Re: Live migration stops working...

[Avi Kivity <avi@redhat.com>]

On 08/17/2009 08:15 PM, Stephane Bakhos wrote:
>>>  since upgrade from qemu-kvm 0.10.5 to 0.10.6 (Debian Lenny, 
>>> Packages from
>>>  http://www.corpit.ru/debian/tls/kvm/, kvm module from kernel 2.6.30)
>>>  live-migration does not work anymore.
>>>
>>>  After "migrate -d tcp:192.168.0.2:4444" info says "migration 
>>> completed",
>>>  but "incoming" kvm machine dies.
>>>
>>>  Any hint how to debug this?
>>>
>>>
>>
>> What do you mean exactly by "dies"?
>
> Not sure if this is related but this is what happens on my system when 
> I try to do a live migration with kvm-88 and the latest kernel 2.6.30 
> (gentoo 2.6.30-gentoo-r5).
>
> [   73.168871] general protection fault: 0000 [#1] SMP
> [   73.169409] last sysfs file: /sys/kernel/uevent_seqnum
> [   73.169733] Modules linked in:
> [   73.169733]
> [   73.169733] Pid: 1, comm: init Not tainted (2.6.30-gentoo-r5 #1)
> [   73.169733] EIP: 0060:[<c0102f01>] EFLAGS: 00010246 CPU: 0
> [   73.169733] EIP is at sysenter_exit+0xf/0x16
> [   73.169733] EAX: 00000000 EBX: 0000000b ECX: bfbc2a80 EDX: b7f90424
> [   73.169733] ESI: 00000000 EDI: bfbc2d74 EBP: 00000000 ESP: df82bfb4
> [   73.169733]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
> [   73.169733] Process init (pid: 1, ti=df82a000 task=df830000 
> task.ti=df82a000)
> [   73.169733] Stack:
> [   73.169733]  0000000b bfbc2c44 00000000 00000000 bfbc2d74 bfbc2d88 
> 00000000 0000007b
> [   73.169733]  0000007b 00000000 00000000 0000008e b7f90424 00000073 
> 00000246 bfbc2a80
> [   73.169733]  0000007b 00000000 00000000
> [   73.169733] Call Trace:
> [   73.169733] Code: 42 c0 89 44 24 18 fa 8d 80 00 00 00 00 8b 4d 08 
> f7 c1 ff fe 00 08 0f 85 56 01 00 00 8b 54 24 30 8b 4c 24 3c 31 ed 8e 
> 64 24 24 fb <0f> 35 8d 44 20 00 90 50 fc 6a 00 0f a0 06 1e 50 55 57 56 
> 52 51

This is the sysexit instruction.

Are you doing cross-vendor migration (AMD->Intel or vice versa)?

This is supported in kvm-88, but not in previous versions.  Are you sure 
the kvm-88 modules are loaded on the target host, and not the modules 
that came with the kernel?

Try 'cat /sys/module/kvm/version'.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.