These instructions only cover Intel GPUs that are compatible with vfio-mdev (5th to 10th generation). Since generation 11th, vfio-mdev has been superseded by SR-IOV.
GPUs compatible with Virtual Function I/O Mediated devices (vfio-mdev) can be split into multiple virtual GPUs (vGPUs).
In turned, these vGPUs can then be assigned to virtual machines or containers.
Contrary to paravirtualized GPUs (e.g. virtio-gpu), virtual GPUs do not need specialized drivers.
How to do so?
Some computers allow you to modify the system memory allocated or shared with the integrated GPU, which may allow you to create more vGPUs.
Before the host operating system boots up, you need to enter the BIOS/UEFI and to look for a setting called GPU aperture size, or GPU shared memory.
Use the highest possible value.
System memory will be reserved for the GPU, so make sure you have enough system memory to accomodate both the GPU and your operating system.
Upon reboot, you should then be able to list available GPUs using the mdevctl command.
mdevctl types
0000:00:02.0
i915-GVTg_V5_1
Available instances: 1
Device API: vfio-pci
Description: low_gm_size: 512MB, high_gm_size: 2048MB, fence: 4, resolution: 1920x1200, weight: 16
i915-GVTg_V5_2
Available instances: 2
Device API: vfio-pci
Description: low_gm_size: 256MB, high_gm_size: 1024MB, fence: 4, resolution: 1920x1200, weight: 8
i915-GVTg_V5_4
Available instances: 5
Device API: vfio-pci
Description: low_gm_size: 128MB, high_gm_size: 512MB, fence: 4, resolution: 1920x1200, weight: 4
i915-GVTg_V5_8
Available instances: 7
Device API: vfio-pci
Description: low_gm_size: 64MB, high_gm_size: 384MB, fence: 4, resolution: 1024x768, weight: 2
Increasing the system memory allocated to the GPU (GPU aperture size), as shown in the previous section, may increase the number and kind of available instances.
In this case, the i915-GVTg_V5_4 kind seems to offer the best trade-offs between the available resolution and the number of available instances.
uuidgen
7686131b-b229-4768-a02c-35d1dbed7c66
i915-GVTg_V5_4 using the previously generated UUIDsudo mdevctl start -u 7686131b-b229-4768-a02c-35d1dbed7c66 -p 0000:00:02.0 --type i915-GVTg_V5_4
sudo mdevctl define -u 7686131b-b229-4768-a02c-35d1dbed7c66
sudo mdevctl modify -u 7686131b-b229-4768-a02c-35d1dbed7c66 --auto
mdevctl list -d
7686131b-b229-4768-a02c-35d1dbed7c66 0000:00:02.0 i915-GVTg_V5_4 auto (active)
Great you have
uuid matches the previously generated UUID.<domain>
[...]
<device>
[...]
<hostdev mode="subsystem" type="mdev" managed="no" model="vfio-pci" display="on" ramfb="on">
<source>
<address uuid="7686131b-b229-4768-a02c-35d1dbed7c66"/>
</source>
<address type="pci" domain="0x0000" bus="0x09" slot="0x00" function="0x0"/>
</hostdev>
[...]
</device>
[...]
</domain>
Notice that the RAMFB is set to on, which activates Drect Memory Access Buffers (DMA-BUFs), making available the output of a virtual monitor before the guest operating system takes over
To-do
virtio-gpu and set the last one to the none.<domain>
[...]
<device>
[...]
<video>
<model type="none"/>
</video>
[...]
</device>
[...]
</domain>