[libvirt] interactions between virDomainSetVcpusFlags and NUMA/pinning?

Hi, Just wondering about interactions between virDomainSetVcpusFlags() and virDomainPinVcpuFlags() and the domain XML. 1) If I add a vCPU to a domain, do I need to pin it after or does it respect the vCPU-to-pCPU mapping specified in the domain XML? 2) Are vCPUs added/removed in strict numerical order such that at any given time the active vCPUs are numbered 0-(N-1) where N is the number of active vCPUs? 3) Will the newly-added vCPUs respect the NUMA topology specified in the domain XML? Thanks, Chris