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. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette