Windows VM does not get proper BIOS parameters from KVM libvirt domain

[rkozello]

problem

With default settings of ACS 4.22 libvirt domain is defined with pc-i440fx-8.2 machine type and there is no way to change this from API/UI. However, with this machine type Windows Server 2022 VM reports BIOS without serial number like

PS C:\Users\Administrator> gwmi Win32_BIOS

SMBIOSBIOSVersion :
Manufacturer      :
Name              : Default System BIOS
SerialNumber      :
Version           : BOCHS  - 1

If you change machine type to pc-i440fx-6.2 Windows Server 2022 reports version and serial OK

PS C:\Users\Administrator> gwmi Win32_BIOS

SMBIOSBIOSVersion : 1.16.3-debian-1.16.3-2
Manufacturer      : SeaBIOS
Name              : Default System BIOS
SerialNumber      : 2ccd054e-24aa-47f5-b2fc-37b4605fccf2
Version           : BOCHS  - 1

Seems like a bug in SeaBIOS, not ACS, however, some software does not work properly, or can't be licensed, or refuses to install without BIOS servial number.
Linux VM handles BIOS entries from pc-i440fx-8.2 machine properly

$ sudo dmidecode
# dmidecode 3.5
Getting SMBIOS data from sysfs.
SMBIOS 3.0.0 present.
Table at 0xD54FFD60.

Handle 0x0000, DMI type 0, 24 bytes
BIOS Information
        Vendor: SeaBIOS
        Version: 1.16.3-debian-1.16.3-2
        Release Date: 04/01/2014
        Address: 0xE8000
        Runtime Size: 96 kB
        ROM Size: 64 kB
        Characteristics:
                BIOS characteristics not supported
                Targeted content distribution is supported
        BIOS Revision: 0.0

Handle 0x0100, DMI type 1, 27 bytes
System Information
        Manufacturer: Apache Software Foundation
        Product Name: CloudStack KVM Hypervisor
        Version: pc-i440fx-8.2
        Serial Number: adca5d5b-acde-484b-b456-9b305abd8b21
        UUID: adca5d5b-acde-484b-b456-9b305abd8b21
        Wake-up Type: Power Switch
        SKU Number: Not Specified
        Family: Not Specified

versions

ACS 4.22 on Ubuntu 24.04.3 LTS
libvirtd (libvirt) 10.0.0

The steps to reproduce the bug

1. Deploy Windows Server VM from template or via ISO install
2. In PowerShell, run commang
   gwmi Win32_BIOS or Get-WmiObject -Class Win32_BIOS
3. Check output

What to do about it?

This change fixes problem, however, would be better implement conditional logic to set _machine = 'pc-i440fx-6.2' for Windows VMs only.

~/cloudstack$ git diff plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java
diff --git a/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java b/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java
index bf002b37f3..e78bc7bd65 100644
--- a/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java
+++ b/plugins/hypervisors/kvm/src/main/java/com/cloud/hypervisor/kvm/resource/LibvirtVMDef.java
@@ -211,6 +211,7 @@ public class LibvirtVMDef {
                 guestDef.append("<entry name='product'>" + getProduct() + "</entry>\n");
                 guestDef.append("<entry name='uuid'>" + _uuid + "</entry>\n");
                 guestDef.append("<entry name='serial'>" + _uuid + "</entry>\n");
+                guestDef.append("<entry name='family'>Virtual Machine</entry>\n");
                 guestDef.append("</system>\n");
                 guestDef.append("</sysinfo>\n");

@@ -219,9 +220,7 @@ public class LibvirtVMDef {
                 if (_arch != null) {
                     guestDef.append(" arch='" + _arch + "'");
                 }
-                if (_machine != null) {
-                    guestDef.append(" machine='" + _machine + "'");
-                }
+                guestDef.append(" machine='pc-i440fx-6.2'");
                 guestDef.append(">hvm</type>\n");
                 if (_arch != null && _arch.equals("aarch64")) {
                     guestDef.append("<loader readonly='yes' type='pflash'>/usr/share/AAVMF/AAVMF_CODE.fd</loader>\n");

[nvazquez]

Hi @rkozello CloudStack 4.22.0 does allow changing the machine type for KVM, via settings as per this PR: #11569, even though the UI does not display the setting as a selectable item (that will be fixed on 4.22.1 by #12414).

Can you try stopping the VM and adding the setting: kvm.guest.os.machine.type matching the expected machine type and start the VM again?

[rkozello]

Yes, it works, thank you, @nvazquez

[nvazquez]

Great, thanks @rkozello