Re: [PATCH v9 15/22] KVM: x86: Mark CR4.FRED as not reserved

[Xin Li]

> On Mar 5, 2026, at 9:09 AM, Xin Li <xin@xxxxxxxxx> wrote:
> 
> 
>>> I planned to send out these new kvm unit tests (not just FRED tests) after
>>> KVM FRED patch series gets merged.
>> 
>> Definitely send them before.  Even if no one outside of Intel can run them (I
>> forget when FRED hardware is coming), people like me can at least see what you're
>> testing, which makes it more likely that we'll spot bugs.  E.g. in this case, the
>> lack of negative tests for CR4.FRED is a big red flag.
> 
> No excuse, sadly mk_cr_64() completely escaped my notice.

BTW, mk_cr_64() looks a bad name to me, it’s more like mk_cr_32().

> 
> And I didn’t even think about adding a CR4 test for FRED.
> 
> And as you expected, the happy path doesn’t expose it at all.
> 
> 
>