diff options
| -rw-r--r-- | arch/x86/kvm/ioapic.c | 36 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 10 | ||||
| -rw-r--r-- | virt/kvm/eventfd.c | 41 |
3 files changed, 78 insertions, 9 deletions
diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c index 042dee5561258..995eb50543601 100644 --- a/arch/x86/kvm/ioapic.c +++ b/arch/x86/kvm/ioapic.c @@ -368,9 +368,39 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val) mask_after = e->fields.mask; if (mask_before != mask_after) kvm_fire_mask_notifiers(ioapic->kvm, KVM_IRQCHIP_IOAPIC, index, mask_after); - if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG - && ioapic->irr & (1 << index)) - ioapic_service(ioapic, index, false); + if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG && + ioapic->irr & (1 << index) && !e->fields.mask && !e->fields.remote_irr) { + /* + * Pending status in irr may be outdated: the IRQ line may have + * already been deasserted by a device while the IRQ was masked. + * This occurs, for instance, if the interrupt is handled in a + * Linux guest as a oneshot interrupt (IRQF_ONESHOT). In this + * case the guest acknowledges the interrupt to the device in + * its threaded irq handler, i.e. after the EOI but before + * unmasking, so at the time of unmasking the IRQ line is + * already down but our pending irr bit is still set. In such + * cases, injecting this pending interrupt to the guest is + * buggy: the guest will receive an extra unwanted interrupt. + * + * So we need to check here if the IRQ is actually still pending. + * As we are generally not able to probe the IRQ line status + * directly, we do it through irqfd resampler. Namely, we clear + * the pending status and notify the resampler that this interrupt + * is done, without actually injecting it into the guest. If the + * IRQ line is actually already deasserted, we are done. If it is + * still asserted, a new interrupt will be shortly triggered + * through irqfd and injected into the guest. + * + * If, however, it's not possible to resample (no irqfd resampler + * registered for this irq), then unconditionally inject this + * pending interrupt into the guest, so the guest will not miss + * an interrupt, although may get an extra unwanted interrupt. + */ + if (kvm_notify_irqfd_resampler(ioapic->kvm, KVM_IRQCHIP_IOAPIC, index)) + ioapic->irr &= ~(1 << index); + else + ioapic_service(ioapic, index, false); + } if (e->fields.delivery_mode == APIC_DM_FIXED) { struct kvm_lapic_irq irq; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 9f508c8e66e12..a9adf75344bee 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1987,6 +1987,9 @@ int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args); #ifdef CONFIG_HAVE_KVM_IRQFD int kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args); void kvm_irqfd_release(struct kvm *kvm); +bool kvm_notify_irqfd_resampler(struct kvm *kvm, + unsigned int irqchip, + unsigned int pin); void kvm_irq_routing_update(struct kvm *); #else static inline int kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args) @@ -1995,6 +1998,13 @@ static inline int kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args) } static inline void kvm_irqfd_release(struct kvm *kvm) {} + +static inline bool kvm_notify_irqfd_resampler(struct kvm *kvm, + unsigned int irqchip, + unsigned int pin) +{ + return false; +} #endif #else diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 61aea70dd888d..b0af834ffa950 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -55,6 +55,15 @@ irqfd_inject(struct work_struct *work) irqfd->gsi, 1, false); } +static void irqfd_resampler_notify(struct kvm_kernel_irqfd_resampler *resampler) +{ + struct kvm_kernel_irqfd *irqfd; + + list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link, + srcu_read_lock_held(&resampler->kvm->irq_srcu)) + eventfd_signal(irqfd->resamplefd, 1); +} + /* * Since resampler irqfds share an IRQ source ID, we de-assert once * then notify all of the resampler irqfds using this GSI. We can't @@ -65,7 +74,6 @@ irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian) { struct kvm_kernel_irqfd_resampler *resampler; struct kvm *kvm; - struct kvm_kernel_irqfd *irqfd; int idx; resampler = container_of(kian, @@ -76,11 +84,7 @@ irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian) resampler->notifier.gsi, 0, false); idx = srcu_read_lock(&kvm->irq_srcu); - - list_for_each_entry_srcu(irqfd, &resampler->list, resampler_link, - srcu_read_lock_held(&kvm->irq_srcu)) - eventfd_signal(irqfd->resamplefd, 1); - + irqfd_resampler_notify(resampler); srcu_read_unlock(&kvm->irq_srcu, idx); } @@ -648,6 +652,31 @@ void kvm_irq_routing_update(struct kvm *kvm) spin_unlock_irq(&kvm->irqfds.lock); } +bool kvm_notify_irqfd_resampler(struct kvm *kvm, + unsigned int irqchip, + unsigned int pin) +{ + struct kvm_kernel_irqfd_resampler *resampler; + int gsi, idx; + + idx = srcu_read_lock(&kvm->irq_srcu); + gsi = kvm_irq_map_chip_pin(kvm, irqchip, pin); + if (gsi != -1) { + list_for_each_entry_srcu(resampler, + &kvm->irqfds.resampler_list, link, + srcu_read_lock_held(&kvm->irq_srcu)) { + if (resampler->notifier.gsi == gsi) { + irqfd_resampler_notify(resampler); + srcu_read_unlock(&kvm->irq_srcu, idx); + return true; + } + } + } + srcu_read_unlock(&kvm->irq_srcu, idx); + + return false; +} + /* * create a host-wide workqueue for issuing deferred shutdown requests * aggregated from all vm* instances. We need our own isolated |