In order to inject an interrupt from an external source using an irqfd, we need to allocate a new irq_source_id. This allows us to assert and (later) de-assert an interrupt line independently from users of KVM_IRQ_LINE and avoid lost interrupts.
We also add what may appear like a bit of excessive infrastructure around an object for storing this irq_source_id. However, notice that we only provide a way to assert the interrupt here. A follow-on interface will make use of the same irq_source_id to allow de-assert. Signed-off-by: Alex Williamson <[email protected]> --- Documentation/virtual/kvm/api.txt | 5 ++ arch/x86/kvm/x86.c | 1 include/linux/kvm.h | 3 + virt/kvm/eventfd.c | 95 +++++++++++++++++++++++++++++++++++-- 4 files changed, 99 insertions(+), 5 deletions(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index ea9edce..b216709 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -1981,6 +1981,11 @@ 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_IRQFD_FLAG_LEVEL KVM_IRQFD allocates a new IRQ source ID for +the requested irqfd. This is necessary to share level triggered +interrupts with those injected through KVM_IRQ_LINE. IRQFDs created +with KVM_IRQFD_FLAG_LEVEL must also set this flag when de-assiging. +KVM_IRQFD_FLAG_LEVEL support is indicated by KVM_CAP_IRQFD_LEVEL. 5. The kvm_run structure ------------------------ diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a01a424..80bed07 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2148,6 +2148,7 @@ int kvm_dev_ioctl_check_extension(long ext) case KVM_CAP_GET_TSC_KHZ: case KVM_CAP_PCI_2_3: case KVM_CAP_KVMCLOCK_CTRL: + case KVM_CAP_IRQFD_LEVEL: r = 1; break; case KVM_CAP_COALESCED_MMIO: diff --git a/include/linux/kvm.h b/include/linux/kvm.h index 2ce09aa..b2e6e4f 100644 --- a/include/linux/kvm.h +++ b/include/linux/kvm.h @@ -618,6 +618,7 @@ struct kvm_ppc_smmu_info { #define KVM_CAP_PPC_GET_SMMU_INFO 78 #define KVM_CAP_S390_COW 79 #define KVM_CAP_PPC_ALLOC_HTAB 80 +#define KVM_CAP_IRQFD_LEVEL 81 #ifdef KVM_CAP_IRQ_ROUTING @@ -683,6 +684,8 @@ struct kvm_xen_hvm_config { #endif #define KVM_IRQFD_FLAG_DEASSIGN (1 << 0) +/* Available with KVM_CAP_IRQFD_LEVEL */ +#define KVM_IRQFD_FLAG_LEVEL (1 << 1) struct kvm_irqfd { __u32 fd; diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 7d7e2aa..18cc284 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -36,6 +36,64 @@ #include "iodev.h" /* + * An irq_source_id can be created from KVM_IRQFD for level interrupt + * injections and shared with other interfaces for EOI or de-assert. + * Create an object with reference counting to make it easy to use. + */ +struct _irq_source { + int id; + struct kvm *kvm; + struct kref kref; +}; + +static void release_irq_source(struct kref *kref) +{ + struct _irq_source *source; + + source = container_of(kref, struct _irq_source, kref); + + kvm_free_irq_source_id(source->kvm, source->id); + kfree(source); +} + +static void put_irq_source(struct _irq_source *source) +{ + if (source) + kref_put(&source->kref, release_irq_source); +} + +static struct _irq_source *__attribute__ ((used)) /* white lie for now */ +get_irq_source(struct _irq_source *source) +{ + if (source) + kref_get(&source->kref); + + return source; +} + +static struct _irq_source *new_irq_source(struct kvm *kvm) +{ + struct _irq_source *source; + int id; + + source = kzalloc(sizeof(*source), GFP_KERNEL); + if (!source) + return ERR_PTR(-ENOMEM); + + id = kvm_request_irq_source_id(kvm); + if (id < 0) { + kfree(source); + return ERR_PTR(id); + } + + kref_init(&source->kref); + source->kvm = kvm; + source->id = id; + + return source; +} + +/* * -------------------------------------------------------------------- * irqfd: Allows an fd to be used to inject an interrupt to the guest * @@ -52,6 +110,7 @@ struct _irqfd { /* Used for level IRQ fast-path */ int gsi; struct work_struct inject; + struct _irq_source *source; /* Used for setup/shutdown */ struct eventfd_ctx *eventfd; struct list_head list; @@ -62,7 +121,7 @@ struct _irqfd { static struct workqueue_struct *irqfd_cleanup_wq; static void -irqfd_inject(struct work_struct *work) +irqfd_inject_edge(struct work_struct *work) { struct _irqfd *irqfd = container_of(work, struct _irqfd, inject); struct kvm *kvm = irqfd->kvm; @@ -71,6 +130,14 @@ irqfd_inject(struct work_struct *work) kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0); } +static void +irqfd_inject_level(struct work_struct *work) +{ + struct _irqfd *irqfd = container_of(work, struct _irqfd, inject); + + kvm_set_irq(irqfd->kvm, irqfd->source->id, irqfd->gsi, 1); +} + /* * Race-free decouple logic (ordering is critical) */ @@ -96,6 +163,9 @@ irqfd_shutdown(struct work_struct *work) * It is now safe to release the object's resources */ eventfd_ctx_put(irqfd->eventfd); + + put_irq_source(irqfd->source); + kfree(irqfd); } @@ -214,7 +284,19 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args) irqfd->kvm = kvm; irqfd->gsi = args->gsi; INIT_LIST_HEAD(&irqfd->list); - INIT_WORK(&irqfd->inject, irqfd_inject); + + if (args->flags & KVM_IRQFD_FLAG_LEVEL) { + irqfd->source = new_irq_source(kvm); + if (IS_ERR(irqfd->source)) { + ret = PTR_ERR(irqfd->source); + irqfd->source = NULL; + goto fail; + } + + INIT_WORK(&irqfd->inject, irqfd_inject_level); + } else + INIT_WORK(&irqfd->inject, irqfd_inject_edge); + INIT_WORK(&irqfd->shutdown, irqfd_shutdown); file = eventfd_fget(args->fd); @@ -279,9 +361,10 @@ fail: if (eventfd && !IS_ERR(eventfd)) eventfd_ctx_put(eventfd); - if (!IS_ERR(file)) + if (file && !IS_ERR(file)) fput(file); + put_irq_source(irqfd->source); kfree(irqfd); return ret; } @@ -302,6 +385,7 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args) { struct _irqfd *irqfd, *tmp; struct eventfd_ctx *eventfd; + bool is_level = (args->flags & KVM_IRQFD_FLAG_LEVEL) != 0; eventfd = eventfd_ctx_fdget(args->fd); if (IS_ERR(eventfd)) @@ -310,7 +394,8 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args) spin_lock_irq(&kvm->irqfds.lock); list_for_each_entry_safe(irqfd, tmp, &kvm->irqfds.items, list) { - if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi) { + if (irqfd->eventfd == eventfd && irqfd->gsi == args->gsi && + is_level == (irqfd->source != NULL)) { /* * This rcu_assign_pointer is needed for when * another thread calls kvm_irq_routing_update before @@ -340,7 +425,7 @@ 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_LEVEL)) return -EINVAL; if (args->flags & KVM_IRQFD_FLAG_DEASSIGN) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
