{"id":3526,"date":"2023-03-28T06:31:45","date_gmt":"2023-03-28T10:31:45","guid":{"rendered":"https:\/\/dft.wiki\/?p=3526"},"modified":"2026-02-09T14:50:02","modified_gmt":"2026-02-09T19:50:02","slug":"kvm-and-qemu-cheat-sheet","status":"publish","type":"post","link":"https:\/\/dft.wiki\/?p=3526","title":{"rendered":"KVM and QEMU Cheat Sheet"},"content":{"rendered":"

KVM<\/strong> (Kernel-based Virtual Machine) and QEMU<\/strong> (Quick EMUlator) are both open-source virtualization technologies that run on Linux, but they are different in the way they accomplish the same tasks.<\/p>\n

While KVM<\/strong> [Link<\/a>] is a Linux kernel module that makes it function as a hypervisor with the usage of hardware virtualization features (Intel VT-x and AMD-V), QEMU is an emulator.<\/p>\n

QEMU<\/strong> it is capable of emulating different architectures and peripherals at the expense of related overhead. But it can also work with KVM to take advantage of the hardware virtualization.<\/p>\n

\n

KVM + QEMU<\/strong><\/p>\n

    \n
  • Install steps.<\/li>\n<\/ul>\n
    sudo apt-get update\r\nsudo apt-get install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virt-manager -y\r\nsudo reboot<\/pre>\n
      \n
    • Checking<\/li>\n<\/ul>\n
      egrep -c '(vmx|svm)' \/proc\/cpuinfo\r\nsudo systemctl status libvirtd<\/pre>\n
      Note:<\/strong> if it returns 0<\/strong>, the virtualization must be enabled on the BIOS. The service libvirtd<\/code> must be active (running)<\/strong>. The users that will manage the VMs need to be members of libvirt<\/code> and kvm<\/code> group or use sudo<\/code>.<\/p>\n
      GUI Interface<\/p>\n
      nohup sudo virt-manager &<\/pre>\n
      \n
      KVM<\/strong><\/p>\n
        \n
      • Listing all VMs<\/li>\n<\/ul>\n
        virsh list --all<\/pre>\n
          \n
        • Managing VMs<\/li>\n<\/ul>\n
          virsh start vmName\r\nvirsh suspend vmName\r\nvirsh resume vmName\r\nvirsh shutdown vmName\r\nvirsh destroy vmName\r\nvirsh undefine vmName\r\nvirsh console vmName<\/pre>\n
            \n
          • Snapshots of a VM<\/li>\n<\/ul>\n
            virsh snapshot-list vmName\r\nvirsh snapshot-create-as --domain vmName --name snapshotName --description \"Add description or comments here.\"\r\nvirsh snapshot-revert vmName snapshotName\r\nvirsh snapshot-delete vmName snapshotName<\/pre>\n
              \n
            • Getting information about OS Variants.<\/li>\n<\/ul>\n
              virt-install --os-variant list\r\nvirt-install --osinfo ubuntu22.04<\/pre>\n
                \n
              • Deploying a Kali VM from an ISO with VNC and a bridged network.<\/li>\n<\/ul>\n
                virt-install --name Kali --memory 4096 --vcpus 4 --os-variant debian11 --network bridge=virbr0 --graphics vnc --cdrom kali.iso --disk size=100,format=qcow2<\/pre>\n
                Note:<\/strong> to proceed with the installation, use a VNC client from the host machine connecting to 127.0.0.1<\/strong> or use SSH<\/strong> to port forward port 5900<\/strong>.<\/p>\n
                  \n
                • Connecting via VNC<\/li>\n<\/ul>\n
                  virsh vncdisplay vmName<\/pre>\n
                  In its VM configuration file it will look like the following:<\/p>\n
                  <graphics type='vnc' port='-1' autoport='yes'>\r\n  <listen type='address'\/>\r\n<\/graphics><\/pre>\n
                  Configure it accordingly. For example:<\/p>\n
                  <graphics type='vnc' port='5900' autoport='no' tls='yes'>\r\n  <listen type='address' address='192.168.10.10'\/>\r\n<\/graphics><\/pre>\n
                    \n
                  • Cloning a VM<\/li>\n<\/ul>\n
                    virt-clone --original vmName --name vmNameCloned --auto-clone<\/pre>\n
                    OR<\/p>\n
                    virt-clone --original vmName --name vmNameCloned --file \/var\/lib\/libvirt\/images\/vmNameCloned.qcow2<\/pre>\n
                    Note:<\/strong> the path \/var\/lib\/libvirt\/images<\/code> is where virtual disks are stored by default, while \/etc\/libvirt\/qemu\/<\/code> is where each VM configuration is located.<\/p>\n
                      \n
                    • Configuring a VM<\/li>\n<\/ul>\n
                      virsh dominfo vmName\r\nvirsh autostart vmName\r\nvirsh edit vmName<\/pre>\n
                        \n
                      • Managing Networks<\/li>\n<\/ul>\n
