Tom Fenton has an article in Virtualization Review on the latest version of VMWare’s vSphere 6.5, and this release includes UEFI changes:
[…]Another major security upgrade in this release is “Secure Boot,” to prevent unauthorized operating systems and software from loading during the startup process. Secure Boot is a feature enabled by UEFI, and can be used not only when booting the hypervisor, but also when booting up the guests. VMware has also updated its logging to include the ability to track who did what on a vSphere system. […]
https://virtualizationreview.com/articles/2016/10/18/vsphere-6_5-first-look.aspx
Firmware Security 