virtio-ccw: Wire up ioeventfd.

On hosts that support ioeventfd, make use of it for host-to-guest
notifications via diagnose 500.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
index 4d9ac4ad0c..650d3a5da9 100644
--- a/target-s390x/kvm.c
+++ b/target-s390x/kvm.c
@@ -932,3 +932,22 @@ void kvm_s390_enable_css_support(S390CPU *cpu)
 void kvm_arch_init_irq_routing(KVMState *s)
 {
 }
+
+int kvm_s390_assign_subch_ioeventfd(int fd, uint32_t sch, int vq, bool assign)
+{
+    struct kvm_ioeventfd kick = {
+        .flags = KVM_IOEVENTFD_FLAG_VIRTIO_CCW_NOTIFY |
+        KVM_IOEVENTFD_FLAG_DATAMATCH,
+        .fd = fd,
+        .datamatch = vq,
+        .addr = sch,
+        .len = 8,
+    };
+    if (!kvm_check_extension(kvm_state, KVM_CAP_IOEVENTFD)) {
+        return -ENOSYS;
+    }
+    if (!assign) {
+        kick.flags |= KVM_IOEVENTFD_FLAG_DEASSIGN;
+    }
+    return kvm_vm_ioctl(kvm_state, KVM_IOEVENTFD, &kick);
+}