[Libvir] Proposal for a new Libvirt function: change number of virtual CPUs

For our administration, we need to dynamically reduce the number of virtual CPUs in each domain, in same way as Xen command "xm vcpu-set". It seems that no Libvirt function is currently provided for that purpose. I successfully tried some simple changes in libvirt.c an xend_internal.c, mainly the following: snprintf(buf, sizeof(buf), "%d", vcpus); return xend_op(domain->conn, domain->name, "op", "set_vcpus", "vcpus", buf, NULL); We suggest to add this new function "virDomainSetVcpus" to Libvirt. I have not tried the hypervisor and xen store accesses for this function. Do you think they would be necessary? I am also working on two other functions to reproduce "xm vcpu-pin" and "xm vcpu-list" from Libvirt.