Commit 7a8fcca9 authored by Francesc Guasch's avatar Francesc Guasch
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doc: PCI Passthrough

NVIDIA GPU example with working CUDA
parent eb027f04
PCI Device Passthrough
In this document we show how to add a NVIDIA GPU to a KVM virtual Machine
in Ravada VDI. Any PCI device could be added in a similar way.
Please note that this is a very active topic and the instructions outlined here
might not work in your environment
* A NVidia GPU
* A properly configured kernel along with a recent version of qemu. We were successful with Ubuntu 20.04.
Hardware Identification
.. prompt:: bash $
sudo lspci -Dnn | grep NVIDIA
0000:1b:00.0 VGA compatible controller [0300]: NVIDIA Corporation Device [10de:2204] (rev a1)
0000:1b:00.1 Audio device [0403]: NVIDIA Corporation Device [10de:1aef] (rev a1)
As you can see there are two devices attached to this PCI, that is because the video
card has also an audio device. From here we gather:
* PCI data: 0000:1b:00.0 and 0000:1b:00.1
* Devices: 10de:2204 and 10de:1aef
OS Configuration
This is the configuration for the host server. We must setup the kernel so the
PCI device is not used in any way so it can be passed to the virtual machine.
Add this to GRUB_CMDLINE_LINUX line in */etc/default/grub*. This is suited for Intel
computers. Notice we added the devices identified in the previous step to *pci-stub*.
Here we are preventing the GPU to be used by the main host so it can be passed
to the virtual machine.
.. :
GRUB_CMDLINE_LINUX_DEFAULT="snd_hda_intel.blacklist=1 nouveau.blacklist=1 intel_iommu=on rd.driver.pre=vfio-pci pci-stub.ids=10de:2204,10de:1aef"
AMD require a similar setup adding
.. :
GRUB_CMDLINE_LINUX_DEFAULT="snd_hda_intel.blacklist=1 nouveau.blacklist=1 amd_iommu=on iommu=pt kvm_amd.npt=1 kvm_amd.avic=1 rd.driver.pre=vfio-pci pci-stub.ids=10de:2204,10de:1aef"
Blacklist modules creating the file /etc/modprobe.d/blacklist-gpu.conf
.. :
blacklist nouveau
blacklist radeon
blacklist amdgpu
blacklist snd_hda_intel
blacklist nvidiafb
Also prevent the nvidia drivers to load and raise vfio-pci instead in /etc/modprobe.d/nvidia.conf
.. :
softdep nouveau pre: vfio-pci
softdep nvidia pre: vfio-pci
softdep nvidia* pre: vfio-pci
Add the modules so they are loaded on boot in /etc/modules
.. :
vfio vfio_iommu_type1 vfio_pci ids=10de:2204,10de:1aef
Pass the device identifiers to vfio-pci in /etc/modprobe.d/vfio.conf. This is duplicated
from the previous step, it may be removed eventually from this doc if we find it
unnecessary. Anyway it doesn't harm.
.. :
options vfio-pci ids=10de:2204,10de:1aef disable_vga=1
When loading KVM make it ignore MSRS in /etc/modprobe.d/kvm.conf
options kvm ignore_msrs=1
.. :
options kvm ignore_msrs=1
Update the grub and initram configuration and reboot.
.. prompt:: bash $
sudo update-grub
sudo update-initramfs -u
sudo reboot
No nvidia nor nouveau should be loaded:
.. prompt:: bash $
sudo lsmod | egrep -i "(nouveau|nvidia)"
The device should use vfio driver:
.. prompt:: bash $
lspci -k | egrep -A 5 -i nvidia
.. ::
1b:00.0 VGA compatible controller: NVIDIA Corporation Device 2204 (rev a1)
Subsystem: Gigabyte Technology Co., Ltd Device 403b
Kernel driver in use: vfio-pci
Kernel modules: nvidiafb, nouveau
1b:00.1 Audio device: NVIDIA Corporation Device 1aef (rev a1)
Subsystem: Gigabyte Technology Co., Ltd Device 403b
Kernel modules: snd_hda_intel
See that thouch in the NVIDIA VGA the preferred kernel modules are nvidiafb and nouveau,
it actually loads vfio-pci which is great.
Check it is enabled
.. prompt:: bash $
dmesg | grep -i iommu | grep -i enabled
.. ::
[ 0.873154] DMAR: IOMMU enabled
Verify the iommu groups. Both devices should be in the same group. We use *grep*
to search for the PCI device numbers we found in the very first step.
.. prompt:: bash $
dmesg | grep iommu | grep 1b:00
.. ::
[ 2.474726] pci 0000:1b:00.0: Adding to iommu group 38
[ 2.474807] pci 0000:1b:00.1: Adding to iommu group 38
Virtual Machine Setup
We must hide KVM in the virtual machine and pass the PCI device.
Edit the virtual machine configuration with `sudo virsh edit virtual-machine`.
Hide KVM
Some vendor drivers refuse to load when they detect KVM.
Add inside features this to hide KVM to the virtual machine.
There are more unlisted features that may be different from yours. Keep them
in your virtual machine. The important part is the **KVM** entry.
.. ::
<hidden state='on'/>
<vmport state='off'/>
Pass the Device
This is the part where we pass the real device to the Virtual Machine. Only one
started virtual machine can have it.
Add it anywhere inside the *devices* section.
The source address must be created with the PCI information we found in the first step.
So the device 0000:1b:00.0 will have:
* domain: 0x0000
* bus: 0x1b
* slot: 0x00
* function: 0x0
We set the *rombar* to *on* just in case, please report to us if you have more insight
about this issue.
Finally we create a PCI device in the virtual machine, so we find a free PCI
spot and add it. If it is duplicated it will warn on startup, you can change it
as you like.
.. ::
<hostdev mode='subsystem' type='pci' managed='yes'>
<address domain='0x0000' bus='0x1b' slot='0x00' function='0x0'/>
<rom bar='on'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x01' function='0x0'/>
Virtual Machine GPU Ubuntu setup
As an example we load the GPU in Ubuntu and verify it is being used.
Configure from the graphical interface to load propietary drivers
for NVIDIA server. This is the list of packages for our setup:
* nvidia-compute-utils-460-server
* nvidia-dkms-460-server
* nvidia-driver-460-server
* nvidia-kernel-common-460-server
* nvidia-kernel-source-460-server
* nvidia-settings
* nvidia-utils-460-server
In this particular installation we wanted to try CUDA. We install the
package and check if it works:
.. prompt:: bash $
$ sudo apt install nvidia-cuda-toolkit
$ nvidia-smi
If it works nvidia smi will show the detected hardware:
.. ::
| NVIDIA-SMI 460.73.01 Driver Version: 460.73.01 CUDA Version: 11.2 |
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
| | | MIG M. |
| 0 GeForce RTX 3090 Off | 00000000:01:01.0 Off | N/A |
| 30% 38C P0 61W / 350W | 0MiB / 24268MiB | 0% Default |
| | | N/A |
......@@ -88,7 +88,6 @@ Do you feel like giving us a hand? Here you have all the information you need as
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