                        virsh net-list --all\r\nvirsh net-define \/PATH\/networkConfig.xml\r\nvirsh net-start networkName\r\nvirsh net-autostart networkName<\/pre>\n
                        Example for adding a bridge network (bridged-network<\/code>) by creating a bridge interface (br0<\/code>) to a physical interface (ens192<\/code>) on the host that will give direct access to the LAN<\/strong>.<\/p>\n
                        nmcli connection add type bridge autoconnect yes con-name br0 ifname br0\r\nnmcli connection modify br0 bridge.stp no\r\nnmcli connection add type bridge-slave autoconnect yes con-name ens192-br slave-type bridge master br0 ifname ens192\r\nnmcli connection modify br0 ipv4.method auto\r\nnmcli connection modify br0 ipv6.method ignore\r\nnmcli connection up br0\r\nnano bridged-network.xml<\/pre>\n
                        <network>\r\n  <name>bridged-network<\/name>\r\n  <forward mode='bridge'\/>\r\n  <bridge name='br0'\/>\r\n<\/network><\/pre>\n
                        virsh net-define bridged-network.xml\r\nvirsh net-autostart bridged-network\r\nvirsh net-start bridged-network<\/pre>\n
                        Note:<\/strong> out of the box the default<\/code> network might be not started and not set to auto-start. And alternatively, to the command line, KVM has a nice GUI<\/strong> called Virtual Machine Manager<\/strong> if you are running on a host with a graphic environment.<\/p>\n
                        \n
                        QEMU<\/strong><\/p>\n
                          \n
                        • Listing all VMs<\/li>\n<\/ul>\n
                          Because QEMU emulates virtual machines, each one will be shown as a separate process and can be identified and killed using htop<\/code>, for example.<\/p>\n
                            \n
                          • Creating a Disk<\/li>\n<\/ul>\n
                            qemu-img create -f qcow2 \/PATH\/vmImage.qcow2 100G<\/pre>\n
                              \n
                            • Attacking Disk<\/li>\n<\/ul>\n
                              virsh attach-disk vmName --source \/var\/lib\/libvirt\/images\/vmImage.qcow2 --target vdb --persistent --subdriver qcow2 --driver qemu --type disk<\/pre>\n
                                \n
                              • Launching a VM – Basic Syntax\n
                                  \n
                                • [arch]<\/strong>\n
                                    \n
                                  • x86-64<\/code> for x86 64 bits.<\/li>\n
                                  • i386<\/code> for x86 32 bits.<\/li>\n
                                  • arch64<\/code> for ARM 64 bits.<\/li>\n
                                  • arm<\/code> for ARM 32 bits.<\/li>\n
                                  • ppc<\/code> for PowerPC.<\/li>\n
                                  • more<\/li>\n<\/ul>\n<\/li>\n
                                  • [memory]<\/strong>\n
                                      \n
                                    • 2048<\/code> for explicit in megabytes (default).<\/li>\n
                                    • 2G<\/code> for explicit in gigabytes.<\/li>\n<\/ul>\n<\/li>\n
                                    • [cores]<\/strong>\n
                                        \n
                                      • 2<\/code> for the number of virtual cores\/threads (integer).<\/li>\n<\/ul>\n<\/li>\n
                                      • [boot]<\/strong>\n
                                          \n
                                        • order=d<\/code> (or just d<\/code>) to first try to boot the disk.<\/li>\n
                                        • menu=on<\/code> will prompt a menu that will allow the selection of the desired boot order.<\/li>\n<\/ul>\n<\/li>\n
                                        • -drive<\/code>\n
                                            \n
                                          • It is the complete way or setting disks to the VM and optionally accepts additional options. It is compatible with .vhd<\/code> (VirtualPC), .vdi<\/code> (VirtualBox), .vmdk<\/code> (VMWare), and more.<\/li>\n
                                          • E.g. -drive file=vmImage.qcow2<\/code>\u00a0or -drive file=vmImage.img,if=ide,format=raw,cache=writeback<\/code><\/li>\n<\/ul>\n<\/li>\n
                                          • -hda<\/code>, -hdb<\/code>, -hdc<\/code>, and so on.\n
                                              \n
