This new ioctl enables an eventfd to be triggered when an EOI is
written for a specified irqchip pin. By default this is a simple
notification, but we can also tie the eoifd to a level irqfd, which
enables the irqchip pin to be automatically de-asserted on EOI.
This mode is particularly useful for device-assignment applications
where the unmask and notify triggers a hardware unmask. The default
mode is most applicable to simple notify with no side-effects for
userspace usage, such as Qemu.
Here we make use of the reference counting of the _irq_source
object allowing us to share it with an irqfd and cleanup regardless
of the release order.
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
Documentation/virtual/kvm/api.txt | 21 ++++
arch/x86/kvm/x86.c | 1
include/linux/kvm.h | 14 ++
include/linux/kvm_host.h | 13 ++
virt/kvm/eventfd.c | 208 +++++++++++++++++++++++++++++++++++++
virt/kvm/kvm_main.c | 11 ++
6 files changed, 266 insertions(+), 2 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c7267d5..a38af14 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1988,6 +1988,27 @@ to independently assert level interrupts. The KVM_IRQFD_FLAG_LEVEL
is only necessary on setup, teardown is identical to that above.
KVM_IRQFD_FLAG_LEVEL support is indicated by KVM_CAP_IRQFD_LEVEL.
+4.77 KVM_EOIFD
+
+Capability: KVM_CAP_EOIFD
+Architectures: x86
+Type: vm ioctl
+Parameters: struct kvm_eoifd (in)
+Returns: 0 on success, -1 on error
+
+KVM_EOIFD allows userspace to receive interrupt EOI notification
+through an eventfd. kvm_eoifd.fd specifies the eventfd used for
+notification and kvm_eoifd.gsi specifies the irchip pin, similar to
+KVM_IRQFD. The eoifd is removed using the KVM_EOIFD_FLAG_DEASSIGN
+flag, specifying both kvm_eoifd.fd and kvm_eoifd.gsi.
+
+The KVM_EOIFD_FLAG_LEVEL_IRQFD flag indicates that the provided
+kvm_eoifd stucture includes a valid kvm_eoifd.irqfd file descriptor
+for a level irqfd configured using the KVM_IRQFD_FLAG_LEVEL flag.
+In this mode the level interrupt is de-asserted prior to EOI eventfd
+notification. The KVM_EOIFD_FLAG_LEVEL_IRQFD is only necessary on
+setup, teardown is identical to that above.
+
5. The kvm_run structure
------------------------
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 80bed07..62d6eca 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2149,6 +2149,7 @@ int kvm_dev_ioctl_check_extension(long ext)
case KVM_CAP_PCI_2_3:
case KVM_CAP_KVMCLOCK_CTRL:
case KVM_CAP_IRQFD_LEVEL:
+ case KVM_CAP_EOIFD:
r = 1;
break;
case KVM_CAP_COALESCED_MMIO:
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index b2e6e4f..7567e7d 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -619,6 +619,7 @@ struct kvm_ppc_smmu_info {
#define KVM_CAP_S390_COW 79
#define KVM_CAP_PPC_ALLOC_HTAB 80
#define KVM_CAP_IRQFD_LEVEL 81
+#define KVM_CAP_EOIFD 82
#ifdef KVM_CAP_IRQ_ROUTING
@@ -694,6 +695,17 @@ struct kvm_irqfd {
__u8 pad[20];
};
+#define KVM_EOIFD_FLAG_DEASSIGN (1 << 0)
+#define KVM_EOIFD_FLAG_LEVEL_IRQFD (1 << 1)
+
+struct kvm_eoifd {
+ __u32 fd;
+ __u32 gsi;
+ __u32 flags;
+ __u32 irqfd;
+ __u8 pad[16];
+};
+
struct kvm_clock_data {
__u64 clock;
__u32 flags;
@@ -834,6 +846,8 @@ struct kvm_s390_ucas_mapping {
#define KVM_PPC_GET_SMMU_INFO _IOR(KVMIO, 0xa6, struct kvm_ppc_smmu_info)
/* Available with KVM_CAP_PPC_ALLOC_HTAB */
#define KVM_PPC_ALLOCATE_HTAB _IOWR(KVMIO, 0xa7, __u32)
+/* Available with KVM_CAP_EOIFD */
+#define KVM_EOIFD _IOW(KVMIO, 0xa8, struct kvm_eoifd)
/*
* ioctls for vcpu fds
