I've learned that CirrusCI offers nested virtualization in their free package for public repos and I am trying to make use of it for testing my Ansible playbooks.
Unfortunately, libvirt is insisting that CI environment has no support for full virtualization. All checks (known to me) testify of the opposite, and qemu-kvm works fine when called directly. I'm almost certain the problem is with my host OS configuration, and not with the CI engine. I've seen other people use full virtualization on CirrusCI for their purposes (Android emulation, redox testing).
I use Debian 10 for host system, slim image from DockerHub with the following extra packages installed (--no-install-recommends):
bridge-utils libguestfs-tools python3-dev coreutils libosinfo-bin python3-venv cpu-checker libssl-dev qemu-kvm curl libvirt-clients qemu-kvm gcc libvirt-daemon qemu-utils gpg libvirt-daemon-system systemd gpg-agent linux-image-amd64 vagrant iproute2 make vagrant-libvirt kmod procps virt-goodies libc-dev python3 virtinst libffi-dev
What may I be missing? Why would libvirt tell that there is no KVM when qemu-kvm works perfectly?
Error while creating domain: Error saving the server: Call to virDomainDefineXML failed: invalid argument: could not find capabilities for domaintype=kvm
virsh capabilities contains only
<domain type='qemu'/> entries.
Demo of inconsistent behavior
Any tool based on libvirt fails to invoke KVM:
$ virt-install --import --virt-type kvm --name debian10-vm --memory 512 --disk path=/debian.qcow2,format=qcow2 --os-variant debian10 --noautoconsole || echo "Exit code: $?" ERROR Host does not support domain type kvm for virtualization type 'hvm' arch 'x86_64' Exit code: 1
But qemu-kvm works when executed directly:
$ kvm -nographic /debian.qcow2 cSeaBIOS (version 1.12.0-1) iPXE (http://ipxe.org) 00:03.0 C980 PCI2.10 PnP PMM+07F900F0+07ED00F0 C980 Press Ctrl-B to configure iPXE (PCI 00:03.0)... Booting from Hard Disk... GNU GRUB version 2.02+dfsg1-20 ...
lsmodshows that kvm and kvm_intel are loaded
cat /proc/cpuinfo- contains vmx flag
lscpu- Virtualization type: full
ls -l /dev/kvm- exists, owned by root:rdma
ls -l /var/run/libvirt- sockets exist, owned by root:root
groups $(whoami)- root
systemctl status- systemd is not started, libvirtd was launched via CI rules
virt-host-validate- all checks pass, except IOMMU - should not be important for my use case
Full listings are available in the CI log, section "kvm_before".