On Sat, Sep 30, 2017 at 12:01 AM, Michael S. Tsirkin [off-list ref] 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.

Thanks,
Rafael