docs(ins): additional information qga (#5728)

* docs(ins): additional information qga

* docs(ins): update wording

* feat(ins): add info about scaleway-vmagent

* docs(ins): add configuration information

* Update pages/instances/reference-content/understanding-qemu-guest-agent.mdx

Co-authored-by: Rowena Jones <[email protected]>

---------

Co-authored-by: Rowena Jones <[email protected]>

Author: bene2k1

pages/instances/reference-content/understanding-qemu-guest-agent.mdx

@@ -15,6 +15,28 @@ This page provides essential insights into this mechanism.
   This documentation page does not apply to Instances running the Microsoft Windows operating system.
 </Message>
 
+## What is the QGA?
+
+The QEMU Guest Agent (QGA) is a daemon designed to run inside virtual machines, enabling communication between the guest operating system and the QEMU hypervisor. It supports tasks such as system configuration and resource monitoring.
+
+The QGA source code is publicly available in the [QEMU repository on GitLab](https://gitlab.com/qemu-project/qemu/-/blob/master/docs/interop/qemu-ga.rst).
+
+<Message type="note">
+  In addition to the QGA, another daemon is preinstalled on recently created Instances: `scaleway-vmagent`. This agent was developed by Scaleway's engineering teams and is used to send metrics about your VM to [Cockpit](/cockpit/) to monitor the status of your Instance. 
+  You can find the source code of the agent on Scaleway's [Launchpad repository](https://launchpad.net/~scaleway/+archive/ubuntu/stable/+packages).
+</Message>
+
+## Which tasks are allowed for the QGA?
+
+Scaleway has intentionally restricted the QGA to the following allowed tasks (configured in `/etc/qemu/qemu-ga.conf`):
+
+* `guest-file-close`
+* `guest-file-open`
+* `guest-file-write`
+* `guest-ping`
+
+All other Remote Procedure Calls (RPCs) are disabled to limit the scope of external execution from the QEMU hypervisor.
+
 ## What are the features provided by QGA?
 
 Running the QEMU Guest Agent (QGA) on your Instance currently enables the following feature:
@@ -23,6 +45,11 @@ Running the QEMU Guest Agent (QGA) on your Instance currently enables the follow
 
 Additional features may be added in the future.
 
+## What is the performance impact of running the QGA inside my VM?
+
+The performance impact of running the QGA is negligible. The agent consumes very little RAM (<5 MB) and CPU (<0.1%), and there is no measurable I/O or network overhead when idle.
+The only operation the agent performs is reading from or writing to a file **in the VM** each time a public IP is attached to or detached from the VM.
+
 ## Checking QGA's status
 
 Since March 1st, 2024, all Scaleway-provided GNU/Linux and InstantApp images for Instances come with QGA pre-installed and enabled by default.