Re: [PATCH v2 14/17] kvm: x86: Introduce kvmclock device to save/restore its state

Jan Kiszka
2011-01-03T16:48:38Z

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Am 03.01.2011 17:37, Glauber Costa wrote:
> On Mon, 2011-01-03 at 09:33 +0100, 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.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
>> CC: Glauber Costa <glommer@redhat.com>
>
> Hi Jan.
>
> I've just recently posted a patch (not sure what was made from it), that
> fixes a bug that you reintroduce here.

Hmm, must have missed it.

>
> The bug is: if we call KVM_GET_CLOCK ioctl in pre_save, this means that
> this value will change every time we issue savevm, even if the machine
> is not run in between.
>
> Ideally, we'd like to have two consecutive savevms returning the exact
> same thing in that situation.
>
> I like the general approach of moving it to sysbus, but please move the
> ioctl to change state notifiers.

OK, will look into this.

Jan

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