Chapter 4. Optimizing Windows virtual machines

• Block (storage) devices
• Network interface controllers
• Video controllers
• Memory ballooning device
• Paravirtualized memory device
• Paravirtual serial port device
• Entropy source device
• Paravirtual panic device
• Input devices, such as mice, keyboards, or tablets
• VirtIO FS Device
• QEMU FwCfg Device
• A small set of emulated devices

• Windows Server versions: See Certified guest operating systems for Red Hat Enterprise Linux with KVM in the Red Hat Knowledgebase.

• Windows Desktop (non-server) versions:

  • Windows 10 (32-bit and 64-bit versions)
  • Windows 11 (64-bit)

Prerequisites

• Ensure that virtualization is enabled in your RHEL 10 host system. For more information, see Preparing RHEL to host virtual machines.
• Ensure that you have root access privileges to the VM.

Prerequisites

• An installation medium with the KVM virtio drivers must be attached to the VM. For instructions on preparing the medium, see Preparing virtio driver installation media on a host machine.

Next steps

• If you installed the NetKVM driver, you might also need to configure the Windows guest’s networking parameters. For more information, see Configuring NetKVM driver parameters.

Prerequisites

• A Windows guest OS with virtio drivers installed.
• If not using Windows Update, an installation medium with up-to-date KVM virtio drivers must be attached to the Windows VM. For instructions on preparing the medium, see Preparing virtio driver installation media on a host machine.

Procedure

• On Windows 10, Windows Server 2016 and later operating systems, check if the driver updates are available by using the Windows Update graphical interface:

  1. Start the Windows VM and log in to its guest OS.

  2. Navigate to the Optional updates page:

     Settings Windows Update Advanced options Optional updates

  3. Install all updates from Red Hat, Inc.

• On operating systems that preceed Windows 10 and Windows Server 2016, or if the OS does not have access to Windows Update, reinstall the drivers.

  This restores the Windows guest OS network configuration to default (DHCP). If you want to preserve a customized network configuration, you also need to create a backup and restore it by using the netsh utility:

  1. Start the Windows VM and log in to its guest OS.

  2. Open the Windows Command Prompt:

     1. Use the Super+R keyboard shortcut.
     2. In the window that is displayed, type cmd and press Ctrl+Shift+Enter to run as administrator.

  3. Back up the OS network configuration by using the Windows Command Prompt:

     C:\WINDOWS\system32\netsh dump > backup.txt

  4. Reinstall KVM virtio drivers from the attached installation media. Do one of the following:

     • Reinstall the drivers by using the Windows Command Prompt, where X is the installation media drive letter. The following commands install all virtio drivers.

       • If using a 64-bit vCPU:

         C:\WINDOWS\system32\msiexec.exe /i X:\virtio-win-gt-x64.msi /passive /norestart

       • If using a 32-bit vCPU:

         C:\WINDOWS\system32\msiexec.exe /i X:\virtio-win-gt-x86.msi /passive /norestart

     • Reinstall the drivers using the graphical interface without rebooting the VM.

  5. Restore the OS network configuration using the Windows Command Prompt:

     C:\WINDOWS\system32\netsh -f backup.txt

  6. Reboot the VM to complete the driver installation.

  7. Optional: If you use a centralized update or configuration management system, such as Windows Server Update Services (WSUS), configure the system to allow drivers published by Red Hat, Inc.

     Some enterprise management services require specific vendors or drivers to be added to a trust-list. If Red Hat is not explicitly permitted, the system blocks virtio-win updates.

     +

     Note

     Approving Red Hat driver updates in WSUS is not sufficient. To receive regular driver updates, ensure that your management policy specifically permits the Red Hat vendor.

Verification

• Use the virsh dumpxml command to display the XML configuration of the running VM. If it includes the following segments, the Hyper-V enlightenments are enabled on the VM.

  <hyperv>
    <relaxed state='on'/>
    <vapic state='on'/>
    <spinlocks state='on' retries='8191'/>
    <vendor_id state='on' value='KVM Hv'/>
    <vpindex state='on'/>
    <runtime state='on' />
    <synic state='on'/>
    <frequencies state='on'/>
    <reset state='on'/>
    <tlbflush state='on'/>
    <reenlightenment state='on'/>
    <stimer state='on'>
      <direct state='on'/>
    </stimer>
    <ipi state='on'/>
    <evmcs state='on'/>
  </hyperv>
  
  <clock offset='localtime'>
    ...
    <timer name='hypervclock' present='yes'/>
  </clock>