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Date: Mon, 03 Jan 2011 18:41:59 +0200
From: Avi Kivity <avi@redhat.com>
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Subject: [Qemu-devel] Re: [PATCH v2 14/17] kvm: x86: Introduce kvmclock
 device to save/restore its state
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To: Jan Kiszka <jan.kiszka@web.de>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, Glauber Costa <glommer@redhat.com>, Marcelo Tosatti <mtosatti@redhat.com>, qemu-devel@nongnu.org, kvm@vger.kernel.org

On 01/03/2011 06:30 PM, Jan Kiszka wrote:
> Am 03.01.2011 17:04, Avi Kivity wrote:
> >  On 01/03/2011 10:33 AM, Jan Kiszka wrote:
> >>  From: Jan Kiszka<jan.kiszka@siemens.com>
> >>
> >>  If kvmclock is used, which implies the kernel supports it, register a
> >>  kvmclock device with the sysbus. Its main purpose is to save and restore
> >>  the kernel state on migration, but this will also allow to visualize it
> >>  one day.
> >>
> >
> >  kvmclock is a per-cpu affair.
>
> Nope, it's state (the one save/restored here) is per VM.
>
> >
> >>
> >>  @@ -534,6 +599,10 @@ int kvm_arch_init(int smp_cpus)
> >>        int ret;
> >>        struct utsname utsname;
> >>
> >>  +#ifdef KVM_CAP_ADJUST_CLOCK
> >>  +    sysbus_register_withprop(&kvmclock_info);
> >>  +#endif
> >>  +
> >
> >  So this doesn't look right.  I think we're fine with just migrating the
> >  MSRs, like we migrate anything else that has to do with the cpu.
> >
>
> The kvmclock state is not contained in any MSR. It's an independent
> machine state that can be indirectly obtained via MSR access. Therefore,
> qemu-kvm currently registers only one vmstate entry per machine, and
> this patch just turns this into a clean device - because that's what
> kvmclock is in the end, something like an HPET.

Okay, thanks for the correction.

-- 
error compiling committee.c: too many arguments to function