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

[Alexander Graf]

> Am 05.05.2014 um 19:46 schrieb Marcin Gibuła <address@hidden>:
> 
> W dniu 2014-05-05 15:51, Alexander Graf pisze:
>> When we migrate we ask the kernel about its current belief on what the guest
>> time would be. However, I've seen cases where the kvmclock guest structure
>> indicates a time more recent than the kvm returned time.
> 
> Hi,
> 
> 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 :)

Alex

> 
> -- 
> mg
> 
> 
>