There is hugge difference between “not working, becouse of difficult environment” and “not working, becouse of lack of one of the most important, mainline drivers”. Look at similar problem at VyOS: https://phabricator.vyos.net/T389
Difficulty level Easy (less than an hour)
It’s not only my whim to run CHR on KVM with SCSI-virtio. Look at the problem like this: KVM VPS hosting is cheapest full virtualisation on the market. If I want to provide homogenicall network environment with Routerboard devices It’s natural to use CHR. If I can’t use it becouse using obslate mode (driver) of Virtio storage (look closely at: https://pve.proxmox.com/wiki/Paravirtualized_Block_Drivers_for_Windows ) everything is going to be more and more complicated (more expensive VPS with vmware or diffrent OS).
I tell it once more: Nowdays it’s absolutly crucial to have support of VirtIO SCSI in CHR, please MT developers, make it work (please, please, please) 
Edit:
Fixed in >= 6.42rc52