[Qemu-devel] Re: Bugs in kvm guest migration

[Jan Kiszka <jan.kiszka@web.de>]

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Jan Kiszka wrote:
> Avi Kivity wrote:
>> On 12/03/2009 09:23 PM, Jan Kiszka wrote:
>>> Jan Kiszka wrote:
>>>    
>>>> Problem 2
>>>> ---------
>>>> Setup: qemu head with vmstate fixes. kvm-kmod master, 64-bit host&  guest.
>>>> Effect: The migration target either locks up or reboots immediately.
>>>> I've nailed this down to 84d0b66c778d881eafca2a5d0d66678211c4e861. Every
>>>> kvm module build before that works, everything including and after
>>>> 26ede77f536d1bb369527a96c7fe7fdc8ba2f890 shows the effect (everything in
>>>> between crashes the host for known reasons). It's still unclear if this
>>>> is an kvm-kmod wrapping issue of the user-space return notifiers. Will
>>>> check once problem #1 is understood.
>>>>      
>>> It is kernel-related, using kvm.git as host kernel makes no difference.
>>>
>>> This may now mean that kvm is buggy or that it triggers some msr
>>> save/restore related issues in qemu. Digging even deeper...
>>>    
>> Does calling drop_user_return_notifiers() (static in x86.c, will need 
>> exporting) in vmx_load_host_state() within the preempt-disable region help?
>>
> 
> Nope.
> 

It was a qemu bug, resolved by "KVM: x86: Fix initial kvm_has_msr_star".

Jan


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