It would probably not stop all theoretically possible attacks, but it would stop many of them. Say you find a bug in the GPU driver that let's you execute arbi

It would probably not stop all theoretically possible attacks, but it would stop many of them. Say you find a bug in the GPU driver that let's you execute arbitrary code as root. That still all happens within the VM. To attack the host, you'd still need to break out of the VM, and if the VM is unprivileged (which I assume it is), you'd next need gain privileges on the host. There are other channels -- perhaps you can get the GPU to do something funky on PCI level, perhaps you can get the GPU to crash the host -- but VM isolation does add a solid layer of protection.