2 files changed, 23 insertions, 13 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index c5f51566ecd6..3369677a7df7 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -711,6 +711,7 @@ struct s390_io_adapter {
 struct kvm_s390_cpu_model {
         /* facility mask supported by kvm & hosting machine */
         __u64 fac_mask[S390_ARCH_FAC_LIST_SIZE_U64];
+        struct kvm_s390_vm_cpu_subfunc subfuncs;
         /* facility list requested by guest (in dma page) */
         __u64 *fac_list;
         u64 cpuid;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 2e47c724679e..82a95afa6629 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1266,11 +1266,20 @@ static int kvm_s390_set_processor_feat(struct kvm *kvm,
 static int kvm_s390_set_processor_subfunc(struct kvm *kvm,
                                           struct kvm_device_attr *attr)
 {
-        /*
-         * Once supported by kernel + hw, we have to store the subfunctions
-         * in kvm->arch and remember that user space configured them.
-         */
-        return -ENXIO;
+        mutex_lock(&kvm->lock);
+        if (kvm->created_vcpus) {
+                mutex_unlock(&kvm->lock);
+                return -EBUSY;
+        }
+
+        if (copy_from_user(&kvm->arch.model.subfuncs, (void __user *)attr->addr,
+                           sizeof(struct kvm_s390_vm_cpu_subfunc))) {
+                mutex_unlock(&kvm->lock);
+                return -EFAULT;
+        }
+        mutex_unlock(&kvm->lock);
+
+        return 0;
 }
 
 static int kvm_s390_set_cpu_model(struct kvm *kvm, struct kvm_device_attr *attr)
@@ -1389,12 +1398,11 @@ static int kvm_s390_get_machine_feat(struct kvm *kvm,
 static int kvm_s390_get_processor_subfunc(struct kvm *kvm,
                                           struct kvm_device_attr *attr)
 {
-        /*
-         * Once we can actually configure subfunctions (kernel + hw support),
-         * we have to check if they were already set by user space, if so copy
-         * them from kvm->arch.
-         */
-        return -ENXIO;
+        if (copy_to_user((void __user *)attr->addr, &kvm->arch.model.subfuncs,
+            sizeof(struct kvm_s390_vm_cpu_subfunc)))
+                return -EFAULT;
+
+        return 0;
 }
 
 static int kvm_s390_get_machine_subfunc(struct kvm *kvm,
@@ -1405,6 +1413,7 @@ static int kvm_s390_get_machine_subfunc(struct kvm *kvm,
                 return -EFAULT;
         return 0;
 }
+
 static int kvm_s390_get_cpu_model(struct kvm *kvm, struct kvm_device_attr *attr)
 {
         int ret = -ENXIO;
@@ -1522,10 +1531,9 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
                 case KVM_S390_VM_CPU_PROCESSOR_FEAT:
                 case KVM_S390_VM_CPU_MACHINE_FEAT:
                 case KVM_S390_VM_CPU_MACHINE_SUBFUNC:
+                case KVM_S390_VM_CPU_PROCESSOR_SUBFUNC:
                         ret = 0;
                         break;
-                /* configuring subfunctions is not supported yet */
-                case KVM_S390_VM_CPU_PROCESSOR_SUBFUNC:
                 default:
                         ret = -ENXIO;
                         break;
@@ -2227,6 +2235,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
                 kvm->arch.model.fac_list[i] = S390_lowcore.stfle_fac_list[i] &
                                               kvm_s390_fac_base[i];
         }
+        kvm->arch.model.subfuncs = kvm_s390_available_subfunc;
 
         /* we are always in czam mode - even on pre z14 machines */
         set_kvm_facility(kvm->arch.model.fac_mask, 138);