On 28/01/2019 16:41, Marc Zyngier wrote: > 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"? > The reason I did not go for "setup_percpu_nmi" is because I didn't want it to be assimilated to "setup_irq"/"__setup_irq" which sets up all the resources for an IRQ line. I guess "prepare_percpu_nmi()" could do the trick unless I come up with a better name. >> +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. > Sure, I can elaborate a bit. >> +{ >> + 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. > Oh yes, well spotted! Thanks, >> + } >> + >> + 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. > -- Julien Thierry
