The use of hard disk controllers is described at
Virtual I/O Device SCSI is a standard to connect virtual storage devices like hard disks or optical drives to a VM. Recent Linux and Windows versions support these devices, but Windows needs additional drivers. Drivers are available from Oracle Support.
The virtio-scsi controller will only be seen by OSes with device support for it. In particular, there is no built-in support in Windows. So Windows will not see such disks unless you install additional drivers.
Up to 256 slots can be attached to the virtio-scsi controller, if enabled and supported by the guest OS.