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

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

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>

> @@ -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.

~Andrew