linux-kernel - Re: system time goes weird in kvm guest after host suspend/resume

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Message-ID: <4c3c4a5a-e11b-1a27-0e25-9696e407bd0a@redhat.com>
Date:   Fri, 5 Jun 2020 10:09:24 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Miklos Szeredi <miklos@...redi.hu>
Cc:     Thomas Gleixner <tglx@...utronix.de>, kvm@...r.kernel.org,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org
Subject: Re: system time goes weird in kvm guest after host suspend/resume

On 05/06/20 09:35, Miklos Szeredi wrote:
>> time(2) instead should actually be gettimeofday(2), which just returns
>> tk->xtime_sec.  So the problem is the nanosecond part which is off by
>> 2199*10^9 nanoseconds, and that is suspiciously close to 2^31...
> Yep: looking at the nanosecond values as well, the difference is
> exactly 2199023255552 which is 2^41.

Umpf, I was off by 3, it's not related to 2^31.  But yeah the cause of
the bug seems to be the botched nanosecond part, which I'm sure is not
supposed to be much bigger than 10^9.

Paolo