system_powerdown causes SMP OpenBSD guest to freeze

[Robert Urban]

system_powerdown causes an SMP OpenBSD guest to freeze. I can reproduce it with the following systems/versions:

  - Debian 6: QEMU PC emulator version 0.12.5 (qemu-kvm-0.12.5)
  - Fedora 20:
     qemu-system-x86-1.6.1 (from Fedora repository)
     qemu-1.7.0 (latest release version)
     qemu-1.7.50 (latest development snapshot, "git cloned" today, 20140212)

all of the above hosts are running x86_64 linux.

The first OpenBSD version that I ran as a VM, v5.1, experienced the problem. All subsequent versions experience the problem. The above tests were performed using OpenBSD v5.4 (amd64).

I will open an OpenBSD bug report for this problem as well, and update this report with the OpenBSD bug ID.

There's an interesting RedHat bug report concerning this problem:
  URL: https://bugzilla.redhat.com/show_bug.cgi?id=508801#c34

Here an excerpt:
-snip-
Gleb Natapov 2009-12-23 10:37:44 EST

I posted patch to provide correct PCI irq routing info in mptable to kvm
mailing list. It works for all devices except for SCI interrupt. BIOS
programs SCI interrupt to be 9 as spec requires, but OpenBSD thinks that
it is smarter and moves it to interrupts 10. Qemu will still send it on
vector 9 and OpenBSD will enter the same infinity recursion. This can
be triggered by issuing system_powerdown on qemu monitor.
-snip-

Michael Tokarev reported this problem on the kvm mailing list in 2011:
  URL: http://www.spinics.net/lists/kvm/msg51311.html

I compiled qemu as follows:
-snip-
cd qemu-src-dir
mkdir -p bin/native
cd bin/native
../../configure \
 --prefix=/usr/local/qemu-dev-snapshot-20140212 \
 --target-list=x86_64-softmmu \
 --enable-kvm \
 --enable-spice \
 --with-gtkabi="3.0" \
 --audio-drv-list=pa,sdl,alsa,oss \
 --extra-cflags='-I/usr/include/SDL'
-snip-

I'm running OpenBSD with the following command:
-snip-
#!/bin/bash

DEF=/usr/bin/qemu-system-x86_64
QEMU_LATEST=/usr/local/qemu-1.7.0/bin/qemu-system-x86_64
QEMU_DEV=/usr/local/qemu-dev-snapshot-20140212/bin/qemu-system-x86_64

$QEMU_DEV \
 -machine accel=kvm \
 -name obsdtest-v54 \
 -S \
 -machine pc-i440fx-1.6,accel=kvm,usb=off \
 -boot c \
 -m 2048 \
 -realtime mlock=off \
 -smp 2,sockets=2,cores=1,threads=1 \
 -uuid 8b685793-2510-473e-b97e-822a4cf2fbca \
 -no-user-config \
 -monitor stdio \
 -rtc base=utc,driftfix=slew \
 -global kvm-pit.lost_tick_policy=discard \
 -no-hpet \
 -drive file=/guest_images/obsdtest_v54.raw,if=none,id=drive-virtio-disk0,format=raw,cache=none \
 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 \
 -drive if=none,id=drive-ide0-0-0,readonly=on,format=raw \
 -device ide-cd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 \
 -chardev pty,id=charserial0 \
 -device isa-serial,chardev=charserial0,id=serial0 \
 -k en-us \
 -device cirrus-vga,id=video0,bus=pci.0,addr=0x3 \
 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 \
 -net nic \
 -net user
-snip-

The OpenBSD disk image I used for testing is 143MB compressed, 10G uncompressed. It can be found here:

  http://www.spielwiese.de/OpenBSD/obsd54.raw.7z

The root password is "x".

Rob Urban

[Robert Urban (urban-m)]

I opened an OpenBSD bug. OpenBSD does not use a bug-tracking database, AFAICT, but rather the mailing-list <email address hidden>. I will post any replies to the OpenBSD bug report in comments here.

[Robert Urban (urban-m)]

hoping to increase the OpenBSD developers' inclination to investigate this bug, I reproduced it using OpenBSD 5.4 as the host.

I used the stock qemu-1.5.1 that is available as an OpenBSD package. Booting the GENERIC.MP kernel in the VM was painfully slow, but it eventually came up to multi-user mode.

The script to run the OpenBSD 5.4 guest on the OpenBSD 5.4 host:
-snip-
#!/bin/sh

qemu-system-x86_64 \
        -S \
        -m 2048 \
        -smp 2,sockets=2,cores=1,threads=1 \
        -monitor stdio \
        -vnc :0 \
        -no-fd-bootchk \
        -net nic \
        -net user \
        -cdrom /space/install54.iso \
        -drive file=/space/obsd54test.raw,index=0,media=disk,cache=none,format=raw
-snip-

As usual, issuing the "system_powerdown" command in the monitor caused the guest to freeze totally.

Rob Urban

[Robert Urban (urban-m)]

If someone needs to coordinate with someone from the OpenBSD team, please talk to Mike Larkin <email address hidden>. He expressed an intention to look into this problem from the OpenBSD side. I would be delighted if I could supply Mike with a qemu contact person, of if someone could contact him directly (and copy me, please), as I think he wanted to investigate shortly.

Also worth mentioning: the problem can be reproduced using the OpenBSD uniprocessor kernel in the guest, as long as mpbios(4) is enabled, which is the default. Thus, a VM configured with a single CPU is sufficient to reproduce.

To boot the uniprocessor kernel from my guest image, at the OpenBSD boot prompt, type "boot /bsd". To make it permanent, edit /etc/boot.conf and change "bsd.mp" to "bsd", or remove boot.conf entirely.

Rob Urban

[Thomas Huth (th-huth)]

Triaging old bug tickets... can you still reproduce this issue with the latest version of QEMU and OpenBSD? Or could we close this ticket nowadays?

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]