KVM: s390: Add a routine for setting userspace CPU state

This capability exists, but we don't record anything when userspace
enables it. Let's refactor that code so that a note can be made in
the debug logs that it was enabled.

Signed-off-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20211008203112.1979843-7-farman@linux.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/kvm-s390.c

@@ -2487,8 +2487,8 @@ long kvm_arch_vm_ioctl(struct file *filp,
 	case KVM_S390_PV_COMMAND: {
 		struct kvm_pv_cmd args;
 
-		/* protvirt means user sigp */
-		kvm->arch.user_cpu_state_ctrl = 1;
+		/* protvirt means user cpu state */
+		kvm_s390_set_user_cpu_state_ctrl(kvm);
 		r = 0;
 		if (!is_prot_virt_host()) {
 			r = -EINVAL;
@@ -3802,7 +3802,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 	vcpu_load(vcpu);
 
 	/* user space knows about this interface - let it control the state */
-	vcpu->kvm->arch.user_cpu_state_ctrl = 1;
+	kvm_s390_set_user_cpu_state_ctrl(vcpu->kvm);
 
 	switch (mp_state->mp_state) {
 	case KVM_MP_STATE_STOPPED:

arch/s390/kvm/kvm-s390.h

@@ -208,6 +208,15 @@ static inline int kvm_s390_user_cpu_state_ctrl(struct kvm *kvm)
 	return kvm->arch.user_cpu_state_ctrl != 0;
 }
 
+static inline void kvm_s390_set_user_cpu_state_ctrl(struct kvm *kvm)
+{
+	if (kvm->arch.user_cpu_state_ctrl)
+		return;
+
+	VM_EVENT(kvm, 3, "%s", "ENABLE: Userspace CPU state control");
+	kvm->arch.user_cpu_state_ctrl = 1;
+}
+
 /* implemented in pv.c */
 int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);
 int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);