Running Systems

Let me first say, that it does work for Linux guest. It doesn’t work on Windows guest because there is a know bug (/issue) with the default hardware layout – made of i440FX BIOS. VirtManager would not allow us to replace the settings, so we need to create the VM ourselves using XML. You can export your XML settings (of an existing VM) using the command

virsh dumpxml  > /tmp/VM_NAME.xml

There are relevant fields there which you might want to save for later, like MAC addresses, network settings, and so on.

You can use this XML file to build your VM anew. Note that you will want to modify the network settings, the name and the UUID. Also – you will need a newer QEMU command (through the package qemu-system-x86), you can find in the Centos updates repository, . It has been providing me with /usr/bin/qemu-system-x86_64 command, which I am using, instead of the default qemu command used by default by VirtManager.

My Windows VM XML file (as a reference you can copy and use) is provided below. Major modifications are required to the hardware settings of the Windows VM – moving from PCI to PCIE, changing from IDE to SATA or VirtIO – and the provided XML gives a good reference of how this file should look like. This was taken from a machine tested to allow USB hot-add/remove via the method provided in my previous post.

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<domain type='kvm' id='1'>
  <name>Windows</name>                             <!-- Change the name to match your settings -->
  <uuid>9a10dc43-5c39-411d-8dc9-f6c6b849d212</uuid> <!-- Make sure you change the UUID. Dont have duplicates -->
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <vcpu placement='static'>2</vcpu>
  <resource>
    <partition>/machine</partition>
  </resource>
  <os>
    <type arch='x86_64' machine='pc-q35-2.0'>hvm</type> <!-- This is the key part - using different machine type -->
  </os>
  <features>
    <acpi/>
    <apic/>
    <hyperv>
      <relaxed state='on'/>
      <vapic state='on'/>
      <spinlocks state='on' retries='8191'/>
    </hyperv>
  </features>
  <clock offset='localtime'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
    <timer name='hypervclock' present='yes'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <pm>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
  </pm>
  <devices>
    <emulator>/usr/bin/qemu-system-x86_64</emulator> <!-- This is important! -->
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/images/Windows-test1.qcow2'/>  <!-- Point to the right file. It can be raw or qcow2, so change the line above accordingly -->
      <backingStore/>
      <target dev='sda' bus='sata'/> <!-- I have used SATA and not VirtIO, because the later requires drivers on Windows. I will need to handle that in the future, but for our example, it should work -->
      <alias name='sata0-0-0'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <backingStore/>
      <target dev='sdb' bus='sata'/>
      <readonly/>
      <boot order='1'/>
      <alias name='sata0-0-1'/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
    </disk>
    <controller type='usb' index='0' model='ich9-ehci1'>
      <alias name='usb'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x05' function='0x7'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci1'>
      <alias name='usb'/>
      <master startport='0'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x05' function='0x0' multifunction='on'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci2'>
      <alias name='usb'/>
      <master startport='2'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x05' function='0x1'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci3'>
      <alias name='usb'/>
      <master startport='4'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x05' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pcie-root'>
      <alias name='pcie.0'/>
    </controller>
    <controller type='pci' index='1' model='dmi-to-pci-bridge'>
      <model name='i82801b11-bridge'/>
      <alias name='pci.1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
    </controller>
    <controller type='pci' index='2' model='pci-bridge'>
      <model name='pci-bridge'/>
      <target chassisNr='2'/>
      <alias name='pci.2'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
    </controller>
    <controller type='pci' index='3' model='pcie-root-port'>
      <model name='ioh3420'/>
      <target chassis='3' port='0x10'/>
      <alias name='pci.3'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <alias name='virtio-serial0'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x06' function='0x0'/>
    </controller>
    <controller type='sata' index='0'>
      <alias name='ide'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
    </controller>
    <interface type='bridge'>
      <mac address='11:12:14:12:a1:03'/>  <!-- Change the MAC address! -->
      <source bridge='bridge'/>
      <model type='rtl8139'/>    <!-- Also wanted VirtIO, but needs drivers -->
      <alias name='net0'/>
      <address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <source path='/dev/pts/10'/>
      <target port='0'/>
      <alias name='serial0'/>
    </serial>
    <console type='pty' tty='/dev/pts/10'>
      <source path='/dev/pts/10'/>
      <target type='serial' port='0'/>
      <alias name='serial0'/>
    </console>
    <channel type='spicevmc'>
      <target type='virtio' name='com.redhat.spice.0'/>
      <alias name='channel0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <input type='tablet' bus='usb'>
      <alias name='input0'/>
      <address type='usb' bus='0' port='1'/>
    </input>
    <input type='mouse' bus='ps2'>
      <alias name='input1'/>
    </input>
    <input type='keyboard' bus='ps2'>
      <alias name='input2'/>
    </input>
    <graphics type='spice' port='5900' autoport='yes' listen='127.0.0.1'>
      <listen type='address' address='127.0.0.1'/>
      <image compression='off'/>
    </graphics>
    <sound model='ich6'>
      <alias name='sound0'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x04' function='0x0'/>
    </sound>
    <video>
      <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
      <alias name='video0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
    </video>
    <redirdev bus='usb' type='spicevmc'>
      <alias name='redir0'/>
      <address type='usb' bus='0' port='2'/>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
      <alias name='redir1'/>
      <address type='usb' bus='0' port='3'/>
    </redirdev>
    <memballoon model='virtio'>
      <stats period='5'/>
      <alias name='balloon0'/>
      <address type='pci' domain='0x0000' bus='0x01' slot='0x07' function='0x0'/>
    </memballoon>
  </devices>
  <seclabel type='none' model='none'/>
  <seclabel type='dynamic' model='dac' relabel='yes'>
    <label>+107:+107</label>
    <imagelabel>+107:+107</imagelabel>
  </seclabel>
</domain>

Now just import the VM using

virsh define /tmp/NEW_MACHINE.xml

and your changes are available via VirtManager, where you can edit (some of them).

