Re: [PATCH] target/i386: Add more features enumerated by CPUID.7.2.EDX

[Chao Gao <chao.gao@intel.com>]

>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index 85ef7452c0..18ba958f46 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -1148,8 +1148,8 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>>      [FEAT_7_2_EDX] = {
>>          .type = CPUID_FEATURE_WORD,
>>          .feat_names = {
>> -            NULL, NULL, NULL, NULL,
>> -            NULL, "mcdt-no", NULL, NULL,
>> +            "intel-psfd", "ipred-ctrl", "rrsba-ctrl", "ddpd-u",
>> +            "bhi-ctrl", "mcdt-no", NULL, NULL,
>
>IIUC, these bits depend on "spec-ctrl", which indicates the presence of
>IA32_SPEC_CTRL.
>
>Then I think we'd better add dependencies in feature_dependencies[].

(+ kvm mailing list)

Thanks for pointing that out. It seems that any of these bits imply the
presence of IA32_SPEC_CTRL. According to SDM vol4, chapter 2, table 2.2,
the 'Comment' column for the IA32_SPEC_CTRL MSR states:

  If any one of the enumeration conditions for defined bit field positions holds.

So, it might be more appropriate to fix KVM's handling of the
IA32_SPEC_CTRL MSR (i.e., guest_has_spec_ctrl_msr()).

what do you think?

>
>-Zhao
>
>>              NULL, NULL, NULL, NULL,
>>              NULL, NULL, NULL, NULL,
>>              NULL, NULL, NULL, NULL,
>> -- 
>> 2.46.1
>> 
>>