docs: create gofurther/vfio-mdev

2024-11-05 11:51:10 +00:00 · 2022-07-21 21:10:43 +00:00 · 2022-07-21 21:10:43 +00:00 · 1b7abc1514
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+---
+title: Virtual Function I/O Mediated devices (vfio-mdev)
+description: Create and Configure Virtual Function I/O Mediated devices (vfio-mdev)
+published: true
+date: 2022-07-21T21:10:41.046Z
+tags: 
+editor: markdown
+dateCreated: 2022-07-21T21:10:41.046Z
+---
+
+# Configure Virtual Function I/O Mediated devices (vfio-mdev)
+
+Virtual Function I/O Mediated devices (vfio-mdev) allows you to split your GPU into virtual GPUs (vGPus), which are multiple virtual instances that can be managed using the native driver of your GPU. 
+
+These instructions only cover Intel GPUs that are compatible with Virtual Function I/O (VFIO) Mediated devices (gen 5th to gen 9th, perhaps 10th). 
+
+For Xe Intel graphics (11th and onward) and other cards, use SR-IOV-based GPUs.
+
+## Preparation
+
+* Make sure to update the grub first
+
+```
+sudo grub2-mkconfig -o /boot/grub2/grub.cfg
+```
+
+* Reboot
+
+```
+Reboot
+```
+
+* Modify available GPU Aperture size (GPU memory) in the BIOS/UEFI.
+
+```
+To-do
+```
+
+## Create a virtual GPU
+
+* List available virtual GPUs
+
+```
+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
+```
+
+* You may need to increase GPU aperture size, or memory, if there is no available instance
+
+
+The `i915-GVTg_V5_4` kind seems to offer the best trade-offs between the available resolution and the number of available instances.
+
+* Generate unique id
+
+```
+uuidgen
+```
+
+```
+7686131b-b229-4768-a02c-35d1dbed7c66
+```
+
+* Start a vGPU based off this id and of type `i915-GVTg_V5_4`
+ 
+```
+sudo mdevctl start -u 7686131b-b229-4768-a02c-35d1dbed7c66 -p 0000:00:02.0 --type i915-GVTg_V5_4
+```
+
+* Define, or make this vGPU permanent.
+
+```
+sudo mdevctl define -u 7686131b-b229-4768-a02c-35d1dbed7c66
+```
+
+* Set it to auto-start when the host has boot up.
+
+```
+sudo mdevctl modify -u 7686131b-b229-4768-a02c-35d1dbed7c66 --auto
+``` 
+
+* Verify it has successfully been created
+
+```
+mdevctl list -d
+``` 
+
+```
+7686131b-b229-4768-a02c-35d1dbed7c66 0000:00:02.0 i915-GVTg_V5_4 auto (active)
+```
+
+## Assign a virtual GPU to a virtual machine
+
+* Add that segment to a virtual machine's definition. Modify the UUID address according to the previously generated UUID.
+
+```
+    <hostdev mode="subsystem" type="mdev" managed="no" model="vfio-pci" display="on">
+      <source>
+        <address uuid="7686131b-b229-4768-a02c-35d1dbed7c66"/>
+      </source>
+      <address type="pci" domain="0x0000" bus="0x09" slot="0x00" function="0x0"/>
+    </hostdev>
+```
+
+* Notice the display on, and the the RAMFB section, which allows to see the output before an operating system takes over.
+
+## Remove any video device
+
+* Remove any video device
+
+
+## Resources
+
+* Official page: https://www.kernel.org/doc/html/latest/driver-api/vfio-mediated-device.html
+* Archlinux's entry on Intel GVT-g: https://wiki.archlinux.org/title/Intel_GVT-g