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--- linux_wiki:kernel-based_virtual_machine_kvm [2015/02/13 21:47]
billdozor
+++ linux_wiki:kernel-based_virtual_machine_kvm [2019/05/25 23:50] (current)
@@ Line 1: / Line 1: @@
 ====== Kernel-based Virtual Machine (KVM) ======
-Description: KVM is "a full virtualization solution for Linux on x86 hardware containing virtualization extensions." ([[http://www.linux-kvm.org/page/Main_Page|KVM Main Page]]) It can be run on the desktop with GUI managers or on a headless server.
+**General Information**
-Assumption: Some Red Hat based distro is already installed. (CentOS, Scientific, RHEL, etc)
+KVM is "a full virtualization solution for Linux on x86 hardware containing virtualization extensions." ([[http://www.linux-kvm.org/page/Main_Page|KVM Main Page]]) It can be run on the desktop with GUI managers or on a headless server.
--02-13: These are rough notes and in progress as I learn KVM.
+**Checklist**
+  * Distro(s): Enterprise Linux 6
+  * Other: This page was written using CentOS 6.6 with GNOME desktop (headless KVM is on the to do list!)
+  * 2015-02-13: These are rough notes and in progress as I learn KVM.
-===== Installation =====
+----
+====== Installation ======
-  * Install: Virtualization Groups
+==== Install: Required Virtualization Packages (CLI) ====
 <code bash>
-yum groupinstall "Virtualization*"
+yum install qemu-kvm python-virtinst virt-top libvirt libvirt-client
 </code>
-**Group Explanations**
+**CLI Package Explanations**
-This will install the following package groups:
+  * qemu-kvm => The main KVM package.
-  * Virtualization Tools => Tools for offline virtual image management.
+  * python-virtinst => CLI tools and libraries for creating VMs.
-  * Virtualization Platform => Provides an interface for accessing and controlling virtualized guests and containers.
+  * virt-top => CLI VM stats.
-  * Virtualization Client => Clients for installing and managing virtualization instances.
+  * libvirt => Toolkit for libvirtd service.
-  * Virtualization => Provides an environment for hosting virtualized guests.
+  * libvirt-client => Toolkit for VM clients.
-For detailed info and a list of packages that will be installed:
+==== Install: Optional Virtualization Packages (GUI) ====
 <code bash>
-yum groupinfo "Virtualization*"
+yum install virt-manager virt-viewer
 </code>
-  * Install: Additional Useful Packages
+**GUI Package Explanations**
+  * virt-manager => GUI VM administration tool.
+  * virt-viewer => GUI local console connection to VMs.
+==== Install: Optional Useful Packages ====
 <code bash>
 yum install bridge-utils dejavu-lgc-sans-fonts tigervnc xorg-x11-xauth
@@ Line 35: / Line 45: @@
   * bridge-utils => network bridging to allow the VMs to use the host machine's physical interfaces as a bridge.
   * dejavu-lgc-sans-fonts => Fonts for virt-manager (GUI VM manager)
-  * tigervnc => VNC to connect locally to VM console
+  * tigervnc => VNC to connect remotely to VM's GUI.
   * xorg-x11-xauth => X11 forwarding through ssh. (Remote virt-manager for headless servers)
 ----
-===== Verify Installation and Start Services =====
+====== Verify Installation and Start Services ======
   * Ensure that the KVM kernel module is loaded
 <code bash>
-lsmod | grep kvm
+[root@bash ~]# lsmod | grep kvm
+kvm_intel              55496  0
+kvm                   337900  1 kvm_intel
+</code>
+    * If it is not loaded, attempt to load the module:
+<code bash>
+modprobe -v kvm
 </code>
@@ Line 60: / Line 77: @@
 </code>
-  * Verify libvirtd is running successfully
+  * Verify libvirtd is running successfully (Yes, 3 forward slashes)
 <code bash>
 service libvirtd status
-virsh -c qemu://system list
+virsh -c qemu:///system list
 </code>
 ----
-===== Setup Networking =====
+====== Setup Networking ======
 By default, VMs will be on a private network with no access to the outside world unless they use a physical host network interface as a bridge.
@@ Line 125: / Line 142: @@
 NETMASK="255.255.255.0"
 GATEWAY="192.168.0.1"
+DNS1="208.67.222.222"
+DNS2="208.67.220.220"
 </code>
+Note: Those DNS entries are for OpenDNS.
 ==== IP Forwarding ====
@@ Line 148: / Line 168: @@
 ----
-===== SELinux =====
+====== SELinux ======
-If SELinux is in Enforcing mode, there is additional configuration if you change the default directory for VM images.
+If SELinux is on and in Enforcing mode, there is additional configuration if you change the default directory for VM images.
+**Check if SELinux is on/enabled**
+<code bash>
+[bash]# sestatus
+SELinux status:                 enabled
+SELinuxfs mount:                /selinux
+Current mode:                   enforcing
+</code>
 **Default VM Image directory:** /var/lib/libvirt/images/
@@ Line 159: / Line 187: @@
 </code>
-  * Install the following package to enable use of the "semanage" utility.
+  * Set the context of the new directory, referencing the default
 <code bash>
-yum install policycoreutils-python
+chcon -R --reference /var/lib/libvirt/images /vm-images
 </code>
-  * Set security context for the vm-images directory and everything that is created under it.
+  * Verify
 <code bash>
-semanage fcontext -a -t virt_image_t "/vm-images(/.*)?"
+ls -Z /vm-images
 </code>
-  * Restore the security context (I don't know why you have to do this yet...but you do)
+  * Create a symlink to the new location to ensure that is survives a SELinux relabel.
 <code bash>
-restorecon -R /vm-images
+rmdir /var/lib/libvirt/images
-</code>
+ln -s /vm-images /var/lib/libvirt/images
-  * Verify
-<code bash>
-ls -Z /vm-images
 </code>
 ----
-===== Creating VMs =====
+====== Creating VMs ======
 VMs can be installed via a command line tool (virt-install) or a GUI (virt-manager).
@@ Line 256: / Line 276: @@
 ==== GUI: virt-manager ====
+Installing locally via a GUI.
+  * Open a terminal and type:
+<code bash>
+virt-manager
+</code>
+  * The virt-manager GUI will open.
+  * Select the name of the host (probably "localhost (QEMU)")
+  * Click the "Create a New Virtual Machine" button (the monitor with a play button on it)
+    * Step 1 =>
+      * Name: Name the virtual machine
+      * Choose how to install: Select the install method
+    * Step 2 =>
+      * Browse for the media
+      * OS Type/Version: Optionally, select the OS type and version
+    * Step 3 =>
+      * Memory/CPU: Select memory and CPU.
+    * Step 4 =>
+      * Storage: Create or use existing storage
+    * Step 5 =>
+      * Ready to install: Confirm settings, set advanced options such as Host network device.
+----
+====== Disabling virbr0 NAT Interface ======
+On some desktop installations, a NAT interface "virbr0" is auto created.
+To disable this interface:
+  * View the interface<code bash>virsh net-list</code>
+  * Turn off the interface<code bash>virsh net-destroy default</code>
+  * Disable auto start on the interface<code bash>virsh net-autostart default –disable</code>
+  * Verify State is "inactive" and Autostart is "no", then ensure virbr0 is not in the interface list<code bash>virsh net-list --all
+ip addr show</code>
+  * Restart the network service
+    * EL6<code bash>service network restart</code>
+    * EL7<code bash>systemctl restart network</code>
+----