Guide to setup a KVM from scratch
Nối tiếp phần 1, phần này sẽ mô tả chi tiết về việc cài đặt máy ảo KVM. Phần hướng dẫn này sẽ được mô tả bằng tiếng Anh.
Before getting started, ensure that you meet the following prerequisites:
Linux System: Ubuntu 20.04 - kernel v5.15.
Bios: Make sure Intel Virtualization Technology (Intel VT) and Intel ® VT-d must be enabled from server BIOS
CPU Support: Check if your CPU supports virtualization and IOMMU (Input-Output Memory Management Unit) by running:
egrep -c '(vmx|svm)' /proc/cpuinfo
If the command returns a value of 0, your processor is not capable of running KVM. On the other hand, any other number means you can proceed with the installation.
You are now ready to start installing KVM.
sudo apt update
sudo apt install qemu-kvm libvirt-clients libvirt-daemon-system virtinst bridge-utils cpu-checker virt-viewer virt-manager qemu-system
sudo kvm-ok
The output should look like this:
tesla@tesla:~/kvm$ kvm-ok
INFO: /dev/kvm exists
KVM acceleration can be used
Then run the virt-host-validate utility to run a whole set of checks against your virtualization ability and KVM readiness.
$ sudo virt-host-validate
QEMU: Checking for hardware virtualization : PASS
QEMU: Checking if device /dev/kvm exists : PASS
QEMU: Checking if device /dev/kvm is accessible : PASS
QEMU: Checking if device /dev/vhost-net exists : PASS
QEMU: Checking if device /dev/net/tun exists : PASS
QEMU: Checking for cgroup 'memory' controller support : PASS
QEMU: Checking for cgroup 'memory' controller mount-point : PASS
QEMU: Checking for cgroup 'cpu' controller support : PASS
QEMU: Checking for cgroup 'cpu' controller mount-point : PASS
QEMU: Checking for cgroup 'cpuacct' controller support : PASS
QEMU: Checking for cgroup 'cpuacct' controller mount-point : PASS
QEMU: Checking for cgroup 'cpuset' controller support : PASS
QEMU: Checking for cgroup 'cpuset' controller mount-point : PASS
QEMU: Checking for cgroup 'devices' controller support : PASS
QEMU: Checking for cgroup 'devices' controller mount-point : PASS
QEMU: Checking for cgroup 'blkio' controller support : PASS
QEMU: Checking for cgroup 'blkio' controller mount-point : PASS
QEMU: Checking for device assignment IOMMU support : PASS
LXC: Checking for Linux >= 2.6.26 : PASS
LXC: Checking for namespace ipc : PASS
LXC: Checking for namespace mnt : PASS
LXC: Checking for namespace pid : PASS
LXC: Checking for namespace uts : PASS
LXC: Checking for namespace net : PASS
LXC: Checking for namespace user : PASS
LXC: Checking for cgroup 'memory' controller support : PASS
LXC: Checking for cgroup 'memory' controller mount-point : PASS
LXC: Checking for cgroup 'cpu' controller support : PASS
LXC: Checking for cgroup 'cpu' controller mount-point : PASS
LXC: Checking for cgroup 'cpuacct' controller support : PASS
LXC: Checking for cgroup 'cpuacct' controller mount-point : PASS
LXC: Checking for cgroup 'cpuset' controller support : PASS
LXC: Checking for cgroup 'cpuset' controller mount-point : PASS
LXC: Checking for cgroup 'devices' controller support : PASS
LXC: Checking for cgroup 'devices' controller mount-point : PASS
LXC: Checking for cgroup 'blkio' controller support : PASS
LXC: Checking for cgroup 'blkio' controller mount-point : PASS
LXC: Checking if device /sys/fs/fuse/connections exists : PASS
To allow the current user to manage the guest VM without sudo, we can add ourselves to all of the libvirt groups (e.g. libvirt, libvirt-qemu) and the kvm group
cat /etc/group | grep libvirt | awk -F':' {'print $1'} | xargs -n1 sudo adduser $USER
# add user to kvm group also
sudo adduser $USER kvm
# relogin, then show group membership
exec su -l $USER
id | grep libvirt
Group membership requires a user to log back in, so if the id command does not show your libvirt* group membership, logout and log back in, or try exec su -l $USER.
