x86, perf events: Check if we have APIC enabled

Ralf Hildebrandt reported this boot warning:

| Running a vanilla 2.6.32 as Xen DomU, I'm getting:
|
| [    0.000999] CPU: Physical Processor ID: 0
| [    0.000999] CPU: Processor Core ID: 1
| [    0.000999] Performance Events: AMD PMU driver.
| [    0.000999] ------------[ cut here ]------------
| [    0.000999] WARNING: at arch/x86/kernel/apic/apic.c:249 native_apic_write_dummy

So we need to check if APIC functionality is available, and
not just in the P6 driver but elsewhere as well.
Reported-by: NRalf Hildebrandt <Ralf.Hildebrandt@charite.de>
Signed-off-by: NCyrill Gorcunov <gorcunov@openvz.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091210165634.GF5086@lenovo>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/kernel/cpu/perf_event.c

@@ -2066,12 +2066,6 @@ static __init int p6_pmu_init(void)
 
 	x86_pmu = p6_pmu;
 
-	if (!cpu_has_apic) {
-		pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
-		pr_info("no hardware sampling interrupt available.\n");
-		x86_pmu.apic = 0;
-	}
-
 	return 0;
 }
 
@@ -2163,6 +2157,16 @@ static __init int amd_pmu_init(void)
 	return 0;
 }
 
+static void __init pmu_check_apic(void)
+{
+	if (cpu_has_apic)
+		return;
+
+	x86_pmu.apic = 0;
+	pr_info("no APIC, boot with the \"lapic\" boot parameter to force-enable it.\n");
+	pr_info("no hardware sampling interrupt available.\n");
+}
+
 void __init init_hw_perf_events(void)
 {
 	int err;
@@ -2184,6 +2188,8 @@ void __init init_hw_perf_events(void)
 		return;
 	}
 
+	pmu_check_apic();
+
 	pr_cont("%s PMU driver.\n", x86_pmu.name);
 
 	if (x86_pmu.num_events > X86_PMC_MAX_GENERIC) {