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Subject[PATCH v6 2/4] genirq: Provide NMI management for percpu_devid interrupts
Date
Add support for percpu_devid interrupts treated as NMIs.

Percpu_devid NMIs need to be setup/torn down on each CPU they target.

The same restrictions as for global NMIs still apply for percpu_devid NMIs.

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
---
include/linux/interrupt.h | 9 +++
kernel/irq/manage.c | 177 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 186 insertions(+)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 9941d1a..831ddcd 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -168,10 +168,15 @@ struct irqaction {
devname, percpu_dev_id);
}

+extern int __must_check
+request_percpu_nmi(unsigned int irq, irq_handler_t handler,
+ const char *devname, void __percpu *dev);
+
extern const void *free_irq(unsigned int, void *);
extern void free_percpu_irq(unsigned int, void __percpu *);

extern const void *free_nmi(unsigned int irq, void *dev_id);
+extern void free_percpu_nmi(unsigned int irq, void __percpu *percpu_dev_id);

struct device;

@@ -224,7 +229,11 @@ struct irqaction {
extern void irq_wake_thread(unsigned int irq, void *dev_id);

extern void disable_nmi_nosync(unsigned int irq);
+extern void disable_percpu_nmi(unsigned int irq);
extern void enable_nmi(unsigned int irq);
+extern void enable_percpu_nmi(unsigned int irq, unsigned int type);
+extern int prepare_percpu_nmi(unsigned int irq);
+extern void teardown_percpu_nmi(unsigned int irq);

/* The following three functions are for the core kernel use only. */
extern void suspend_device_irqs(void);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 9472ae9..0a1ebc0 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -2182,6 +2182,11 @@ void enable_percpu_irq(unsigned int irq, unsigned int type)
}
EXPORT_SYMBOL_GPL(enable_percpu_irq);

+void enable_percpu_nmi(unsigned int irq, unsigned int type)
+{
+ enable_percpu_irq(irq, type);
+}
+
/**
* irq_percpu_is_enabled - Check whether the per cpu irq is enabled
* @irq: Linux irq number to check for
@@ -2221,6 +2226,11 @@ void disable_percpu_irq(unsigned int irq)
}
EXPORT_SYMBOL_GPL(disable_percpu_irq);

+void disable_percpu_nmi(unsigned int irq)
+{
+ disable_percpu_irq(irq);
+}
+
/*
* Internal function to unregister a percpu irqaction.
*/
@@ -2252,6 +2262,8 @@ static struct irqaction *__free_percpu_irq(unsigned int irq, void __percpu *dev_
/* Found it - now remove it from the list of entries: */
desc->action = NULL;

+ desc->istate &= ~IRQS_NMI;
+
raw_spin_unlock_irqrestore(&desc->lock, flags);

unregister_handler_proc(irq, action);
@@ -2305,6 +2317,19 @@ void free_percpu_irq(unsigned int irq, void __percpu *dev_id)
}
EXPORT_SYMBOL_GPL(free_percpu_irq);

+void free_percpu_nmi(unsigned int irq, void __percpu *dev_id)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+
+ if (!desc || !irq_settings_is_per_cpu_devid(desc))
+ return;
+
+ if (WARN_ON(!(desc->istate & IRQS_NMI)))
+ return;
+
+ kfree(__free_percpu_irq(irq, dev_id));
+}
+
/**
* setup_percpu_irq - setup a per-cpu interrupt
* @irq: Interrupt line to setup
@@ -2395,6 +2420,158 @@ int __request_percpu_irq(unsigned int irq, irq_handler_t handler,
EXPORT_SYMBOL_GPL(__request_percpu_irq);

