On s390x: ioctl(KVM_CREATE_VM) failed: 22 Invalid argument

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Environment

SUSE Linux Enterprise Server 12 Service Pack 2 (SLES 12 SP2)

Situation

Deploying a new Virtual Machine via Virtual Machine Manager on s390x fails.
The following error is shown in the /var/log/libvirt/qemu/ logs:

<date> <time>: starting up libvirt version: 2.0.0, qemu version: 2.6.1 (SUSE Linux Enterprise 12), hostname: host.foo.com
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin QEMU_AUDIO_DRV=none /usr/bin/qemu-system-s390x 
-name guest=sles12sp2,debug-threads=on ....
....
char device redirected to /dev/pts/3 (label charconsole0)
ioctl(KVM_CREATE_VM) failed: 22 Invalid argument
Host kernel setup problem detected. Please verify:
- for kernels supporting the switch_amode or user_mode parameters, whether
  user space is running in primary address space
- for kernels supporting the vm.allocate_pgste sysctl, whether it is enabled
failed to initialize KVM: Invalid argument
<date> <time>: shutting down

Resolution

The qemu update, qemu-2.6.2-41.9.1 released March 2017 includes the patch to resolve the problem.
Please install the recommended update.

Cause

To allow KVM to run on s390x, the sysctl value "vm.allocate_pgste =" needs to be '1': vm.allocate_pgste = 1.
The /etc/sysctl.d/50-allow-kvm-on-s390x includes the correct value but the file was missing it's .conf ending so it wasn't used.

Additional Information

Disclaimer

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