An internal project caused the question how Microsoft SQL Server 2014 licenses have to be counted in a virtual environment. What are the rules that apply in this scenario?

For core-based licensing of SQL Server 2014, the number of virtual CPUs (vCPUs, virtual cores, v-cores) per virtual machine (VM) is crucial. The minimum licensing of 4 vCPUs per VM must also be considered. If you use a VM with only 2 vCPUs, 4 vCPUs must still be licensed. Physical cores are not to be considered in this scenario. If you are using a big number of VMs, as an alternative to the v-core licensing, you can license the entire physical server with Enterprise Edition core licenses and cover those licenses with Software Assurance (SA).

Source: Licensing Guide_Microsoft_SQL Server 2014 (Page 12)