                                            • Alternatively to the -drive<\/code>, it is a shorthand to set hard disk images.<\/li>\n
                                            • E.g. -hda vmImage.qcow2<\/code><\/li>\n<\/ul>\n<\/li>\n
                                            • -cdrom<\/code>\n
                                                \n
                                              • It is used to run an installation or recovery live CD.<\/li>\n<\/ul>\n<\/li>\n
                                              • -enable-kvm -cpu host<\/code>\n
                                                  \n
                                                • Allows QEMU to use the hardware virtualization features of KVM for better performance because it will not emulate the CPU if the Guest has the same architecture of the Host.<\/li>\n<\/ul>\n<\/li>\n
                                                • -vga virtio -display [display]<\/code>\n
                                                    \n
                                                  • virtio<\/code> is a paravirtualised video device.\n
                                                      \n
                                                    • vnc=127.0.0.1:0<\/code> it is strongly recommended to only bind on localhost<\/strong> and use an SSH tunnel<\/strong> to connect to. If set to bind on one or all interfaces of the Host, make sure the firewall rules as restricted appropriately.<\/li>\n
                                                    • sdl<\/code> uses Simple DirectMedia Layer library and provides a good performance because it supports 3D<\/strong> emulation.<\/span><\/li>\n
                                                    • gtk<\/code> uses GIMP Toolkit library but does not provide not optimal performance.<\/li>\n
                                                    • none<\/code> does not display video output (headless).<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n
                                                    • -vga qxl<\/code>\n
                                                        \n
                                                      • Uses SPICE to remote desktop and requires enabling the module by issuing sudo modprobe qxl bochs_drm<\/code>.<\/li>\n<\/ul>\n<\/li>\n
                                                      • -device virtio-gpu-pci<\/code>\n
                                                          \n
                                                        • Check this option to “pass-through” a GPU<\/strong>\/Video adapter placed in a PCI Express<\/strong> slot to the VM.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
                                                          qemu-system-[arch]<\/strong> -m [memory]<\/strong> -smp [cores] <\/strong>-boot [boot]<\/strong> -hda [PATH]<\/strong> -cdrom [PATH]<\/strong> -enable-kvm -cpu host -vga virtio -display [display]<\/strong><\/pre>\n
                                                          qemu-system-x86_64<\/strong> -m 4G<\/strong> -smp 4 <\/strong>-boot menu=on<\/strong> -hda \/PATH\/vmImage.qcow2<\/strong> -cdrom \/PATH\/file.iso<\/strong> -enable-kvm -cpu host -vga virtio<\/strong> -display vnc=127.0.0.1:0<\/strong><\/pre>\n
                                                          qemu-system-x86_64<\/strong> -m 2048<\/strong> -drive file=vmImage.qcow2,format=qcow2<\/strong> -netdev tap,id=net0,ifname=tap0,script=no,downscript=no<\/strong> -device virtio-net-pci,netdev=net0,mac=52:54:00:12:34:56<\/strong><\/pre>\n
                                                          qemu-system-x86_64<\/strong> -m 2G<\/strong> -hda vmImage.qcow2<\/strong> -usb -device usb-host,hostbus=2,hostaddr=4<\/strong><\/pre>\n
                                                          Note:<\/strong> use lsusb<\/code> to find out the bus and address of the USB<\/strong> device you want to pass-through<\/strong>.<\/p>\n
                                                            \n
                                                          • Managing Volumes<\/li>\n<\/ul>\n
                                                            cd \/var\/lib\/libvirt\/images\/\r\nqemu-img info vmImage.qcow2<\/strong>\r\nqemu-img resize vmImage.qcow2<\/strong> +10<\/strong>G\r\nqemu-img commit vmImage.qcow2\r\n<\/strong>qemu-img convert -O vmdk<\/strong> -O qcow2 <\/strong>vmImage.vmdk<\/strong> vmImage.qcow2<\/strong> \r\n<\/pre>\n
                                                              \n
