On Sat, 30 Sep 2017 01:21:43 +0200 "Rafael J. Wysocki" <rafael@xxxxxxxxxx> wrote: > On Sat, Sep 30, 2017 at 12:01 AM, Michael S. Tsirkin <mst@xxxxxxxxxx> > wrote: > > intel idle driver does not DTRT when running within a VM: > > when going into a deep power state, the right thing to > > do is to exit to hypervisor rather than to keep polling > > within guest using mwait. > > > > Currently the solution is just to exit to hypervisor each time we go > > idle - this is why kvm does not expose the mwait leaf to guests even > > when it allows guests to do mwait. > > > > But that's not ideal - it seems better to use the idle driver to > > guess when will the next interrupt arrive. > > The idle driver alone is not sufficient for that, though. > I second that. Why try to solve this problem at vendor specific driver level? perhaps just a pv idle driver that decide whether to vmexit based on something like local per vCPU timer expiration? I guess we can't predict other wake events such as interrupts. e.g. if (get_next_timer_interrupt() > kvm_halt_target_residency) vmexit else poll Jacob
