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>

2 files changed, 35 insertions, 0 deletions

diff --git a/target-s390x/cpu.h b/target-s390x/cpu.h
index 0ce82cf830..918c819c64 100644
--- a/target-s390x/cpu.h
+++ b/target-s390x/cpu.h
@@ -1081,6 +1081,7 @@ void kvm_s390_io_interrupt(S390CPU *cpu, uint16_t subchannel_id,
 void kvm_s390_crw_mchk(S390CPU *cpu);
 void kvm_s390_enable_css_support(S390CPU *cpu);
 int kvm_s390_get_registers_partial(CPUState *cpu);
+int kvm_s390_assign_subch_ioeventfd(int fd, uint32_t sch, int vq, bool assign);
 #else
 static inline void kvm_s390_io_interrupt(S390CPU *cpu,
                                         uint16_t subchannel_id,
@@ -1099,6 +1100,11 @@ static inline int kvm_s390_get_registers_partial(CPUState *cpu)
 {
     return -ENOSYS;
 }
+static inline int kvm_s390_assign_subch_ioeventfd(int fd, uint32_t sch, int vq,
+                                                  bool assign)
+{
+    return -ENOSYS;
+}
 #endif
 
 static inline void s390_io_interrupt(S390CPU *cpu,
@@ -1125,4 +1131,14 @@ static inline void s390_crw_mchk(S390CPU *cpu)
     }
 }
 
+static inline int s390_assign_subch_ioeventfd(int fd, uint32_t sch_id, int vq,
+                                              bool assign)
+{
+    if (kvm_enabled()) {
+        return kvm_s390_assign_subch_ioeventfd(fd, sch_id, vq, assign);
+    } else {
+        return -ENOSYS;
+    }
+}
+
 #endif
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);
+}