Comment 2 for bug 1322441

The bug occurred when upgrading from 12.04.1 (3.2 kernel) to 14.04 (3.13 kernel). Booting with the old 3.2 kernel resolves the problem.

Guest command line -
qemu-system-x86_64 -enable-kvm -name test -S-machine pc-i440fx-1.4,accel=kvm,usb=off -cpu qemu64,hv_relaxed -m 4096 -realtimemlock=off -smp 2,sockets=2,cores=1,threads=1 -uuid e00d6bde-ca3e-8e6c-2c92-d5b5ec632b9a -no-user-config -nodefaults -chardevsocket,id=charmonitor,path=/var/lib/libvirt/qemu/test.monitor,server,nowait -monchardev=charmonitor,id=monitor,mode=contro l-rtcbase=localtime,driftfix=slew -no-hpet -no-shutdown -bootstrict=on -devicepiix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=rbd:ssd/test:auth_supported=none,if=none,id=drive-virtio-disk0-devicevirtio-blk-pci,scsi=off,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=2 -drive if=none,id=drive-ide0-1-0,readonly=on,format=raw-deviceide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0,bootindex=1 -netdevtap,fd=24,id=hostnet0,vhost=on,vhostfd=25 -devicevirtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:48:81:8a,bus=pci.0,addr=0x3-chardevpty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0-vnc127.0.0.1:0 -devicecirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4

Attached is a perf record of the qemu process whilst the fault was occuring.