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====== Nested KVM ====== Some random notes (to be sorted at some point) on running KVM inside KVM, e.g. to test-run Cloudmin/Proxmox/CoreOS without affecting your machine. Notice nesting is not enabled by default, it can be checked on ''/sys'' and enabled by passing ''nested=1'' as an option to the module: $ cat /sys/module/kvm_intel/parameters/nested N rmmod kvm-intel modprobe kvm-intel nested=1 $ cat /sys/module/kvm_intel/parameters/nested Y Command-line example: # kvm -hda /dev/vg/lvkvm -cdrom osinstall.iso -boot d -m 1G \ -vnc :2 -netdev tap,id=net0,ifname=tap0 -device virtio-net,netdev=net0,mac=52:54:00:12:34:56 -cpu host Explanation: * ''-hda /dev/vg/lvkvm'' → Use an LVM Logical Volume as the first hard disk * ''-cdrom osinstall.iso -boot d'' → Connect this ISO to the guest's DVD drive and boot from it * ''-m 1G'' → Provide the guest 1 GB of RAM * ''-vnc :2'' → Run the display as a VNC server * ''-netdev tap,id=net0,ifname=tap0 -device virtio-net,netdev=net0,mac=52:54:00:12:34:56'' → Use TAP networking with virtio drivers (combined with a host bridge it integrates in the LAN), see [[linux:bonding-bridge]] * -cpu host → The key here, expose all the CPU features (including KVM) Sources * http://www.rdoxenham.com/?p=275 * https://fedoraproject.org/wiki/How_to_enable_nested_virtualization_in_KVM * ''$ qemu -cpu help''