On 27/05/19 12:30, Peter Zijlstra wrote: >> This patch adds support for UMONITOR, UMWAIT and TPAUSE instructions >> in kvm, and by default dont't expose it to kvm and provide a capability >> to enable it. > > I'm thinking this should be conditional on the guest being a 1:1 guest, > and I also seem to remember we have bits for that already -- they were > used to disable paravirt spinlocks for example. This should be userspace's choice. It would indeed be silly to enable this while overcommitted, but KVM doesn't really care. Paolo