KVM: s390: KVM_GET/SET_ONEREG for s390

This patch enables KVM_CAP_ONE_REG for s390 and implements stubs
for KVM_GET/SET_ONE_REG. This is based on the ppc implementation.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/s390/kvm/kvm-s390.c

@@ -135,6 +135,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_S390_UCONTROL:
 #endif
 	case KVM_CAP_SYNC_REGS:
+	case KVM_CAP_ONE_REG:
 		r = 1;
 		break;
 	case KVM_CAP_NR_VCPUS:
@@ -439,6 +440,31 @@ int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+static int kvm_arch_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
+					   struct kvm_one_reg *reg)
+{
+	int r = -EINVAL;
+
+	switch (reg->id) {
+	default:
+		break;
+	}
+
+	return r;
+}
+
+static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
+					   struct kvm_one_reg *reg)
+{
+	int r = -EINVAL;
+
+	switch (reg->id) {
+	default:
+		break;
+	}
+
+	return r;
+}
 
 static int kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
 {
@@ -770,6 +796,18 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 	case KVM_S390_INITIAL_RESET:
 		r = kvm_arch_vcpu_ioctl_initial_reset(vcpu);
 		break;
+	case KVM_SET_ONE_REG:
+	case KVM_GET_ONE_REG: {
+		struct kvm_one_reg reg;
+		r = -EFAULT;
+		if (copy_from_user(&reg, argp, sizeof(reg)))
+			break;
+		if (ioctl == KVM_SET_ONE_REG)
+			r = kvm_arch_vcpu_ioctl_set_one_reg(vcpu, &reg);
+		else
+			r = kvm_arch_vcpu_ioctl_get_one_reg(vcpu, &reg);
+		break;
+	}
 #ifdef CONFIG_KVM_S390_UCONTROL
 	case KVM_S390_UCAS_MAP: {
 		struct kvm_s390_ucas_mapping ucasmap;