Re: [PATCH] KVM: x86: Expose Predictive Store Forwarding Disable

[Paolo Bonzini]

On 27/09/21 12:59, Borislav Petkov wrote:
> On Thu, Sep 23, 2021 at 08:15:28PM -0500, Babu Moger wrote:
> > Linux kernel does not have the interface to enable/disable PSFD yet. Plan
> > here is to expose the PSFD technology to KVM so that the guest kernel can
> > make use of it if they wish to.
>
> Why should the guest kernel expose it if we said that for now we want to
> disable it with the SSBD control?

Because the guest kernel needs to know which MSRs to write when you 
touch the SSBD prctl, so that PSFD is properly disabled *inside the guest*.

Paolo