cpu_hot_plug test in ubuntu_kernel_selftest failed on X/B/C s390x KVM

$ sudo make -C linux/tools/testing/selftests TARGETS=cpu-hotplug run_tests
make: Entering directory '/home/ubuntu/src/linux/tools/testing/selftests'
make[1]: Entering directory '/home/ubuntu/src/linux/tools/testing/selftests/cpu-hotplug'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/home/ubuntu/src/linux/tools/testing/selftests/cpu-hotplug'
make[1]: Entering directory '/home/ubuntu/src/linux/tools/testing/selftests/cpu-hotplug'
TAP version 13
selftests: cpu-on-off-test.sh
========================================
pid 18238's current affinity mask: 3
pid 18238's new affinity mask: 1
CPU online/offline summary:
  Cpus in online state: 0-1
  Cpus in offline state: 2
Limited scope test: one hotplug cpu
  (leaves cpu in the original state):
  online to offline to online: cpu 1
  offline to online to offline: cpu 2
./cpu-on-off-test.sh: line 85: /sys/devices/system/cpu/cpu2/online: No such file or directory
online_cpu_expect_success 2: unexpected fail
not ok 1..1 selftests: cpu-on-off-test.sh [FAIL]
make[1]: Leaving directory '/home/ubuntu/src/linux/tools/testing/selftests/cpu-hotplug'
make: Leaving directory '/home/ubuntu/src/linux/tools/testing/selftests'

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-4.15.0-43-generic 4.15.0-43.46
ProcVersionSignature: Ubuntu 4.15.0-43.46-generic 4.15.18
Uname: Linux 4.15.0-43-generic s390x
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
AlsaDevices: Error: command ['ls', '-l', '/dev/snd/'] failed with exit code 2: ls: cannot access '/dev/snd/': No such file or directory
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay': 'aplay'
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: s390x
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord': 'arecord'
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
CurrentDmesg:

Date: Fri Dec 21 10:38:05 2018
HibernationDevice: RESUME=UUID=caaee9b2-6bc1-4c8e-b26c-69038c092091
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig': 'iwconfig'
Lspci:

Lsusb: Error: command ['lsusb'] failed with exit code 1:
PciMultimedia:

ProcFB: Error: [Errno 2] No such file or directory: '/proc/fb'
ProcKernelCmdLine: root=UUID=c7d7bbcb-a039-4ead-abfe-7672dea0add4 crashkernel=196M
RelatedPackageVersions:
 linux-restricted-modules-4.15.0-43-generic N/A
 linux-backports-modules-4.15.0-43-generic N/A
 linux-firmware 1.173.2
RfKill: Error: [Errno 2] No such file or directory: 'rfkill': 'rfkill'
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)