Re: [Qemu-devel] [PATCH v3 06/19] target-i386: add socket/core/thread properties to X86CPU

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 13 Jul 2016 18:22:18 -0400
Bandan Das <bsd@redhat.com> wrote:

> Igor Mammedov <imammedo@redhat.com> writes:
> 
> > these properties will be used by as address where to plug
> > CPU with help -device/device_add commands.
> >
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> > v3:
> >   - use %u for printing topo ids
> >   - add to error message topo ids from set apic_id
> > v2:
> >   - rename socket/core/thread properties to socket-id/core-id/thread-id
> >   - add mismatch checks for apic_id and socket-id/core-id/thread-id
> >     in case both are set
> > ---
> >  hw/i386/pc.c      | 29 +++++++++++++++++++++++++++++
> >  target-i386/cpu.c |  6 ++++++
> >  target-i386/cpu.h |  4 ++++
> >  3 files changed, 39 insertions(+)
> >
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 99dfbe0..24231ca 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -1763,6 +1763,7 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
> >                              DeviceState *dev, Error **errp)
> >  {
> >      int idx;
> > +    X86CPUTopoInfo topo;
> >      X86CPU *cpu = X86_CPU(dev);
> >      PCMachineState *pcms = PC_MACHINE(hotplug_dev);
> >      CPUArchId *cpu_slot = pc_find_cpu_slot(pcms, CPU(dev), &idx);
> > @@ -1780,6 +1781,34 @@ static void pc_cpu_pre_plug(HotplugHandler *hotplug_dev,
> >                     cpu->apic_id);
> >          return;
> >      }
> > +
> > +    /* if 'address' properties socket-id/core-id/thread-id are not set, set them
> > +     * so that query_hotpluggable_cpus would show correct values
> > +     */
> > +    /* TODO: move socket_id/core_id/thread_id checks into x86_cpu_realizefn()
> > +     * once -smp refactoring is complete and there will be CPU private
> > +     * CPUState::nr_cores and CPUState::nr_threads fields instead of globals */
> > +    x86_topo_ids_from_apicid(cpu->apic_id, smp_cores, smp_threads, &topo);
> > +    if (cpu->socket_id != -1 && cpu->socket_id != topo.pkg_id) {
> > +        error_setg(errp, "property socket-id: %u doesn't match set apic-id:"
> > +            " 0x%x (socket-id: %u)", cpu->socket_id, cpu->apic_id, topo.pkg_id);
> > +        return;
> > +    }
> > +    cpu->socket_id = topo.pkg_id;
> > +
> > +    if (cpu->core_id != -1 && cpu->core_id != topo.core_id) {
> > +        error_setg(errp, "property core-id: %u doesn't match set apic-id:"
> > +            " 0x%x (core-id: %u)", cpu->core_id, cpu->apic_id, topo.core_id);
> > +        return;
> > +    }
> > +    cpu->core_id = topo.core_id;
> > +
> > +    if (cpu->thread_id != -1 && cpu->thread_id != topo.smt_id) {
> > +        error_setg(errp, "property thread-id: %u doesn't match set apic-id:"
> > +            " 0x%x (thread-id: %u)", cpu->thread_id, cpu->apic_id, topo.smt_id);
> > +        return;
> > +    }
> > +    cpu->thread_id = topo.smt_id;
> >  }  
> 
> What is the case where these fields are already populated ? When the cpus are online
> at system boot followed by an unplug and then a hotplug ?
there fields are supposed to be populated by -device/device_add callers
who specify them using socket-id/core-id/thread-id properties

> 
> >  static void pc_machine_device_pre_plug_cb(HotplugHandler *hotplug_dev,
> > diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> > index 9294b3d..1ec40a0 100644
> > --- a/target-i386/cpu.c
> > +++ b/target-i386/cpu.c
> > @@ -3164,8 +3164,14 @@ static Property x86_cpu_properties[] = {
> >  #ifdef CONFIG_USER_ONLY
> >      /* apic_id = 0 by default for *-user, see commit 9886e834 */
> >      DEFINE_PROP_UINT32("apic-id", X86CPU, apic_id, 0),
> > +    DEFINE_PROP_INT32("thread-id", X86CPU, thread_id, 0),
> > +    DEFINE_PROP_INT32("core-id", X86CPU, core_id, 0),
> > +    DEFINE_PROP_INT32("socket-id", X86CPU, socket_id, 0),
> >  #else
> >      DEFINE_PROP_UINT32("apic-id", X86CPU, apic_id, UNASSIGNED_APIC_ID),
> > +    DEFINE_PROP_INT32("thread-id", X86CPU, thread_id, -1),
> > +    DEFINE_PROP_INT32("core-id", X86CPU, core_id, -1),
> > +    DEFINE_PROP_INT32("socket-id", X86CPU, socket_id, -1),  
> 
> Are these values (including the UNASSIGNED_APIC_ID) mandated by spec
> or just convenient values ?
it's convenience values 

> 
> Bandan
> 
> >  #endif
> >      DEFINE_PROP_BOOL("pmu", X86CPU, enable_pmu, false),
> >      { .name  = "hv-spinlocks", .info  = &qdev_prop_spinlocks },
> > diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> > index 00de199..0612181 100644
> > --- a/target-i386/cpu.h
> > +++ b/target-i386/cpu.h
> > @@ -1193,6 +1193,10 @@ struct X86CPU {
> >      Notifier machine_done;
> >  
> >      struct kvm_msrs *kvm_msr_buf;
> > +
> > +    int32_t socket_id;
> > +    int32_t core_id;
> > +    int32_t thread_id;
> >  };
> >  
> >  static inline X86CPU *x86_env_get_cpu(CPUX86State *env)