Enable Nested Virtualization on RHEL 7

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Follow the steps shown below if you want to be able to run nested virtual machines on RHEL 7 via KVM.

In this particular situation I have a physical Supermicro server that I want to use to host OpenStack.

Note that my home server has Intel Xeon processors, so I first enable nested virtualization via the KVM intel module.  AMD procs use a different module.

[code language=”css”]
cat << EOF > /etc/modprobe.d/kvm_intel.conf
options kvm-intel nested=1
options kvm-intel enable_shadow_vmcs=1
options kvm-intel enable_apicv=1
options kvm-intel ept=1
EOF
[/code]

Also, in order to communicate with your nested VMs you will need to disable reverse path filtering, otherwise RHEL will discard any network packets in order to prevent asymmetric routing. See below.

[code language=”css”]
cat << EOF > /etc/sysctl.d/98-rp-filter.conf
net.ipv4.conf.default.rp_filter = 0
net.ipv4.conf.all.rp_filter = 0
EOF
[/code]

The simplest way to enable these changes is via a reboot of the physical host.

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