To support VFIO based device assignment, we need to be able to get
an EOI out of the KVM irqchip. This introduces a mechanism to do
that by registering an eventfd to be signaled when the IRQ is ACKed.
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
include/linux/kvm.h | 13 ++++++
include/linux/kvm_host.h | 6 +++
virt/kvm/eventfd.c | 95 ++++++++++++++++++++++++++++++++++++++++++++++
virt/kvm/kvm_main.c | 8 ++++
4 files changed, 122 insertions(+), 0 deletions(-)
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index ea2dc1a..92d5b27 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -541,6 +541,7 @@ struct kvm_ppc_pvinfo {
#define KVM_CAP_PPC_GET_PVINFO 57
#define KVM_CAP_PPC_IRQ_LEVEL 58
#define KVM_CAP_ASYNC_PF 59
+#define KVM_CAP_EOI_EVENTFD 60
#ifdef KVM_CAP_IRQ_ROUTING
@@ -620,6 +621,16 @@ struct kvm_clock_data {
__u32 pad[9];
};
+#define KVM_EOI_EVENTFD_FLAG_DEASSIGN (1 << 0)
+#define KVM_EOI_EVENTFD_FLAG_DEASSERT (1 << 1)
+
+struct kvm_eoi {
+ __u32 fd;
+ __u32 gsi;
+ __u32 flags;
+ __u8 pad[20];
+};
+
/*
* ioctls for VM fds
*/
@@ -677,6 +688,8 @@ struct kvm_clock_data {
#define KVM_SET_PIT2 _IOW(KVMIO, 0xa0, struct kvm_pit_state2)
/* Available with KVM_CAP_PPC_GET_PVINFO */
#define KVM_PPC_GET_PVINFO _IOW(KVMIO, 0xa1, struct kvm_ppc_pvinfo)
+/* Available with KVM_CAP_EOI_EVENTFD */
+#define KVM_EOI_EVENTFD _IOW(KVMIO, 0xa2, struct kvm_eoi)
/*
* ioctls for vcpu fds
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ee4314e..5d50a7e 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -227,6 +227,7 @@ struct kvm {
struct list_head items;
} irqfds;
struct list_head ioeventfds;
+ struct list_head eoi_eventfds;
#endif
struct kvm_vm_stat stat;
struct kvm_arch arch;
@@ -643,6 +644,7 @@ void kvm_eventfd_init(struct kvm *kvm);
int kvm_irqfd(struct kvm *kvm, int fd, int gsi, int flags);
void kvm_irqfd_release(struct kvm *kvm);
int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args);
+int kvm_eoi_eventfd(struct kvm *kvm, struct kvm_eoi *eoi);
#else
@@ -658,6 +660,10 @@ static inline int kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
return -ENOSYS;
}
+static inline int kvm_eoi_eventfd(struct kvm *kvm, struct kvm_eoi *eoi)
+{
+ return -ENOSYS;
+}
#endif /* CONFIG_HAVE_KVM_EVENTFD */
#ifdef CONFIG_KVM_APIC_ARCHITECTURE
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index c1f1e3c..3dbfb21 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -253,6 +253,7 @@ kvm_eventfd_init(struct kvm *kvm)
spin_lock_init(&kvm->irqfds.lock);
INIT_LIST_HEAD(&kvm->irqfds.items);
INIT_LIST_HEAD(&kvm->ioeventfds);
+ INIT_LIST_HEAD(&kvm->eoi_eventfds);
}
/*
@@ -586,3 +587,97 @@ kvm_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args)
return kvm_assign_ioeventfd(kvm, args);
}
+
+/*
+ * --------------------------------------------------------------------
+ * eoi_eventfd: Translate KVM APIC/IOAPIC EOI into eventfd signal.
+ *
+ * userspace can register GSIs with an eventfd for receiving notification
+ * when an EOI occurs.
+ * --------------------------------------------------------------------
+ */
+
+struct _eoi_eventfd {
+ struct list_head list;
+ struct kvm *kvm;
+ struct eventfd_ctx *eventfd;
+ bool deassert;
+ struct kvm_irq_ack_notifier notifier;
+};
+
+static void kvm_eoi_eventfd_acked(struct kvm_irq_ack_notifier *notifier)
+{
+ struct _eoi_eventfd *p;
+
+ p = container_of(notifier, struct _eoi_eventfd, notifier);
+
+ if (p->deassert)
+ kvm_set_irq(p->kvm, KVM_USERSPACE_IRQ_SOURCE_ID,
+ notifier->gsi, 0);
+
+ eventfd_signal(p->eventfd, 1);
+}
+
+static int kvm_assign_eoi_eventfd(struct kvm *kvm, struct kvm_eoi *eoi)
+{
+ struct eventfd_ctx *eventfd;
+ struct _eoi_eventfd *p;
+
+ eventfd = eventfd_ctx_fdget(eoi->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p) {
+ eventfd_ctx_put(eventfd);
+ return -ENOMEM;
+ }
+
+ INIT_LIST_HEAD(&p->list);
+ p->kvm = kvm;
+ p->eventfd = eventfd;
+ p->deassert = !!(eoi->flags & KVM_EOI_EVENTFD_FLAG_DEASSERT);
+
+ p->notifier.gsi = eoi->gsi;
+ p->notifier.irq_acked = kvm_eoi_eventfd_acked;
+
+ list_add_tail(&p->list, &kvm->eoi_eventfds);
+ kvm_register_irq_ack_notifier(kvm, &p->notifier);
+
+ return 0;
+}
+
+static int kvm_deassign_eoi_eventfd(struct kvm *kvm, struct kvm_eoi *eoi)
+{
+ struct eventfd_ctx *eventfd;
+ struct _eoi_eventfd *p, *tmp;
+ int ret = -ENOENT;
+
+ eventfd = eventfd_ctx_fdget(eoi->fd);
+ if (IS_ERR(eventfd))
+ return PTR_ERR(eventfd);
+
+ list_for_each_entry_safe(p, tmp, &kvm->eoi_eventfds, list) {
+ if (p->eventfd != eventfd || p->notifier.gsi != eoi->gsi)
+ continue;
+
+ kvm_unregister_irq_ack_notifier(kvm, &p->notifier);
+ eventfd_ctx_put(p->eventfd);
+ list_del(&p->list);
+ kfree(p);
+ ret = 0;
+ break;
+ }
+
+ eventfd_ctx_put(eventfd);
+
+ return ret;
+}
+
+int kvm_eoi_eventfd(struct kvm *kvm, struct kvm_eoi *eoi)
+{
+ if (eoi->flags & KVM_EOI_EVENTFD_FLAG_DEASSIGN)
+ return kvm_deassign_eoi_eventfd(kvm, eoi);
+
+ return kvm_assign_eoi_eventfd(kvm, eoi);
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 88d869e..7ca6f13 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1807,6 +1807,14 @@ static long kvm_vm_ioctl(struct file *filp,
mutex_unlock(&kvm->lock);
break;
#endif
+ case KVM_EOI_EVENTFD: {
+ struct kvm_eoi eoi;
+ r = -EFAULT;
+ if (copy_from_user(&eoi, argp, sizeof eoi))
+ goto out;
+ r = kvm_eoi_eventfd(kvm, &eoi);
+ break;
+ }
default:
r = kvm_arch_vm_ioctl(filp, ioctl, arg);
if (r == -ENOTTY)
--
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