2023/server-configs/vms/README.md

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# Virtual Machines
## Resources used
| Name | vCPU | Memory (MiB) | Disk (GiB) | VLANs |
| --------------- | ---- | ------------ | ---------- | ----- |
| gateway-openwrt | 8 | 4096 | 1 | all |
| dns | 2 | 4096 | 20 | all |
| monitoring | 4 | 4096 | 40 | 20 |
| voip | 2 | 2048 | 20 | 26 |
## SR-IOV
Intel's X520 network adapters we are currently using support passing through a virtual function of the NIC directly to the VM.
### Host configuration
SR-IOV should be enabled in the server's BIOS.
To create virtual functions on boot, a `udev` rule has to be created.
On dual-port cards even VF numbers are given to the first port (`..f0`). Odd ones are connected to the second port (`..f1`).
```bash
cat > /etc/udev/rules.d/enp1s0f0.rules << EOF
KERNEL=="0000:01:00.0", SUBSYSTEM=="pci", DRIVER=="ixgbe", ATTR{vendor}=="0x8086", ATTR{device}=="0x154d", ATTR{sriov_numvfs}="15"
KERNEL=="0000:01:00.1", SUBSYSTEM=="pci", DRIVER=="ixgbe", ATTR{vendor}=="0x8086", ATTR{device}=="0x154d", ATTR{sriov_numvfs}="15"
EOF
```
### Attaching a virtual function to a VM
We have to manually edit the VM's XML definition.
The function IDs must be unique as each virtual function can be used exclusively by a single VM (and is detached from the host).
Depending on our needs, we can attach:
#### In a specific VLAN (the NIC/hypervisor is responsible for tagging the frames)
```xml
<interface type='hostdev' managed='yes'>
<driver name='vfio'/>
<source>
<address type='pci' domain='0x0000' bus='0x01' slot='0x10' function='{{$FUNCTION}}'/>
</source>
<vlan>
<tag id='{{$VLAN_ID}}'/>
</vlan>
<alias name='hostdev0'/>
<address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
</interface>
```
#### Directly (to use as a dot1q trunk)
```xml
<interface type='hostdev' managed='yes'>
<driver name='vfio'/>
<source>
<address type='pci' domain='0x0000' bus='0x01' slot='0x10' function='{{$FUNCTION}}'/>
</source>
<alias name='hostdev0'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</interface>
```
All offloading features work on virtual functions, including VLAN tagging.