We just created a short tutorial for installing a current windows. This includes VirtIO drivers, Qemu-disk agent and Balloon Service installation inside Windows. We used windows 2016, but its also the same for Windows 10.
We used the VirtIO drivers from the Fedora project.
Install Windows 2016 Server on Proxmox VE
We used the VirtIO drivers from the Fedora project.
Install Windows 2016 Server on Proxmox VE