c30657d7de
* ReST doesn't allow monospace in italic sections.
bash$ grep -R \`\` doc/build/html/ --include "*.html"
* The code-block section "::" needed an empty line before the code,
otherwise it gets shown in the HTML output.
bash$ egrep -R "<dt>::" doc/build/html/ --include "*.html"
* Monospaced font incorrectly marked with a single back tick
bash$ egrep -nR '\w`(\s|[\.,;:])' doc/source/ --include "*.rst"
Change-Id: I66c3f685f33851c3f3f0f859996037fc24930246
140 lines
3.7 KiB
ReStructuredText
140 lines
3.7 KiB
ReStructuredText
=======================================================
|
|
Configure DevStack with KVM-based Nested Virtualization
|
|
=======================================================
|
|
|
|
When using virtualization technologies like KVM, one can take advantage
|
|
of "Nested VMX" (i.e. the ability to run KVM on KVM) so that the VMs in
|
|
cloud (Nova guests) can run relatively faster than with plain QEMU
|
|
emulation.
|
|
|
|
Kernels shipped with Linux distributions doesn't have this enabled by
|
|
default. This guide outlines the configuration details to enable nested
|
|
virtualization in KVM-based environments. And how to setup DevStack
|
|
(that'll run in a VM) to take advantage of this.
|
|
|
|
|
|
Nested Virtualization Configuration
|
|
===================================
|
|
|
|
Configure Nested KVM for Intel-based Machines
|
|
---------------------------------------------
|
|
|
|
Procedure to enable nested KVM virtualization on Intel-based machines.
|
|
|
|
Check if the nested KVM Kernel parameter is enabled:
|
|
|
|
::
|
|
|
|
cat /sys/module/kvm_intel/parameters/nested
|
|
N
|
|
|
|
Temporarily remove the KVM intel Kernel module, enable nested
|
|
virtualization to be persistent across reboots and add the Kernel
|
|
module back:
|
|
|
|
::
|
|
|
|
sudo rmmod kvm-intel
|
|
sudo sh -c "echo 'options kvm-intel nested=y' >> /etc/modprobe.d/dist.conf"
|
|
sudo modprobe kvm-intel
|
|
|
|
Ensure the Nested KVM Kernel module parameter for Intel is enabled on
|
|
the host:
|
|
|
|
::
|
|
|
|
cat /sys/module/kvm_intel/parameters/nested
|
|
Y
|
|
|
|
modinfo kvm_intel | grep nested
|
|
parm: nested:bool
|
|
|
|
Start your VM, now it should have KVM capabilities -- you can verify
|
|
that by ensuring ``/dev/kvm`` character device is present.
|
|
|
|
|
|
Configure Nested KVM for AMD-based Machines
|
|
-------------------------------------------
|
|
|
|
Procedure to enable nested KVM virtualization on AMD-based machines.
|
|
|
|
Check if the nested KVM Kernel parameter is enabled:
|
|
|
|
::
|
|
|
|
cat /sys/module/kvm_amd/parameters/nested
|
|
0
|
|
|
|
|
|
Temporarily remove the KVM AMD Kernel module, enable nested
|
|
virtualization to be persistent across reboots and add the Kernel module
|
|
back:
|
|
|
|
::
|
|
|
|
sudo rmmod kvm-amd
|
|
sudo sh -c "echo 'options amd nested=1' >> /etc/modprobe.d/dist.conf"
|
|
sudo modprobe kvm-amd
|
|
|
|
Ensure the Nested KVM Kernel module parameter for AMD is enabled on the
|
|
host:
|
|
|
|
::
|
|
|
|
cat /sys/module/kvm_amd/parameters/nested
|
|
1
|
|
|
|
modinfo kvm_amd | grep -i nested
|
|
parm: nested:int
|
|
|
|
To make the above value persistent across reboots, add an entry in
|
|
/etc/modprobe.d/dist.conf so it looks as below::
|
|
|
|
cat /etc/modprobe.d/dist.conf
|
|
options kvm-amd nested=y
|
|
|
|
|
|
Expose Virtualization Extensions to DevStack VM
|
|
-----------------------------------------------
|
|
|
|
Edit the VM's libvirt XML configuration via ``virsh`` utility:
|
|
|
|
::
|
|
|
|
sudo virsh edit devstack-vm
|
|
|
|
Add the below snippet to expose the host CPU features to the VM:
|
|
|
|
::
|
|
|
|
<cpu mode='host-passthrough'>
|
|
</cpu>
|
|
|
|
|
|
Ensure DevStack VM is Using KVM
|
|
-------------------------------
|
|
|
|
Before invoking ``stack.sh`` in the VM, ensure that KVM is enabled. This
|
|
can be verified by checking for the presence of the file ``/dev/kvm`` in
|
|
your VM. If it is present, DevStack will default to using the config
|
|
attribute ``virt_type = kvm`` in ``/etc/nova.conf``; otherwise, it'll fall
|
|
back to ``virt_type=qemu``, i.e. plain QEMU emulation.
|
|
|
|
Optionally, to explicitly set the type of virtualization, to KVM, by the
|
|
libvirt driver in nova, the below config attribute can be used in
|
|
DevStack's ``local.conf``:
|
|
|
|
::
|
|
|
|
LIBVIRT_TYPE=kvm
|
|
|
|
|
|
Once DevStack is configured successfully, verify if the Nova instances
|
|
are using KVM by noticing the QEMU CLI invoked by Nova is using the
|
|
parameter ``accel=kvm``, e.g.:
|
|
|
|
::
|
|
|
|
ps -ef | grep -i qemu
|
|
root 29773 1 0 11:24 ? 00:00:00 /usr/bin/qemu-system-x86_64 -machine accel=kvm [. . .]
|