[PATCH 01/11] genirq: Add fasteoi IPI flow

From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Cc: Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Russell King <linux@arm.linux.org.uk>,
	Thomas Gleixner <tglx@linutronix.de>,
	Jason Cooper <jason@lakedaemon.net>,
	Sumit Garg <sumit.garg@linaro.org>,
	kernel-team@android.com
Subject: [PATCH 01/11] genirq: Add fasteoi IPI flow
Date: Tue, 19 May 2020 17:17:45 +0100	[thread overview]
Message-ID: <20200519161755.209565-2-maz@kernel.org> (raw)
In-Reply-To: <20200519161755.209565-1-maz@kernel.org>

For irqchips using the fasteoi flow, IPIs are a bit special.

They need to be EOId early (before calling the handler), as
funny things may happen in the handler (they do not necessarily
behave like a normal interrupt), and that the arch code is
already handling the stats.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 include/linux/irq.h |  1 +
 kernel/irq/chip.c   | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 8d5bc2c237d7..726f94d8b8cc 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -621,6 +621,7 @@ static inline int irq_set_parent(int irq, int parent_irq)
  */
 extern void handle_level_irq(struct irq_desc *desc);
 extern void handle_fasteoi_irq(struct irq_desc *desc);
+extern void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc);
 extern void handle_edge_irq(struct irq_desc *desc);
 extern void handle_edge_eoi_irq(struct irq_desc *desc);
 extern void handle_simple_irq(struct irq_desc *desc);
diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 41e7e37a0928..7b0b789cfed4 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -955,6 +955,32 @@ void handle_percpu_devid_irq(struct irq_desc *desc)
 		chip->irq_eoi(&desc->irq_data);
 }
 
+/**
+ * handle_percpu_devid_fasteoi_ipi - Per CPU local IPI handler with per cpu
+ *				     dev ids
+ * @desc:	the interrupt description structure for this irq
+ *
+ * The biggest differences with the IRQ version are that:
+ * - the interrupt is EOIed early, as the IPI could result in a context
+ *   switch, and we need to make sure the IPI can fire again
+ * - Stats are usually handled at the architecture level, so we ignore them
+ *   here
+ */
+void handle_percpu_devid_fasteoi_ipi(struct irq_desc *desc)
+{
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	struct irqaction *action = desc->action;
+	unsigned int irq = irq_desc_get_irq(desc);
+	irqreturn_t res;
+
+	if (chip->irq_eoi)
+		chip->irq_eoi(&desc->irq_data);
+
+	trace_irq_handler_entry(irq, action);
+	res = action->handler(irq, raw_cpu_ptr(action->percpu_dev_id));
+	trace_irq_handler_exit(irq, action, res);
+}
+
 /**
  * handle_percpu_devid_fasteoi_nmi - Per CPU local NMI handler with per cpu
  *				     dev ids
-- 
2.26.2

