On 13/07/20 20:48, Eduardo Habkost wrote:
> On Tue, Jul 14, 2020 at 01:44:36AM +0800, Xiaoyao Li wrote:
>> Features unavailable due to absent of their dependent features should
>> not be added to env->user_features. env->user_features only contains the
>> feature explicity specified with -feature/+feature by user.
>>
>> Fixes: 99e24dbdaa68 ("target/i386: introduce generic feature dependency
>> mechanism")
>> Signed-off-by: Xiaoyao Li <xiaoyao...@intel.com>
>
> Paolo, do you remember why that line existed? It doesn't make
> sense to me.
>
> There are exactly 2 lines of code reading user_features, and both
> of them are inside x86_cpu_expand_features() above this hunk.
I think it was just to be safe in case in the future something else adds
features automatically, in the same way as the cpu->max_features case:
env->features[w] |=
x86_cpu_get_supported_feature_word(w, cpu->migratable) &
~env->user_features[w] &
~feature_word_info[w].no_autoenable_flags;
It would prevent the unavailable dependent features from being added.
But yeah, it would just be enough to place it above this hunk.
Paolo
> Reviewed-by: Eduardo Habkost <ehabk...@redhat.com>
>
>> ---
>> target/i386/cpu.c | 1 -
>> 1 file changed, 1 deletion(-)
>>
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index 9812d5747f35..fb1de1bd6165 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -6370,7 +6370,6 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error
>> **errp)
>> unavailable_features &
>> env->user_features[d->to.index],
>> "This feature depends on other
>> features that were not requested");
>>
>> - env->user_features[d->to.index] |= unavailable_features;
>> env->features[d->to.index] &= ~unavailable_features;
>> }
>> }
>> --
>> 2.18.4
>>
>
