x86: introduce smpboot_clear_io_apic

x86_64 has two nr_ioapics = 0 statements. In 32-bit, it can be done
too. We do it through the smpboot_clear_io_apic() inline function,
to cope with subarchitectures (visws) that does not compile mpparse in

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/kernel/smpboot_32.c

@@ -155,6 +155,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
 		printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
 			boot_cpu_physical_apicid);
 		printk(KERN_ERR "... forcing use of dummy APIC emulation. (tell your hw vendor)\n");
+		smpboot_clear_io_apic();
 		return -1;
 	}
 
@@ -173,6 +174,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
 			setup_local_APIC();
 			end_local_APIC_setup();
 		}
+		smpboot_clear_io_apic();
 		return -1;
 	}
 	return 0;

arch/x86/kernel/smpboot_64.c

@@ -134,7 +134,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
 		printk(KERN_ERR "BIOS bug, local APIC #%d not detected!...\n",
 			boot_cpu_physical_apicid);
 		printk(KERN_ERR "... forcing use of dummy APIC emulation. (tell your hw vendor)\n");
-		nr_ioapics = 0;
+		smpboot_clear_io_apic();
 		return -1;
 	}
 
@@ -145,7 +145,7 @@ static int __init smp_sanity_check(unsigned max_cpus)
 	 */
 	if (!max_cpus) {
 		printk(KERN_INFO "SMP mode deactivated, forcing use of dummy APIC emulation.\n");
-		nr_ioapics = 0;
+		smpboot_clear_io_apic();
 		return -1;
 	}
 

include/asm-x86/mach-default/smpboot_hooks.h

@@ -44,3 +44,8 @@ static inline void smpboot_setup_io_apic(void)
 	else
 		nr_ioapics = 0;
 }
+
+static inline void smpboot_clear_io_apic(void)
+{
+	nr_ioapics = 0;
+}

include/asm-x86/mach-visws/smpboot_hooks.h

@@ -22,3 +22,7 @@ static inline void smpboot_restore_warm_reset_vector(void)
 static inline void smpboot_setup_io_apic(void)
 {
 }
+
+static inline void smpboot_clear_io_apic(void)
+{
+}