In boxes there is a toggle that is labeled “3D acceleration” if you flip the toggle your VM will have GPU acceleration.
That’s not GPU passthrough. That just enables VirGL, which is a translation layer that passes some OpenGL calls through to the host’s Mesa installation. It has rather poor performance though, it’s extremely limited and is rather buggy too. You certainly can’t use it for cutting edge gaming.
GPU passthrough is when you pass through an entire GPU device as-is to the virtual machine. That is: if you have an Nvidia RTX 3060, the guest operating system will see an Nvidia RTX 3060 and it can use the native drivers for it. This gives you near-native performance for gaming.
Now, I didn’t even know this was possible with VirtualBox (if so: cool!), but it’s certainly doable with KVM if you have the right motherboard and GPU combination. I have done it, but it is quite the hassle indeed though that isn’t really KVM’s fault.
That’s why it failed for me, I don’t have an Nvidia GPU. I wanted to pass my GPU to my windows install but it never worked and I blamed kvm 🤦🏽♂️ I knew about the first part that the “3rd acceleration” isn’t a full GPU passthrough, but didn’t know the latter was Nvidia only.
It does work with AMD GPUs too, I did it with an RX6800XT myself, but there are some (most…) AMD GPUs that have a reset bug which means they hang if you reboot the guest and you need to powercycle the physical host machine to make the GPU usable for the guest again.
