While we the topic of VirtIO drivers has already been touched in Sarab’s post on Installing Windows VM and VirtIO drivers, we would like to bring two more KBs to your attention.
One is on AHV | How to install VirtIO drivers for Microsoft Windows Server 2008 (KB-5666) and the other one is AHV | Nutanix VirtIO drivers for Windows Server 2019 (KB-6495).
N.B! Nutanix does not release or maintain VirtIO drivers for Microsoft Windows Server 2008. However, you can still use stable VirtIO drivers available from Fedora project website.
Nutanix recommends to use the Stable VirtIO-Win drivers.