powerpc/book3e: Hookup doorbells exceptions on 64-bit Book3E

Note that critical doorbells are an unimplemented stub just like
other critical or machine check handlers, since we haven't done
support for "levelled" exceptions yet.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/irq.c

@@ -64,6 +64,8 @@
 #include <asm/ptrace.h>
 #include <asm/machdep.h>
 #include <asm/udbg.h>
+#include <asm/dbell.h>
+
 #ifdef CONFIG_PPC64
 #include <asm/paca.h>
 #include <asm/firmware.h>
@@ -153,6 +155,11 @@ notrace void raw_local_irq_restore(unsigned long en)
 	if (get_hard_enabled())
 		return;
 
+#if defined(CONFIG_BOOKE) && defined(CONFIG_SMP)
+	/* Check for pending doorbell interrupts on SMP */
+	doorbell_exception(NULL);
+#endif
+
 	/*
 	 * Need to hard-enable interrupts here.  Since currently disabled,
 	 * no need to take further asm precautions against preemption; but