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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Andy Lutomirski <luto@amacapital.net>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Maxim Levitsky <mlevitsk@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Marcelo Tosatti <mtosatti@redhat.com>,
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        Jim Mattson <jmattson@google.com>,
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        Ingo Molnar <mingo@redhat.com>,
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Subject: Re: [PATCH v2 1/3] KVM: x86: implement KVM_{GET|SET}_TSC_STATE
In-Reply-To: <D4FDC64D-C632-42CF-A4F1-A9584C94AFD9@amacapital.net>
References: <87v9d9i9dt.fsf@nanos.tec.linutronix.de> <D4FDC64D-C632-42CF-A4F1-A9584C94AFD9@amacapital.net>
Date:   Fri, 11 Dec 2020 01:03:47 +0100
Message-ID: <87lfe5i4yk.fsf@nanos.tec.linutronix.de>
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On Thu, Dec 10 2020 at 15:19, Andy Lutomirski wrote:
>> On Dec 10, 2020, at 2:28 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
>> Can we please focus on real problems instead of making up new ones?
>>=20
>> Correctness of time is a real problem despite the believe of virt folks
>> that it can be ignored or duct taped to death.
>>=20
> I=E2=80=99m fine with this as long as it=E2=80=99s intentional. If we say=
 =E2=80=9Cguest
> timekeeping across host suspend is correct because we notify the
> guest=E2=80=9D, then we have a hole. But if we say =E2=80=9Cthe host will=
 try to
> notify the guest, and if the guest is out to lunch then the host
> reserves the right to suspend without waiting, and the guest should
> deal with this=E2=80=9D, then okay.

Yes of course this would be intentional and documented behaviour, which
is an infinite improvement over the current situation.

Thanks,

        tglx