Re: [RFC v2 0/2] kvm: Use host timekeeping in guest.

[Konrad Rzeszutek Wilk]

.snip..
> I wonder how feasible it is to map the host's vdso into the guest and
> thus make the guest use the *same* (as opposed to "synchronized") clock
> as the host's userspace?  Another benefit is that it's essentially an
> ABI so is not changed as liberally as internal structures like
> timekeeper, etc.  There is probably certain complication in handling the
> syscall fallback in the vdso when used in the guest kernel, though.
> 
> You'll also need to ensure neither tsc scaling and nor offsetting is
> applied to the VM once this clock is enabled.

This is how Xen does it - you can register the hypervisor to timestamp
your vDSO regions if you want it. See xen_setup_vsyscall_time_info

> 
> Roman.