Re: [kvm-devel] pv clock: kvm is incompatible with xen :-(

[Glauber C. <gc...@re...>]

Gerd Hoffmann wrote:
> Jeremy Fitzhardinge wrote:
>> Xen could change the parameters in the instant after get_time_values(). 
>> That change could be as a result of suspend-resume, so the parameters
>> and the tsc could be wildly different.
> 
> Ah, ok, forgot the rdtsc in the picture.  With that in mind I fully
> agree that the loop is needed.  I think kvm guests can even hit that one
> with the vcpu migrating to a different physical cpu, so we better handle
> it correctly ;)

It's probably not needed for kvm, since we update everything everytime 
we get scheduled in the host side, which would cover the case for 
migration between physical cpus. But it's probably okay to do it to get 
a common denominator with xen, if needed.