irqchip/gic-v3-its: Don't bind LPI to unavailable NUMA node

On a NUMA system, if an ITS is local to an offline node, the ITS driver may
pick an offline CPU to bind the LPI.  In this case, pick an online CPU (and
the first one will do).

But on some systems, binding an LPI to non-local node CPU may cause
deadlock (see Cavium erratum 23144).  In this case, just fail the activate
and return an error code.

Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
Cc: Sumit Garg <sumit.garg@linaro.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180622095254.5906-5-marc.zyngier@arm.com

drivers/irqchip/irq-gic-v3-its.c

@@ -2310,7 +2310,14 @@ static int its_irq_domain_activate(struct irq_domain *domain,
 		cpu_mask = cpumask_of_node(its_dev->its->numa_node);
 
 	/* Bind the LPI to the first possible CPU */
-	cpu = cpumask_first(cpu_mask);
+	cpu = cpumask_first_and(cpu_mask, cpu_online_mask);
+	if (cpu >= nr_cpu_ids) {
+		if (its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144)
+			return -EINVAL;
+
+		cpu = cpumask_first(cpu_online_mask);
+	}
+
 	its_dev->event_map.col_map[event] = cpu;
 	irq_data_update_effective_affinity(d, cpumask_of(cpu));