Virtualization

Nested Virtualization in Centos 6

kvm qemu

In the course of testing our puppet manifests with beaker I came across the necessity to run KVM virtual machines inside KVM guests. Normally this has a severe performance penalty as the CPUs need to be fully emulated and cannot take advantage of performance enhancing CPU instructions. Several years ago Intel and AMD added functionality which basically enables CPU instruction passthrough to the guests to get around this limitation. You can see these extensions on a host CPU in /proc/cpuinfo

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