[nel]

Summary

A VM with cpus: 10 running Windows 11 reports only 2 CPUs (NUMBER_OF_PROCESSORS=2).

Without a <topology> element, libvirt shows each vCPU to the guest as a separate physical processor with one core, so cpus: 10 looks like a machine with ten single-core processors. Windows 10 and 11 (Home, Pro, Enterprise) use at most two physical processors, so the guest uses two cores and ignores the rest. Linux guests use every vCPU either way.

This shows the vCPUs as one processor with cpus cores:

<cpu mode='host-passthrough'>
  <topology sockets='1' cores='{{.CPUs}}' threads='1'/>
</cpu>

In libvirt's terms, sockets is the number of physical processors. The VM still has the same number of vCPUs; only the layout the guest sees changes.

Closes #49

Test plan

• Template test checks the topology
• make test, golangci-lint run (2.15.0), gofmt -s
• Windows 11 guest with cpus: 10 on Ubuntu 26.04 / libvirt 12.0.0: 2 CPUs before, 10 after