Migration problems

[Chris Lalancette <clalance-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

All,
     I've been doing some migration testing of KVM guests, and have been running
into some problems.  Let me describe the setup and what I've tried, and maybe
somebody has some ideas about what might be going on here.

Setup:
     2 identical Intel SDV boxes,  Intel(R) Core(TM)2 Duo CPU     E6850  @ 3.00GHz
     Both machines are running F-8 kernel, 2.6.23.8-63.fc8 x86_64, with updated
KVM kernel modules from git.
     On one machine, I have a /kvm directory that holds my guest disk image;
this directory is exported via NFS and mounted as /kvm on the secondary machine.

The guest in question is also an F-8 x86_64 guest, running the same kernel as
the hosts.  I start it up with the following command-line:

qemu-system-x86_64 -hda /kvm/f8x86_64.dsk -boot c -m 385 -net
nic,vlan=0,macaddr=00:13:6e:12:34:56 -net tap,vlan=0,script=/etc/kvm-ifup
-monitor stdio

The guest starts up just fine.  On the secondary machine, I use the following
command-line:

qemu-system-x86_64 -hda /kvm/f8x86_64.dsk -boot c -m 385 -net
nic,vlan=0,macaddr=00:13:6e:12:34:56 -net tap,vlan=0,script=/etc/kvm-ifup
-monitor stdio -incoming tcp://0:4444

(i.e. exactly the same, but I add the -incoming parameter).  When I try to do
live migration this way, things seem like they work, and it even seems like a
few instructions get executed on the destination side.  However, fairly quickly
I'll get "Disabling IRQ #11" on the console of the guest at the destination, and
the qemu process will just spin at 100%, with no interaction possible.  IRQ #11,
incidentally, is the IRQ associated with the emulated rtl8139 card.

This led me to suspect the in-kernel PIC/APIC emulation, and, sure enough, if I
pass -no-kvm-irqchip (on both the source and destination), things are better; I
can at least migrate from the host to the destination without the "Disabling IRQ
#11" message.  However, if I put any sort of load on the guest while doing
migration, I still get a hang-up, even with -no-kvm-irqchip.

Has anyone else seen this, or have ideas where I can start debugging it?

Thanks,
Chris Lalancette

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