x86, mce: Add boot options for corrected errors

This patch introduces three boot options (no_cmci, dont_log_ce
and ignore_ce) to control handling for corrected errors.

The "mce=no_cmci" boot option disables the CMCI feature.

Since CMCI is a new feature so having boot controls to disable
it will be a help if the hardware is misbehaving.

The "mce=dont_log_ce" boot option disables logging for corrected
errors. All reported corrected errors will be cleared silently.
This option will be useful if you never care about corrected
errors.

The "mce=ignore_ce" boot option disables features for corrected
errors, i.e. polling timer and cmci.  All corrected events are
not cleared and kept in bank MSRs.

Usually this disablement is not recommended, however it will be
a help if there are some conflict with the BIOS or hardware
monitoring applications etc., that clears corrected events in
banks instead of OS.

[ And trivial cleanup (space -> tab) for doc is included. ]

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <4A30ACDF.5030408@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 22 insertions, 2 deletions

diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index 82978ad12072..540a466e50f5 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -119,6 +119,8 @@ extern void (*threshold_cpu_callback)(unsigned long action, unsigned int cpu);
 #define MAX_NR_BANKS (MCE_EXTENDED_BANK - 1)
 
 #ifdef CONFIG_X86_MCE_INTEL
+extern int mce_cmci_disabled;
+extern int mce_ignore_ce;
 void mce_intel_feature_init(struct cpuinfo_x86 *c);
 void cmci_clear(void);
 void cmci_reenable(void);
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 6a3127ecb5cc..fabba15e4558 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -84,6 +84,9 @@ static int			rip_msr;
 static int                      mce_bootlog = -1;
 static int                      monarch_timeout = -1;
 static int                      mce_panic_timeout;
+static int                      mce_dont_log_ce;
+int                             mce_cmci_disabled;
+int                             mce_ignore_ce;
 int                             mce_ser;
 
 static char                     trigger[128];
@@ -526,7 +529,7 @@ void machine_check_poll(enum mcp_flags flags, mce_banks_t *b)
                  * Don't get the IP here because it's unlikely to
                  * have anything to do with the actual error location.
                  */
-                if (!(flags & MCP_DONTLOG)) {
+                if (!(flags & MCP_DONTLOG) && !mce_dont_log_ce) {
                         mce_log(&m);
                         add_taint(TAINT_MACHINE_CHECK);
                 }
@@ -1307,6 +1310,9 @@ static void mce_init_timer(void)
         struct timer_list *t = &__get_cpu_var(mce_timer);
         int *n = &__get_cpu_var(next_interval);
 
+        if (mce_ignore_ce)
+                return;
+
         *n = check_interval * HZ;
         if (!*n)
                 return;
@@ -1517,7 +1523,10 @@ static struct miscdevice mce_log_device = {
 };
 
 /*
- * mce=off disables machine check
+ * mce=off Disables machine check
+ * mce=no_cmci Disables CMCI
+ * mce=dont_log_ce Clears corrected events silently, no log created for CEs.
+ * mce=ignore_ce Disables polling and CMCI, corrected events are not cleared.
  * mce=TOLERANCELEVEL[,monarchtimeout] (number, see above)
  *      monarchtimeout is how long to wait for other CPUs on machine
  *      check, or 0 to not wait
@@ -1532,6 +1541,12 @@ static int __init mcheck_enable(char *str)
                 str++;
         if (!strcmp(str, "off"))
                 mce_disabled = 1;
+        else if (!strcmp(str, "no_cmci"))
+                mce_cmci_disabled = 1;
+        else if (!strcmp(str, "dont_log_ce"))
+                mce_dont_log_ce = 1;
+        else if (!strcmp(str, "ignore_ce"))
+                mce_ignore_ce = 1;
         else if (!strcmp(str, "bootlog") || !strcmp(str, "nobootlog"))
                 mce_bootlog = (str[0] == 'b');
         else if (isdigit(str[0])) {
diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel_64.c b/arch/x86/kernel/cpu/mcheck/mce_intel_64.c
index b7c5a2470b40..046087e9808f 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_intel_64.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_intel_64.c
@@ -57,6 +57,9 @@ static int cmci_supported(int *banks)
 {
         u64 cap;
 
+        if (mce_cmci_disabled || mce_ignore_ce)
+                return 0;
+
         /*
          * Vendor check is not strictly needed, but the initial
          * initialization is vendor keyed and this