The problem seems to be related to how qemu allocates the virtual cores and threads to the VM.
Starting the VMs with the following command I cannot reproduce the issue: $ qemu-system-ppc64le -m 1024 -smp 16,threads=8 -nographic -net nic,model=virtio -net user,hostfwd=tcp::10022-:22 -drive file =./autopkgtest-xenial-ppc64el.img -enable-kvm As long the number of cpus and threads provided to the -smp parameter follow the topology of the p8 processor, making qemu use more than one core only if the number of threads is multiple of 8, I can't reproduce the hang. If the parameters provided makes qemu spread the virtual threads on more than one physical cpu without using all the 8 threads (e.g. '-smp 2', '-smp 4,threads=2', '-smp 8,threads=4') then the guest kernel hangs at some point. This is the environment being tested: Machine type-model: 8247-22L Host: Artful kernel 4.13.0-17-generic qemu 2.10+dfsg-0ubuntu3 Guests: Xenial, Zesty and Artful with latest kernel from -updates. Could someone from IBM please confirm if this is a known or expected behavior? This issue seems to be around for a long time and it's odd that this hasn't come up before. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1733864 Title: kernel 4.10.0-40 is hanging with a CPU soft lock To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-power-systems/+bug/1733864/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
