> For the complete documentation index, see [llms.txt](https://platform9.com/kb/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://platform9.com/kb/pmo/how-to/how-to-expose-all-physical-cpu-features-to-kvm.md).

# How-To Expose all Physical CPU Features to KVM

## Problem

You want to expose a flag present on the physical CPU to the virtual machines running on the host.

## Environment

* Platform9 Managed OpenStack - All versions
* Nova
* KVM/qemu

## Procedure

1. Update the *Nova* configuration file locate at */opt/pf9/etc/nova/conf.d/nova\_override.conf* and make sure the following option is set within the **\[libvirt]** stanza.

{% tabs %}
{% tab title="None" %}

```none
[pf9@lab01~]$ cat /opt/pf9/etc/nova/conf.d/nova_override.conf.........[libvirt]cpu_mode=host-model
```

{% endtab %}
{% endtabs %}

2. Once the file has been modified, restart the *pf9-ostackhost* service by running the following command.

{% tabs %}
{% tab title="None" %}

```none
# sudo systemctl restart pf9-ostackhost
```

{% endtab %}
{% endtabs %}

3. Hard reboot the VMs where you want to see the additional flags by running the following command.

{% tabs %}
{% tab title="None" %}

```none
# openstack server reboot --hard [Instance_UUID]
```

{% endtab %}
{% endtabs %}

## Additional Information

Using `host-model` is a safe choice if your compute node CPUs are largely identical. However, if your compute nodes span multiple processor generations, you may be better advised to select a `custom` CPU model.

<https://docs.openstack.org/nova/rocky/admin/configuration/hypervisor-kvm.html#host-model-default-for-kvm-qemu>


---

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