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ae3b426..83472eb 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -285,6 +285,10 @@ struct kvm {
struct list_head items;
} irqfds;
struct list_head ioeventfds;
+ struct {
+ spinlock_t lock;
+ struct list_head items;
+ } eoifds;
#endif
struct kvm_vm_stat stat;
struct kvm_arch arch;
@@ -828,6 +832,8 @@ int kvm_irqfd(struct kvm *kvm, struct kvm_irqfd *args);
void kvm_irqfd_release(struct kvm *kvm);
void kvm_irq_routing_update(struct kvm *, struct kvm_irq_routing_table *);
int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args);
+int kvm_eoifd(struct kvm *kvm, struct kvm_eoifd *args);
+void kvm_eoifd_release(struct kvm *kvm);
#else
@@ -853,6 +859,13 @@ static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
return -ENOSYS;
}
+static inline int kvm_eoifd(struct kvm *kvm, struct kvm_eoifd *args)
+{
+ return -ENOSYS;
+}
+
+static inline void kvm_eoifd_release(struct kvm *kvm) {}
+
#endif /* CONFIG_HAVE_KVM_EVENTFD */
#ifdef CONFIG_KVM_APIC_ARCHITECTURE
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index 92aa5ba..2bc9768 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -62,8 +62,7 @@ static void _irq_source_put(struct _irq_source *source)
kref_put(&source->kref, _irq_source_release);
}
-static struct _irq_source *__attribute__ ((used)) /* white lie for now */
-_irq_source_get(struct _irq_source *source)
+static struct _irq_source *_irq_source_get(struct _irq_source *source)
{
if (source)
kref_get(&source->kref);
@@ -119,6 +118,39 @@ struct _irqfd {
struct work_struct shutdown;
};
+static struct _irqfd *_irqfd_fdget(struct kvm *kvm, int fd)
+{
+ struct eventfd_ctx *eventfd;
+ struct _irqfd *tmp, *irqfd = NULL;
+
+ eventfd = eventfd_ctx_fdget(fd);
+ if (IS_ERR(eventfd))
+ return (struct _irqfd *)eventfd;
+
+ spin_lock_irq(&kvm->irqfds.lock);
+
+ list_for_each_entry(tmp, &kvm->irqfds.items, list) {
+ if (tmp->eventfd == eventfd) {
+ irqfd = tmp;
+ break;
+ }
+ }
+
+ spin_unlock_irq(&kvm->irqfds.lock);
+
+ if (!irqfd) {
+ eventfd_ctx_put(eventfd);
+ return ERR_PTR(-ENODEV);
+ }
+
+ return irqfd;
+}
+
+static void _irqfd_put(struct _irqfd *irqfd)
+{
+ eventfd_ctx_put(irqfd->eventfd);
+}
+
static struct workqueue_struct *irqfd_cleanup_wq;
static void
@@ -387,6 +419,8 @@ kvm_eventfd_init(struct kvm *kvm)
spin_lock_init(&kvm->irqfds.lock);
INIT_LIST_HEAD(&kvm->irqfds.items);
INIT_LIST_HEAD(&kvm->ioeventfds);
+ spin_lock_init(&kvm->eoifds.lock);
+ INIT_LIST_HEAD(&kvm->eoifds.items);
}
/*
@@ -753,3 +787,173 @@ kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
return kvm_assign_ioeventfd(kvm, args);
}
+
+/*
+ * --------------------------------------------------------------------
+ * eoifd: Translate KVM APIC/IOAPIC EOI into eventfd signal.
+ *
+ * userspace can register GSIs with an eventfd for receiving
+ * notification when an EOI occurs.
+ * --------------------------------------------------------------------
+ */
+
+struct _eoifd {
+ struct eventfd_ctx *eventfd;
+ struct _irq_source *source; /* for de-asserting level irqfd */
+ struct kvm *kvm;
+ struct kvm_irq_ack_notifier notifier;
+ struct list_head list;
+};
+
+static void eoifd_event(struct kvm_irq_ack_notifier *notifier)
+{
+ struct _eoifd *eoifd;
+
+ eoifd = container_of(notifier, struct _eoifd, notifier);
+
+ /*
+ * If the eoifd is tied to a level irqfd we de-assert it here.
+ * The user is responsible for re-asserting it if their device
+ * still needs attention. For notification-only, skip this.
