diff options
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 13 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 4 | ||||
| -rw-r--r-- | include/linux/kvm.h | 12 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 5 | ||||
| -rw-r--r-- | virt/kvm/eventfd.c | 150 | ||||
| -rw-r--r-- | virt/kvm/irq_comm.c | 6 |
6 files changed, 184 insertions, 6 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 36befa775fdb..f6ec3a92e621 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1950,6 +1950,19 @@ the guest using the specified gsi pin. The irqfd is removed using the KVM_IRQFD_FLAG_DEASSIGN flag, specifying both kvm_irqfd.fd and kvm_irqfd.gsi. +With KVM_CAP_IRQFD_RESAMPLE, KVM_IRQFD supports a de-assert and notify +mechanism allowing emulation of level-triggered, irqfd-based +interrupts. When KVM_IRQFD_FLAG_RESAMPLE is set the user must pass an +additional eventfd in the kvm_irqfd.resamplefd field. When operating +in resample mode, posting of an interrupt through kvm_irq.fd asserts +the specified gsi in the irqchip. When the irqchip is resampled, such +as from an EOI, the gsi is de-asserted and the user is notifed via +kvm_irqfd.resamplefd. It is the user's responsibility to re-queue +the interrupt if the device making use of it still requires service. +Note that closing the resamplefd is not sufficient to disable the +irqfd. The KVM_IRQFD_FLAG_RESAMPLE is only necessary on assignment +and need not be specified with KVM_IRQFD_FLAG_DEASSIGN. + 4.76 KVM_PPC_ALLOCATE_HTAB Capability: KVM_CAP_PPC_ALLOC_HTAB diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index fc2a0a132e4b..7d44204c6041 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2176,6 +2176,7 @@ int kvm_dev_ioctl_check_extension(long ext) case KVM_CAP_PCI_2_3: case KVM_CAP_KVMCLOCK_CTRL: case KVM_CAP_READONLY_MEM: + case KVM_CAP_IRQFD_RESAMPLE: r = 1; break; case KVM_CAP_COALESCED_MMIO: @@ -6268,6 +6269,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) /* Reserve bit 0 of irq_sources_bitmap for userspace irq source */ set_bit(KVM_USERSPACE_IRQ_SOURCE_ID, &kvm->arch.irq_sources_bitmap); + /* Reserve bit 1 of irq_sources_bitmap for irqfd-resampler */ + set_bit(KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + &kvm->arch.irq_sources_bitmap); raw_spin_lock_init(&kvm->arch.tsc_write_lock); mutex_init(&kvm->arch.apic_map_lock); diff --git a/include/linux/kvm.h b/include/linux/kvm.h index d808694673f9..0a6d6ba44c85 100644 --- a/include/linux/kvm.h +++ b/include/linux/kvm.h @@ -625,6 +625,7 @@ struct kvm_ppc_smmu_info { #ifdef __KVM_HAVE_READONLY_MEM #define KVM_CAP_READONLY_MEM 81 #endif +#define KVM_CAP_IRQFD_RESAMPLE 82 #ifdef KVM_CAP_IRQ_ROUTING @@ -690,12 +691,21 @@ struct kvm_xen_hvm_config { #endif #define KVM_IRQFD_FLAG_DEASSIGN (1 << 0) +/* + * Available with KVM_CAP_IRQFD_RESAMPLE + * + * KVM_IRQFD_FLAG_RESAMPLE indicates resamplefd is valid and specifies + * the irqfd to operate in resampling mode for level triggered interrupt + * emlation. See Documentation/virtual/kvm/api.txt. + */ +#define KVM_IRQFD_FLAG_RESAMPLE (1 << 1) struct kvm_irqfd { __u32 fd; __u32 gsi; __u32 flags; - __u8 pad[20]; + __u32 resamplefd; + __u8 pad[16]; }; struct kvm_clock_data { diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 80bfc880921e..2850656e2e96 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -119,7 +119,8 @@ static inline bool is_error_page(struct page *page) #define KVM_REQ_PMU 16 #define KVM_REQ_PMI 17 -#define KVM_USERSPACE_IRQ_SOURCE_ID 0 +#define KVM_USERSPACE_IRQ_SOURCE_ID 0 +#define KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID 