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VirtIO Drivers for Windows Guests (QEMU/KVM on Gentoo)

VirtIO drivers provide paravirtualized performance for Windows guests running under QEMU/KVM. This guide covers installation of virtio-win on Gentoo, attaching the ISO in virt‑manager, and installing only the required drivers inside Windows.

Install virtio-win

emerge --ask app-emulation/virtio-win
Output from above installation 
* Package:    app-emulation/virtio-win-0.1.285.1:0
* Repository: gentoo
* Maintainer: kaichun.ning@gmail.com proxy-maint@gentoo.org
* USE:        abi_x86_64 amd64 elibc_glibc kernel_linux
* FEATURES:   network-sandbox preserve-libs sandbox userpriv usersandbox
* Final size of installed tree: 771172 KiB (753.0 MiB)
* VirtIO drivers have been installed as a CD-ROM image to:
*   /usr/share/drivers/windows/virtio-win.iso

Attach the VirtIO ISO in virt-manager

The ISO contains all VirtIO drivers for Windows: NetKVM, Balloon, Block, SCSI, RNG, Guest Agent, and more

Attach VirtIO ISO in virt-manager

Open your VM in virt-manager.

Click the blue "i" icon (Show Virtual Hardware).

At the bottom left, click "Add Hardware".

Select "Storage" from the list.

Under "Device type", choose "CDROM device".

Under "Select or create custom storage", click "Browse..." and select:
    /usr/share/drivers/windows/virtio-win.iso

Click Finish.

Start the Windows guest. The ISO will appear as a D: drive (or similar).

Keeping the ISO permanently attached is useful for future driver updates

This is the cleanest method if you only need VirtIO networking without installing unnecessary components.

Install only the VirtIO network driver

Open Device Manager (devmgmt.msc).

Right-click "Ethernet Controller" (yellow exclamation mark).

Select:
    Update Driver →
    Browse my computer for drivers

Browse to:
    D:\NetKVM\w10\amd64

Click Next. Windows installs the VirtIO network driver.

(Optional) Install all VirtIO drivers

The adapter will now appear as Red Hat VirtIO Ethernet Adapter

Open the VirtIO ISO in Windows Explorer.

virtio-win-gt-x64.msi

This installs:

  • VirtIO Block
  • VirtIO SCSI
  • VirtIO NetKVM
  • Balloon driver
  • RNG driver
  • Guest Agent (optional)

This installs more components than most users need

Verify network functionality

Verify network status

Get-NetAdapter

Expected output:

Field Value
Status Up
Name Red Hat VirtIO Ethernet Adapter
Link Speed Depends on VM configuration

(Optional) Switch Windows from SATA → VirtIO Disk

If Windows was originally installed using a SATA disk, you can migrate to VirtIO for improved performance.

Enable VirtIO disk

Shut down the VM.

In virt-manager:
    Change disk bus: SATA → VirtIO

Start Windows.

Windows will automatically install the VirtIO block driver from the ISO.

Tip

If Windows fails to boot:
revert to SATA → install the VirtIO disk driver manually → switch again.

VirtIO RNG improves entropy inside the Windows guest.

Add VirtIO RNG device

In virt-manager:
    Add Hardware → RNG
    Backend: /dev/random or /dev/hwrng

Windows will install the RNG driver automatically.

Resouce(s)

  • Gentoo Wiki: QEMU/Windows guest
  • /usr/share/doc/virtio-win-*/README.gentoo
  • Red Hat VirtIO driver documentation