diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 988a0d2535b25..5b4753e602def 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5462,6 +5462,14 @@ as generic guest with no PV drivers. Currently support XEN HVM, KVM, HYPER_V and VMWARE guest. + xen.event_eoi_delay= [XEN] + How long to delay EOI handling in case of event + storms (jiffies). Default is 10. + + xen.event_loop_timeout= [XEN] + After which time (jiffies) the event handling loop + should start to delay EOI handling. Default is 2. + xirc2ps_cs= [NET,PCMCIA] Format: ,,,,,[,[,[,]]] diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c index e4b75693600ef..f026624898e7a 100644 --- a/drivers/xen/events/events_2l.c +++ b/drivers/xen/events/events_2l.c @@ -161,7 +161,7 @@ static inline xen_ulong_t active_evtchns(unsigned int cpu, * a bitset of words which contain pending event bits. The second * level is a bitset of pending events themselves. */ -static void evtchn_2l_handle_events(unsigned cpu) +static void evtchn_2l_handle_events(unsigned cpu, struct evtchn_loop_ctrl *ctrl) { int irq; xen_ulong_t pending_words; @@ -242,10 +242,7 @@ static void evtchn_2l_handle_events(unsigned cpu) /* Process port. */ port = (word_idx * BITS_PER_EVTCHN_WORD) + bit_idx; - irq = get_evtchn_to_irq(port); - - if (irq != -1) - generic_handle_irq(irq); + handle_irq_for_port(port, ctrl); bit_idx = (bit_idx + 1) % BITS_PER_EVTCHN_WORD; diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index b2b5eccdc5dfd..f67b92a488da2 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -35,6 +35,8 @@ #include #include #include +#include +#include #ifdef CONFIG_X86 #include @@ -64,6 +66,15 @@ #include "events_internal.h" +#undef MODULE_PARAM_PREFIX +#define MODULE_PARAM_PREFIX "xen." + +static uint __read_mostly event_loop_timeout = 2; +module_param(event_loop_timeout, uint, 0644); + +static uint __read_mostly event_eoi_delay = 10; +module_param(event_eoi_delay, uint, 0644); + const struct evtchn_ops *evtchn_ops; /* @@ -87,6 +98,7 @@ static DEFINE_RWLOCK(evtchn_rwlock); * irq_mapping_update_lock * evtchn_rwlock * IRQ-desc lock + * percpu eoi_list_lock */ static LIST_HEAD(xen_irq_list_head); @@ -119,6 +131,8 @@ static struct irq_chip xen_pirq_chip; static void enable_dynirq(struct irq_data *data); static void disable_dynirq(struct irq_data *data); +static DEFINE_PER_CPU(unsigned int, irq_epoch); + static void clear_evtchn_to_irq_row(unsigned row) { unsigned col; @@ -398,17 +412,120 @@ void notify_remote_via_irq(int irq) } EXPORT_SYMBOL_GPL(notify_remote_via_irq); +struct lateeoi_work { + struct delayed_work delayed; + spinlock_t eoi_list_lock; + struct list_head eoi_list; +}; + +static DEFINE_PER_CPU(struct lateeoi_work, lateeoi); + +static void lateeoi_list_del(struct irq_info *info) +{ + struct lateeoi_work *eoi = &per_cpu(lateeoi, info->eoi_cpu); + unsigned long flags; + + spin_lock_irqsave(&eoi->eoi_list_lock, flags); + list_del_init(&info->eoi_list); + spin_unlock_irqrestore(&eoi->eoi_list_lock, flags); +} + +static void lateeoi_list_add(struct irq_info *info) +{ + struct lateeoi_work *eoi = &per_cpu(lateeoi, info->eoi_cpu); + struct irq_info *elem; + u64 now = get_jiffies_64(); + unsigned