Re: [RFC 09/52] hw/machine: Introduce core type for hybrid topology

[Zhao Liu]

On Tue, Feb 14, 2023 at 09:14:13AM +0800, Mi, Dapeng1 wrote:
> Date: Tue, 14 Feb 2023 09:14:13 +0800
> From: "Mi, Dapeng1" <dapeng1.mi@intel.com>
> Subject: RE: [RFC 09/52] hw/machine: Introduce core type for hybrid topology
> 
> > From: Zhao Liu <zhao1.liu@linux.intel.com>
> > Sent: Monday, February 13, 2023 5:50 PM
> > To: Eduardo Habkost <eduardo@habkost.net>; Marcel Apfelbaum
> > <marcel.apfelbaum@gmail.com>; Philippe Mathieu-Daud? <philmd@linaro.org>;
> > Yanan Wang <wangyanan55@huawei.com>; Michael S . Tsirkin
> > <mst@redhat.com>; Richard Henderson <richard.henderson@linaro.org>; Paolo
> > Bonzini <pbonzini@redhat.com>; Eric Blake <eblake@redhat.com>; Markus
> > Armbruster <armbru@redhat.com>
> > Cc: qemu-devel@nongnu.org; Wang, Zhenyu Z <zhenyu.z.wang@intel.com>; Mi,
> > Dapeng1 <dapeng1.mi@intel.com>; Ding, Zhuocheng
> > <zhuocheng.ding@intel.com>; Robert Hoo <robert.hu@linux.intel.com>;
> > Christopherson,, Sean <seanjc@google.com>; Like Xu
> > <like.xu.linux@gmail.com>; Liu, Zhao1 <zhao1.liu@intel.com>
> > Subject: [RFC 09/52] hw/machine: Introduce core type for hybrid topology
> > 
> > From: Zhao Liu <zhao1.liu@intel.com>
> > 
> > Under the hybrid cpu topology, some CPUs care about the core type.
> > For example, Intel's Alder Lake series CPU contains two types of cores:
> > Intel Core and Intel Atom. The type information of these two types is 
> > exposed in
> > 1A leaf of CPUID.
> > 
> > Core type should also be part of the hybrid topology, and
> > MachineState.cpu_type cannot provide different type information for 
> > different
> > cpus in the same machine, so add a type field for the core level in the 
> > hybrid cpu
> > topology.
> > 
> > Additionally, add a helper to get core type information from MachineState.
> > Though core_type is only used in hybrid case, don't use assert since it may 
> > be
> > used to initialize some generic fields.
> > 
> > Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> > ---
> >  hw/core/machine-topo.c        | 12 ++++++++++++
> >  include/hw/boards.h           |  3 +++
> >  include/hw/cpu/cpu-topology.h |  2 ++
> >  3 files changed, 17 insertions(+)
> > 
> > diff --git a/hw/core/machine-topo.c b/hw/core/machine-topo.c index
> > b20160479629..e0ec07b53d42 100644
> > --- a/hw/core/machine-topo.c
> > +++ b/hw/core/machine-topo.c
> > @@ -51,6 +51,18 @@ unsigned int machine_topo_get_smp_threads(const
> > MachineState *ms)
> >      return ms->topo.smp.threads;
> >  }
> > 
> > +unsigned int machine_topo_get_hybrid_core_type(const MachineState *ms,
> > +                                               unsigned int cluster_id,
> > +                                               unsigned int core_id) {
> > +    if (!machine_topo_is_smp(ms)) {
> > +        return ms->topo.hybrid.cluster_list[cluster_id]
> > +                       .core_list[core_id].core_type;
> > +    } else {
> > +        return 0;
> > +    }
> > +}
> > +
> 
> We'd better not to return the hard-coded '0'. Suggest to define a 'enum'
> data structure to represent the core_type. This makes the code look more 
> intuitively.

Yes. I defined a core type 'enum' in x86 code, Here I can use a macro to
avoid hardcoding.

Zhao

> 
> >  unsigned int machine_topo_get_threads(const MachineState *ms,
> >                                        unsigned int cluster_id,
> >                                        unsigned int core_id) diff --git 
> > a/include/hw/boards.h
> > b/include/hw/boards.h index 34b64b012022..78e52af38cb1 100644
> > --- a/include/hw/boards.h
> > +++ b/include/hw/boards.h
> > @@ -484,6 +484,9 @@ unsigned int machine_topo_get_dies(const
> > MachineState *ms);  unsigned int machine_topo_get_clusters(const
> > MachineState *ms);  unsigned int machine_topo_get_smp_cores(const
> > MachineState *ms);  unsigned int machine_topo_get_smp_threads(const
> > MachineState *ms);
> > +unsigned int machine_topo_get_hybrid_core_type(const MachineState *ms,
> > +                                               unsigned int cluster_id,
> > +                                               unsigned int core_id);
> >  unsigned int machine_topo_get_threads(const MachineState *ms,
> >                                        unsigned int cluster_id,
> >                                        unsigned int core_id); diff --git 
> > a/include/hw/cpu/cpu-
> > topology.h b/include/hw/cpu/cpu-topology.h index
> > 8268ea3a8569..87d832556229 100644
> > --- a/include/hw/cpu/cpu-topology.h
> > +++ b/include/hw/cpu/cpu-topology.h
> > @@ -45,9 +45,11 @@ typedef struct SmpCpuTopology {
> >  /**
> >   * HybridCore - hybrid core topology defination:
> >   * @threads: the number of threads in one core.
> > + * @core_type: the type of current core.
> >   */
> >  typedef struct HybridCore {
> >      unsigned int threads;
> > +    unsigned int core_type;
> >  } HybridCore;
> > 
> >  /**
> > --
> > 2.34.1
>