Re: [Qemu-devel] Steal time MSR not set properly during live migration?

[Alexandre DERUMIER]

Hi,

I have add this bug today on 3 debian jessie guests (kernel 3.16), after 
migration from qemu 2.3 to qemu 2.4.

Is it a qemu bug or guest kernel 3.16 ?

Regards,

Alexandre Derumier


----- Mail original -----
De: "Michael Tokarev" <address@hidden>
À: "qemu-devel" <address@hidden>, address@hidden
Cc: "Marcelo Tosatti" <address@hidden>, "Gleb Natapov" <address@hidden>
Envoyé: Jeudi 11 Juin 2015 23:42:02
Objet: Re: [Qemu-devel] Steal time MSR not set properly during live     
migration?

11.06.2015 23:46, Apollon Oikonomopoulos wrote: 
> On 15:12 Wed 03 Jun , Apollon Oikonomopoulos wrote: 
>> Any ideas? 
> 
> As far as I understand, there is an issue when reading the MSR on the 
> incoming side: there is a KVM_SET_MSRS vcpu ioctl issued by the main 
> thread during initialization, that causes the initial vCPU steal time 
> value to be set using the main thread's (and not the vCPU thread's) 
> run_delay. Then, upon resuming execution, kvm_arch_load_vcpu uses the 
> vCPU thread's run_delay to determine steal time, causing an overflow. 
> The issue was introduced by commit 
> 917367aa968fd4fef29d340e0c7ec8c608dffaab. 
> 
> For the full analysis, see https://bugs.debian.org/785557#64 and the 
> followup e-mail. 

Adding Cc's... 

Thanks, 

/mjt