Re: [Qemu-devel] [PATCH for-2.12 REPOST] spapr_cpu_core: instantiate CPUs separately

[David Gibson]

On Mon, Nov 20, 2017 at 03:56:48PM +0100, Igor Mammedov wrote:
> On Mon, 20 Nov 2017 10:19:54 +0100
> Greg Kurz <address@hidden> wrote:
> 
> > The current code assumes that only the CPU core object holds a
> > reference on each individual CPU object, and happily frees their
> > allocated memory when the core is unrealized. This is dangerous
> > as some other code can legitimely keep a pointer to a CPU if it
> > calls object_ref(), but it would end up with a dangling pointer.
> > 
> > Let's allocate all CPUs with object_new() and let QOM frees them
> s/frees/free/
> 
> > when their reference count reaches zero. This greatly simplify the
> > code as we don't have to fiddle with the instance size anymore.
> > 
> > Signed-off-by: Greg Kurz <address@hidden>
> Acked-by: Igor Mammedov <address@hidden>

Applied to ppc-for-2.12 with the typo above fixed.


> 
> > ---
> >  hw/ppc/spapr.c                  |   11 +++--------
> >  hw/ppc/spapr_cpu_core.c         |   19 +++++++------------
> >  include/hw/ppc/spapr_cpu_core.h |    2 +-
> >  3 files changed, 11 insertions(+), 21 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 174e7ff0678d..fc92b9d914a5 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -3173,12 +3173,10 @@ void spapr_core_release(DeviceState *dev)
> >  
> >      if (smc->pre_2_10_has_unused_icps) {
> >          sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> > -        sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(cc));
> > -        size_t size = object_type_get_instance_size(scc->cpu_type);
> >          int i;
> >  
> >          for (i = 0; i < cc->nr_threads; i++) {
> > -            CPUState *cs = CPU(sc->threads + i * size);
> > +            CPUState *cs = CPU(sc->threads[i]);
> >  
> >              pre_2_10_vmstate_register_dummy_icp(cs->cpu_index);
> >          }
> > @@ -3224,7 +3222,7 @@ static void spapr_core_plug(HotplugHandler 
> > *hotplug_dev, DeviceState *dev,
> >      sPAPRMachineClass *smc = SPAPR_MACHINE_CLASS(mc);
> >      sPAPRCPUCore *core = SPAPR_CPU_CORE(OBJECT(dev));
> >      CPUCore *cc = CPU_CORE(dev);
> > -    CPUState *cs = CPU(core->threads);
> > +    CPUState *cs = CPU(core->threads[0]);
> >      sPAPRDRConnector *drc;
> >      Error *local_err = NULL;
> >      int smt = kvmppc_smt_threads();
> > @@ -3269,15 +3267,12 @@ static void spapr_core_plug(HotplugHandler 
> > *hotplug_dev, DeviceState *dev,
> >      core_slot->cpu = OBJECT(dev);
> >  
> >      if (smc->pre_2_10_has_unused_icps) {
> > -        sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(cc));
> > -        size_t size = object_type_get_instance_size(scc->cpu_type);
> >          int i;
> >  
> >          for (i = 0; i < cc->nr_threads; i++) {
> >              sPAPRCPUCore *sc = SPAPR_CPU_CORE(dev);
> > -            void *obj = sc->threads + i * size;
> >  
> > -            cs = CPU(obj);
> > +            cs = CPU(sc->threads[i]);
> >              pre_2_10_vmstate_unregister_dummy_icp(cs->cpu_index);
> >          }
> >      }
> > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> > index 3a4c17401226..588f9b45714a 100644
> > --- a/hw/ppc/spapr_cpu_core.c
> > +++ b/hw/ppc/spapr_cpu_core.c
> > @@ -79,13 +79,11 @@ const char *spapr_get_cpu_core_type(const char 
> > *cpu_type)
> >  static void spapr_cpu_core_unrealizefn(DeviceState *dev, Error **errp)
> >  {
> >      sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> > -    sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(dev));
> > -    size_t size = object_type_get_instance_size(scc->cpu_type);
> >      CPUCore *cc = CPU_CORE(dev);
> >      int i;
> >  
> >      for (i = 0; i < cc->nr_threads; i++) {
> > -        void *obj = sc->threads + i * size;
> > +        Object *obj = OBJECT(sc->threads[i]);
> >          DeviceState *dev = DEVICE(obj);
> >          CPUState *cs = CPU(dev);
> >          PowerPCCPU *cpu = POWERPC_CPU(cs);
> > @@ -146,9 +144,8 @@ static void spapr_cpu_core_realize(DeviceState *dev, 
> > Error **errp)
> >      sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
> >      sPAPRCPUCoreClass *scc = SPAPR_CPU_CORE_GET_CLASS(OBJECT(dev));
> >      CPUCore *cc = CPU_CORE(OBJECT(dev));
> > -    size_t size;
> >      Error *local_err = NULL;
> > -    void *obj;
> > +    Object *obj;
> >      int i, j;
> >  
> >      if (!spapr) {
> > @@ -156,18 +153,16 @@ static void spapr_cpu_core_realize(DeviceState *dev, 
> > Error **errp)
> >          return;
> >      }
> >  
> > -    size = object_type_get_instance_size(scc->cpu_type);
> > -    sc->threads = g_malloc0(size * cc->nr_threads);
> > +    sc->threads = g_new(PowerPCCPU *, cc->nr_threads);
> >      for (i = 0; i < cc->nr_threads; i++) {
> >          char id[32];
> >          CPUState *cs;
> >          PowerPCCPU *cpu;
> >  
> > -        obj = sc->threads + i * size;
> > +        obj = object_new(scc->cpu_type);
> >  
> > -        object_initialize(obj, size, scc->cpu_type);
> >          cs = CPU(obj);
> > -        cpu = POWERPC_CPU(cs);
> > +        cpu = sc->threads[i] = POWERPC_CPU(obj);
> >          cs->cpu_index = cc->core_id + i;
> >          cpu->vcpu_id = (cc->core_id * spapr->vsmt / smp_threads) + i;
> >          if (kvm_enabled() && !kvm_vcpu_id_is_valid(cpu->vcpu_id)) {
> > @@ -192,7 +187,7 @@ static void spapr_cpu_core_realize(DeviceState *dev, 
> > Error **errp)
> >      }
> >  
> >      for (j = 0; j < cc->nr_threads; j++) {
> > -        obj = sc->threads + j * size;
> > +        obj = OBJECT(sc->threads[j]);
> >  
> >          spapr_cpu_core_realize_child(obj, spapr, &local_err);
> >          if (local_err) {
> > @@ -203,7 +198,7 @@ static void spapr_cpu_core_realize(DeviceState *dev, 
> > Error **errp)
> >  
> >  err:
> >      while (--i >= 0) {
> > -        obj = sc->threads + i * size;
> > +        obj = OBJECT(sc->threads[i]);
> >          object_unparent(obj);
> >      }
> >      g_free(sc->threads);
> > diff --git a/include/hw/ppc/spapr_cpu_core.h 
> > b/include/hw/ppc/spapr_cpu_core.h
> > index f2d48d6a6786..1129f344aa0c 100644
> > --- a/include/hw/ppc/spapr_cpu_core.h
> > +++ b/include/hw/ppc/spapr_cpu_core.h
> > @@ -28,7 +28,7 @@ typedef struct sPAPRCPUCore {
> >      CPUCore parent_obj;
> >  
> >      /*< public >*/
> > -    void *threads;
> > +    PowerPCCPU **threads;
> >      int node_id;
> >  } sPAPRCPUCore;
> >  
> > 
> > 
> 

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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