VM managed by corosync not detecting new CPUs

I have an HA cluster managed by corosync, and I need to increase the CPU allocation to one of the VMs. I have done the following: * pcs resource disable myVM * Wait for VM to stop * Edit the xml file (confirmed the correct file by pcs sources show --full) - within the cpu section I changed the entry: `` to change the number of cores to 8. * Make sure that xml file is synced across all physical hosts * pcs resource enable myVM But when the VM comes back up, /proc/cpuinfo shows that it still has only 4 cores (I don't have hot plug CPUs enabled / am not sure how to enable this). There are plenty of CPU cores available on the physical hosts. Can anyone tell me what I'm doing wrong that's preventing the VM from starting up with 8 cores instead of 4? It must be something obvious but I can't see it!