cfg.tolerant is cranked up, we'll try anyway.
+	 * MCE.
 	 */
 	no_way_out = 0;
 
@@ -1481,7 +1471,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
 	 * severity is MCE_AR_SEVERITY we have other options.
 	 */
 	if (!(m.mcgstatus & MCG_STATUS_RIPV))
-		kill_current_task = (cfg->tolerant == 3) ? 0 : 1;
+		kill_current_task = 1;
 	/*
 	 * Check if this MCE is signaled to only this logical processor,
 	 * on Intel, Zhaoxin only.
@@ -1498,7 +1488,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
 	 * to see it will clear it.
 	 */
 	if (lmce) {
-		if (no_way_out && cfg->tolerant < 3)
+		if (no_way_out)
 			mce_panic("Fatal local machine check", &m, msg);
 	} else {
 		order = mce_start(&no_way_out);
@@ -1518,7 +1508,7 @@ noinstr void do_machine_check(struct pt_regs *regs)
 			if (!no_way_out)
 				no_way_out = worst >= MCE_PANIC_SEVERITY;
 
-			if (no_way_out && cfg->tolerant < 3)
+			if (no_way_out)
 				mce_panic("Fatal machine check on current CPU", &m, msg);
 		}
 	} else {
@@ -1530,8 +1520,8 @@ noinstr void do_machine_check(struct pt_regs *regs)
 		 * fatal error. We call "mce_severity()" again to
 		 * make sure we have the right "msg".
 		 */
-		if (worst >= MCE_PANIC_SEVERITY && mca_cfg.tolerant < 3) {
-			mce_severity(&m, regs, cfg->tolerant, &msg, true);
+		if (worst >= MCE_PANIC_SEVERITY) {
+			mce_severity(&m, regs, &msg, true);
 			mce_panic("Local fatal machine check!", &m, msg);
 		}
 	}
@@ -2267,10 +2257,9 @@ static int __init mcheck_enable(char *str)
 		cfg->bios_cmci_threshold = 1;
 	else if (!strcmp(str, "recovery"))
 		cfg->recovery = 1;
-	else if (isdigit(str[0])) {
-		if (get_option(&str, &cfg->tolerant) == 2)
-			get_option(&str, &(cfg->monarch_timeout));
-	} else {
+	else if (isdigit(str[0]))
+		get_option(&str, &(cfg->monarch_timeout));
+	else {
 		pr_info("mce argument %s ignored. Please use /sys\n", str);
 		return 0;
 	}
@@ -2520,7 +2509,6 @@ static ssize_t store_int_with_restart(struct device *s,
 	return ret;
 }
 
-static DEVICE_INT_ATTR(tolerant, 0644, mca_cfg.tolerant);
 static DEVICE_INT_ATTR(monarch_timeout, 0644, mca_cfg.monarch_timeout);
 static DEVICE_BOOL_ATTR(dont_log_ce, 0644, mca_cfg.dont_log_ce);
 static DEVICE_BOOL_ATTR(print_all, 0644, mca_cfg.print_all);
@@ -2541,7 +2529,6 @@ static struct dev_ext_attribute dev_attr_cmci_disabled = {
 };
 
 static struct device_attribute *mce_device_attrs[] = {
-	&dev_attr_tolerant.attr,
 	&dev_attr_check_interval.attr,
 #ifdef CONFIG_X86_MCELOG_LEGACY
 	&dev_attr_trigger,