+ */
+ if (eoifd->source)
+ kvm_set_irq(eoifd->kvm, eoifd->source->id,
+ eoifd->notifier.gsi, 0);
+
+ eventfd_signal(eoifd->eventfd, 1);
+}
+
+static int kvm_assign_eoifd(struct kvm *kvm, struct kvm_eoifd *args)
+{
+ struct eventfd_ctx *eventfd;
+ struct _eoifd *eoifd, *tmp;
+ struct _irq_source *source = NULL;
+
+ if (args->flags & KVM_EOIFD_FLAG_LEVEL_IRQFD) {
+ struct _irqfd *irqfd = _irqfd_fdget(kvm, args->irqfd);
+ if (IS_ERR(irqfd))
+ return PTR_ERR(irqfd);
+
+ if (irqfd->gsi != args->gsi) {
+ _irqfd_put(irqfd);
+ return -EINVAL;
+ }
+
+ source = _irq_source_get(irqfd->source);
+ _irqfd_put(irqfd);
+ if (!source)
+ return -EINVAL;
+ }
+
+ eventfd = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(eventfd)) {
+ _irq_source_put(source);
+ return PTR_ERR(eventfd);
+ }
+
+ eoifd = kzalloc(sizeof(*eoifd), GFP_KERNEL);
+ if (!eoifd) {
+ _irq_source_put(source);
+ eventfd_ctx_put(eventfd);
+ return -ENOMEM;
+ }
+
+ INIT_LIST_HEAD(&eoifd->list);
+ eoifd->kvm = kvm;
+ eoifd->eventfd = eventfd;
+ eoifd->source = source;
+ eoifd->notifier.gsi = args->gsi;
+ eoifd->notifier.irq_acked = eoifd_event;
+
+ spin_lock_irq(&kvm->eoifds.lock);
+
+ list_for_each_entry(tmp, &kvm->eoifds.items, list) {
+ if (eoifd->eventfd != tmp->eventfd)
+ continue;
+
+ spin_unlock_irq(&kvm->eoifds.lock);
+ _irq_source_put(source);
+ eventfd_ctx_put(eventfd);
+ kfree(eoifd);
+ return -EBUSY;
+ }
+
+ list_add_tail(&eoifd->list, &kvm->eoifds.items);
+
+ spin_unlock_irq(&kvm->eoifds.lock);
+
+ kvm_register_irq_ack_notifier(kvm, &eoifd->notifier);
+
+ return 0;
+}
+
+static void eoifd_deactivate(struct kvm *kvm, struct _eoifd *eoifd)
+{
+ kvm_unregister_irq_ack_notifier(kvm, &eoifd->notifier);
+ _irq_source_put(eoifd->source);
+ eventfd_ctx_put(eoifd->eventfd);
+ kfree(eoifd);
+}
+
+void kvm_eoifd_release(struct kvm *kvm)
+{
+ spin_lock_irq(&kvm->eoifds.lock);
+
+ while (!list_empty(&kvm->eoifds.items)) {
+ struct _eoifd *eoifd;
+
+ eoifd = list_first_entry(&kvm->eoifds.items,
+ struct _eoifd, list);
+ list_del(&eoifd->list);
+
+ /* Drop spinlocks since eoifd_deactivate can sleep */
+ spin_unlock_irq(&kvm->eoifds.lock);
+ eoifd_deactivate(kvm, eoifd);
+ spin_lock_irq(&kvm->eoifds.lock);
+ }
+
+ spin_unlock_irq(&kvm->eoifds.lock);
+}
+
+static int kvm_deassign_eoifd(struct kvm *kvm, struct kvm_eoifd *args)
+{
+ struct eventfd_ctx *eventfd;
+ struct _eoifd *tmp, *eoifd = NULL;
+
+ eventfd = eventfd_ctx_fdget(args->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ spin_lock_irq(&kvm->eoifds.lock);
+
+ list_for_each_entry(tmp, &kvm->eoifds.items, list) {
+ if (tmp->eventfd == eventfd && tmp->notifier.gsi == args->gsi) {
+ eoifd = tmp;
+ list_del(&eoifd->list);
+ break;
+ }
+ }
+
+ spin_unlock_irq(&kvm->eoifds.lock);
+
+ eventfd_ctx_put(eventfd);
+
+ if (!eoifd)
+ return -ENOENT;
+
+ eoifd_deactivate(kvm, eoifd);
+
+ return 0;
+}
+
+int kvm_eoifd(struct kvm *kvm, struct kvm_eoifd *args)
+{
+ if (args->flags & ~(KVM_EOIFD_FLAG_DEASSIGN |
+ KVM_EOIFD_FLAG_LEVEL_IRQFD))
+ return -EINVAL;
+
+ if (args->flags & KVM_EOIFD_FLAG_DEASSIGN)
+ return kvm_deassign_eoifd(kvm, args);
+
+ return kvm_assign_eoifd(kvm, args);
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b4ad14cc..5b41df1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -620,6 +620,8 @@ static int kvm_vm_release(struct inode *inode, struct file *filp)
kvm_irqfd_release(kvm);
+ kvm_eoifd_release(kvm);
+
kvm_put_kvm(kvm);
return 0;
}
@@ -2093,6 +2095,15 @@ static long kvm_vm_ioctl(struct file *filp,
break;
}
#endif
+ case KVM_EOIFD: {
+ struct kvm_eoifd data;
+
+ r = -EFAULT;
+ if (copy_from_user(&data, argp, sizeof data))
+ goto out;
+ r = kvm_eoifd(kvm, &data);
+ break;
+ }
default:
r = kvm_arch_vm_ioctl(filp, ioctl, arg);
if (r == -ENOTTY)
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