firq-nonlinear-cpu-ids-tcg in ubuntu_kvm_unit_tests failed with Bionic 4.15 s390x

[Po-Hsu Lin]

This issue happens after kvm-unit-test repo updated to d8a4f9e5 (ci: Update the list of tests that we run in the Fedora Cirrus-CI),

Test failed with timeout.

Running '/home/ubuntu/autotest/client/tmp/ubuntu_kvm_unit_tests/src/kvm-unit-tests/tests/firq-nonlinear-cpu-ids-tcg'
 BUILD_HEAD=35a22051
 timeout -k 1s --foreground 20 /usr/bin/qemu-system-s390x -nodefaults -nographic -machine s390-ccw-virtio,accel=tcg -chardev stdio,id=con0 -device sclpconsole,chardev=con0 -kernel /tmp/tmp.MJnxjDU4aN -smp 1 -smp 1,maxcpus=3 -cpu qemu -device qemu-s390x-cpu,core-id=2 -device qemu-s390x-cpu,core-id=1 # -initrd /tmp/tmp.o7utHfZiZy
 qemu-system-s390x: WARNING: SMP support on s390x is experimental!
 SMP: Initializing, found 3 cpus
 qemu-system-s390x: terminating on signal 15 from pid 10989 (timeout)
 FAIL firq-nonlinear-cpu-ids-tcg (timeout; duration=20)