From 82f499c8811149069ec958b72a86643a7a289b25 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Fri, 22 Jun 2018 10:52:54 +0100 Subject: [PATCH] irqchip/gic-v3-its: Fix reprogramming of redistributors on CPU hotplug Enabling LPIs was made a lot stricter recently, by checking that they are disabled before enabling them. By doing so, the CPU hotplug case was missed altogether, which leaves LPIs enabled on hotplug off (expecting the CPU to eventually come back), and won't write a different value anyway on hotplug on. So skip that check if that particular case is detected Fixes: 6eb486b66a30 ("irqchip/gic-v3: Ensure GICR_CTLR.EnableLPI=0 is observed before enabling") Reported-by: Sumit Garg Signed-off-by: Marc Zyngier Signed-off-by: Thomas Gleixner Tested-by: Sumit Garg Cc: Jason Cooper Cc: Alexandre Belloni Cc: Yang Yingliang Link: https://lkml.kernel.org/r/20180622095254.5906-8-marc.zyngier@arm.com --- drivers/irqchip/irq-gic-v3-its.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index 0269ffb93f6e..d7842d312d3e 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -3427,6 +3427,16 @@ static int redist_disable_lpis(void) u64 timeout = USEC_PER_SEC; u64 val; + /* + * If coming via a CPU hotplug event, we don't need to disable + * LPIs before trying to re-enable them. They are already + * configured and all is well in the world. Detect this case + * by checking the allocation of the pending table for the + * current CPU. + */ + if (gic_data_rdist()->pend_page) + return 0; + if (!gic_rdists_supports_plpis()) { pr_info("CPU%d: LPIs not supported\n", smp_processor_id()); return -ENXIO; -- 2.30.2