Re: [PATCH v3 10/21] KVM:x86: Add #CP support in guest exception classification

Yang, Weijiang
2023-07-01T01:59:11Z

On 6/30/2023 11:15 PM, Sean Christopherson wrote:
> On Fri, Jun 30, 2023, Gil Neiger wrote:
>> Intel will not produce any CPU with CET that does not enumerate IA32_VMX_BASIC[56] as 1.
>>
>> One can check that bit before injecting a #CP with error code, but it should
>> not be necessary if CET is enumerated.
>>
>> Of course, if the KVM may run as a guest of another VMM/hypervisor, it may be
>> that the virtual CPU in which KVM operates may enumerate CET but clear the
>> bit in IA32_VMX_BASIC.
> Yeah, I think KVM should be paranoid and expose CET to the guest if and only if
> IA32_VMX_BASIC[56] is 1. That'll also help validate nested support, e.g. will
> make it more obvious if userspace+KVM provides a "bad" model to L1.

OK, will do it, thanks you two!