GPU Passthrough on KVM: An Advanced VFIO Implementation Guide
A GPU passthrough KVM setup assigns a physical PCIe graphics device directly to a virtual machine through VFIO. The guest loads the native vendor driver and controls the GPU with far less virtualization overhead than an emulated display. The hard part is not adding a PCI address. It is proving that firmware, PCIe topology, kernel driver ownership, DMA isolation, reset behavior, and guest firmware all agree on the assignment. This guide assumes you already administer Linux virtualization hosts and understand KVM, QEMU, libvirt, initramfs, and PCI addressing. The workflow targets a dedicated host with console or out-of-band access. Do not perform the first reboot remotely without a recovery path, especially when the selected GPU is also the host boot display. The safest design uses a GPU that the host never needs, an isolated IOMMU group, a Q35 machine type, OVMF UEFI, and explicit assignment of every required PCI function. Before changing boot parameters, record the current kernel comma...