nested virtualisation

Hands-on guide to nested virtualization for AI/ML on Linux: run KVM-accelerated L2 VMs inside L1 guests to achieve reproducible labs, stronger isolation than containers, CI for CUDA/ROCm images, and teaching sandboxes. Covers L0/L1 checks, enabling vmx/svm, installing QEMU/KVM/libvirt, building L1/L2 with host-passthrough, validation, performance tuning (hugepages, pinning, virtio), GPU caveats, real-world patterns, and troubleshooting.