/* * Xen event channels * * Xen models interrupts with abstract event channels. Because each * domain gets 1024 event channels, but NR_IRQ is not that large, we * must dynamically map irqs<->event channels. The event channels * interface with the rest of the kernel by defining a xen interrupt * chip. When an event is recieved, it is mapped to an irq and sent * through the normal interrupt processing path. * * There are four kinds of events which can be mapped to an event * channel: * * 1. Inter-domain notifications. This includes all the virtual * device events, since they're driven by front-ends in another domain * (typically dom0). * 2. VIRQs, typically used for timers. These are per-cpu events. * 3. IPIs. * 4. Hardware interrupts. Not supported at present. * * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007 */ #include <linux/linkage.h> #include <linux/interrupt.h> #include <linux/irq.h> #include <linux/module.h> #include <linux/string.h> #include <asm/ptrace.h> #include <asm/irq.h> #include <asm/sync_bitops.h> #include <asm/xen/hypercall.h> #include <asm/xen/hypervisor.h> #include <xen/xen-ops.h> #include <xen/events.h> #include <xen/interface/xen.h> #include <xen/interface/event_channel.h> /* * This lock protects updates to the following mapping and reference-count * arrays. The lock does not need to be acquired to read the mapping tables. */ static DEFINE_SPINLOCK(irq_mapping_update_lock); /* IRQ <-> VIRQ mapping. */ static DEFINE_PER_CPU(int, virq_to_irq[NR_VIRQS]) = {[0 ... NR_VIRQS-1] = -1}; /* IRQ <-> IPI mapping */ static DEFINE_PER_CPU(int, ipi_to_irq[XEN_NR_IPIS]) = {[0 ... XEN_NR_IPIS-1] = -1}; /* Packed IRQ information: binding type, sub-type index, and event channel. */ struct packed_irq { unsigned short evtchn; unsigned char index; unsigned char type; }; static struct packed_irq irq_info[NR_IRQS]; /* Binding types. */ enum { IRQT_UNBOUND, IRQT_PIRQ, IRQT_VIRQ, IRQT_IPI, IRQT_EVTCHN }; /* Convenient shorthand for packed representation of an unbound IRQ. */ #define IRQ_UNBOUND mk_irq_info(IRQT_UNBOUND, 0, 0) static int evtchn_to_irq[NR_EVENT_CHANNELS] = { [0 ... NR_EVENT_CHANNELS-1] = -1 }; static unsigned long cpu_evtchn_mask[NR_CPUS][NR_EVENT_CHANNELS/BITS_PER_LONG]; static u8 cpu_evtchn[NR_EVENT_CHANNELS]; /* Reference counts for bindings to IRQs. */ static int irq_bindcount[NR_IRQS]; /* Xen will never allocate port zero for any purpose. */ #define VALID_EVTCHN(chn) ((chn) != 0) static struct irq_chip xen_dynamic_chip; /* Constructor for packed IRQ information. */ static inline struct packed_irq mk_irq_info(u32 type, u32 index, u32 evtchn) { return (struct packed_irq) { evtchn, index, type }; } /* * Accessors for packed IRQ information. */ static inline unsigned int evtchn_from_irq(int irq) { return irq_info[irq].evtchn; } static inline unsigned int index_from_irq(int irq) { return irq_info[irq].index; } static inline unsigned int type_from_irq(int irq) { return irq_info[irq].type; } static inline unsigned long active_evtchns(unsigned int cpu, struct shared_info *sh, unsigned int idx) { return (sh->evtchn_pending[idx] & cpu_evtchn_mask[cpu][idx] & ~sh->evtchn_mask[idx]); } static void bind_evtchn_to_cpu(unsigned int chn, unsigned int cpu) { int irq = evtchn_to_irq[chn]; BUG_ON(irq == -1); #ifdef CONFIG_SMP irq_to_desc(irq)->affinity = cpumask_of_cpu(cpu); #endif __clear_bit(chn, cpu_evtchn_mask[cpu_evtchn[chn]]); __set_bit(chn, cpu_evtchn_mask[cpu]); cpu_evtchn[chn] = cpu; } static void init_evtchn_cpu_bindings(void) { #ifdef CONFIG_SMP struct irq_desc *desc; int i; /* By default all event channels notify CPU#0. */ for_each_irq_desc(i, desc) { desc->affinity = cpumask_of_cpu(0); } #endif memset(cpu_evtchn, 