x86/apic: Add NMI_VECTOR wait to IPI shorthand

To support NMI shorthand broadcasts add the safe wait for ICR idle for NMI
vector delivery.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20190722105220.185838026@linutronix.de

arch/x86/kernel/apic/ipi.c

@@ -30,6 +30,9 @@ void __default_send_IPI_shortcut(unsigned int shortcut, int vector)
 	/*
 	 * Wait for idle.
 	 */
+	if (unlikely(vector == NMI_VECTOR))
+		safe_apic_wait_icr_idle();
+	else
 		__xapic_wait_icr_idle();
 
 	/*