The device tree presented to pseries machine type guests includes an
ibm,chip-id property which gives essentially the socket number of each
vcpu core (individual vcpu threads don't get a node in the device
tree).
To calculate this, it uses a vcpus_per_socket variable computed as
(smp_cpus / #sockets). This is correct for the usual case where
smp_cpus == smp_threads * smp_cores * #sockets.
However, you can start QEMU with the number of cores and threads
mismatching the total number of vcpus (whether that _should_ be
permitted is a topic for another day). It's a bit hard to say what
the "real" number of vcpus per socket here is, but for most purposes
(smp_threads * smp_cores) will more meaningfully match how QEMU
behaves with respect to socket boundaries.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
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