long delay; + unsigned long flags; + + if (now < info->eoi_time) + delay = info->eoi_time - now; + else + delay = 1; + + spin_lock_irqsave(&eoi->eoi_list_lock, flags); + + if (list_empty(&eoi->eoi_list)) { + list_add(&info->eoi_list, &eoi->eoi_list); + mod_delayed_work_on(info->eoi_cpu, system_wq, + &eoi->delayed, delay); + } else { + list_for_each_entry_reverse(elem, &eoi->eoi_list, eoi_list) { + if (elem->eoi_time <= info->eoi_time) + break; + } + list_add(&info->eoi_list, &elem->eoi_list); + } + + spin_unlock_irqrestore(&eoi->eoi_list_lock, flags); +} + static void xen_irq_lateeoi_locked(struct irq_info *info) { evtchn_port_t evtchn; + unsigned int cpu; evtchn = info->evtchn; - if (!VALID_EVTCHN(evtchn)) + if (!VALID_EVTCHN(evtchn) || !list_empty(&info->eoi_list)) return; + cpu = info->eoi_cpu; + if (info->eoi_time && info->irq_epoch == per_cpu(irq_epoch, cpu)) { + lateeoi_list_add(info); + return; + } + + info->eoi_time = 0; unmask_evtchn(evtchn); } +static void xen_irq_lateeoi_worker(struct work_struct *work) +{ + struct lateeoi_work *eoi; + struct irq_info *info; + u64 now = get_jiffies_64(); + unsigned long flags; + + eoi = container_of(to_delayed_work(work), struct lateeoi_work, delayed); + + read_lock_irqsave(&evtchn_rwlock, flags); + + while (true) { + spin_lock(&eoi->eoi_list_lock); + + info = list_first_entry_or_null(&eoi->eoi_list, struct irq_info, + eoi_list); + + if (info == NULL || now < info->eoi_time) { + spin_unlock(&eoi->eoi_list_lock); + break; + } + + list_del_init(&info->eoi_list); + + spin_unlock(&eoi->eoi_list_lock); + + info->eoi_time = 0; + + xen_irq_lateeoi_locked(info); + } + + if (info) + mod_delayed_work_on(info->eoi_cpu, system_wq, + &eoi->delayed, info->eoi_time - now); + + read_unlock_irqrestore(&evtchn_rwlock, flags); +} + +static void xen_cpu_init_eoi(unsigned int cpu) +{ + struct lateeoi_work *eoi = &per_cpu(lateeoi, cpu); + + INIT_DELAYED_WORK(&eoi->delayed, xen_irq_lateeoi_worker); + spin_lock_init(&eoi->eoi_list_lock); + INIT_LIST_HEAD(&eoi->eoi_list); +} + void xen_irq_lateeoi(unsigned int irq, unsigned int eoi_flags) { struct irq_info *info; @@ -428,6 +545,7 @@ EXPORT_SYMBOL_GPL(xen_irq_lateeoi); static void xen_irq_init(unsigned irq) { struct irq_info *info; + #ifdef CONFIG_SMP /* By default all event channels notify CPU#0. */ cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(0)); @@ -442,6 +560,7 @@ static void xen_irq_init(unsigned irq) set_info_for_irq(irq, info); + INIT_LIST_HEAD(&info->eoi_list); list_add_tail(&info->list, &xen_irq_list_head); } @@ -497,6 +616,9 @@ static void xen_free_irq(unsigned irq) write_lock_irqsave(&evtchn_rwlock, flags); + if (!list_empty(&info->eoi_list)) + lateeoi_list_del(info); + list_del(&info->list); set_info_for_irq(irq, NULL); @@ -1356,6 +1478,54 @@ void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector) notify_remote_via_irq(irq); } +struct evtchn_loop_ctrl { + ktime_t timeout; + unsigned count; + bool defer_eoi; +}; + +void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl) +{ + int irq; + struct irq_info *info; + + irq = get_evtchn_to_irq(port); + if (irq == -1) + return; + + /* + * Check for timeout every 256 events. + * We are setting the timeout value only after the first 256 + * events in order to not hurt the common case of few loop + * iterations. The 256 is basically an arbitrary value. + * + * In case we are hitting the timeout we need to defer all further + * EOIs in order to ensure to leave the event handling loop rather + * sooner than later. + */ + if (!ctrl->defer_eoi && !