[PATCH 4/4] irqdesc: Add domain handler for NMIs

From: Julien Thierry
Date: Tue Jul 24 2018 - 07:07:25 EST


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@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
include/linux/irqdesc.h | 3 +++
kernel/irq/irqdesc.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 36 insertions(+)

diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index dd1e40d..7c0a243 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -171,6 +171,9 @@ static inline int handle_domain_irq(struct irq_domain *domain,
{
return __handle_domain_irq(domain, hwirq, true, regs);
}
+
+int handle_domain_nmi(struct irq_domain *domain, unsigned int hwirq,
+ struct pt_regs *regs);
#endif

/* Test to see if a driver has successfully requested an irq */
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index afc7f90..f2b6f9d 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -664,6 +664,39 @@ int __handle_domain_irq(struct irq_domain *domain, unsigned int hwirq,
set_irq_regs(old_regs);
return ret;
}
+
+/**
+ * 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

/* Dynamic interrupt handling */
--
1.9.1