s390x: fix smp support for kvm

Currently smp support for kvm does not work. Qemu does a kvm run even on
secondary CPUs which dont have a sane state (initial psw == 0)
triggering some program faults. Architecturally these cpus are in the stopped
state, so we should not do the kvm run ioctl. (these CPUs will be started
by a SIGP restart later during the boot process)

We need to tell the loop that this cpu should not run. Jan Kiszka pointed
out that kvm_arch_process_async_events is the right place to do.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NAlexander Graf <agraf@suse.de>

target-s390x/kvm.c

@@ -179,7 +179,7 @@ void kvm_arch_post_run(CPUState *env, struct kvm_run *run)
 
 int kvm_arch_process_async_events(CPUState *env)
 {
-    return 0;
+    return env->halted;
 }
 
 void kvm_s390_interrupt_internal(CPUState *env, int type, uint32_t parm,