The infamous error 43 is triggered by the Nvidia Windows driver, in case it recognizes the GPU is used inside a virtual machine with GPU passthrough. This means the driver won’t load correctly during the system startup leaving you with cumbersome 800 by 600 display resolution.Update: With Nvidia driver v465 (or later) Nvidia officially supports the use of consumer GPUs in virtual environments. Thus, edits recommended in this article are no longer required. Thank you!
An examination of the Windows Device Manager will unveil the culprit – Code 43
Windows has stopped this device because it has reported problems. (Code 43)
Luckily, KVM/QEMU is able to hide the fact that the Nvidia driver is running a virtual environment.
The tested system setup
This method has been tested for the following versions
- OS: Ubuntu 18.04, as well as a 16.04
- Kernel: 4.15 – 5.3.6
- Hypervisor: QEMU 2.12.0 up to 4.1
- Libvirt: version 4.6.0 up to 4.7.0
One can use
virsh version in order to display the current version status.
- OS: Windows 10 1803 – 1903
- VM chipset: i440FX, Q35
- Nvidia driver: 399.07 – 441.12
- GPU: Geforce GTX 970 and Geforce GTX 1060
Fixing error 43
In order to hide that the system is running on a hypervisor, KVM supports the “hidden” flag.
Depending on whether you call QEMU directly or call it via Libvirt the flag syntax differs.
Set KVM hidden via Libvirt xml
In order edit the virtual machines configuration use:
virsh edit your-windows-vm-name
Once your done editing, you can use
CTRL+x CTRL+y to save the changes.
For QEMU 3.0 and later the required flags are “
vendor_id” in the hyperv section, and “
hidden” in the kvm section, of the features block, of the virtual machines xml definiton. I think it is recommended to use a 12 character value (see excerpt marked green).
Additionally, in case you are using QEMU 4.0 (or higher) in combination with a Q35 chip, the flag ‘
ioapic driver='kvm'‘ needs to be added in the features section (see excerpt marked blue).
Excerpt from libvirt xml file
<spinlocks state='on' retries='8191'/>
<vendor_id state='on' value='1234567890ab'/>
Set KVM hidden for direct QEMU usage
In case you call QEMU directly you have to add the flags ‘
kvm=off‘ and ‘
vendor_id=null‘ on your cpu argument (see excerpt marked green).
Additionally, in case you are using QEMU 4.0 (or higher) in combination with a Q35 chip, use the machine argument ‘
Example for virtual machine with host-passthrough set as CPU model and Q35 as machine type:
-cpu 'host,kvm=off,hv_vendor_id=null' \ -machine 'type=q35,kernel_irqchip=on' \
Using QEMU command arguments in the libvirt XML definition
Just for the sake of completeness (and historical compatibility of this article), there is a third way of enabling the hypervisor spoofing. Actually it is a combination of the two described earlier, as it is possible to add QEMU arguments to the libvirt xml defintion file.
These arguments are called after the definition has been parsed, and usually overwrite the settings made via XML structure. Thus it is not recommended to use both ways for one setting in the same definition file.
First of all find the very first line, which should read:
and replace it with:
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
Find the line which ends with
and add the following block afterwards (or alter the block if it already exists):
Attention: Make sure
<qemu:commandline> have the same indent.
Thats it – these settings work for me.
As usual, the glorious arch wiki has further information and help; i.e. it recommends using a 12-character alphanumeric string as vendor ID.
21.09.2019 – added further information regarding qemu 4.0 and error 43
07.11.2019 – updated the article structure