0, sizeof(cpu_evtchn)); memset(cpu_evtchn_mask[0], ~0, sizeof(cpu_evtchn_mask[0])); } static inline unsigned int cpu_from_evtchn(unsigned int evtchn) { return cpu_evtchn[evtchn]; } static inline void clear_evtchn(int port) { struct shared_info *s = HYPERVISOR_shared_info; sync_clear_bit(port, &s->evtchn_pending[0]); } static inline void set_evtchn(int port) { struct shared_info *s = HYPERVISOR_shared_info; sync_set_bit(port, &s->evtchn_pending[0]); } static inline int test_evtchn(int port) { struct shared_info *s = HYPERVISOR_shared_info; return sync_test_bit(port, &s->evtchn_pending[0]); } /** * notify_remote_via_irq - send event to remote end of event channel via irq * @irq: irq of event channel to send event to * * Unlike notify_remote_via_evtchn(), this is safe to use across * save/restore. Notifications on a broken connection are silently * dropped. */ void notify_remote_via_irq(int irq) { int evtchn = evtchn_from_irq(irq); if (VALID_EVTCHN(evtchn)) notify_remote_via_evtchn(evtchn); } EXPORT_SYMBOL_GPL(notify_remote_via_irq); static void mask_evtchn(int port) { struct shared_info *s = HYPERVISOR_shared_info; sync_set_bit(port, &s->evtchn_mask[0]); } static void unmask_evtchn(int port) { struct shared_info *s = HYPERVISOR_shared_info; unsigned int cpu = get_cpu(); BUG_ON(!irqs_disabled()); /* Slow path (hypercall) if this is a non-local port. */ if (unlikely(cpu != cpu_from_evtchn(port))) { struct evtchn_unmask unmask = { .port = port }; (void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask); } else { struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu); sync_clear_bit(port, &s->evtchn_mask[0]); /* * The following is basically the equivalent of * 'hw_resend_irq'. Just like a real IO-APIC we 'lose * the interrupt edge' if the channel is masked. */ if (sync_test_bit(port, &s->evtchn_pending[0]) && !sync_test_and_set_bit(port / BITS_PER_LONG, &vcpu_info->evtchn_pending_sel)) vcpu_info->evtchn_upcall_pending = 1; } put_cpu(); } static int find_unbound_irq(void) { int irq; struct irq_desc *desc; /* Only allocate from dynirq range */ for (irq = 0; irq < nr_irqs; irq++) if (irq_bindcount[irq] == 0) break; if (irq == nr_irqs) panic("No available IRQ to bind to: increase nr_irqs!\n"); desc = irq_to_desc_alloc_cpu(irq, 0); if (WARN_ON(desc == NULL)) return -1; return irq; } int bind_evtchn_to_irq(unsigned int evtchn) { int irq; spin_lock(&irq_mapping_update_lock); irq = evtchn_to_irq[evtchn]; if (irq == -1) { irq = find_unbound_irq(); dynamic_irq_init(irq); set_irq_chip_and_handler_name(irq, &xen_dynamic_chip, handle_level_irq, "event"); evtchn_to_irq[evtchn] = irq; irq_info[irq] = mk_irq_info(IRQT_EVTCHN, 0, evtchn); } irq_bindcount[irq]++; spin_unlock(&irq_mapping_update_lock); return irq; } EXPORT_SYMBOL_GPL(bind_evtchn_to_irq); static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu) { struct evtchn_bind_ipi bind_ipi; int evtchn, irq; spin_lock(&irq_mapping_update_lock); irq = per_cpu(ipi_to_irq, cpu)[ipi]; if (irq == -1) { irq = find_unbound_irq(); if (irq < 0) goto out; dynamic_irq_init(irq); set_irq_chip_and_handler_name(irq, &xen_dynamic_chip, handle_level_irq, "ipi"); bind_ipi.vcpu = cpu; if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi, &bind_ipi) != 0) BUG(); evtchn = bind_ipi.port; evtchn_to_irq[evtchn] = irq; irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn); per_cpu(ipi_to_irq, cpu)[ipi] = irq; bind_evtchn_to_cpu(evtchn, cpu); } irq_bindcount[irq]++; out: spin_unlock(&irq_mapping_update_lock); return irq; } static int bind_virq_to_irq(unsigned int virq, unsigned int cpu) { struct evtchn_bind_virq bind_virq; int evtchn, irq; spin_lock(&irq_mapping_update_lock); irq = per_cpu(virq_to_irq, cpu)[virq]; if (irq == -1) { bind_virq.virq = virq; bind_virq.vcpu = cpu; if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq, &bind_virq) != 0) BUG(); evtchn = bind_virq.port; irq = find_unbound_irq(); dynamic_irq_init(irq); set_irq_chip_and_handler_name(irq, &xen_dynamic_chip, handle_level_irq, "virq"); evtchn_to_irq[evtchn] = irq; irq_info[irq] = mk_irq_info(IRQT_VIRQ, virq, evtchn); per_cpu(virq_to_irq, cpu)[virq] = irq; bind_evtchn_to_cpu(evtchn, cpu); } irq_bindcount[irq]++; spin_unlock(&irq_mapping_update_lock); return irq; } static void unbind_from_irq(unsigned int irq) { struct evtchn_close close; int evtchn = evtchn_from_irq(irq); spin_lock(&irq_mapping_update_lock); if ((--irq_bindcount[irq] == 0) && VALID_EVTCHN(evtchn)) { close.port = evtchn; if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0) BUG(); switch (type_from_irq(irq)) { case IRQT_VIRQ: per_cpu(virq_to_irq, cpu_from_evtchn(evtchn)) [index_from_irq(irq)] = -1; break; case IRQT_IPI: per_cpu(ipi_to_irq, cpu_from_evtchn(evtchn)) [index_from_irq(irq)] = -1; break; default: break; } /* Closed ports are implicitly re-bound to VCPU0. */ bind_evtchn_to_cpu(evtchn, 0); evtchn_to_irq[evtchn] = -1; irq_info[irq] = IRQ_UNBOUND; dynamic_irq_cleanup(irq); } spin_unlock(&irq_mapping_update_lock); } int bind_evtchn_to_irqhandler(unsigned int evtchn, irq_handler_t handler, unsigned long irqflags, const char *devname, void *dev_id) { unsigned int irq; int retval; irq = bind_evtchn_to_irq(evtchn); retval = request_irq(irq, handler, irqflags, devname, dev_id); if (retval != 0) { unbind_from_irq(irq); return retval; } return irq; } EXPORT_SYMBOL_GPL(bind_evtchn_to_irqhandler); int bind_virq_to_irqhandler(unsigned int virq, unsigned int cpu, irq_handler_t handler, unsigned long irqflags, const char *devname, void *dev_id) { unsigned int irq; int retval; irq = bind_virq_to_irq(virq, cpu); retval = request_irq(irq, handler, irqflags, devname, dev_id); if (retval != 0) { unbind_from_irq(irq); return retval; } return irq; } EXPORT_SYMBOL_GPL(bind_virq_to_irqhandler); int bind_ipi_to_irqhandler(enum ipi_vector ipi, unsigned int cpu, irq_handler_t handler, unsigned long irqflags, const char *devname, void *dev_id) { int irq, retval; irq = bind_ipi_to_irq(ipi, cpu); if (irq < 0) return irq; retval = request_irq(irq, handler, irqflags, devname, dev_id); if (retval != 0) { unbind_from_irq(irq); return retval; } return irq; } void unbind_from_irqhandler(unsigned int irq, void *dev_id) { free_irq(irq, dev_id); unbind_from_irq(irq); } EXPORT_SYMBOL_GPL(unbind_from_irqhandler); void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector) { int irq = per_cpu(ipi_to_irq, cpu)[vector]; BUG_ON(irq < 0); notify_remote_via_irq(irq); } irqreturn_t xen_debug_interrupt(int irq, void *dev_id) { struct shared_info *sh = HYPERVISOR_shared_info; int cpu = smp_processor_id(); int i; unsigned long flags; static DEFINE_SPINLOCK(debug_lock); spin_lock_irqsave(&debug_lock, flags); printk("vcpu %d\n ", cpu); for_each_online_cpu(i) { struct vcpu_info *v = per_cpu(xen_vcpu, i); printk("%d: masked=%d pending=%d event_sel %08lx\n ", i, (get_irq_regs() && i == cpu) ? xen_irqs_disabled(get_irq_regs()) : v->evtchn_upcall_mask, v->evtchn_upcall_pending, v->evtchn_pending_sel); } printk("pending:\n "); for(i = ARRAY_SIZE(sh->evtchn_pending)-1; i >= 0; i--) printk("%08lx%s", sh->evtchn_pending[i], i % 8 == 0 ? "\n " : " "); printk("\nmasks:\n "); for(i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) printk("%08lx%s", sh->evtchn_mask[i], i % 8 == 0 ? "\n " : " "); printk("\nunmasked:\n "); for(i = ARRAY_SIZE(sh->evtchn_mask)-1; i >= 0; i--) printk("%08lx%s", sh->evtchn_pending[i] & ~sh->evtchn_mask[i], i % 8 == 0 ? "\n " : " "); printk("\npending