On Mon, 15 Jan 2018, Paolo Bonzini wrote: > On 13/01/2018 11:16, Longpeng (Mike) wrote: > >> + /* > >> + * FIXME: this is only needed until SPEC_CTRL is supported > >> + * by upstream Linux in cpufeatures, then it can be replaced > >> + * with static_cpu_has. > >> + */ > >> + have_spec_ctrl = cpu_has_spec_ctrl(); > >> + if (have_spec_ctrl) > >> + pr_info("kvm: SPEC_CTRL available\n"); > >> + else > >> + pr_info("kvm: SPEC_CTRL not available\n"); > >> + > > > > In this approach, we must reload these modules if we update the microcode later ? > > I strongly suggest using early microcode update anyway. We had the discussion already and we are not going to support late micro code loading. It's just not worth the trouble. Also please do not commit any of this before we have sorted out the bare metal IBRS/IBPB support. We really don't want to have two variants of that in tree. Thanks, tglx