On Mon, Sep 27, 2021 at 5:17 PM Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote: > > So I think there are two possibilities that makes sense: > > > > * track what is using KVM_CAP_HALT_POLL, and make writes to halt_poll_ns follow that > > what about using halt_poll_ns for those VMs that did not uses KVM_CAP_HALT_POLL and the private number for those that did. Yes, that's what I meant. David pointed out that doesn't allow you to disable halt polling altogether, but for that you can always ask each VM's userspace one by one, or just not use KVM_CAP_HALT_POLL. (Also, I don't know about Google's usecase, but mine was actually more about using KVM_CAP_HALT_POLL to *disable* halt polling on some VMs!). Paolo
