The QEMU cpu affinity is used in NUMA scenarios to ensure that
guest memory is allocated from a specific node. Normally memory
is allocate on demand in vCPU threads, but when using hugepages
the initial thread leader allocates memory upfront. libvirt was
not setting affinity of the thread leader, or I/O threads. This
patch changes the code to set the process affinity in between
the fork()/exec() of QEMU. This ensures that every single QEMU
thread gets the affinity

* src/qemu/qemu_driver.c: Set affinity on entire QEMU process
  at startup