[ACPI] disable LAPIC at reboot and poweroff if Linux forced it on

http://bugzilla.kernel.org/show_bug.cgi?id=3643Signed-off-by: Alexey Y Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Len Brown <len.brown@intel.com>

arch/i386/kernel/apic.c

@@ -491,12 +491,25 @@ void __init setup_local_APIC (void)
 	apic_pm_activate();
 }
 
+/*
+ * If Linux enabled the LAPIC against the BIOS default
+ * disable it down before re-entering the BIOS on shutdown.
+ * Otherwise the BIOS may get confused and not power-off.
+ */
+void
+lapic_shutdown()
+{
+	if (!cpu_has_apic || !enabled_via_apicbase)
+		return;
+
+	local_irq_disable();
+	disable_local_APIC();
+	local_irq_enable();
+}
+
 #ifdef CONFIG_PM
 
 static struct {
-	/* 'active' is true if the local APIC was enabled by us and
-	   not the BIOS; this signifies that we are also responsible
-	   for disabling it before entering apm/acpi suspend */
 	int active;
 	/* r/w apic fields */
 	unsigned int apic_id;
@@ -584,6 +597,10 @@ static int lapic_resume(struct sys_device *dev)
 	return 0;
 }
 
+/*
+ * This device has no shutdown method - fully functioning local APICs
+ * are needed on every CPU up until machine_halt/restart/poweroff.
+ */
 
 static struct sysdev_class lapic_sysclass = {
 	set_kset_name("lapic"),

arch/i386/kernel/reboot.c

@@ -331,13 +331,10 @@ void machine_restart(char * __unused)
 	 * other OSs see a clean IRQ state.
 	 */
 	smp_send_stop();
-#elif defined(CONFIG_X86_LOCAL_APIC)
-	if (cpu_has_apic) {
-		local_irq_disable();
-		disable_local_APIC();
-		local_irq_enable();
-	}
-#endif
+#endif /* CONFIG_SMP */
+
+	lapic_shutdown();
+
 #ifdef CONFIG_X86_IO_APIC
 	disable_IO_APIC();
 #endif
@@ -373,6 +370,8 @@ EXPORT_SYMBOL(machine_halt);
 
 void machine_power_off(void)
 {
+	lapic_shutdown();
+
 	if (efi_enabled)
 		efi.reset_system(EFI_RESET_SHUTDOWN, EFI_SUCCESS, 0, NULL);
 	if (pm_power_off)

include/asm-i386/apic.h

@@ -88,6 +88,7 @@ extern void clear_local_APIC(void);
 extern void connect_bsp_APIC (void);
 extern void disconnect_bsp_APIC (void);
 extern void disable_local_APIC (void);
+extern void lapic_shutdown (void);
 extern int verify_local_APIC (void);
 extern void cache_APIC_registers (void);
 extern void sync_Arb_IDs (void);
@@ -116,6 +117,9 @@ extern unsigned int nmi_watchdog;
 #define NMI_LOCAL_APIC	2
 #define NMI_INVALID	3
 
-#endif /* CONFIG_X86_LOCAL_APIC */
+#else /* !CONFIG_X86_LOCAL_APIC */
+static inline void lapic_shutdown(void) { }
+
+#endif /* !CONFIG_X86_LOCAL_APIC */
 
 #endif /* __ASM_APIC_H */