x86: sanity check APIC timer frequency

Check the APIC timer calibration result for sanity. When the frequency
is out of range, issue a warning and disable the local APIC timer.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/x86/kernel/apic_64.c b/arch/x86/kernel/apic_64.c
index d1a696673d9d..731b48660fc4 100644
--- a/arch/x86/kernel/apic_64.c
+++ b/arch/x86/kernel/apic_64.c
@@ -384,6 +384,18 @@ void __init setup_boot_APIC_clock(void)
         calibrate_APIC_clock();
 
         /*
+         * Do a sanity check on the APIC calibration result
+         */
+        if (calibration_result < (1000000 / HZ)) {
+                printk(KERN_WARNING
+                       "APIC frequency too slow, disabling apic timer\n");
+                /* No broadcast on UP ! */
+                if (num_possible_cpus() > 1)
+                        setup_APIC_timer();
+                return;
+        }
+
+        /*
          * If nmi_watchdog is set to IO_APIC, we need the
          * PIT/HPET going.  Otherwise register lapic as a dummy
          * device.