KVM: PPC: Book3S HV: Fix preempted vcore stolen time calculation

Whenever a vcore state is VCORE_PREEMPT we need to be counting stolen
time for it.  This currently isn't the case when we have a vcore that
no longer has any runnable threads in it but still has a runner task,
so we do an explicit call to kvmppc_core_start_stolen() in that case.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/kvm/book3s_hv.c

@@ -2283,9 +2283,14 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master)
 	}
 	list_del_init(&vc->preempt_list);
 	if (!is_master) {
-		vc->vcore_state = vc->runner ? VCORE_PREEMPT : VCORE_INACTIVE;
-		if (still_running > 0)
+		if (still_running > 0) {
 			kvmppc_vcore_preempt(vc);
+		} else if (vc->runner) {
+			vc->vcore_state = VCORE_PREEMPT;
+			kvmppc_core_start_stolen(vc);
+		} else {
+			vc->vcore_state = VCORE_INACTIVE;
+		}
 		if (vc->n_runnable > 0 && vc->runner == NULL) {
 			/* make sure there's a candidate runner awake */
 			vcpu = list_first_entry(&vc->runnable_threads,