Commit 4b03d59167f4a4c6ec57def315a61d977466e75b changed the pinning
behavior in a way that makes some machines non-startable.
The comment mentioning that we cannot control each vcpu when there is
not VCPU<-> PID mapping available is true, however, this isn't
necessarily an error, because this can be caused by old QEMU without
support for "query-cpus" command as well as a software emulated
machines that don't create more than one process.
16ebec2b7c