Re: [Qemu-devel] [PATCH] kvmclock: Ensure time in migration never goes backward

[Marcin Gibuła]

> > is it possible to have kvmclock jumping forward?
> >
> > Because I've reproducible case when at about 1 per 20 vm restores, VM freezes 
> > for couple of hours and then resumes with date few hundreds years ahead. 
> > Happens only with kvmclock.
> >
> > And this patch seems to fix very similar issue so maybe it's all the same bug.
>
> I'm fairly sure it is the exact same bug. Jumping backward is like jumping 
> forward by a biiiiig amount :)

Hi,

I've tested your path on my test VM... don't know if it's pure luck or 
not, but it didn't hang with over 70 restores.

The message "KVM Clock migrated backwards, using later time" fires every 
time, but VM is healthy after resume.

--
mg