Re: [libvirt-users] Nested KVM: L0 guest produces kernel BUG on wakeup from managed save (while a nested VM is running)

On Wed, Feb 07, 2018 at 11:26:14PM +0100, David Hildenbrand wrote: > On 07.02.2018 16:31, Kashyap Chamarthy wrote: [...] > Sounds like a similar problem as in > https://bugzilla.kernel.org/show_bug.cgi?id=198621 > > In short: there is no (live) migration support for nested VMX yet. So as > soon as your guest is using VMX itself ("nVMX"), this is not expected to > work. Actually, live migration with nVMX _does_ work insofar as you have _identical_ CPUs on both source and destination — i.e. use the QEMU '-cpu host' for the L1 guests. At least that's been the case in my experience. FWIW, I frequently use that setup in my test environments.

Just to be quadruple sure, I did the test: Migrate an L2 guest (with non-shared storage), and it worked just fine. (No 'oops'es, no stack traces, no "kernel BUG" in `dmesg` or serial consoles on L1s. And I can login to the L2 guest on the destination L1 just fine.) Once you have the password-less SSH between source and destination, and a bit of libvirt config setup. I ran the migrate command as following: $ virsh migrate --verbose --copy-storage-all \ --live cvm1 qemu+tcp://root@f26-vm2/system Migration: [100 %] $ echo $? 0 Full details: https://kashyapc.fedorapeople.org/virt/Migrate-a-nested-guest-08Feb2018.txt (At the end of the document above, I also posted the libvirt config and the version details across L0, L1 and L2. So this is a fully repeatable test.)