x86: implement missing x86_64 function smp_call_function_mask()

This patch defines the missing function smp_call_function_mask() for x86_64,
this is more or less a cut&paste of i386 function. It removes also some
duplicate code.

This function is needed by KVM to execute a function on some CPUs.

AK: Fixed description
AK: Moved WARN_ON(irqs_disabled) one level up to not warn in the panic case.
[ tglx: arch/x86 adaptation ]

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/include/asm-x86/smp_64.h b/include/asm-x86/smp_64.h
index d30e9b6..9d35018 100644
--- a/include/asm-x86/smp_64.h
+++ b/include/asm-x86/smp_64.h
@@ -37,6 +37,8 @@
 extern void unlock_ipi_call_lock(void);
 extern int smp_num_siblings;
 extern void smp_send_reschedule(int cpu);
+extern int smp_call_function_mask(cpumask_t mask, void (*func)(void *),
+				  void *info, int wait);
 
 /*
  * cpu_sibling_map and cpu_core_map now live