linux-kernel - [PATCH] irqdomain: Avoid activating interrupts more than once

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Message-Id: <1484668848-24361-1-git-send-email-marc.zyngier@arm.com>
Date:   Tue, 17 Jan 2017 16:00:48 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Andre Przywara <andre.przywara@....com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH] irqdomain: Avoid activating interrupts more than once

Since commit f3b0946d629c ("genirq/msi: Make sure PCI MSIs are
activated early"), we can end-up activating a PCI/MSI twice (once
at allocation time, and once at startup time).

This is normally of no consequences, except that there is some
HW out there that may misbehave if activate is used more than once
(the GICv3 ITS, for example, uses the activate callback
to issue the MAPVI command, and the architecture spec says that
"If there is an existing mapping for the EventID-DeviceID
combination, behavior is UNPREDICTABLE").

While this could be worked around in each individual driver, it may
make more sense to tackle the issue at the core level. In order to
avoid getting in that situation, let's have a per-interrupt flag
to remember if we have already activated that interrupt or not.

Fixes: f3b0946d629c ("genirq/msi: Make sure PCI MSIs are activated early")
Reported-by: Andre Przywara <andre.przywara@....com>
Tested-by: Andre Przywara <andre.przywara@....com>
Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
 include/linux/irq.h    | 17 +++++++++++++++++
 kernel/irq/irqdomain.c | 44 ++++++++++++++++++++++++++++++--------------
 2 files changed, 47 insertions(+), 14 deletions(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index e798755..39e3254 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -184,6 +184,7 @@ struct irq_data {
  *
  * IRQD_TRIGGER_MASK		- Mask for the trigger type bits
  * IRQD_SETAFFINITY_PENDING	- Affinity setting is pending
+ * IRQD_ACTIVATED		- Interrupt has already been activated
  * IRQD_NO_BALANCING		- Balancing disabled for this IRQ
  * IRQD_PER_CPU			- Interrupt is per cpu
  * IRQD_AFFINITY_SET		- Interrupt affinity was set
@@ -202,6 +203,7 @@ struct irq_data {
 enum {
 	IRQD_TRIGGER_MASK		= 0xf,
 	IRQD_SETAFFINITY_PENDING	= (1 <<  8),
+	IRQD_ACTIVATED			= (1 <<  9),
 	IRQD_NO_BALANCING		= (1 << 10),
 	IRQD_PER_CPU			= (1 << 11),
 	IRQD_AFFINITY_SET		= (1 << 12),
@@ -312,6 +314,21 @@ static inline bool irqd_affinity_is_managed(struct irq_data *d)
 	return __irqd_to_state(d) & IRQD_AFFINITY_MANAGED;
 }
 
+static inline bool irqd_is_activated(struct irq_data *d)
+{
+	return __irqd_to_state(d) & IRQD_ACTIVATED;
+}
+
+static inline void irqd_set_activated(struct irq_data *d)
+{
+	__irqd_to_state(d) |= IRQD_ACTIVATED;
+}
+
+static inline void irqd_clr_activated(struct irq_data *d)
+{
+	__irqd_to_state(d) &= ~IRQD_ACTIVATED;
+}
+
 #undef __irqd_to_state
 
 static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 8c0a0ae..b59e676 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1346,6 +1346,30 @@ void irq_domain_free_irqs_parent(struct irq_domain *domain,
 }
 EXPORT_SYMBOL_GPL(irq_domain_free_irqs_parent);
 
+static void __irq_domain_activate_irq(struct irq_data *irq_data)
+{
+	if (irq_data && irq_data->domain) {
+		struct irq_domain *domain = irq_data->domain;
+
+		if (irq_data->parent_data)
+			__irq_domain_activate_irq(irq_data->parent_data);
+		if (domain->ops->activate)
+			domain->ops->activate(domain, irq_data);
+	}
+}
+
+static void __irq_domain_deactivate_irq(struct irq_data *irq_data)
+{
+	if (irq_data && irq_data->domain) {
+		struct irq_domain *domain = irq_data->domain;
+
+		if (domain->ops->deactivate)
+			domain->ops->deactivate(domain, irq_data);
+		if (irq_data->parent_data)
+			__irq_domain_deactivate_irq(irq_data->parent_data);
+	}
+}
+
 /**
  * irq_domain_activate_irq - Call domain_ops->activate recursively to activate
  *			     interrupt
@@ -1356,13 +1380,9 @@ EXPORT_SYMBOL_GPL(irq_domain_free_irqs_parent);
  */
 void irq_domain_activate_irq(struct irq_data *irq_data)
 {
-	if (irq_data && irq_data->domain) {
-		struct irq_domain *domain = irq_data->domain;
-
-		if (irq_data->parent_data)
-			irq_domain_activate_irq(irq_data->parent_data);
-		if (domain->ops->activate)
-			domain->ops->activate(domain, irq_data);
+	if (!irqd_is_activated(irq_data)) {
+		__irq_domain_activate_irq(irq_data);
+		irqd_set_activated(irq_data);
 	}
 }
 
@@ -1376,13 +1396,9 @@ void irq_domain_activate_irq(struct irq_data *irq_data)
  */
 void irq_domain_deactivate_irq(struct irq_data *irq_data)
 {
-	if (irq_data && irq_data->domain) {
-		struct irq_domain *domain = irq_data->domain;
-
-		if (domain->ops->deactivate)
-			domain->ops->deactivate(domain, irq_data);
-		if (irq_data->parent_data)
-			irq_domain_deactivate_irq(irq_data->parent_data);
+	if (irqd_is_activated(irq_data)) {
+		__irq_domain_deactivate_irq(irq_data);
+		irqd_clr_activated(irq_data);
 	}
 }
 
-- 
2.1.4