Re: [PATCH v2 07/25] KVM: VMX: Set intercept for FRED MSRs

[Xin Li <xin@zytor.com>]

>>> When FRED is advertised to a guest, KVM should allow FRED SSP MSRs
>>> accesses through disabling FRED SSP MSRs interception no matter whether
>>> supervisor shadow stacks are enabled or not.
>>
>> KVM doesn't necessarily need to disabling MSR interception, e.g. if 
>> the expectation
>> is that the guest will rarely/never access the MSRs when CET is 
>> unsupported, then
>> we're likely better off going with a trap-and-emulate model.  KVM 
>> needs to emulate
>> RDMSR and WRMSR no matter what, e.g. in case the guest triggers a 
>> WRMSR when KVM
>> is emulating, and so that userspace can get/set MSR values.
>>
>> And this means that yes, FRED virtualization needs to land after CET 
>> virtualization,
>> otherwise managing the conflicts/dependencies will be a nightmare.
>>

I still plan to send another iteration of the FRED patch set for review,
however I haven't seen your x86 KVM changes land into Linus' tree, it
will happen soon, right?

> 
> No argument.