If not explicitly set, the userspace QEMU connection will be to qemu:///session, and not to qemu:///system. This will cause you to see different domains, networks, and disk pool when executing virsh as your regular user versus sudo.
Modify your profile so that the environment variable below is exported to your login sessions.
# use same connection and objects as sudo
export LIBVIRT_DEFAULT_URI=qemu:///system
By default, KVM creates a virtual switch that shows up as a host interface named virbr0 using 192.168.122.0/24.
This interface should be visible from the Host using the “ip” command below.
$ ip addr show virbr0
3: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
valid_lft forever preferred_lft forever
virbr0 operates in NAT mode, which allows the guest OS to communicate out, but only allowing the Host(and those VMs in its subnet) to make incoming connections.
To enable guest VMs on the same network as the Host, you should create a bridged network to your physical interface (e.g. eth0, ens4, epn1s0).
Read my article here for how to use NetPlan on Ubuntu to bridge your physical network interface to br0 at the OS level. And then use that to create a libvirt network named host-bridge that uses br0.
# bridge to physical network
$ virsh net-dumpxml host-bridge
<network connections='2'>
<name>host-bridge</name>
<uuid>44d2c3f5-6301-4fc6-be81-5ae2be4a47d8</uuid>
<forward mode='bridge'/>
<bridge name='br0'/>
</network>
This host-bridge will be required in later articles.
Instruction to setup host’s OS to create br0 here
In order to handle NAT and routed networks for KVM, enable IPv4 forwarding on this host.
# this needs to be "1"
cat /proc/sys/net/ipv4/ip_forward
# if not, then add it
echo net.ipv4.ip_forward=1 | sudo tee -a /etc/sysctl.conf
# make permanent
sudo sysctl -p /etc/sysctl.conf
The “default” storage pool for guest disks is /var/lib/libvirt/images. This is fine for test purposes, but if you have another mount that you want to use for guest OS disks, then you should create a custom storage pool.
Below are the commands to create a “kvmpool” on an SSD mounted at /data/kvm/pool.
$ virsh pool-list --all
Name State Autostart
-------------------------------------------
default active yes
$ virsh pool-define-as kvmpool --type dir --target /data/kvm/pool
Pool kvmpool defined
$ virsh pool-list --all
$ virsh pool-start kvmpool
$ virsh pool-autostart kvmpool
$ virsh pool-list --all
Name State Autostart
-------------------------------------------
default active yes
kvmpool active yes
virt-install In order to test you need an OS boot image. Since we are on an Ubuntu host, let’s download the ISO for the network installer of Ubuntu 20.04 Focal. When complete, you should have a local file named ~/kvm/mini.iso
wget https://releases.ubuntu.com/20.04.6/ubuntu-20.04.6-desktop-amd64.iso -O ~/kvm/mini.iso
First list what virtual machines are running on our host:
# chown is only necessary if virsh was run previously as sudo
ls -l ~/.virtinst
sudo chown -R $USER:$USER ~/.virtinst
# list VMs
virsh list --all
This should return an empty list of VMs, because no guest OS have been deployed.
ukvm2004 VMvirt-install --virt-type=kvm --name=ukvm2004 --ram 8192 --vcpus=4 --virt-type=kvm --hvm --cdrom ~/kvm/mini.iso --network network=default --disk pool=default,size=20,bus=virtio,format=qcow2 --noautoconsole --machine q35
Note: When creating VM’s using virt-manager, make sure to also select q35 as the machine type for full support of pcie in your guests.
ukvm2004 4 8G default virbr0 NAT network default and size = 20GBdefault - spice# open console to VM
virt-viewer ukvm2004
virt-viewer will popup a window for the Guest OS, when you click the mouse in the window and then press
virt-manager provides a convenient interface for creating or managing a guest OS, and any guest OS you create from the CLI using virt-install will show up in this list also.
If you want to delete this guest OS completely, close the GUI window opened with virt-viewer, then use the following commands:
virsh destroy ukvm2004
virsh undefine ukvm2004
Visit kvm all commands and Xilinx instruction