                                                            • ARM VMs<\/li>\n<\/ul>\n
                                                              sudo apt-get install qemu-system-arm -y\r\nqemu-system-arm -M help\r\nqemu-system-arm -M virt<\/strong> -enable-kvm -m 256 -kernel vmlinuz-3.2.0-4-virt<\/strong> -initrd initrd.img-3.2.0-4-virt<\/strong> -hda ARMvmImage.qcow2<\/strong> -append \"root=\/dev\/vda1\"<\/strong> -netdev user,id=usernet,hostfwd=tcp::2222-:22 -device virtio-net-device,netdev=usernet<\/strong><\/pre>\n
                                                              Note:<\/strong> the volumes and networks are managed similarly for all architectures.<\/p>\n
                                                              \n
                                                              GUEST AGENT<\/strong><\/p>\n
                                                                \n
                                                              • Install on the guest OS<\/li>\n<\/ul>\n
                                                                sudo apt update && sudo apt -y install qemu-guest-agent -y\r\nsudo systemctl enable qemu-guest-agent --now<\/pre>\n
                                                                OR<\/strong><\/p>\n
                                                                sudo apt update && sudo apt install spice-vdagent -y<\/pre>\n
                                                                \n
                                                                REFLECTIONS<\/strong><\/p>\n
                                                                Unless there is a reason to emulate a VM, like a different architecture for example, it is recommended to use KVM in most cases<\/strong>.<\/p>\n
                                                                The configuration files for each VM are stored at \/etc\/libvirt\/qemu<\/code>.<\/p>\n
                                                                \n
                                                                BONUS<\/strong><\/p>\n
                                                                To install Windows 11 on QEMU\/KVM it is usually useful to send key combinations to the guest:<\/p>\n
                                                                virsh send-key Win11_VM_Name<\/strong> --holdtime 1000 KEY_LEFTSHIFT KEY_F10<\/pre>\n
                                                                This will allow to enter the following command to bypass the sign-in feature and install Windows 11 offline.<\/p>\n
                                                                OOBE\\BYPASSNRO<\/pre>\n
                                                                Or to create a new user from the Terminal, enter the following commands.<\/p>\n
                                                                net user Administrator \/active:yes\r\nnet user \/add userName<\/strong> userPassword\r\nnet localgroup administrators userName<\/strong> \/add\r\n%windir%\\system32\\oobe\\msoobe.exe<\/pre>\n
                                                                For troubleshooting dynamically guest memory.<\/p>\n
                                                                virsh dommemstat vmName<\/strong>\r\nvirsh setmem vmName<\/strong> 32768M --live\r\nvirsh dumpxml vmName<\/strong><\/pre>\n","protected":false},"excerpt":{"rendered":"
                                                                KVM (Kernel-based Virtual Machine) and QEMU (Quick EMUlator) are both open-source virtualization technologies that run […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-3526","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/posts\/3526","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dft.wiki\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=3526"}],"version-history":[{"count":27,"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/posts\/3526\/revisions"}],"predecessor-version":[{"id":5288,"href":"https:\/\/dft.wiki\/index.php?rest_route=\/wp\/v2\/posts\/3526\/revisions\/5288"}],"wp:attachment":[{"href":"https:\/\/dft.wiki\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=3526"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dft.wiki\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=3526"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dft.wiki\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=3526"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}