On Mon, 28 Jan 2019 15:38:25 +0000, Julien Thierry <[email protected]> wrote: > > 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.
A quick overall view of the new API would be good, specially as some of the bits are not 100% obvious. > > Signed-off-by: Julien Thierry <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Marc Zyngier <[email protected]> > --- > include/linux/interrupt.h | 9 +++ > kernel/irq/manage.c | 148 > ++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 157 insertions(+) > > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h > index 37a4b0c6..be146bd 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 ready_percpu_nmi(unsigned int irq); ready_percpu_nmi seems a very bizarre name, as I cannot figure out what that does. How about something along the line of "setup_percpu_nmi"? > +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 a168b2d8f..602a622 100644 > --- a/kernel/irq/manage.c > +++ b/kernel/irq/manage.c > @@ -2185,6 +2185,11 @@ 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 > @@ -2224,6 +2229,11 @@ 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. > */ > @@ -2255,6 +2265,8 @@ 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); > @@ -2308,6 +2320,19 @@ 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 > @@ -2398,6 +2423,129 @@ 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; > +} > + > +int ready_percpu_nmi(unsigned int irq) Name issue withstanding, this could do with some documentation. You probably want to indicate that this is expected to be called from a non-preemptible section. > +{ > + unsigned long flags; > + struct irq_desc *desc = irq_get_desc_lock(irq, &flags, > + IRQ_GET_DESC_CHECK_PERCPU); > + int ret = 0; > + > + if (!desc) { > + ret = -EINVAL; > + goto out; Ouch. Bad idea. > + } > + > + if (WARN(!(desc->istate & IRQS_NMI), > + KERN_ERR "ready_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; > +} > + > +void teardown_percpu_nmi(unsigned int irq) > +{ > + unsigned long flags; > + struct irq_desc *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 > Thanks, M. -- Jazz is not dead, it just smell funny.
