From f556f008f704a8777c73fb3a4177dc57c0dbe769 Mon Sep 17 00:00:00 2001 From: Karl Mehltretter Date: Mon, 28 Sep 2026 05:54:08 +0200 Subject: [PATCH] irqchip/jcore-aic: Fix lost IPIs on SMP Since commit bdf4e2ac295fe ("genirq: Allow per-cpu interrupt sharing for non-overlapping affinities"), handle_percpu_devid_irq() only runs an action whose affinity mask contains the current CPU. Only actions set up through the percpu_devid request functions have such a mask. handle_jcore_irq() passes every per-CPU interrupt to handle_percpu_devid_irq(). The J2 IPI is not a percpu_devid interrupt. j2_prepare_cpus() requests it with request_irq() and IRQF_PERCPU, so its action has no affinity mask and cpumask_test_cpu() reads through a NULL pointer. J2 has no MMU to catch this. The read returns whatever is at address 0, the action is not found, and IPIs are dropped as spurious ("Spurious percpu IRQ20 on CPU1", printed once). Pass only percpu_devid interrupts (the PIT) to handle_percpu_devid_irq() and the other per-CPU interrupts to handle_percpu_irq() again, as before commit d7e3fd658248f ("irqchip/jcore-aic, clocksource/drivers/jcore: Fix jcore-pit interrupt request"). Found with a two-CPU J2 model simulated from the J-Core RTL. Without this change the boot stalls with both CPUs idle shortly after "smp: Brought up 1 node, 2 CPUs". With it, the boot reaches userspace. Fixes: bdf4e2ac295fe ("genirq: Allow per-cpu interrupt sharing for non-overlapping affinities") Signed-off-by: Karl Mehltretter Signed-off-by: Thomas Gleixner Assisted-by: LLM Tested-by: John Paul Adrian Glaubitz Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260928035408.25871-1-kmehltretter@gmail.com --- drivers/irqchip/irq-jcore-aic.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/irqchip/irq-jcore-aic.c b/drivers/irqchip/irq-jcore-aic.c index 94c05cf974be..b4fee02997ee 100644 --- a/drivers/irqchip/irq-jcore-aic.c +++ b/drivers/irqchip/irq-jcore-aic.c @@ -37,8 +37,10 @@ static struct irq_chip jcore_aic; static void handle_jcore_irq(struct irq_desc *desc) { - if (irqd_is_per_cpu(irq_desc_get_irq_data(desc))) + if (irq_is_percpu_devid(irq_desc_get_irq(desc))) handle_percpu_devid_irq(desc); + else if (irqd_is_per_cpu(irq_desc_get_irq_data(desc))) + handle_percpu_irq(desc); else handle_simple_irq(desc); }