[PATCH 1/8] x86, apic.c: Disable irq0 if CPU enables ARAT for local apic timer

["Fenghua Yu" <fenghua.yu@intel.com>]

From: Fenghua Yu <fenghua.yu@intel.com>

irq0 won't generate any interrupt after local apic timers is enabled and ARAT
is enabled. Disable irq0 in this case. Thus irq0 won't block BSP offline.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
 arch/x86/kernel/apic/apic.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 52fa563..8813acf 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -506,6 +506,7 @@ static DEFINE_PER_CPU(struct clock_event_device, lapic_events);
 static void __cpuinit setup_APIC_timer(void)
 {
 	struct clock_event_device *levt = &__get_cpu_var(lapic_events);
+	int cpu = smp_processor_id();
 
 	if (this_cpu_has(X86_FEATURE_ARAT)) {
 		lapic_clockevent.features &= ~CLOCK_EVT_FEAT_C3STOP;
@@ -517,6 +518,10 @@ static void __cpuinit setup_APIC_timer(void)
 	levt->cpumask = cpumask_of(smp_processor_id());
 
 	clockevents_register_device(levt);
+
+	/* irq0 won't be used any more if CPU supports ARAT feature. */
+	if (cpu == 0 && this_cpu_has(X86_FEATURE_ARAT))
+		disable_irq(0);
 }
 
 /*
-- 
1.6.0.3