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

Reiji Watanabe
2021-05-01T01:52:01Z

> > 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