(++ctrl->count & 0xff)) { + ktime_t kt = ktime_get(); + + if (!ctrl->timeout) { + kt = ktime_add_ms(kt, + jiffies_to_msecs(event_loop_timeout)); + ctrl->timeout = kt; + } else if (kt > ctrl->timeout) { + ctrl->defer_eoi = true; + } + } + + info = info_for_irq(irq); + + if (ctrl->defer_eoi) { + info->eoi_cpu = smp_processor_id(); + info->irq_epoch = __this_cpu_read(irq_epoch); + info->eoi_time = get_jiffies_64() + event_eoi_delay; + } + + generic_handle_irq(irq); +} + static DEFINE_PER_CPU(unsigned, xed_nesting_count); static void __xen_evtchn_do_upcall(void) @@ -1363,6 +1533,7 @@ static void __xen_evtchn_do_upcall(void) struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu); int cpu = get_cpu(); unsigned count; + struct evtchn_loop_ctrl ctrl = { 0 }; read_lock(&evtchn_rwlock); @@ -1372,7 +1543,7 @@ static void __xen_evtchn_do_upcall(void) if (__this_cpu_inc_return(xed_nesting_count) - 1) goto out; - xen_evtchn_handle_events(cpu); + xen_evtchn_handle_events(cpu, &ctrl); BUG_ON(!irqs_disabled()); @@ -1383,6 +1554,13 @@ static void __xen_evtchn_do_upcall(void) out: read_unlock(&evtchn_rwlock); + /* + * Increment irq_epoch only now to defer EOIs only for + * xen_irq_lateeoi() invocations occurring from inside the loop + * above. + */ + __this_cpu_inc(irq_epoch); + put_cpu(); } @@ -1829,9 +2007,6 @@ void xen_callback_vector(void) void xen_callback_vector(void) {} #endif -#undef MODULE_PARAM_PREFIX -#define MODULE_PARAM_PREFIX "xen." - static bool fifo_events = true; module_param(fifo_events, bool, 0); @@ -1839,6 +2014,8 @@ static int xen_evtchn_cpu_prepare(unsigned int cpu) { int ret = 0; + xen_cpu_init_eoi(cpu); + if (evtchn_ops->percpu_init) ret = evtchn_ops->percpu_init(cpu); @@ -1865,6 +2042,8 @@ void __init xen_init_IRQ(void) if (ret < 0) xen_evtchn_2l_init(); + xen_cpu_init_eoi(smp_processor_id()); + cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE, "xen/evtchn:prepare", xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead); diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c index 59e6002c96995..33462521bfd0f 100644 --- a/drivers/xen/events/events_fifo.c +++ b/drivers/xen/events/events_fifo.c @@ -275,19 +275,9 @@ static uint32_t clear_linked(volatile event_word_t *word) return w & EVTCHN_FIFO_LINK_MASK; } -static void handle_irq_for_port(unsigned port) -{ - int irq; - - irq = get_evtchn_to_irq(port); - if (irq != -1) - generic_handle_irq(irq); -} - -static void consume_one_event(unsigned cpu, +static void consume_one_event(unsigned cpu, struct evtchn_loop_ctrl *ctrl, struct evtchn_fifo_control_block *control_block, - unsigned priority, unsigned long *ready, - bool drop) + unsigned priority, unsigned long *ready) { struct evtchn_fifo_queue *q = &per_cpu(cpu_queue, cpu); uint32_t head; @@ -320,16 +310,17 @@ static void