diff options
Diffstat (limited to 'arch/x86/kernel/apic/vector.c')
| -rw-r--r-- | arch/x86/kernel/apic/vector.c | 231 |
1 files changed, 108 insertions, 123 deletions
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c index 736f62812f5c..72fa4bb78f0a 100644 --- a/arch/x86/kernel/apic/vector.c +++ b/arch/x86/kernel/apic/vector.c @@ -888,8 +888,109 @@ static int apic_set_affinity(struct irq_data *irqd, return err ? err : IRQ_SET_MASK_OK; } +static void free_moved_vector(struct apic_chip_data *apicd) +{ + unsigned int vector = apicd->prev_vector; + unsigned int cpu = apicd->prev_cpu; + bool managed = apicd->is_managed; + + /* + * Managed interrupts are usually not migrated away + * from an online CPU, but CPU isolation 'managed_irq' + * can make that happen. + * 1) Activation does not take the isolation into account + * to keep the code simple + * 2) Migration away from an isolated CPU can happen when + * a non-isolated CPU which is in the calculated + * affinity mask comes online. + */ + trace_vector_free_moved(apicd->irq, cpu, vector, managed); + irq_matrix_free(vector_matrix, cpu, vector, managed); + per_cpu(vector_irq, cpu)[vector] = VECTOR_UNUSED; + hlist_del_init(&apicd->clist); + apicd->prev_vector = 0; + apicd->move_in_progress = 0; +} + +/* + * Called from fixup_irqs() with @desc->lock held and interrupts disabled. + */ +static void apic_force_complete_move(struct irq_data *irqd) +{ + unsigned int cpu = smp_processor_id(); + struct apic_chip_data *apicd; + unsigned int vector; + + guard(raw_spinlock)(&vector_lock); + apicd = apic_chip_data(irqd); + if (!apicd) + return; + + /* + * If prev_vector is empty or the descriptor is neither currently + * nor previously on the outgoing CPU no action required. + */ + vector = apicd->prev_vector; + if (!vector || (apicd->cpu != cpu && apicd->prev_cpu != cpu)) + return; + + /* + * This is tricky. If the cleanup of the old vector has not been + * done yet, then the following setaffinity call will fail with + * -EBUSY. This can leave the interrupt in a stale state. + * + * All CPUs are stuck in stop machine with interrupts disabled so + * calling __irq_complete_move() would be completely pointless. + * + * 1) The interrupt is in move_in_progress state. That means that we + * have not seen an interrupt since the io_apic was reprogrammed to + * the new vector. + * + * 2) The interrupt has fired on the new vector, but the cleanup IPIs + * have not been processed yet. + */ + if (apicd->move_in_progress) { + /* + * In theory there is a race: + * + * set_ioapic(new_vector) <-- Interrupt is raised before update + * is effective, i.e. it's raised on + * the old vector. + * + * So if the target cpu cannot handle that interrupt before + * the old vector is cleaned up, we get a spurious interrupt + * and in the worst case the ioapic irq line becomes stale. + * + * But in case of cpu hotplug this should be a non issue + * because if the affinity update happens right before all + * cpus rendezvous in stop machine, there is no way that the + * interrupt can be blocked on the target cpu because all cpus + * loops first with interrupts enabled in stop machine, so the + * old vector is not yet cleaned up when the interrupt fires. + * + * So the only way to run into this issue is if the delivery + * of the interrupt on the apic/system bus would be delayed + * beyond the point where the target cpu disables interrupts + * in stop machine. I doubt that it can happen, but at least + * there is a theoretical chance. Virtualization might be + * able to expose this, but AFAICT the IOAPIC emulation is not + * as stupid as the real hardware. + * + * Anyway, there is nothing we can do about that at this point + * w/o refactoring the whole fixup_irq() business completely. + * We print at least the irq number and the old vector number, + * so we have the necessary information when a problem in that + * area arises. + */ + pr_warn("IRQ fixup: irq %d move in progress, old vector %d\n", + irqd->irq, vector); + } + free_moved_vector(apicd); +} + #else -# define apic_set_affinity NULL +# define apic_set_affinity NULL +# define apic_force_complete_move NULL #endif static int apic_retrigger_irq(struct irq_data *irqd) @@ -923,39 +1024,16 @@ static void x86_vector_msi_compose_msg(struct irq_data *data, } static struct irq_chip lapic_controller = { - .name = "APIC", - .irq_ack = apic_ack_edge, - .irq_set_affinity = apic_set_affinity, - .irq_compose_msi_msg = x86_vector_msi_compose_msg, - .irq_retrigger = apic_retrigger_irq, + .name = "APIC", + .irq_ack = apic_ack_edge, + .irq_set_affinity = apic_set_affinity, + .irq_compose_msi_msg = x86_vector_msi_compose_msg, + .irq_force_complete_move = apic_force_complete_move, + .irq_retrigger = apic_retrigger_irq, }; #ifdef CONFIG_SMP -static void free_moved_vector(struct apic_chip_data *apicd) -{ - unsigned int vector = apicd->prev_vector; - unsigned int cpu = apicd->prev_cpu; - bool managed = apicd->is_managed; - - /* - * Managed interrupts are usually not migrated away - * from an online CPU, but CPU isolation 'managed_irq' - * can make that happen. - * 1) Activation does not take the isolation into account - * to keep the code simple - * 2) Migration away from an isolated CPU can happen when - * a non-isolated CPU which is in the calculated - * affinity mask comes online. - */ - trace_vector_free_moved(apicd->irq, cpu, vector, managed); - irq_matrix_free(vector_matrix, cpu, vector, managed); - per_cpu(vector_irq, cpu)[vector] = VECTOR_UNUSED; - hlist_del_init(&apicd->clist); - apicd->prev_vector = 0; - apicd->move_in_progress = 0; -} - static void __vector_cleanup(struct vector_cleanup *cl, bool check_irr) { struct apic_chip_data *apicd; @@ -1068,99 +1146,6 @@ void irq_complete_move(struct irq_cfg *cfg) __vector_schedule_cleanup(apicd); } -/* - * Called from fixup_irqs() with @desc->lock held and interrupts disabled. - */ -void irq_force_complete_move(struct irq_desc *desc) -{ - unsigned int cpu = smp_processor_id(); - struct apic_chip_data *apicd; - struct irq_data *irqd; - unsigned int vector; - - /* - * The function is called for all descriptors regardless of which - * irqdomain they belong to. For example if an IRQ is provided by - * an irq_chip as part of a GPIO driver, the chip data for that - * descriptor is specific to the irq_chip in question. - * - * Check first that the chip_data is what we expect - * (apic_chip_data) before touching it any further. - */ - irqd = irq_domain_get_irq_data(x86_vector_domain, - irq_desc_get_irq(desc)); - if (!irqd) - return; - - raw_spin_lock(&vector_lock); - apicd = apic_chip_data(irqd); - if (!apicd) - goto unlock; - - /* - * If prev_vector is empty or the descriptor is neither currently - * nor previously on the outgoing CPU no action required. - */ - vector = apicd->prev_vector; - if (!vector || (apicd->cpu != cpu && apicd->prev_cpu != cpu)) - goto unlock; - - /* - * This is tricky. If the cleanup of the old vector has not been - * done yet, then the following setaffinity call will fail with - * -EBUSY. This can leave the interrupt in a stale state. - * - * All CPUs are stuck in stop machine with interrupts disabled so - * calling __irq_complete_move() would be completely pointless. - * - * 1) The interrupt is in move_in_progress state. That means that we - * have not seen an interrupt since the io_apic was reprogrammed to - * the new vector. - * - * 2) The interrupt has fired on the new vector, but the cleanup IPIs - * have not been processed yet. - */ - if (apicd->move_in_progress) { - /* - * In theory there is a race: - * - * set_ioapic(new_vector) <-- Interrupt is raised before update - * is effective, i.e. it's raised on - * the old vector. - * - * So if the target cpu cannot handle that interrupt before - * the old vector is cleaned up, we get a spurious interrupt - * and in the worst case the ioapic irq line becomes stale. - * - * But in case of cpu hotplug this should be a non issue - * because if the affinity update happens right before all - * cpus rendezvous in stop machine, there is no way that the - * interrupt can be blocked on the target cpu because all cpus - * loops first with interrupts enabled in stop machine, so the - * old vector is not yet cleaned up when the interrupt fires. - * - * So the only way to run into this issue is if the delivery - * of the interrupt on the apic/system bus would be delayed - * beyond the point where the target cpu disables interrupts - * in stop machine. I doubt that it can happen, but at least - * there is a theoretical chance. Virtualization might be - * able to expose this, but AFAICT the IOAPIC emulation is not - * as stupid as the real hardware. - * - * Anyway, there is nothing we can do about that at this point - * w/o refactoring the whole fixup_irq() business completely. - * We print at least the irq number and the old vector number, - * so we have the necessary information when a problem in that - * area arises. - */ - pr_warn("IRQ fixup: irq %d move in progress, old vector %d\n", - irqd->irq, vector); - } - free_moved_vector(apicd); -unlock: - raw_spin_unlock(&vector_lock); -} - #ifdef CONFIG_HOTPLUG_CPU /* * Note, this is not accurate accounting, but at least good enough to |