Am 03.01.2011 17:04, Avi Kivity wrote: > On 01/03/2011 10:33 AM, Jan Kiszka wrote: >> From: Jan Kiszka<jan.kiszka@xxxxxxxxxxx> >> >> 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. Jan
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