list:\n"); for(i = 0; i < NR_EVENT_CHANNELS; i++) { if (sync_test_bit(i, sh->evtchn_pending)) { printk(" %d: event %d -> irq %d\n", cpu_evtchn[i], i, evtchn_to_irq[i]); } } spin_unlock_irqrestore(&debug_lock, flags); return IRQ_HANDLED; } /* * Search the CPUs pending events bitmasks. For each one found, map * the event number to an irq, and feed it into do_IRQ() for * handling. * * Xen uses a two-level bitmap to speed searching. The first level is * a bitset of words which contain pending event bits. The second * level is a bitset of pending events themselves. */ void xen_evtchn_do_upcall(struct pt_regs *regs) { int cpu = get_cpu(); struct shared_info *s = HYPERVISOR_shared_info; struct vcpu_info *vcpu_info = __get_cpu_var(xen_vcpu); static DEFINE_PER_CPU(unsigned, nesting_count); unsigned count; do { unsigned long pending_words; vcpu_info->evtchn_upcall_pending = 0; if (__get_cpu_var(nesting_count)++) goto out; #ifndef CONFIG_X86 /* No need for a barrier -- XCHG is a barrier on x86. */ /* Clear master flag /before/ clearing selector flag. */ wmb(); #endif pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0); while (pending_words != 0) { unsigned long pending_bits; int word_idx = __ffs(pending_words); pending_words &= ~(1UL << word_idx); while ((pending_bits = active_evtchns(cpu, s, word_idx)) != 0) { int bit_idx = __ffs(pending_bits); int port = (word_idx * BITS_PER_LONG) + bit_idx; int irq = evtchn_to_irq[port]; if (irq != -1) xen_do_IRQ(irq, regs); } } BUG_ON(!irqs_disabled()); count = __get_cpu_var(nesting_count); __get_cpu_var(nesting_count) = 0; } while(count != 1); out: put_cpu(); } /* Rebind a new event channel to an existing irq. */ void rebind_evtchn_irq(int evtchn, int irq) { /* Make sure the irq is masked, since the new event channel will also be masked. */ disable_irq(irq); spin_lock(&irq_mapping_update_lock); /* After resume the irq<->evtchn mappings are all cleared out */ BUG_ON(evtchn_to_irq[evtchn] != -1); /* Expect irq to have been bound before, so the bindcount should be non-0 */ BUG_ON(irq_bindcount[irq] == 0); evtchn_to_irq[evtchn] = irq; irq_info[irq] = mk_irq_info(IRQT_EVTCHN, 0, evtchn); spin_unlock(&irq_mapping_update_lock); /* new event channels are always bound to cpu 0 */ irq_set_affinity(irq, cpumask_of(0)); /* Unmask the event channel. */ enable_irq(irq); } /* Rebind an evtchn so that it gets delivered to a specific cpu */ static void rebind_irq_to_cpu(unsigned irq, unsigned tcpu) { struct evtchn_bind_vcpu bind_vcpu; int evtchn = evtchn_from_irq(irq); if (!VALID_EVTCHN(evtchn)) return; /* Send future instances of this interrupt to other vcpu. */ bind_vcpu.port = evtchn; bind_vcpu.vcpu = tcpu; /* * If this fails, it usually just indicates that we're dealing with a * virq or IPI channel, which don't actually need to be rebound. Ignore * it, but don't do the xenlinux-level rebind in that case. */ if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0) bind_evtchn_to_cpu(evtchn, tcpu); } static void set_affinity_irq(unsigned irq, const struct cpumask *dest) { unsigned tcpu = cpumask_first(dest); rebind_irq_to_cpu(irq, tcpu); } int resend_irq_on_evtchn(unsigned int irq) { int masked, evtchn = evtchn_from_irq(irq); struct shared_info *s = HYPERVISOR_shared_info; if (!VALID_EVTCHN(evtchn)) return 1; masked = sync_test_and_set_bit(evtchn, s->evtchn_mask); sync_set_bit(evtchn, s->evtchn_pending); if (!masked) unmask_evtchn(evtchn); return 1; } static void enable_dynirq(unsigned int irq) { int evtchn = evtchn_from_irq(irq); if (VALID_EVTCHN(evtchn)) unmask_evtchn(evtchn); } static void disable_dynirq(unsigned int irq) { int evtchn = evtchn_from_irq(irq); if (VALID_EVTCHN(evtchn)) mask_evtchn(evtchn); } static void