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

From: Borislav Petkov
Date: Mon Sep 27 2021 - 09:39:05 EST

On Mon, Sep 27, 2021 at 02:54:08PM +0200, Paolo Bonzini wrote:
> There are other guests than Linux. This patch is just telling userspace
> that KVM knows what the PSFD bit is. It is also possible to expose the bit
> in KVM without having any #define in cpufeatures.h

Ok, then there's no need for the cpufeatures.h hunk.

> or without the kernel using it. For example KVM had been exposing
> FSGSBASE long before Linux supported it.

Ok, please do that for now then, if you want to expose it to other
guests. I'm sceptical they will have a use case for it either but I'm
always open to suggestions.

For the same reason as for baremetal, though, I wouldn't do that and do
that solely through the SSBD control but that's your call.