1 struct kvm; struct kvm_vcpu; @@ -343,6 +344,8 @@ struct kvm { struct { spinlock_t lock; struct list_head items; + struct list_head resampler_list; + struct mutex resampler_lock; } irqfds; struct list_head ioeventfds; #endif diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 7d7e2aaffece..356965c9d107 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -43,6 +43,31 @@ * -------------------------------------------------------------------- */ +/* + * Resampling irqfds are a special variety of irqfds used to emulate + * level triggered interrupts. The interrupt is asserted on eventfd + * trigger. On acknowledgement through the irq ack notifier, the + * interrupt is de-asserted and userspace is notified through the + * resamplefd. All resamplers on the same gsi are de-asserted + * together, so we don't need to track the state of each individual + * user. We can also therefore share the same irq source ID. + */ +struct _irqfd_resampler { + struct kvm *kvm; + /* + * List of resampling struct _irqfd objects sharing this gsi. + * RCU list modified under kvm->irqfds.resampler_lock + */ + struct list_head list; + struct kvm_irq_ack_notifier notifier; + /* + * Entry in list of kvm->irqfd.resampler_list. Use for sharing + * resamplers among irqfds on the same gsi. + * Accessed and modified under kvm->irqfds.resampler_lock + */ + struct list_head link; +}; + struct _irqfd { /* Used for MSI fast-path */ struct kvm *kvm; @@ -52,6 +77,12 @@ struct _irqfd { /* Used for level IRQ fast-path */ int gsi; struct work_struct inject; + /* The resampler used by this irqfd (resampler-only) */ + struct _irqfd_resampler *resampler; + /* Eventfd notified on resample (resampler-only) */ + struct eventfd_ctx *resamplefd; + /* Entry in list of irqfds for a resampler (resampler-only) */ + struct list_head resampler_link; /* Used for setup/shutdown */ struct eventfd_ctx *eventfd; struct list_head list; @@ -67,8 +98,58 @@ irqfd_inject(struct work_struct *work) struct _irqfd *irqfd = container_of(work, struct _irqfd, inject); struct kvm *kvm = irqfd->kvm; - kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1); - kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0); + if (!irqfd->resampler) { + kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1); + kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0); + } else + kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + irqfd->gsi, 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 + * do multiple de-asserts or we risk racing with incoming re-asserts. + */ +static void +irqfd_resampler_ack(struct kvm_irq_ack_notifier *kian) +{ + struct _irqfd_resampler *resampler; + struct _irqfd *irqfd; + + resampler = container_of(kian, struct _irqfd_resampler, notifier); + + kvm_set_irq(resampler->kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + resampler->notifier.gsi, 0); + + rcu_read_lock(); + + list_for_each_entry_rcu(irqfd, &resampler->list, resampler_link) + eventfd_signal(irqfd->resamplefd, 1); + + rcu_read_unlock(); +} + +static void +irqfd_resampler_shutdown(struct _irqfd *irqfd) +{ + struct _irqfd_resampler *resampler = irqfd->resampler; + struct kvm *kvm = resampler->kvm; + + mutex_lock(&kvm->irqfds.resampler_lock); + + list_del_rcu(&irqfd->resampler_link); + synchronize_rcu(); + + if (list_empty(&resampler->list)) { + list_del(&resampler->link); + kvm_unregister_irq_ack_notifier(kvm, &resampler->notifier); + kvm_set_irq(kvm, KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID, + resampler->notifier.gsi, 0); + kfree(resampler); + } + + mutex_unlock(&kvm->irqfds.resampler_lock); } /* @@ -92,6 +173,11 @@ irqfd_shutdown(struct work_struct *work) */ flush_work_sync(&irqfd->inject); + if (irqfd->resampler) { + irqfd_resampler_shutdown(irqfd); + eventfd_ctx_put(irqfd->resamplefd); + } + /* * It is now safe to release the object's resources */ @@ -203,7 +289,7 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) struct kvm_irq_routing_table *irq_rt; struct _irqfd *irqfd, *tmp; struct file *file = NULL; - struct eventfd_ctx *eventfd = NULL; + struct eventfd_ctx *eventfd = NULL, *resamplefd = NULL; int ret; unsigned int events; @@ -231,6 +317,54 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) irqfd->eventfd = eventfd; + if (args->flags & KVM_IRQFD_FLAG_RESAMPLE) { + struct _irqfd_resampler *resampler; + + resamplefd = eventfd_ctx_fdget(args->resamplefd); + if (IS_ERR(resamplefd)) { + ret = PTR_ERR(resamplefd); + goto fail; + } + + irqfd->resamplefd = resamplefd; + INIT_LIST_HEAD(&irqfd->resampler_link); + + mutex_lock(&kvm->irqfds.resampler_lock); + + list_for_each_entry(resampler, + &kvm->irqfds.resampler_list, list) { + if (resampler->notifier.gsi == irqfd->gsi) { + irqfd->resampler = resampler; + break; + } + } + + if (!irqfd->resampler) { + resampler = kzalloc(sizeof(*resampler), GFP_KERNEL); + if (!resampler) { + ret = -ENOMEM; + mutex_unlock(&kvm->irqfds.resampler_lock); + goto fail; + } + + resampler->kvm = kvm; + INIT_LIST_HEAD(&resampler->list); + resampler->notifier.gsi = irqfd->gsi; + resampler->notifier.irq_acked = irqfd_resampler_ack; + INIT_LIST_HEAD(&resampler->link); + + list_add(&resampler->link, &kvm->irqfds.resampler_list); + kvm_register_irq_ack_notifier(kvm, + &resampler->notifier); + irqfd->resampler = resampler; + } + + list_add_rcu(&irqfd->resampler_link, &irqfd->resampler->list); + synchronize_rcu(); + + mutex_unlock(&kvm->irqfds.resampler_lock); + } + /* * Install our own custom wake-up handling so we are notified via * a callback whenever someone signals the underlying eventfd @@ -276,6 +410,12 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) return 0; fail: + if (irqfd->resampler) + irqfd_resampler_shutdown(irqfd); + + if (resamplefd && !IS_ERR(resamplefd)) + eventfd_ctx_put(resamplefd); + if (eventfd && !IS_ERR(eventfd)) eventfd_ctx_put(eventfd); @@ -291,6 +431,8 @@ kvm_eventfd_init(struct kvm *kvm) { spin_lock_init(&kvm->irqfds.lock); INIT_LIST_HEAD(&kvm->irqfds.items); + INIT_LIST_HEAD(&kvm->irqfds.resampler_list); + mutex_init(&kvm->irqfds.resampler_lock); INIT_LIST_HEAD(&kvm->ioeventfds); } @@ -340,7 +482,7 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args) int kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args) { - if (args->flags & ~KVM_IRQFD_FLAG_DEASSIGN) + if (args->flags & ~(KVM_IRQFD_FLAG_DEASSIGN | KVM_IRQFD_FLAG_RESAMPLE)) return -EINVAL; if (args->flags & KVM_IRQFD_FLAG_DEASSIGN) diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c index 3ca89c451d6b..2eb58af7ee99 100644 --- a/virt/kvm/irq_comm.c +++ b/virt/kvm/irq_comm.c @@ -228,6 +228,9 @@ int kvm_request_irq_source_id(struct kvm *kvm) } ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID); +#ifdef CONFIG_X86 + ASSERT(irq_source_id != KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID); +#endif set_bit(irq_source_id, bitmap); unlock: mutex_unlock(&kvm->irq_lock); @@ -238,6 +241,9 @@ unlock: void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id) { ASSERT(irq_source_id != KVM_USERSPACE_IRQ_SOURCE_ID); +#ifdef CONFIG_X86 + ASSERT(irq_source_id != KVM_IRQFD_RESAMPLE_IRQ_SOURCE_ID); +#endif mutex_lock(&kvm->irq_lock); if (irq_source_id < 0 || |