lkml.org 
[lkml]   [2019]   [Jan]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH v5 2/4] genirq: Provide NMI management for percpu_devid interrupts
On Mon, 28 Jan 2019 15:38:25 +0000,
Julien Thierry <julien.thierry@arm.com> 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 <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 | 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.

\
 
 \ /
  Last update: 2019-01-28 17:42    [W:0.086 / U:0.416 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site