Re: [PATCH v8 04/12] x86emul: support SERIALIZE

[Jan Beulich <jbeulich@xxxxxxxx>]

On 07.05.2020 21:32, Andrew Cooper wrote:
> On 05/05/2020 09:14, Jan Beulich wrote:
>> ... enabling its use by all guest kinds at the same time.
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Thanks.

>> @@ -5660,6 +5661,18 @@ x86_emulate(
>>                  goto done;
>>              break;
>>  
>> +        case 0xe8:
>> +            switch ( vex.pfx )
>> +            {
>> +            case vex_none: /* serialize */
>> +                host_and_vcpu_must_have(serialize);
>> +                asm volatile ( ".byte 0x0f, 0x01, 0xe8" );
> 
> There is very little need for an actual implementation here.  The VMExit
> to get here is good enough.
> 
> The only question is whether pre-unrestricted_guest Intel boxes are
> liable to find this in real mode code.

Apart from this we also shouldn't assume HVM in the core emulator,
I think.

Jan