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--- linux:apps:kvm [2023/08/06 09:07] – oscar
+++ linux:apps:kvm [2025/10/21 20:15] (current) – oscar
@@ Line 1: / Line 1: @@
 ====== KVM ======
+----
 ===== Installation =====
@@ Line 51: / Line 53: @@
 irqbypass              16384  1 kvm
 </code>
+===== Configuration =====
+=== User priviliges ===
 In order to manage virtual machines as a regular user, that user needs to be added to the libvirt group:
-  # adduser <youruser> libvirt
+  # adduser <username> libvirt
+       or  (not sure if kvm group is needed)
+  # usermod -aG libvirt,kvm <username>
+=== User-specific and system-wide VMs ===
+By default, if virsh is run as a normal user it will connect to libvirt using: **qemu:%%///%%session** URI string. This URI allows virsh to manage only the set of VMs belonging to this particular user.
+To manage the system set of VMs (i.e., VMs belonging to root) virsh should be run as root or with: **qemu:%%///%%system** URI:
+  $ virsh --connect qemu:///system list --all
+To avoid having to use the --connect flag on every command, the URI string can be set in the LIBVIRT_DEFAULT_URI environment variable:
+  $ export LIBVIRT_DEFAULT_URI='qemu:///system'
+===== Libvirt default network =====
+If you use libvirt to manage your VMs, libvirt provides a NATed bridged network named "default/virbr0" that allows the host to communicate with the guests.
+<code>
+: virbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
+    link/ether 52:54:00:f5:c4:41 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
+</code>
+This network is available only for the system domains (that is VMs created by root or using the "qemu:system" connection URI). VMs using this network end up in 192.168.122.1/24 and DHCP is provided to them via dnsmasq. This network is not automatically started. To start it use:
+  virsh --connect=qemu:///system net-start default
+To make the default network start automatically use:
+  virsh --connect=qemu:///system net-autostart default
+===== Change XML configuration =====
+Extract the xml from an existing qcow2 image by:
+  virsh dumpxml Windows-11 > Windows-11.xml
+Edit and modify the tags in the XML file.
+Undefine the XML config from the old vm to prevent an error because of a duplicate UUID:
+  virsh undefine --nvram Windows-11
+  or
+  virsh undefine Windows-11
+Import / define the new XML file:
+  virsh define Windows-11.xml
+Of course you will have to stop and start the vm for the changes to take effect:
+  virsh destroy name_of_vm
+  virsh start name_of_vm
+===== Error Access ISO files, etc. =====
+Directory, that libvirt is using for storing/reading ISO and qcow2 files needs to be readable by libvirt-qemu user. In case of an error opening an ISO or image file, the "libvirt-qemu" user does not have access to the file or the directories holding the files. The "libvirt-qemu" user needs **"r+x"** permissions **all the way up the path**. You can check if unix permissions are correct by running a shell under user "libvirt-qemu" and see if you can ls along the path all the way up to the files:
+  $ sudo su -s /bin/bash libvirt-qemu
+If you can't ls with an account that does have access yields a result with a permission line that contains a dot such as drwxrwxr-x. meaning extended ACL permissions.
+=== Fix 1: ===
+Put the iso or image into one of the pool directories of libvirt manager. E.g. /var/lib/libvirt/images
+Or any other paths that have full r others rights.
+===== Convert VirtualBox to KVM =====
+  qemu-img convert -f vdi -O qcow2 virtualbox-name.vdi kvm-name.qcow2
+===== Shrink KVM  qcow2 image =====
+  qemu-img convert -O qcow2 source.qcow2 shrunk.qcow2
+===== Make SATA disk available in Windows Client =====
+To make a SATA disk partition available in a Windows VM add the disk to the domain’s xml config file by hand. First find the id of the partition that you want to add. Rather than using /dev/sda you should use /dev/disk/by-id/ where you get from
+   ls -l /dev/disk/by-id
+Now edit the ///etc/libvirt/qemu/${YOUR_VM}.xml// file and add a <disk> section to the <devices> section:
+<code>
+# nano /etc/libvirt/qemu/${YOUR_VM}.xml
+or
+virsh edit ${YOUR_VM}
+----------------------------------------------
+<disk type='block' device='disk'>
+    <driver name='qemu' type='raw'/>
+    <source dev='/dev/disk/by-id/{the-partition-id}'/>
+    <target dev='vdb' bus='virtio'/>
+</disk>
+</code>
+This will make the host’s partition available in the guest as /dev/vdb (D:). After changing a domain’s config by hand, you have to reload the config by hand. Log in to your host and issue this command:
+  # virsh define /etc/libvirt/qemu/${YOUR_VM}.xml
+  Domain YOUR_VM defined from /etc/libvirt/qemu/${YOUR_VM}.xml
+===== Links =====
+  * [[https://wiki.debian.org/KVM#Installation]]