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KVM

Table of Contents

Bridge Configuration

Set up a bridge on interface for VMs 

sudo apt install bridge-utils

Disable netfilter for bridges

Listing 1: /etc/sysctl.d/bridge.conf
net.bridge.bridge-nf-call-ip6tables=0
net.bridge.bridge-nf-call-iptables=0
net.bridge.bridge-nf-call-arptables=0
Listing 2: /etc/udev/rules.d/99-bridge.rules
ACTION=="add", SUBSYSTEM=="module", KERNEL=="br_netfilter", RUN+="/sbin/sysctl -p /etc/sysctl.d/bridge.conf"

Note that gateway shouldn't be set more than once in the interfaces file or it will cause errors for the systemd networking unit.

Listing 3: /etc/network/interfaces
# Bridge interface for VMs
iface enp9s0 inet manual

auto br0
iface br0 inet static
        hwaddress ether fa:ke:ma:ca:dd:rs
        address 0.0.0.0
        bridge_ports enp9s0
        bridge_stp off
        bridge_fd 0

Reset virtual network

virsh --connect qemu:///system net-destroy default
virsh --connect qemu:///system net-start default

VM Install

apt install qemu-kvm libvirt-clients qemu-utils libvirt-daemon-system

Initial vm setup 

virt-install --virt-type kvm --name pixy --memory 4096 --cdrom downloads/debian-9.9.0-amd64-netinst.iso --disk size=30 --os-variant debian9 --network bridge=br0
virsh --connect qemu:///system autostart <vmname>

Do some network setup after install just like a normal debian host.

Allocate extra vcpus if needed.

A few commands for general work on the VM: 

virsh --connect qemu:///system list --all
virsh --connect qemu:///system edit <vmname>
virsh --connect qemu:///system shutdown <vmname>
virsh --connect qemu:///system undefine <vmname>
virsh --connect qemu:///system destroy <vmname>

Give the guest read only access to a host directory (use virsh edit)

Listing 4: /etc/libvirt/qemu/<vmname>.xml (excerpt)
<domain type='kvm'>
    <devices>

        <filesystem type='mount' accessmode='passthrough'>
            <source dir='/path/to/video'/>
            <target dir='/mnt/video'/>
            <readonly/>
            <address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
        </filesystem>

    </devices>
</domain>
Listing 5: /etc/fstab
video   /mnt/video      9p      trans=virtio    0       0