From 56c0b48b1e443efa5d6f4d60513302c934e55b17 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Fri, 11 May 2018 03:20:05 +1000 Subject: [PATCH] powerpc/powernv: process all OPAL event interrupts with kopald Using irq_work for processing OPAL event interrupts is not necessary. irq_work is typically used to schedule work from NMI context, a softirq may be more appropriate. However OPAL events are not particularly performance or latency critical, so they can all be invoked by kopald. This patch removes the irq_work queueing, and instead wakes up kopald when there is an event to be processed. kopald processes interrupts individually, enabling irqs and calling cond_resched between each one to minimise latencies. Event handlers themselves should still use threaded handlers, workqueues, etc. as necessary to avoid high interrupts-off latencies within any single interrupt. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/platforms/powernv/opal-irqchip.c | 87 +++++++++---------- arch/powerpc/platforms/powernv/opal.c | 23 +++-- arch/powerpc/platforms/powernv/powernv.h | 3 +- 3 files changed, 52 insertions(+), 61 deletions(-) diff --git a/arch/powerpc/platforms/powernv/opal-irqchip.c b/arch/powerpc/platforms/powernv/opal-irqchip.c index 05ffe05f0fdc..605c7e5d52c2 100644 --- a/arch/powerpc/platforms/powernv/opal-irqchip.c +++ b/arch/powerpc/platforms/powernv/opal-irqchip.c @@ -22,7 +22,6 @@ #include #include #include -#include #include #include @@ -38,37 +37,47 @@ struct opal_event_irqchip { unsigned long mask; }; static struct opal_event_irqchip opal_event_irqchip; - +static u64 last_outstanding_events; static unsigned int opal_irq_count; static unsigned int *opal_irqs; -static void opal_handle_irq_work(struct irq_work *work); -static u64 last_outstanding_events; -static struct irq_work opal_event_irq_work = { - .func = opal_handle_irq_work, -}; - -void opal_handle_events(uint64_t events) +void opal_handle_events(void) { - int virq, hwirq = 0; - u64 mask = opal_event_irqchip.mask; + __be64 events = 0; + u64 e; + + e = READ_ONCE(last_outstanding_events) & opal_event_irqchip.mask; +again: + while (e) { + int virq, hwirq; + + hwirq = fls64(e) - 1; + e &= ~BIT_ULL(hwirq); + + local_irq_disable(); + virq = irq_find_mapping(opal_event_irqchip.domain, hwirq); + if (virq) { + irq_enter(); + generic_handle_irq(virq); + irq_exit(); + } + local_irq_enable(); - if (!in_irq() && (events & mask)) { - last_outstanding_events = events; - irq_work_queue(&opal_event_irq_work); - return; + cond_resched(); } + last_outstanding_events = 0; + if (opal_poll_events(&events) != OPAL_SUCCESS) + return; + e = be64_to_cpu(events) & opal_event_irqchip.mask; + if (e) + goto again; +} - while (events & mask) { - hwirq = fls64(events) - 1; - if (BIT_ULL(hwirq) & mask) { - virq = irq_find_mapping(opal_event_irqchip.domain, - hwirq); - if (virq) - generic_handle_irq(virq); - } - events &= ~BIT_ULL(hwirq); - } +bool opal_have_pending_events(void) +{ + if (last_outstanding_events & opal_event_irqchip.mask) + return true; + return false; } static void opal_event_mask(struct irq_data *d) @@ -78,24 +87,9 @@ static void opal_event_mask(struct irq_data *d) static void opal_event_unmask(struct irq_data *d) { - __be64 events; - set_bit(d->hwirq, &opal_event_irqchip.mask); - - opal_poll_events(&events); - last_outstanding_events = be64_to_cpu(events); - - /* - * We can't just handle the events now with opal_handle_events(). - * If we did we would deadlock when opal_event_unmask() is called from - * handle_level_irq() with the irq descriptor lock held, because - * calling opal_handle_events() would call generic_handle_irq() and - * then handle_level_irq() which would try to take the descriptor lock - * again. Instead queue the events for later. - */ - if (last_outstanding_events & opal_event_irqchip.mask) - /* Need to retrigger the interrupt */ - irq_work_queue(&opal_event_irq_work); + if (opal_have_pending_events()) + opal_wake_poller(); } static int opal_event_set_type(struct irq_data *d, unsigned int flow_type) @@ -136,16 +130,13 @@ static irqreturn_t opal_interrupt(int irq, void *data) __be64 events; opal_handle_interrupt(virq_to_hw(irq), &events); - opal_handle_events(be64_to_cpu(events)); + last_outstanding_events = be64_to_cpu(events); + if (opal_have_pending_events()) + opal_wake_poller(); return IRQ_HANDLED; } -static void opal_handle_irq_work(struct irq_work *work) -{ - opal_handle_events(last_outstanding_events); -} - static int opal_event_match(struct irq_domain *h, struct device_node *node, enum irq_domain_bus_token bus_token) { diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c index 48fbb41af5d1..0d539c661748 100644 --- a/arch/powerpc/platforms/powernv/opal.c +++ b/arch/powerpc/platforms/powernv/opal.c @@ -540,21 +540,15 @@ int opal_hmi_exception_early(struct pt_regs *regs) /* HMI exception handler called in virtual mode during check_irq_replay. */ int opal_handle_hmi_exception(struct pt_regs *regs) { - s64 rc; - __be64 evt = 0; - /* * Check if HMI event is available. - * if Yes, then call opal_poll_events to pull opal messages and - * process them. + * if Yes, then wake kopald to process them. */ if (!local_paca->hmi_event_available) return 0; local_paca->hmi_event_available = 0; - rc = opal_poll_events(&evt); - if (rc == OPAL_SUCCESS && evt) - opal_handle_events(be64_to_cpu(evt)); + opal_wake_poller(); return 1; } @@ -757,14 +751,19 @@ static void __init opal_imc_init_dev(void) static int kopald(void *unused) { unsigned long timeout = msecs_to_jiffies(opal_heartbeat) + 1; - __be64 events; set_freezable(); do { try_to_freeze(); - opal_poll_events(&events); - opal_handle_events(be64_to_cpu(events)); - schedule_timeout_interruptible(timeout); + + opal_handle_events(); + + set_current_state(TASK_INTERRUPTIBLE); + if (opal_have_pending_events()) + __set_current_state(TASK_RUNNING); + else + schedule_timeout(timeout); + } while (!kthread_should_stop()); return 0; diff --git a/arch/powerpc/platforms/powernv/powernv.h b/arch/powerpc/platforms/powernv/powernv.h index 94f17ab1374b..fd4a1c5a6369 100644 --- a/arch/powerpc/platforms/powernv/powernv.h +++ b/arch/powerpc/platforms/powernv/powernv.h @@ -24,7 +24,8 @@ extern u32 pnv_get_supported_cpuidle_states(void); extern void pnv_lpc_init(void); -extern void opal_handle_events(uint64_t events); +extern void opal_handle_events(void); +extern bool opal_have_pending_events(void); extern void opal_event_shutdown(void); bool cpu_core_split_required(void); -- 2.39.5