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

Ryan Harper
2009-12-02T18:35:48Z

* 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?

> Jan
>
> --
> Siemens AG, Corporate Technology, CT T DE IT 1
> Corporate Competence Center Embedded Linux

--
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
ryanh@us.ibm.com