From: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: marc.zyngier@arm.com, tglx@linutronix.de, jason@lakedaemon.net,
        catalin.marinas@arm.com, will.deacon@arm.com, jnair@caviumnetworks.com,
        Robert.Richter@cavium.com, Jan.Glauber@cavium.com, gklkml16@gmail.com
Subject: [PATCH] irqchip/gic-v3-its: Flush GICR caching for a cross node collection move of an irq
Date: Wed, 20 Dec 2017 14:45:44 +0530
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When an interrupt is moved, it is possible that an implementation that
supports caching might still have cached data for a previous
(no longer valid) mapping of the interrupt. In particular, in a distributed
GIC implementation like multi-socket SoC platfroms. Hence it is necessary
to flush cached entries after cross node collection migration.

Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
---
 drivers/irqchip/irq-gic-v3-its.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 4039e64..ea849a1 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -1119,6 +1119,12 @@ static int its_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
 	if (cpu != its_dev->event_map.col_map[id]) {
 		target_col = &its_dev->its->collections[cpu];
 		its_send_movi(its_dev, target_col, id);
+		/* Issue INV for cross node collection move on
+		 * multi socket systems.
+		 */
+		if (cpu_to_node(cpu) !=
+				cpu_to_node(its_dev->event_map.col_map[id]))
+			its_send_inv(its_dev, id);
 		its_dev->event_map.col_map[id] = cpu;
 		irq_data_update_effective_affinity(d, cpumask_of(cpu));
 	}
-- 
2.9.4