On 09/01/19 18:09, speck for Konrad Rzeszutek Wilk wrote:
> On Thu, Dec 20, 2018 at 04:31:01PM -0800, speck for Andi Kleen wrote:
>>
>> For reference here is the qemu patch needed for using MB_CLEAR in a KVM
>> guest.
> 
> I thought it was called 'MD_CLEAR' ?
> 
>>
>> -Andi
>>
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index 677a3bd5fb25..77a1149e4bb3 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -1038,7 +1038,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
>>          .feat_names = {
>>              NULL, NULL, "avx512-4vnniw", "avx512-4fmaps",
>>              NULL, NULL, NULL, NULL,
>> -            NULL, NULL, NULL, NULL,
>> +            NULL, NULL, "mbclear", NULL,
>>              NULL, NULL, NULL, NULL,
>>              NULL, NULL, "pconfig", NULL,
>>              NULL, NULL, NULL, NULL,

Are there any CPU families which will all have it (e.g. IceLake server,
Cascade Lake?).  Prerelease/prototype silicon does not count.

Paolo