spapr: Set VSMT to smp_threads by default

spapr: Set VSMT to smp_threads by default

Support for setting VSMT is available in KVM since linux-4.13. Most distros
that support KVM on POWER already have it. It thus seem reasonable enough
to have the default machine to set VSMT to smp_threads.

This brings contiguous VCPU ids and thus brings their upper bound down to
the machine's max_cpus. This is especially useful for XIVE KVM devices,
which may thus allocate only one VP descriptor per VCPU.

Signed-off-by: Greg Kurz <[email protected]>
Message-Id: <157010411885.246126.12610015369068227139[email protected]>
Signed-off-by: David Gibson <[email protected]>