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How to Fix “No KVM Error” in GNOME Boxes

The “No KVM Error” in GNOME Boxes usually indicates that the KVM module is unavailable or improperly configured.

Today, we are going to take a look at how to resolve this error and how to prevent it from occurring again.

Why the “No KVM” Error Occurs

GNOME Boxes resorts to slower software emulation when it cannot use KVM. This can be caused by:

1. Virtualization may not be enabled in the system’s BIOS/UEFI settings.
2. Kernel modules like `kvm`, `kvm_intel`, or `kvm_amd` might not be loaded or installed.
3. If KVM packages are missing, GNOME Boxes cannot utilize the virtualization capabilities.
4. The CPU may lack hardware-assisted virtualization support.
5. The current user may lack permission to access KVM devices.
6. Backend configuration problems can block virtualization functionality.
7. Other virtualization tools, such as VirtualBox, might interfere with KVM.

Diagnosing the Issue

1. First, we have to check Virtualization support with this command:

   lscpu | grep Virtualization

   If we see “Virtualization: VT-x” or “Virtualization: AMD-V,” it means the CPU supports it.
2. Restart the system and access BIOS/UEFI.
3. Now, ensure virtualization (Intel VT-x/AMD-V) is enabled.
4. Then, check the KVM modules:

   lsmod | grep kvm

   Look for `kvm` and either `kvm_intel` or `kvm_amd`.
5. Next, check group membership:

   groups

   Ensure the user is part of the `kvm` and `libvirt` groups.
6. Then, test KVM functionality by installing and running the CPU checker:

   sudo apt install cpu-checker
sudo kvm-ok


How to Fix the “No KVM” Error

1. Reboot, access BIOS/UEFI, enable virtualization, and save the changes.
2. Then, install required packages:

   sudo apt install qemu-kvm libvirt-daemon-system libvirt-clients bridge-utils virt-manager
3. Load the modules with these commands:

   sudo modprobe kvm
sudo modprobe kvm_intel # For Intel
sudo modprobe kvm_amd # For AMD

4. Now, add the user tothe  necessary groups:

   sudo usermod -aG kvm,libvirt $USER

   Log out and log back in, or reboot.
5. Then, enable and start the service:

   sudo systemctl enable --now libvirtd
6. Uninstall conflicting hypervisors like VirtualBox if needed.
7. Try creating or running the virtual machine again.

Preventive Tips

1. Keep the system updated:

   sudo apt update && sudo apt upgrade
2. Also, ensure virtualization settings remain enabled after firmware updates.
3. For detailed troubleshooting, we can use `virt-manager` or `virsh`.

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Conclusion

By following these steps, we can resolve the “No KVM Error” in GNOME Boxes and ensure a smooth virtualization experience.

In brief, our Support Experts demonstrated how to fix “No KVM Error” in GNOME Boxes.