/**
+ * request_percpu_nmi - allocate a percpu interrupt line for NMI delivery
+ * @irq: Interrupt line to allocate
+ * @handler: Function to be called when the IRQ occurs.
+ * @name: An ascii name for the claiming device
+ * @dev_id: A percpu cookie passed back to the handler function
+ *
+ * This call allocates interrupt resources for a per CPU NMI. Per CPU NMIs
+ * have to be setup on each CPU by calling ready_percpu_nmi() before being
+ * enabled on the same CPU by using enable_percpu_nmi().
+ *
+ * Dev_id must be globally unique. It is a per-cpu variable, and
+ * the handler gets called with the interrupted CPU's instance of
+ * that variable.
+ *
+ * Interrupt lines requested for NMI delivering should have auto enabling
+ * setting disabled.
+ *
+ * If the interrupt line cannot be used to deliver NMIs, function
+ * will fail returning a negative value.
+ */
+int request_percpu_nmi(unsigned int irq, irq_handler_t handler,
+ const char *name, void __percpu *dev_id)
+{
+ struct irqaction *action;
+ struct irq_desc *desc;
+ unsigned long flags;
+ int retval;
+
+ if (!handler)
+ return -EINVAL;
+
+ desc = irq_to_desc(irq);
+
+ if (!desc || !irq_settings_can_request(desc) ||
+ !irq_settings_is_per_cpu_devid(desc) ||
+ irq_settings_can_autoenable(desc) ||
+ !irq_supports_nmi(desc))
+ return -EINVAL;
+
+ /* The line cannot already be NMI */
+ if (desc->istate & IRQS_NMI)
+ return -EINVAL;
+
+ action = kzalloc(sizeof(struct irqaction), GFP_KERNEL);
+ if (!action)
+ return -ENOMEM;
+
+ action->handler = handler;
+ action->flags = IRQF_PERCPU | IRQF_NO_SUSPEND | IRQF_NO_THREAD
+ | IRQF_NOBALANCING;
+ action->name = name;
+ action->percpu_dev_id = dev_id;
+
+ retval = irq_chip_pm_get(&desc->irq_data);
+ if (retval < 0)
+ goto err_out;
+
+ retval = __setup_irq(irq, desc, action);
+ if (retval)
+ goto err_irq_setup;
+
+ raw_spin_lock_irqsave(&desc->lock, flags);
+ desc->istate |= IRQS_NMI;
+ raw_spin_unlock_irqrestore(&desc->lock, flags);
+
+ return 0;
+
+err_irq_setup:
+ irq_chip_pm_put(&desc->irq_data);
+err_out:
+ kfree(action);
+
+ return retval;
+}
+
+/**
+ * prepare_percpu_nmi - performs CPU local setup for NMI delivery
+ * @irq: Interrupt line to prepare for NMI delivery
+ *
+ * This call prepares an interrupt line to deliver NMI on the current CPU,
+ * before that interrupt line gets enabled with enable_percpu_nmi().
+ *
+ * As a CPU local operation, this should be called from non-preemptible
+ * context.
+ *
+ * If the interrupt line cannot be used to deliver NMIs, function
+ * will fail returning a negative value.
+ */
+int prepare_percpu_nmi(unsigned int irq)
+{
+ unsigned long flags;
+ struct irq_desc *desc;
+ int ret = 0;
+
+ WARN_ON(preemptible());
+
+ desc = irq_get_desc_lock(irq, &flags,
+ IRQ_GET_DESC_CHECK_PERCPU);
+ if (!desc)
+ return -EINVAL;
+
+ if (WARN(!(desc->istate & IRQS_NMI),
+ KERN_ERR "prepare_percpu_nmi called for a non-NMI interrupt: irq %u\n",
+ irq)) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = irq_nmi_setup(desc);
+ if (ret) {
+ pr_err("Failed to setup NMI delivery: irq %u\n", irq);
+ goto out;
+ }
+
+out:
+ irq_put_desc_unlock(desc, flags);
+ return ret;
+}
+
+/**
+ * teardown_percpu_nmi - undoes NMI setup of IRQ line
+ * @irq: Interrupt line from which CPU local NMI configuration should be
+ * removed
+ *
+ * This call undoes the setup done by prepare_percpu_nmi().
+ *
+ * IRQ line should not be enabled for the current CPU.
+ *
+ * As a CPU local operation, this should be called from non-preemptible
+ * context.
+ */
+void teardown_percpu_nmi(unsigned int irq)
+{
+ unsigned long flags;
+ struct irq_desc *desc;
+
+ WARN_ON(preemptible());
+
+ desc = irq_get_desc_lock(irq, &flags,
+ IRQ_GET_DESC_CHECK_PERCPU);
+ if (!desc)
+ return;
+
+ if (WARN_ON(!(desc->istate & IRQS_NMI)))
+ goto out;
+
+ irq_nmi_teardown(desc);
+out:
+ irq_put_desc_unlock(desc, flags);
+}
+
+/**
* irq_get_irqchip_state - returns the irqchip state of a interrupt.
* @irq: Interrupt line that is forwarded to a VM
* @which: One of IRQCHIP_STATE_* the caller wants to know about
--
1.9.1
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