GPU Passthrough for Virtual Machines: KVM vs VirtualBox

In the world of virtualization, the ability to pass through a Graphics Processing Unit (GPU) to a virtual machine is a powerful feature. It allows the VM to utilize the full capabilities of the host GPU, enhancing the performance of graphics-intensive applications. In this article, we will compare two popular virtualization platforms – Kernel-based Virtual Machine (KVM) and VirtualBox, focusing on their GPU passthrough capabilities.

What is GPU Passthrough?

GPU passthrough refers to the process of allowing a virtual machine direct access to the graphics card on the host system. This is particularly useful for running applications that require high graphical processing power, such as gaming, 3D rendering, and machine learning applications.

KVM and GPU Passthrough

KVM (Kernel-based Virtual Machine) is a full virtualization solution for Linux on x86 hardware containing virtualization extensions (Intel VT or AMD-V). It allows the host machine to run multiple, isolated virtual machines.

KVM supports GPU passthrough, which can be set up using the vfio-pci module. This module “binds” the GPU to the VM, allowing it to directly control the hardware.

Here is a basic example of how to bind a GPU to a VM in KVM:

echo "options vfio-pci ids=10de:1b81,10de:10f0" > /etc/modprobe.d/vfio.conf

In the above command, 10de:1b81,10de:10f0 are the IDs of the GPU and its audio function. This command tells the vfio-pci module to take control of these devices at boot.

Before proceeding, ensure that VT-D (Intel Virtualization Technology for Directed I/O) is enabled in your system’s BIOS. This technology allows direct access to I/O devices in a virtualized environment.

VirtualBox and GPU Passthrough

VirtualBox is a powerful x86 and AMD64/Intel64 virtualization product for enterprise and home use. It is a general-purpose full virtualizer for x86 hardware, targeted at server, desktop, and embedded use.

Unlike KVM, VirtualBox does not support GPU passthrough for Nvidia GPUs as it lacks the vfio-pci module. However, it does provide a feature called “3D Acceleration”. When you enable 3D acceleration, VirtualBox provides the VM with its own 3D graphics driver, allowing it to run graphics-intensive applications.

To enable 3D acceleration in VirtualBox, navigate to the settings of the VM, select the Display tab, and check the “Enable 3D Acceleration” box.

Please note, this is not the same as GPU passthrough and the performance might not be as good as when using KVM with GPU passthrough.

Conclusion

While both KVM and VirtualBox provide robust virtualization capabilities, they differ significantly in their support for GPU passthrough. KVM, with its support for GPU passthrough, offers superior performance for graphics-intensive applications. On the other hand, VirtualBox, while lacking in GPU passthrough, does provide 3D acceleration, which may be sufficient for less demanding applications.

For users seeking to run high-performance applications in a virtualized environment, KVM would be the recommended choice due to its GPU passthrough capabilities. However, for less graphics-intensive applications, or for those who prefer a simpler setup process, VirtualBox’s 3D acceleration feature should suffice.

Remember, the choice between KVM and VirtualBox will largely depend on your specific use case and the resources available on your host machine. Always ensure to check the compatibility of your hardware with the virtualization platform and the requirements of the software you intend to run on the VM.