consume_one_event(unsigned cpu, clear_bit(priority, ready); if (evtchn_fifo_is_pending(port) && !evtchn_fifo_is_masked(port)) { - if (unlikely(drop)) + if (unlikely(!ctrl)) pr_warn("Dropping pending event for port %u\n", port); else - handle_irq_for_port(port); + handle_irq_for_port(port, ctrl); } q->head[priority] = head; } -static void __evtchn_fifo_handle_events(unsigned cpu, bool drop) +static void __evtchn_fifo_handle_events(unsigned cpu, + struct evtchn_loop_ctrl *ctrl) { struct evtchn_fifo_control_block *control_block; unsigned long ready; @@ -341,14 +332,15 @@ static void __evtchn_fifo_handle_events(unsigned cpu, bool drop) while (ready) { q = find_first_bit(&ready, EVTCHN_FIFO_MAX_QUEUES); - consume_one_event(cpu, control_block, q, &ready, drop); + consume_one_event(cpu, ctrl, control_block, q, &ready); ready |= xchg(&control_block->ready, 0); } } -static void evtchn_fifo_handle_events(unsigned cpu) +static void evtchn_fifo_handle_events(unsigned cpu, + struct evtchn_loop_ctrl *ctrl) { - __evtchn_fifo_handle_events(cpu, false); + __evtchn_fifo_handle_events(cpu, ctrl); } static void evtchn_fifo_resume(void) @@ -416,7 +408,7 @@ static int evtchn_fifo_percpu_init(unsigned int cpu) static int evtchn_fifo_percpu_deinit(unsigned int cpu) { - __evtchn_fifo_handle_events(cpu, true); + __evtchn_fifo_handle_events(cpu, NULL); return 0; } diff --git a/drivers/xen/events/events_internal.h b/drivers/xen/events/events_internal.h index fef1d645261ed..756c87532d332 100644 --- a/drivers/xen/events/events_internal.h +++ b/drivers/xen/events/events_internal.h @@ -30,11 +30,15 @@ enum xen_irq_type { */ struct irq_info { struct list_head list; + struct list_head eoi_list; int refcnt; enum xen_irq_type type; /* type */ unsigned irq; unsigned int evtchn; /* event channel */ unsigned short cpu; /* cpu bound */ + unsigned short eoi_cpu; /* EOI must happen on this cpu */ + unsigned int irq_epoch; /* If eoi_cpu valid: irq_epoch of event */ + u64 eoi_time; /* Time in jiffies when to EOI. */ union { unsigned short virq; @@ -53,6 +57,8 @@ struct irq_info { #define PIRQ_SHAREABLE (1 << 1) #define PIRQ_MSI_GROUP (1 << 2) +struct evtchn_loop_ctrl; + struct evtchn_ops { unsigned (*max_channels)(void); unsigned (*nr_channels)(void); @@ -67,7 +73,7 @@ struct evtchn_ops { void (*mask)(unsigned port); void (*unmask)(unsigned port); - void (*handle_events)(unsigned cpu); + void (*handle_events)(unsigned cpu, struct evtchn_loop_ctrl *ctrl); void (*resume)(void); int (*percpu_init)(unsigned int cpu); @@ -78,6 +84,7 @@ extern const struct evtchn_ops *evtchn_ops; extern int **evtchn_to_irq; int get_evtchn_to_irq(unsigned int evtchn); +void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl); struct irq_info *info_for_irq(unsigned irq); unsigned cpu_from_irq(unsigned irq); @@ -135,9 +142,10 @@ static inline void unmask_evtchn(unsigned port) return evtchn_ops->unmask(port); } -static inline void xen_evtchn_handle_events(unsigned cpu) +static inline void xen_evtchn_handle_events(unsigned cpu, + struct evtchn_loop_ctrl *ctrl) { - return evtchn_ops->handle_events(cpu); + return evtchn_ops->handle_events(cpu, ctrl); } static inline void xen_evtchn_resume(void)