[PATCH v2 2/2] irqchip/riscv-aplic: Apply pending affinity changes for level MSI sources

[Troy Mitchell]

IMSIC rejects an affinity change with -EBUSY while a previous vector
move is still in flight, and the IRQ core then records the new mask as
pending. The change is applied by irq_move_irq() in the IMSIC irq_ack
callback, but level-triggered APLIC MSI interrupts are handled by
handle_fasteoi_irq(), which never calls irq_ack.

The pending change is therefore never applied. While it is pending,
later affinity changes only update the pending mask, so the interrupt
stays on its old CPU.

Use handle_fasteoi_ack_irq() for level-triggered sources. It acks the
interrupt before invoking the handler, so a pending affinity change is
applied on the next interrupt, and the EOI retrigger then targets the
new CPU.

Fixes: 58d868b67a9a ("RISC-V: Select CONFIG_GENERIC_PENDING_IRQ")
Signed-off-by: Troy Mitchell <troy.mitchell at linux.dev>
---
 drivers/irqchip/Kconfig               | 1 +
 drivers/irqchip/irq-riscv-aplic-msi.c | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 136bab41f801..a639a0c2f3d2 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -645,6 +645,7 @@ config RISCV_APLIC_MSI
 	bool
 	depends on RISCV_APLIC
 	select GENERIC_MSI_IRQ
+	select IRQ_FASTEOI_HIERARCHY_HANDLERS
 	default RISCV_APLIC
 
 config RISCV_IMSIC
diff --git a/drivers/irqchip/irq-riscv-aplic-msi.c b/drivers/irqchip/irq-riscv-aplic-msi.c
index 44f0df83f93e..0e71b427da34 100644
--- a/drivers/irqchip/irq-riscv-aplic-msi.c
+++ b/drivers/irqchip/irq-riscv-aplic-msi.c
@@ -75,13 +75,16 @@ static int aplic_msi_irq_set_type(struct irq_data *d, unsigned int type)
 	 * acknowledged before the handler runs. The edge flow handler also
 	 * replays an interrupt which arrives while the previous one is
 	 * still being handled on another CPU after an affinity change.
+	 *
+	 * Level-triggered sources use the fasteoi flow, but still need the
+	 * ack so that the IMSIC parent applies deferred affinity changes.
 	 */
 	if (type & IRQ_TYPE_EDGE_BOTH)
 		irq_set_chip_handler_name_locked(d, irq_data_get_irq_chip(d),
 						 handle_edge_irq, "edge");
 	else
 		irq_set_chip_handler_name_locked(d, irq_data_get_irq_chip(d),
-						 handle_fasteoi_irq, "fasteoi");
+						 handle_fasteoi_ack_irq, "fasteoi");
 
 	/*
 	 * Updating sourcecfg register for level-triggered interrupts
@@ -181,7 +184,7 @@ static const struct msi_domain_template aplic_msi_template = {
 	.info = {
 		.bus_token		= DOMAIN_BUS_WIRED_TO_MSI,
 		.flags			= MSI_FLAG_USE_DEV_FWNODE,
-		.handler		= handle_fasteoi_irq,
+		.handler		= handle_fasteoi_ack_irq,
 		.handler_name		= "fasteoi",
 	},
 };

-- 
2.56.0