13.4. Managing host devices using the web console

To modify the functionality of your virtual machine (VM), you can manage the host devices attached to your VM using the Red Hat Enterprise Linux 9 web console.

Host devices are physical devices that are attached to the host system. Based on your requirements, you can enable your VMs to directly access these hardware devices and components.

You can use the web console to:

13.4.1. Viewing devices attached to virtual machines using the web console

Before adding or modifying the devices attached to your virtual machine (VM), you may want to view the devices that are already attached to your VM. The following procedure provides instructions for viewing such devices using the web console.

Conditions préalables

Procédure

  1. In the Virtual Machines interface, click the VM whose information you want to see.

    A new page opens with detailed information about the VM.

    Page displaying the virtual machine interface.

  2. Scroll to the Host devices section.

    Page displaying the Host devices section of the virtual machine.

Ressources supplémentaires

13.4.2. Attaching devices to virtual machines using the web console

To add specific functionalities to your virtual machine (VM), you can use the web console to attach host devices to the VM.

Note

Attaching multiple host devices at the same time does not work. You can attach only one device at a time.

For more information, see RHEL 9 Known Issues.

Conditions préalables

  • If you are attaching PCI devices, ensure that the status of the managed attribute of the hostdev element is set to yes.

    Note

    When attaching PCI devices to your VM, do not omit the managed attribute of the hostdev element, or set it to no. If you do so, PCI devices cannot automatically detach from the host when you pass them to the VM. They also cannot automatically reattach to the host when you turn off the VM.

    As a consequence, the host may become unresponsive or shut down unexpectedly.

    You can find the status of the managed attribute in your VM’s XML configuration. The following example opens the XML configuration of the Ag47 VM: 

    # virsh edit Ag47
  • Back up important data from the VM.

  • Optional: Back up the XML configuration of your VM. For example, to back up the Centurion VM: 

    # virsh dumpxml Centurion > Centurion.xml
  • The web console VM plug-in is installed on your system.

Procédure

  1. In the Virtual Machines interface, click the VM to which you want to attach a host device.

    A new page opens with an Overview section with basic information about the selected VM and a Console section to access the VM’s graphical interface.

  2. Scroll to Host devices.

    The Host devices section displays information about the devices attached to the VM as well as options to Add or Remove devices.

    Image displaying the host devices section of the selected VM.

  3. Click Add host device.

    The Add host device dialog appears.

    Image displaying the Add host device dialog box.
  4. Select the device you wish to attach to the VM.

  5. Click Add

    The selected device is attached to the VM.

Vérification

  • Run the VM and check if the device appears in the Host devices section.

13.4.3. Removing devices from virtual machines using the web console

To free up resources, modify the functionalities of your VM, or both, you can use the web console to modify the VM and remove host devices that are no longer required.

Avertissement

Removing attached USB host devices using the web console may fail because of incorrect correlation between the device and bus numbers of the USB device.

For more information, see RHEL 9 Known Issues.

As a workaround, remove the <hostdev> part of the USB device, from the VM’s XML configuration, using the "virsh" utility. The following example opens the XML configuration of the Ag47 VM: 

# virsh edit Ag47

Conditions préalables

  • The web console VM plug-in is installed on your system.
  • Optional: Back up the XML configuration of your VM by using virsh dumpxml vm-name and sending the output to a file. For example, the following backs up the configuration of your Motoko VM as the motoko.xml file: 
# virsh dumpxml Motoko > motoko.xml
# cat motoko.xml
<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
  <name>Motoko</name>
  <uuid>ede29304-fe0c-4ca4-abcd-d246481acd18</uuid>
  [...]
</domain>

Procédure

  1. In the Virtual Machines interface, click the VM from which you want to remove a host device.

    A new page opens with an Overview section with basic information about the selected VM and a Console section to access the VM’s graphical interface.

  2. Scroll to Host devices.

    The Host devices section displays information about the devices attached to the VM as well as options to Add or Remove devices.

    Image displaying the host dvices section of the selected VM.

  3. Click the Remove button next to the device you want to remove from the VM.

    A remove device confirmation dialog appears.

    Image displaying the option to remove an attached virtual device.

  4. Click Remove.

    The device is removed from the VM.

Résolution de problèmes

  • If removing a host device causes your VM to become unbootable, use the virsh define utility to restore the XML configuration by reloading the XML configuration file you backed up previously. 

    # virsh define motoko.xml