irqdesc: Add domain handler for NMIs

NMI handling code should be executed between calls to nmi_enter and
nmi_exit.

Add a separate domain handler to properly setup NMI context when handling
an interrupt requested as NMI.
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

include/linux/irqdesc.h

@@ -171,6 +171,11 @@ static inline int handle_domain_irq(struct irq_domain *domain,
 {
 	return __handle_domain_irq(domain, hwirq, true, regs);
 }
+
+#ifdef CONFIG_IRQ_DOMAIN
+int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
+		      struct pt_regs *regs);
+#endif
 #endif
 
 /* Test to see if a driver has successfully requested an irq */

kernel/irq/irqdesc.c

@@ -669,6 +669,41 @@ int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
 	set_irq_regs(old_regs);
 	return ret;
 }
+
+#ifdef CONFIG_IRQ_DOMAIN
+/**
+ * handle_domain_nmi - Invoke the handler for a HW irq belonging to a domain
+ * @domain:	The domain where to perform the lookup
+ * @hwirq:	The HW irq number to convert to a logical one
+ * @regs:	Register file coming from the low-level handling code
+ *
+ * Returns:	0 on success, or -EINVAL if conversion has failed
+ */
+int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
+		      struct pt_regs *regs)
+{
+	struct pt_regs *old_regs = set_irq_regs(regs);
+	unsigned int irq;
+	int ret = 0;
+
+	nmi_enter();
+
+	irq = irq_find_mapping(domain, hwirq);
+
+	/*
+	 * ack_bad_irq is not NMI-safe, just report
+	 * an invalid interrupt.
+	 */
+	if (likely(irq))
+		generic_handle_irq(irq);
+	else
+		ret = -EINVAL;
+
+	nmi_exit();
+	set_irq_regs(old_regs);
+	return ret;
+}
+#endif
 #endif
 
 /* Dynamic interrupt handling */