[PATCH] ppc64: fix nonexistent irq affinity

This fixes a bug where, if we try to set the affinity on an unused
virtual IRQ number on a logically-partitioned pSeries system, we call
the firmware with physical IRQ number = -1, which it doesn't like.

With this patch we just ignore the attempt.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/xics.c

@@ -620,7 +620,7 @@ static void xics_set_affinity(unsigned int virq, cpumask_t cpumask)
 	cpumask_t tmp = CPU_MASK_NONE;
 
 	irq = virt_irq_to_real(irq_offset_down(virq));
-	if (irq == XICS_IPI)
+	if (irq == XICS_IPI || irq == NO_IRQ)
 		return;
 
 	status = rtas_call(ibm_get_xive, 1, 3, (void *)&xics_status, irq);