Re: Live migration of x86-64 kvm guests broken?

Jan Kiszka
2009-12-02T18:44:35Z

Ryan Harper wrote:
> * Jan Kiszka <jan.kiszka@siemens.com> [2009-12-02 12:18]:
>> Ryan Harper wrote:
>>> * Jan Kiszka <jan.kiszka@siemens.com> [2009-12-02 12:07]:
>>>> Ryan Harper wrote:
>>>>> * Jan Kiszka <jan.kiszka@siemens.com> [2009-12-02 09:28]:
>>>>>> Hi,
>>>>>>
>>>>>> I'm facing stalled x86-64 guests after live migration when using kvm
>>>>>> (share disk images). This does not happen with x86-32 guests or when
>>>>>> disabling kvm. Both qemu and qemu-kvm git heads are affected (recent
>>>>>> vmstate fixes applied). Running I/O load during the migration (e.g. a
>>>>>> simple "ls -R /") seems to trigger it reliably.
>>>>>>
>>>>>> Can anyone confirm / comment on this? Do we fail to restore some magic
>>>>>> state that only long mode cares about?
>>>>> Just tested upstream qemu.git (with vmstate fixes) and I could migrate
>>>>> RHEL 5.3 64-bit guest with your light io load over localhost. I'll try
>>>>> remote hosts next.
>>>> Hell, too many variables. It looks like the kernel modules have some if
>>>> not the ultimate impact: kvm-mod-2.6.31.6b on my 2.6.27 host works fine,
>>>> kvm-kmod stable-2.6.32 as well as master cause troubles.
>>>>
>>>> What is your host kernel and/or kvm module version?
>>> Stock 64-bit Ubuntu Karmic:
>>> % uname -a
>>> Linux symmetry 2.6.31-15-generic #50-Ubuntu SMP Tue Nov 10 14:53:52 UTC 2009 x86_64 GNU/Linux
>>>
>>> % modinfo kvm
>>> filename:
>>> /lib/modules/2.6.31-15-generic/kernel/arch/x86/kvm/kvm.ko
>>> license: GPL
>>> author: Qumranet
>>> srcversion: 82D6B673524596F9CF3E84C
>>> depends:
>>> vermagic: 2.6.31-15-generic SMP mod_unload modversions
>>> parm: oos_shadow:bool
>>>
>>> % modinfo kvm-intel
>>> filename: /lib/modules/2.6.31-15-generic/kernel/arch/x86/kvm/kvm-intel.ko
>>> license: GPL
>>> author: Qumranet
>>> srcversion: 8FEA479DFCD7F174DA7864E
>>> depends: kvm
>>> vermagic: 2.6.31-15-generic SMP mod_unload modversions
>>> parm: bypass_guest_pf:bool
>>> parm: vpid:bool
>>> parm: flexpriority:bool
>>> parm: ept:bool
>>> parm: emulate_invalid_guest_state:bool
>>>
>> So far, so consistent. Could you try kvm-kmod-2.6.32-rc7 on top of that?
>>
>
> Sure, can you remind me of the kvm-kmod build magic for building that
> branch?
>

If you want to build from git, check Wolfgang's nice README. But it
might be easier to just download the tarball from sourceforge.

Jan

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