Re: [RFC PATCH 2/2] KVM: x86: add support of kvm-clock stablity in L2

["Radim Krčmář" <rkrcmar@redhat.com>]

2017-06-28 13:55+0300, Denis Plotnikov:
> Get rid of complex shadow monotonic timekeeper support in KVM.
> Extend and use timekeeper infrastructure instead.
> 
> Make kvm-clock stable in L2 using the changed timekeeper

I see this patch as two logical changes:

  1) refactoring that drops host time caching (gtod)
  2) stable kvmclock for L2 when L1 is using kvmclock

Doing it in two patches would definitely be nicer and would allow us to
focus on the (less controversial) L2 enablement.

About (1), the removed pvclock_gtod_notify() also verifid whether the
host is using TSC and disabled master clock otherwise.  Other changes
don't explain why it's not needed anymore -- is it because any changes
that make TSC unusable would be caught elsewhere?

About (2), it seems that there is no event in case the kvmclock is not
reliable anymore.  We probably don't need it now, but it would be good
to have it thought out -- would that use a new notifier?

Thanks.