On AMD chips a CCX unit is 8 cores. All Ryzen, Threadripper, and Epyc CPUs are built around this. The performance differnece between the Ryzen 3100 and the Ryzen 3300 shows the importance of all the cores being on the same CCX. When creating an 8 (16 including HT) core VM, can you force all 8 virtual cores to be on the same CCX?