KVM: s390: only reset CMMA state if it was enabled before

There is no point in resetting the CMMA state if it was never enabled.
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/kvm-s390.c

@@ -344,6 +344,10 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att
 		mutex_unlock(&kvm->lock);
 		break;
 	case KVM_S390_VM_MEM_CLR_CMMA:
+		ret = -EINVAL;
+		if (!kvm->arch.use_cmma)
+			break;
+
 		mutex_lock(&kvm->lock);
 		idx = srcu_read_lock(&kvm->srcu);
 		s390_reset_cmma(kvm->arch.gmap->mm);