[Qemu-devel] Windows 2008 Guest BSODS with CLOCK_WATCHDOG_TIMEOUT on VM migration

[Mikhail Sennikovskii <mikhail.sennikovskii@profitbricks.com>]

Hi all,

I'm running a slitely modified migration over tcp test in virt-test, 
which does a migration from one "smp=2" VM to another on the same host 
over TCP,
and exposes some dummy CPU load inside the GUEST while migration, and 
after a series of runs I'm alwais getting a CLOCK_WATCHDOG_TIMEOUT BSOD 
inside the guest,
which happens when
"
An expected clock interrupt was not received on a secondary processor in an
MP system within the allocated interval. This indicates that the specified
processor is hung and not processing interrupts.
"

This seems to happen with any qemu version I've tested (1.2 and above, 
including upstream),
and I was testing it with 3.13.0-44-generic kernel on my Ubuntu 14.04.1 
LTS with SMP4 host, as well as on 3.12.26-1 kernel with Debian 6 with 
SMP6 host.

One thing I noticed is that exposing a dummy CPU load on the HOST (like 
running multiple instances of the "while true; do false; done" script) 
in parallel with doing migration makes the issue to be quite easily 
reproducible.


Looking inside the windows crash dump, the second CPU is just running at 
IRQL 0, and it aparently not hung, as Windows is able to save its state 
in the crash dump correctly, which assumes running some code on it.
So this aparently seems to be some timing issue (like host scheduler 
does not schedule the thread executing secondary CPU's code in time).

Could you give me some insight on this, i.e. is there a way to customize 
QEMU/KVM to avoid such issue?

If you think this might be a qemu/kvm issue, I can provide you any info, 
like windows crash dumps, or the test-case to reproduce this.


qemu is started as:

from-VM:

qemu-system-x86_64 \
     -S  \
     -name 'virt-tests-vm1'  \
     -sandbox off  \
     -M pc-1.0  \
     -nodefaults  \
     -vga std  \
     -chardev 
socket,id=qmp_id_qmp1,path=/tmp/monitor-qmp1-20150123-112624-aFZmIkNT,server,nowait 
\
     -mon chardev=qmp_id_qmp1,mode=control  \
     -chardev 
socket,id=serial_id_serial0,path=/tmp/serial-serial0-20150123-112624-aFZmIkNT,server,nowait 
\
     -device isa-serial,chardev=serial_id_serial0  \
     -chardev 
socket,id=seabioslog_id_20150123-112624-aFZmIkNT,path=/tmp/seabios-20150123-112624-aFZmIkNT,server,nowait 
\
     -device 
isa-debugcon,chardev=seabioslog_id_20150123-112624-aFZmIkNT,iobase=0x402 \
     -device ich9-usb-uhci1,id=usb1,bus=pci.0,addr=03 \
     -drive id=drive_image1,if=none,file=/path/to/image.qcow2 \
     -device 
virtio-blk-pci,id=image1,drive=drive_image1,bootindex=0,bus=pci.0,addr=04 \
     -device 
virtio-net-pci,mac=9a:74:75:76:77:78,id=idFdaC4M,vectors=4,netdev=idKFZNXH,bus=pci.0,addr=05 
\
     -netdev 
user,id=idKFZNXH,hostfwd=tcp::5000-:22,hostfwd=tcp::5001-:10023  \
     -m 2G  \
     -smp 2,maxcpus=2,cores=1,threads=1,sockets=2  \
     -cpu phenom \
     -device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1  \
     -vnc :0  \
     -rtc base=localtime,clock=host,driftfix=none  \
     -boot order=cdn,once=c,menu=off \
     -enable-kvm

to-VM:

qemu-system-x86_64 \
     -S  \
     -name 'virt-tests-vm1'  \
     -sandbox off  \
     -M pc-1.0  \
     -nodefaults  \
     -vga std  \
     -chardev 
socket,id=qmp_id_qmp1,path=/tmp/monitor-qmp1-20150123-112750-VehjvEqK,server,nowait 
\
     -mon chardev=qmp_id_qmp1,mode=control  \
     -chardev 
socket,id=serial_id_serial0,path=/tmp/serial-serial0-20150123-112750-VehjvEqK,server,nowait 
\
     -device isa-serial,chardev=serial_id_serial0  \
     -chardev 
socket,id=seabioslog_id_20150123-112750-VehjvEqK,path=/tmp/seabios-20150123-112750-VehjvEqK,server,nowait 
\
     -device 
isa-debugcon,chardev=seabioslog_id_20150123-112750-VehjvEqK,iobase=0x402 \
     -device ich9-usb-uhci1,id=usb1,bus=pci.0,addr=03 \
     -drive id=drive_image1,if=none,file=/path/to/image.qcow2 \
     -device 
virtio-blk-pci,id=image1,drive=drive_image1,bootindex=0,bus=pci.0,addr=04 \
     -device 
virtio-net-pci,mac=9a:74:75:76:77:78,id=idI46M9C,vectors=4,netdev=idl9vRQt,bus=pci.0,addr=05 
\
     -netdev 
user,id=idl9vRQt,hostfwd=tcp::5002-:22,hostfwd=tcp::5003-:10023  \
     -m 2G  \
     -smp 2,maxcpus=2,cores=1,threads=1,sockets=2  \
     -cpu phenom \
     -device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1  \
     -vnc :1  \
     -rtc base=localtime,clock=host,driftfix=none  \
     -boot order=cdn,once=c,menu=off \
     -enable-kvm \
     -incoming tcp:0:5200


Thanks,
Mikhail