Re: [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure
From: Andi Kleen
Date: Mon Jan 29 2018 - 17:42:03 EST
> Even if we expose bit to indicate that FMS matches the underlying host, when does the guest know to query that? The VM can be moved at any point in time, including after the guest asks if FMS matches host.
There's no way to enable these mitigations later, so if you always
have to enable the super set of all the mitigations for all the hosts you
might be migrating too.
As of currently that means if you want to ever migrate to Skylake you should
set the Skylake model number and you're good.
-Andi