s390x kvm and smp

Alex,

I have trouble getting kvm smp support running. Turns out that 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 KVM_RUN. (these CPUs will be started by a SIGP restart later during the boot process)

This patch seems to help (it allows me to boot and use more than 1 cpu)

@@ -131,6 +131,10 @@ static void do_vm_stop(int reason)
 
 static int cpu_can_run(CPUState *env)
 {
+    if (env->halted) {
+        return 0;
+    }
+
     if (env->stop) {
         return 0;
     }

but it does not look like the right solution. What are the proper definitions for halted and stopped?

Christian

s390 just need to return a meaningful value from kvm_arch_process_async_events, e.g. env->halted, see other archs.

Jan

Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux

Yes indeed. This patch fixes smp for kvm on s390x.

@@ -172,7 +172,7 @@ 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,

Am 04.05.2011 um 18:13 schrieb Christian Borntraeger <[email protected]>:

Now give it a proper patch description and I'll get it in through my tree :)

Alex

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.

@@ -172,7 +172,7 @@ 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,