We’re nearing the release of oVirt 3.3, and I’ve been testing out all the new features — and using oVirt to do it, courtesy of nested KVM.
KVM takes advantage of virtualization-enabling hardware extensions that most recent processors provide. Nested KVM enables KVM hypervisors to make these extensions available to their guest instances.
Nested KVM typically takes takes a bit of configuration to get up and running: on the host side, you need to make sure that nested virtualization is enabled, and on the guest side, you need to make sure that your guest VM’s is emulating a virt-capable processor.
With oVirt, you can take care of both the host and guest configuration chores by installing a vdsm hook on your host machine(s):
$> sudo yum install -y vdsm-hook-nestedvt
Depending on your networking configuration, there’s a separate hook required to allow your nested host to pass traffic from its guests up through the machine in which it's hosted:
$> sudo yum install -y vdsm-hook-macspoof
Next, you need to enable the mac-spoofing option in oVirt’s web admin console, restart the engine for that setting to take effect, and restart vdsm for the two vdsm hooks to take effect:
$> sudo engine-config -s "UserDefinedVMProperties=macspoof=(true|false)" $> sudo service ovirt-engine restart $> sudo service vdsmd restart
After vdsm restarts, you can check to see that your hooks are installed in your host’s "Host Hooks" tab:
With the nestedvt vdsm hook installed, every guest launched from your nested-enabled hosts will inherit its own KVM-hosting capability. To enable the mac-spoofing, you have to visit the Custom Properties tab of the Edit Server Virtual Machine dialog, select "macspoof" from the "Please select a key" dropdown menu, and set the value to "true."
On my test machine, an HP ProLiant DL380p Gen8 with Sandybridge-family processors, I found that shortly after launching Fedora guest VM on my nested KVM hypervisor, the nested guest would pause and refuse to re-start. Casting about online for a solution, I found other, similar-sounding nested VM pause reports, with a suggested solution of running the problematic VMs with a earlier processor definition.
I got around this issue by changing the processor definition for my guest hypervisor from Sandybridge to Nehalem. oVirt makes this switch fairly easy — I took care of it by changing my cluster CPU type Sandybridge to Nehalem.
Nested KVM comes with a performance hit, but I’ve had no trouble testing oVirt (and other forms of KVM-based virtualization, such as OpenStack) in oVirt-hosted virtual machines.
Stay tuned for more coverage of oVirt 3.3, and be sure to follow us on Twitter at @redhatopen for news on oVirt and other open source projects in the Red Hat world.
About the author
Browse by channel
Automation
The latest on IT automation that spans tech, teams, and environments
Artificial intelligence
Explore the platforms and partners building a faster path for AI
Open hybrid cloud
Explore how we build a more flexible future with hybrid cloud
Security
Explore how we reduce risks across environments and technologies
Edge computing
Updates on the solutions that simplify infrastructure at the edge
Infrastructure
Stay up to date on the world’s leading enterprise Linux platform
Applications
The latest on our solutions to the toughest application challenges
Original shows
Entertaining stories from the makers and leaders in enterprise tech
Products
- Red Hat Enterprise Linux
- Red Hat OpenShift
- Red Hat Ansible Automation Platform
- Cloud services
- See all products
Tools
- Training and certification
- My account
- Developer resources
- Customer support
- Red Hat value calculator
- Red Hat Ecosystem Catalog
- Find a partner
Try, buy, & sell
Communicate
About Red Hat
We’re the world’s leading provider of enterprise open source solutions—including Linux, cloud, container, and Kubernetes. We deliver hardened solutions that make it easier for enterprises to work across platforms and environments, from the core datacenter to the network edge.
Select a language
Red Hat legal and privacy links
- About Red Hat
- Jobs
- Events
- Locations
- Contact Red Hat
- Red Hat Blog
- Diversity, equity, and inclusion
- Cool Stuff Store
- Red Hat Summit