ack_dynirq(unsigned int irq) { int evtchn = evtchn_from_irq(irq); move_native_irq(irq); if (VALID_EVTCHN(evtchn)) clear_evtchn(evtchn); } static int retrigger_dynirq(unsigned int irq) { int evtchn = evtchn_from_irq(irq); struct shared_info *sh = HYPERVISOR_shared_info; int ret = 0; if (VALID_EVTCHN(evtchn)) { int masked; masked = sync_test_and_set_bit(evtchn, sh->evtchn_mask); sync_set_bit(evtchn, sh->evtchn_pending); if (!masked) unmask_evtchn(evtchn); ret = 1; } return ret; } static void restore_cpu_virqs(unsigned int cpu) { struct evtchn_bind_virq bind_virq; int virq, irq, evtchn; for (virq = 0; virq < NR_VIRQS; virq++) { if ((irq = per_cpu(virq_to_irq, cpu)[virq]) == -1) continue; BUG_ON(irq_info[irq].type != IRQT_VIRQ); BUG_ON(irq_info[irq].index != virq); /* Get a new binding from Xen. */ bind_virq.virq = virq; bind_virq.vcpu = cpu; if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq, &bind_virq) != 0) BUG(); evtchn = bind_virq.port; /* Record the new mapping. */ evtchn_to_irq[evtchn] = irq; irq_info[irq] = mk_irq_info(IRQT_VIRQ, virq, evtchn); bind_evtchn_to_cpu(evtchn, cpu); /* Ready for use. */ unmask_evtchn(evtchn); } } static void restore_cpu_ipis(unsigned int cpu) { struct evtchn_bind_ipi bind_ipi; int ipi, irq, evtchn; for (ipi = 0; ipi < XEN_NR_IPIS; ipi++) { if ((irq = per_cpu(ipi_to_irq, cpu)[ipi]) == -1) continue; BUG_ON(irq_info[irq].type != IRQT_IPI); BUG_ON(irq_info[irq].index != ipi); /* Get a new binding from Xen. */ bind_ipi.vcpu = cpu; if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi, &bind_ipi) != 0) BUG(); evtchn = bind_ipi.port; /* Record the new mapping. */ evtchn_to_irq[evtchn] = irq; irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn); bind_evtchn_to_cpu(evtchn, cpu); /* Ready for use. */ unmask_evtchn(evtchn); } } /* Clear an irq's pending state, in preparation for polling on it */ void xen_clear_irq_pending(int irq) { int evtchn = evtchn_from_irq(irq); if (VALID_EVTCHN(evtchn)) clear_evtchn(evtchn); } void xen_set_irq_pending(int irq) { int evtchn = evtchn_from_irq(irq); if (VALID_EVTCHN(evtchn)) set_evtchn(evtchn); } bool xen_test_irq_pending(int irq) { int evtchn = evtchn_from_irq(irq); bool ret = false; if (VALID_EVTCHN(evtchn)) ret = test_evtchn(evtchn); return ret; } /* Poll waiting for an irq to become pending. In the usual case, the irq will be disabled so it won't deliver an interrupt. */ void xen_poll_irq(int irq) { evtchn_port_t evtchn = evtchn_from_irq(irq); if (VALID_EVTCHN(evtchn)) { struct sched_poll poll; poll.nr_ports = 1; poll.timeout = 0; set_xen_guest_handle(poll.ports, &evtchn); if (HYPERVISOR_sched_op(SCHEDOP_poll, &poll) != 0) BUG(); } } void xen_irq_resume(void) { unsigned int cpu, irq, evtchn; init_evtchn_cpu_bindings(); /* New event-channel space is not 'live' yet. */ for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++) mask_evtchn(evtchn); /* No IRQ <-> event-channel mappings. */ for (irq = 0; irq < nr_irqs; irq++) irq_info[irq].evtchn = 0; /* zap event-channel binding */ for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++) evtchn_to_irq[evtchn] = -1; for_each_possible_cpu(cpu) { restore_cpu_virqs(cpu); restore_cpu_ipis(cpu); } } static struct irq_chip xen_dynamic_chip __read_mostly = { .name = "xen-dyn", .mask = disable_dynirq, .unmask = enable_dynirq, .ack = ack_dynirq, .set_affinity = set_affinity_irq, .retrigger = retrigger_dynirq, }; void __init xen_init_IRQ(void) { int i; init_evtchn_cpu_bindings(); /* No event channels are 'live' right now. */ for (i = 0; i < NR_EVENT_CHANNELS; i++) mask_evtchn(i); /* Dynamic IRQ space is currently unbound. Zero the refcnts. */ for (i = 0; i < nr_irqs; i++) irq_bindcount[i] = 0; irq_ctx_init(smp_processor_id()); }