What is your qemu command line ?
Ignoring any additional devices:
s390x-softmmu/qemu-system-s390x -M s390-ccw-virtio,accel=tcg -cpu max -m 1024 -nographic -device virtio-scsi-ccw,id=scsi0,devno=fe.0.0001 -drive file=/home/cohuck/vm-images/vm1.qcow2,format=qcow2,if=none,id=drive-scsi0-0-0-0 -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=1 -sandbox on -kernel ~/git/linux/arch/s390/boot/bzImage -append "root=/dev/sda3"