genirq: Provide NMI management for percpu_devid interrupts

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>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 177 insertions, 0 deletions

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 9472ae987946..0a1ebc004a59 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -2182,6 +2182,11 @@ out:
 }
 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