virt/kvm/running-nested-guests.rst

2 Running nested guests with KVM
6 can be KVM-based or a different hypervisor).  The straightforward
7 example is a KVM guest that in turn runs on a KVM guest (the rest of
18               |          KVM (/dev/kvm)            |
22       |                    KVM (/dev/kvm)                    |
29 - L0 – level-0; the bare metal host, running KVM
32   hypervisor", as it itself is capable of running KVM.
54 There are several scenarios where nested KVM can be useful, to name a
59   Provider, using nested KVM lets you rent a large enough "guest
77 From Linux kernel v4.19 onwards, the ``nested`` KVM parameter is enabled
82 nesting, set the ``nested`` KVM module parameter to ``Y`` or ``1``.  To
87    the KVM modules::
98 3. For the nested KVM configuration to persist across reboots, place the
105 4. Unload and re-load the KVM Intel module::
110 5. Verify if the ``nested`` parameter for KVM is enabled::
157 nested guest with accelerated KVM.
177 3. Now the KVM module can be loaded in the L1 (guest hypervisor)::
182 Live migration with nested KVM
223 - Ensure you are actually running KVM on KVM.  Sometimes people do not
224   have KVM enabled for their guest hypervisor (L1), which results in
226   they think they're running nested KVM.  Thus confusing "nested Virt"
227   (which could also mean, QEMU on KVM) with "nested KVM" (KVM on KVM).