Re: [PATCH v4 1/1] x86/cpufeatures: Implement Predictive Store Forwarding control.

Saripalli, RK
2021-05-04T21:02:00Z

On 4/30/2021 8:50 PM, Reiji Watanabe wrote:
>>> Considering KVM/virtualization for a CPU that has X86_FEATURE_PSFD
>>> but no other existing feature with MSR_IA32_SPEC_CTRL, if a host
>>> doesn't enable PSFD with the new parameter, the host doesn't have
>>> X86_FEATURE_MSR_SPEC_CTRL. Then, it would be a problem if its
>>> guests want to use PSFD looking at x86_virt_spec_ctrl().
>>> (I'm not sure how you will change your previous KVM patch though)
>>
>> Reiji, you are correct that X86_FEATURE_MSR_SPEC_CTRL should be enabled so KVM guests can use PSFD
>> even if host does not use it.
>> I have this change in my KVM patch.
>
>
> Thank you for the response. Yes, that sounds good.
>
> Thanks,
> Reiji
>
Boris / Reiji, I am wondering if I have answered all the questions on these latest patches.
Just checking to see if there are any more changes needed.

Thanks,
RK