x86, hpet: Disable per-cpu hpet timer if ARAT is supported

commit 39fe05e5 upstream.

If CPU support always running local APIC timer, per-cpu hpet
timer could be disabled, which is useless and wasteful in such
case. Let's leave the timers to others.

The effect is that we reserve less timers.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: venkatesh.pallipadi@intel.com
LKML-Reference: <20090812031612.GA10062@sli10-desk.sh.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Renninger <trenn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

arch/x86/kernel/hpet.c

@@ -606,6 +606,8 @@ static void hpet_msi_capability_lookup(unsigned int start_timer)
 	if (hpet_msi_disable)
 		return;
 
+	if (boot_cpu_has(X86_FEATURE_ARAT))
+		return;
 	id = hpet_readl(HPET_ID);
 
 	num_timers = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT);
@@ -894,10 +896,8 @@ int __init hpet_enable(void)
 
 	if (id & HPET_ID_LEGSUP) {
 		hpet_legacy_clockevent_register();
-		hpet_msi_capability_lookup(2);
 		return 1;
 	}
-	hpet_msi_capability_lookup(0);
 	return 0;
 
 out_nohpet:
@@ -930,12 +930,20 @@ static __init int hpet_late_init(void)
 	if (!hpet_virt_address)
 		return -ENODEV;
 
+	if (hpet_readl(HPET_ID) & HPET_ID_LEGSUP)
+		hpet_msi_capability_lookup(2);
+	else
+		hpet_msi_capability_lookup(0);
+
 	hpet_reserve_platform_timers(hpet_readl(HPET_ID));
 	hpet_print_config();
 
 	if (hpet_msi_disable)
 		return 0;
 
+	if (boot_cpu_has(X86_FEATURE_ARAT))
+		return 0;
+
 	for_each_online_cpu(cpu) {
 		hpet_cpuhp_notify(NULL, CPU_ONLINE, (void *)(long)cpu);
 	}