There's nothing much to say besides what the tutorial
 tells us. Nevertheless, there are quite a few notes I took just not to let me completely forget about them, later.
I won't lie to you: it's insufferably slow. And for a good reason: you are virtualising twice, and the first level (Hercules) has zero paravirt. as s390x is a completely different architecture. But, maybe – I said maybe – you can suffer less, giving the VM more CPU's. So, here's how it's done:
When creating the profile, you probably specified 4 max CPU's (
MACHINE ESA 4). But that's it, when the machine is actually IPL'd, it goes up with only one.
So, you take
vmcp, a neat little application which let you issue CP/CMS commands from inside Linux and do as follows
vmcp define cpu 02 type cp
There are other types of CPU other than CP
CP indicates the central processor. IFL indicates the IBM® Integrated Facility for Linux. ZAAP indicates the IBM zEnterprise® Application Assist Processor. ZIIP indicates the IBM z Integrated Information Processor. ICF indicates the Internal Coupling Facility.
But CP is the general kind. And I don't think we should bother much about IFL or others when running z/VM inside an emulated mainframe.
Well, now your VM got a new CPU. It's offline, though:
vmcp q v cpus CPU 01 ID FF0288F728288000 CP CPUAFF ON CPU 02 ID FF0288F728288000 STOPPED CP CPUAFF ON [...]
Tell the guest to rescan for CPU's, by issuing
chcpu -r. If it don't come online (i.e. still ofline in
lscpu -ae), do this:
chcpu -e 02. And it'll probably come online.