Re: [Qemu-ppc] [PATCH 1/7] spapr: Clean up cpu realize/unrealize paths

[Greg Kurz]

On Wed, 13 Jun 2018 10:11:45 +0200
Cédric Le Goater <address@hidden> wrote:

> On 06/13/2018 08:57 AM, David Gibson wrote:
> > spapr_cpu_init() and spapr_cpu_destroy() are only called from the spapr
> > cpu core realize/unrealize paths, and really can only be called from there.
> > 
> > Those are all short functions, so fold the pairs together for simplicity.
> > While we're there rename some functions and change some parameter types
> > for brevity and clarity.
> > 
> > Signed-off-by: David Gibson <address@hidden>  
> 
> Reviewed-by: Cédric Le Goater <address@hidden>
> 
> Still a call to spapr_cpu_reset(cpu). We should try to get rid of it
> one day.
>  

Yeah, CPU reset should ideally be triggered during machine reset or during
hotplug. There have been several tries to do so but we hit an issue with
hotplug... If we don't call spapr_cpu_reset() here then CPUState::halted
isn't set and the CPU can start executing before the hotplug path has a
chance to reset it...

https://lists.nongnu.org/archive/html/qemu-ppc/2018-04/msg00126.html

This requires a deeper investigation.

> Thanks,
> 
> C.
> 
> > ---
> >  hw/ppc/spapr_cpu_core.c | 69 +++++++++++++++--------------------------
> >  1 file changed, 25 insertions(+), 44 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> > index f3e9b879b2..7fdb3b6667 100644
> > --- a/hw/ppc/spapr_cpu_core.c
> > +++ b/hw/ppc/spapr_cpu_core.c
> > @@ -83,26 +83,6 @@ void spapr_cpu_set_entry_state(PowerPCCPU *cpu, 
> > target_ulong nip, target_ulong r
> >      ppc_store_lpcr(cpu, env->spr[SPR_LPCR] | pcc->lpcr_pm);
> >  }
> >  
> > -static void spapr_cpu_destroy(PowerPCCPU *cpu)
> > -{
> > -    qemu_unregister_reset(spapr_cpu_reset, cpu);
> > -}
> > -
> > -static void spapr_cpu_init(sPAPRMachineState *spapr, PowerPCCPU *cpu,
> > -                           Error **errp)
> > -{
> > -    CPUPPCState *env = &cpu->env;
> > -
> > -    /* Set time-base frequency to 512 MHz */
> > -    cpu_ppc_tb_init(env, SPAPR_TIMEBASE_FREQ);
> > -
> > -    cpu_ppc_set_vhyp(cpu, PPC_VIRTUAL_HYPERVISOR(spapr));
> > -    kvmppc_set_papr(cpu);
> > -
> > -    qemu_register_reset(spapr_cpu_reset, cpu);
> > -    spapr_cpu_reset(cpu);
> > -}
> > -
> >  /*
> >   * Return the sPAPR CPU core type for @model which essentially is the CPU
> >   * model specified with -cpu cmdline option.
> > @@ -122,44 +102,47 @@ const char *spapr_get_cpu_core_type(const char 
> > *cpu_type)
> >      return object_class_get_name(oc);
> >  }
> >  
> > -static void spapr_cpu_core_unrealizefn(DeviceState *dev, Error **errp)
> > +static void spapr_unrealize_vcpu(PowerPCCPU *cpu)
> > +{
> > +    qemu_unregister_reset(spapr_cpu_reset, cpu);
> > +    object_unparent(cpu->intc);
> > +    cpu_remove_sync(CPU(cpu));
> > +    object_unparent(OBJECT(cpu));
> > +}
> > +
> > +static void spapr_cpu_core_unrealize(DeviceState *dev, Error **errp)
> >  {
> >      sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> >      CPUCore *cc = CPU_CORE(dev);
> >      int i;
> >  
> >      for (i = 0; i < cc->nr_threads; i++) {
> > -        Object *obj = OBJECT(sc->threads[i]);
> > -        DeviceState *dev = DEVICE(obj);
> > -        CPUState *cs = CPU(dev);
> > -        PowerPCCPU *cpu = POWERPC_CPU(cs);
> > -
> > -        spapr_cpu_destroy(cpu);
> > -        object_unparent(cpu->intc);
> > -        cpu_remove_sync(cs);
> > -        object_unparent(obj);
> > +        spapr_unrealize_vcpu(sc->threads[i]);
> >      }
> >      g_free(sc->threads);
> >  }
> >  
> > -static void spapr_cpu_core_realize_child(Object *child,
> > -                                         sPAPRMachineState *spapr, Error 
> > **errp)
> > +static void spapr_realize_vcpu(PowerPCCPU *cpu, sPAPRMachineState *spapr,
> > +                               Error **errp)
> >  {
> > +    CPUPPCState *env = &cpu->env;
> >      Error *local_err = NULL;
> > -    CPUState *cs = CPU(child);
> > -    PowerPCCPU *cpu = POWERPC_CPU(cs);
> >  
> > -    object_property_set_bool(child, true, "realized", &local_err);
> > +    object_property_set_bool(OBJECT(cpu), true, "realized", &local_err);
> >      if (local_err) {
> >          goto error;
> >      }
> >  
> > -    spapr_cpu_init(spapr, cpu, &local_err);
> > -    if (local_err) {
> > -        goto error;
> > -    }
> > +    /* Set time-base frequency to 512 MHz */
> > +    cpu_ppc_tb_init(env, SPAPR_TIMEBASE_FREQ);
> > +
> > +    cpu_ppc_set_vhyp(cpu, PPC_VIRTUAL_HYPERVISOR(spapr));
> > +    kvmppc_set_papr(cpu);
> >  
> > -    cpu->intc = icp_create(child, spapr->icp_type, XICS_FABRIC(spapr),
> > +    qemu_register_reset(spapr_cpu_reset, cpu);
> > +    spapr_cpu_reset(cpu);
> > +
> > +    cpu->intc = icp_create(OBJECT(cpu), spapr->icp_type, 
> > XICS_FABRIC(spapr),
> >                             &local_err);
> >      if (local_err) {
> >          goto error;
> > @@ -220,9 +203,7 @@ static void spapr_cpu_core_realize(DeviceState *dev, 
> > Error **errp)
> >      }
> >  
> >      for (j = 0; j < cc->nr_threads; j++) {
> > -        obj = OBJECT(sc->threads[j]);
> > -
> > -        spapr_cpu_core_realize_child(obj, spapr, &local_err);
> > +        spapr_realize_vcpu(sc->threads[j], spapr, &local_err);
> >          if (local_err) {
> >              goto err;
> >          }
> > @@ -249,7 +230,7 @@ static void spapr_cpu_core_class_init(ObjectClass *oc, 
> > void *data)
> >      sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_CLASS(oc);
> >  
> >      dc->realize = spapr_cpu_core_realize;
> > -    dc->unrealize = spapr_cpu_core_unrealizefn;
> > +    dc->unrealize = spapr_cpu_core_unrealize;
> >      dc->props = spapr_cpu_core_properties;
> >      scc->cpu_type = data;
> >  }
> >   
>