linux-kernel - [PATCH 4/6] irqchip/gic-v3-its: Don't bind LPI to unavailable NUMA node

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Message-Id: <20180619115546.12196-5-marc.zyngier@arm.com>
Date:   Tue, 19 Jun 2018 12:55:44 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>
Cc:     linux-kernel@...r.kernel.org,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Yang Yingliang <yangyingliang@...wei.com>
Subject: [PATCH 4/6] irqchip/gic-v3-its: Don't bind LPI to unavailable NUMA node

From: Yang Yingliang <yangyingliang@...wei.com>

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,
we need to 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, we
just fail the activate and return an error code.

Cc: stable@...r.kernel.org
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
 drivers/irqchip/irq-gic-v3-its.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 5377d7e2afba..cae53937feeb 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/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));
 
-- 
2.17.1