I was required to auto map a USB DoK to a KVM VM (specific VM, mind you!), as a result of connecting this device to the host. I’ve looked it up on the Internet, and the closest I could get there was this link. It was almost a complete solution, but it had a few bugs, so I will re-describe the whole process, with the fixes I’ve added to the process and udev rules file. While this guide is rather old, it did solve my requirement, which was to map a specific set of devices (“known USB devices”) to the VM, and not any and every USB device (or even – USB DoK) connected to the system.

In my example, I’ve used SanDisk Corp. Ultra Fit, which its USB identifier is 0781:5583, as can be seen using ‘lsusb’ command:

[[email protected] ~]# lsusb
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 020: ID 0781:5583 SanDisk Corp. Ultra Fit

My VM is called “centos7.0” in this example. I am using integrated KVM+QEMU+LIBVIRT on a generic CentOS 7.5 system.

Preparation

You will need to prepare two files:

• USB definitions file (for easier config of libvirt)
• UDEV rules file (which will be triggered by add/remove operation, and will call the USB definitions file)

USB Definitions file

I’ve placed it in /opt/autousb/hostdev-0781:5583.xml , and it holds the following (mind the USB device identifiers!)

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<hostdev mode='subsystem' type='usb'>
  <source>
    <vendor id='0x0781'/>
    <product id='0x5583'/>
  </source>
</hostdev>

I’ve created a file /etc/udev/rules.d/90-libvirt-usb.rules with the content below. Note that the device identifiers are there, but in the “remove” section they appear differently. Remove leading zero(s) and change the string. This is caused because on removal, the device does not report all its properties to the OS. Also – you cannot connect more than three (3) such devices to a VM, so when you fail to detach three devices (following a consecutive insert/remove operations, for example), you will not be able to attach a fourth time.

ACTION=="add", \
    SUBSYSTEM=="usb", \
    ENV{ID_VENDOR_ID}=="0781", \
    ENV{ID_MODEL_ID}=="5583", \
    RUN+="/usr/bin/virsh attach-device centos7.0 /opt/autousb/hostdev-0781:5583.xml"
ACTION=="remove", \
    SUBSYSTEM=="usb", \
    ENV{PRODUCT}=="781/5583/100", \
    RUN+="/usr/bin/virsh detach-device centos7.0 /opt/autousb/config/hostdev-0781:5583.xml"

Now, all that’s left to do is to reload udev using the following command:

udevadm trigger

To monitor the system behaviour, run either of these commands:

udevadm monitor --property --udev 

or

udevadm monitor --environment --udev 

There is a very nice script for Windows dealing with attaching XenServer USB disk to a guest. It can be found here.

This script has several problems, as I see it. The first – this is a Windows batch script, which is a very limited language, and it can handle only a single VDI disk in the SR group called “Removable Storage”.

As I am a *nix guy, and can hardly handle Windows batch scripts, I have rewritten this script to run from Linux CLI (focused on running from the XenServer Domain0), and allowed it to handle multiple USB disks. My assumption is that running this script will map/unmap *all* local USB disks to the VM.

Following downloading this script, you should make sure it is executable, and run it with the arguments “attach” or “detach”, per your needs.

And here it is:

#!/bin/bash
# This script will map USB devices to a specific VM
# Written by Ez-Aton, http://run.tournament.org.il , with the concepts
# taken from http://jamesscanlonitkb.wordpress.com/2012/03/11/xenserver-mount-usb-from-host/
# and http://support.citrix.com/article/CTX118198

# Variables
# Need to change them to match your own!
REMOVABLE_SR_UUID=d03f247d-6fc6-a396-e62b-a4e702aabcf0
VM_UUID=b69e9788-8cd2-0074-5bc1-63cf7870fa0d
DEVICE_NAMES="hdc hde" # Local disk mapping for the VM
XE=/opt/xensource/bin/xe

function attach() {
        # Here we attach the disks
        # Check if storage is attached to VBD
        VBDS=`$XE vdi-list sr-uuid=${REMOVABLE_SR_UUID} params=vbd-uuids --minimal | tr , ' '`
        if [ `echo $VBDS | wc -w` -ne 0 ]
        then
                echo "Disks are allready attached. Check VBD $VBDS for details"
                exit 1
        fi
        # Get devices!
        VDIS=`$XE vdi-list sr-uuid=${REMOVABLE_SR_UUID} --minimal | tr , ' '`
        INDEX=0
        DEVICE_NAMES=( $DEVICE_NAMES )
        for i in $VDIS
        do
                VBD=`$XE vbd-create vm-uuid=${VM_UUID} device=${DEVICE_NAMES[$INDEX]} vdi-uuid=${i}`
                if [ $? -ne 0 ]
                then
                        echo "Failed to connect $i to ${DEVICE_NAMES[$INDEX]}"
                        exit 2
                fi
                $XE vbd-plug uuid=$VBD
                if [ $? -ne 0 ]
                then
                        echo "Failed to plug $VBD"
                        exit 3
                fi
                let INDEX++
        done
}

function detach() {
        # Here we detach the disks
        VBDS=`$XE vdi-list sr-uuid=${REMOVABLE_SR_UUID} params=vbd-uuids --minimal | tr , ' '`
        for i in $VBDS
        do
                $XE vbd-unplug uuid=${i}
                $XE vbd-destroy uuid=${i}
        done
        echo "Storage Detached from VM"
}
case "$1" in
        attach) attach
                ;;
        detach) detach
                ;;
        *)      echo "Usage: $0 [attach|detach]"
                exit 1
esac

Cheers!