Re: [PATCH v5 14/16] hw/i386: Move arch_id decode inside x86_cpus_init

[Babu Moger]

On 3/10/20 3:35 AM, Igor Mammedov wrote:
> On Mon, 9 Mar 2020 14:31:31 -0500
> Babu Moger <address@hidden> wrote:
> 
>> On 3/9/20 10:21 AM, Igor Mammedov wrote:
>>> On Tue, 03 Mar 2020 13:58:24 -0600
>>> Babu Moger <address@hidden> wrote:
>>>   
>>>> Apicid calculation depends on knowing the total number of numa nodes
>>>> for EPYC cpu models. Right now, we are calculating the arch_id while
>>>> parsing the numa(parse_numa). At this time, it is not known how many
>>>> total numa nodes are configured in the system.
>>>>
>>>> Move the arch_id inside x86_cpus_init. At this time smp parameter is 
>>>> already
>>>> completed and numa node information is available.
>>>>
>>>> Signed-off-by: Babu Moger <address@hidden>
>>>> ---
>>>>  hw/i386/x86.c |   17 +++++++++++------
>>>>  1 file changed, 11 insertions(+), 6 deletions(-)
>>>>
>>>> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
>>>> index d46dd4ad9e..66998b065c 100644
>>>> --- a/hw/i386/x86.c
>>>> +++ b/hw/i386/x86.c
>>>> @@ -121,6 +121,9 @@ void x86_cpus_init(X86MachineState *x86ms, int 
>>>> default_cpu_version)
>>>>      MachineState *ms = MACHINE(x86ms);
>>>>      MachineClass *mc = MACHINE_GET_CLASS(x86ms);
>>>>  
>>>> +    /* Initialize apicid handlers first */
>>>> +    cpu_x86_init_apicid_fns(ms);
>>>> +
>>>>      x86_cpu_set_default_version(default_cpu_version);
>>>>  
>>>>      /*
>>>> @@ -134,6 +137,12 @@ void x86_cpus_init(X86MachineState *x86ms, int 
>>>> default_cpu_version)
>>>>      x86ms->apic_id_limit = x86_cpu_apic_id_from_index(x86ms,
>>>>                                                        ms->smp.max_cpus - 
>>>> 1) + 1;
>>>>      possible_cpus = mc->possible_cpu_arch_ids(ms);
>>>> +
>>>> +    for (i = 0; i < ms->smp.cpus; i++) {
>>>> +        ms->possible_cpus->cpus[i].arch_id =
>>>> +            x86_cpu_apic_id_from_index(x86ms, i);
>>>> +    }
>>>> +
>>>>      for (i = 0; i < ms->smp.cpus; i++) {
>>>>          x86_cpu_new(x86ms, possible_cpus->cpus[i].arch_id, &error_fatal);
>>>>      }
>>>> @@ -158,8 +167,7 @@ int64_t x86_get_default_cpu_node_id(const MachineState 
>>>> *ms, int idx)
>>>>     init_topo_info(&topo_info, x86ms);
>>>>  
>>>>     assert(idx < ms->possible_cpus->len);
>>>> -   x86ms->topo_ids_from_apicid(ms->possible_cpus->cpus[idx].arch_id,
>>>> -                               &topo_info, &topo_ids);
>>>> +   x86_topo_ids_from_idx(&topo_info, idx, &topo_ids);  
>>> not necessary if default x86ms->topo_ids_from_apicid were initialized from 
>>> x86 machine class
>>>
>>> I also wonder if this default contraption we have is going to work
>>> in case of EPYC cpu (i.e. is would generate valid nodeids).  
>>
>> From what I understand, we call this x86_get_default_cpu_node_id only when
>> the user does not specify the numa binding requirements. We tried to
>> generate the default node it for a given config. This works fine for EPYC
>> also. I am not sure about changing this right now. what do you think?
> 
> if it work for EPYC with default x86_topo_ids_from_idx() then it's fine.
> 
> Just keep callback here, given that callback is always initialized early 
> (class_init)
> there is no point to create mix of callback/non-callback usage.

Ok. Done.
We did not have callback for x86_topo_ids_from_idx explicity. Now, I have
added this function as callback and using the callback here.

>  
>>>
>>> Bot instead of than trying to fix it if it's broken,
>>> I'd rather deprecate and drop get_default_cpu_node_id() requiring users
>>> to explicitly define CPU mapping to numa nodes.
>>> That would be consistent with req for explicit RAM for numa nodes
>>> (postponed till 5.1 due to libvirt not being ready),
>>> i.e if one wants numa, one should explicitly provide necessary mapping
>>> or machine won't start.
>>>
>>>   
>>>>     return topo_ids.pkg_id % ms->numa_state->num_nodes;
>>>>  }
>>>>  
>>>> @@ -193,10 +201,7 @@ const CPUArchIdList 
>>>> *x86_possible_cpu_arch_ids(MachineState *ms)
>>>>  
>>>>          ms->possible_cpus->cpus[i].type = ms->cpu_type;
>>>>          ms->possible_cpus->cpus[i].vcpus_count = 1;
>>>> -        ms->possible_cpus->cpus[i].arch_id =
>>>> -            x86_cpu_apic_id_from_index(x86ms, i);
>>>> -        x86ms->topo_ids_from_apicid(ms->possible_cpus->cpus[i].arch_id,
>>>> -                                 &topo_info, &topo_ids);
>>>> +        x86_topo_ids_from_idx(&topo_info, i, &topo_ids);  
>>> ditto
>>>   
>>>>          ms->possible_cpus->cpus[i].props.has_socket_id = true;
>>>>          ms->possible_cpus->cpus[i].props.socket_id = topo_ids.pkg_id;
>>>>          if (x86ms->smp_dies > 1) {
>>>>  
>>>   
>>
>