Nvidia MiG Support

[wyatt-made]

Does XCP-ng have support for Nvidia Multi Instance GPU (MiG)? I've been successful at using MxGPU on S7150x2's, but would like to see about using Ampere series Nvidia GPUs.

[olivierlambert]

Hi,

I have no idea, it was called vGPU in XenServer, IDK if MiG is new/different than previous work and if it's supported. It's likely not, since for XenServer there's a small Nvidia binary that we can't redistribute since it's not open source.

edit: after reading, it seems than MiG is creating a PCI address that you can then passthrough to the VM IDK if it's something we can do in Xen, I will ask around.

[wyatt-made]

@olivierlambert Thanks as always Oliver. MiG is a newer tech from Nvidia, I think it came along with the release of the Ampere architecture. Looking forward to what you have to say/what's possible. It'd be a really cool feature to support.

[olivierlambert]

I'd love to explore on actual hardware, but it's not cheap. However, I'll see if a partner could give us access to one card.

[wyatt-made]

@olivierlambert I should have a few of the cards coming in in about a month that I may be able to provide a testbed for if needed. Something to keep in mind.

[Dani]

As I wrote in other @wyatt-made post I'm going to test It next week in a server with a Nvidia A100.
Hope i can help.
Stay in touch.
Dani

[Dani]

Hello everybody,
I've made some tests with XCP-ng and the Nvidia A100 card using distinct drivers. For now I've tried Citrix drivers and RHEL drivers.
This post is a quick summary and then I'm going to write another post, much longer, with detailed results.
Question: Does it works?
Answer: NO

I think the options we have for now to virtualize the GPU are Linux KVM (free), RHEL (paid), Citrix (paid) and VMWare (paid).
However, my knowledge only reaches here so if someone have any idea I'll be pleased to hear it.

@olivierlambert if you wan't me to test something please tell me. We will use the server in production next academic year (in fact a bit sooner because teachers need to prepare the classes) but is in testing phase right now so maybe I can help.

Dani

[splastunov]

Why it is not working?

Did you read my post about how to run Nvidia vGPU on XCP-ng?
https://xcp-ng.org/forum/post/55774

But in any case you will need Nvidia license sever

[Dani]

Test results of XCP-ng 8.2 with Nvidia A100 and Citrix/RHEL drivers

Preface. The way Nvidia drivers work.
First I’m going to write a simplified explanation of how Nvidia drivers work, so we can have the concepts clear and see what we are trying to archieve.
I’ll talk all the time about virtualization of the GPU and the use of Nvidia vCS (virtual Compute Server). vCS is the version of the driver intended for compute workloads, like AI inference, deep learning, high performance computing and so on. The goal is to create a virtual GPU, which is a “slice” of the physical GPU, and then passthrough it to a virtual machine. Then, inside the virtual machine we can use the vGPU as if it were a physical GPU and do our computation tasks. In the end, we will have splitted the physical GPU in various virtual GPUs and passthroughed them to various virtual machines.
Nvidia GRID cards, like the A100, have two modes of operation: MIG (multi-instance GPU) and Time-sliced. MIG is a physical partition of the GPU, made using some hardware present in the card, wich creates isolated instances with separated cores, memory, etc. In the other hand, time-sliced creates more flexible partitions via software. This time-sliced partitions have their own memory but shares the compute cores using an algorithm similar to round-robin.
The way this vGPUs are passed to the virtual machines is using SR-IOV (Single Root Input-Output Virtualization) which is intended to connect PCIe devices to virtual machines having performance similar to native devices. To make use of this, Nvidia creates VFIO (Virtual Function Input-Output) mediated devices, each one with its own PCI ID.

The proccess is like this:

1. Enable virtual functions on the GPU with a script provided with the driver.
   This will create the mediated devices. If, for example, your physical GPU has the PCI ID 0000:81:00.0, the mediated devices will be 0000:81.00.4, 0000:81.00.5 and so on.
2. If you want to use MIG mode then you have to create the partitions in the GPU using the tool nvidia-smi provided with the host driver. In time-sliced mode is not necessary.
3. Map each vGPU you want to use with any virtual function (one virtual funcion can map only one vGPU at a time). Then you will have a mediated device, with its own uuid and pci id, wich represents the vGPU.
4. Create the virtual machine and assign the vGPU to it using this mdev device.
5. Install the client driver from Nvidia inside the virtual machine and work as if it has a real GPU.

Results of the tests.
Common considerations.

• All the drivers have been downloaded from the Nvidia licensing portal.

• Each test had been performed in a clean and updated installation of XCP-ng, to avoid errors due to install and uninstall packets and possible conflicts like files not correctly removed by yum.

• The driver needs IOMMU (Input/Output Memory Management Unit) enabled in the BIOS and loaded at startup. In Debian style distros you have to configure this in grub config, adding “amd_iommu=on” or “intel_iommu=on” to the command line. In XCP-ng this is not the way you do it, but is not important because if we run the command “xe host-param-get uuid=<uuid-of-your-server> param-name=chipset-info param-key=iommu” the output is “true”, so I assume IOMMU is enabled.

• XCP-ng detects the Nvidia A100 but can’t identify the model (A100). I’ve configured this server with Ubuntu server 22.04 (I have the install in other hard drive) and it detects the model correctly, however I think this is only a missing entry in a table with the device IDs and the commercial models so I don’t care about it.

# lspci | grep NVIDIA
XCP-ng: 81:00.0 3D controller: NVIDIA Corporation Device 20b5 (rev a1)
Ubuntu: 81:00.0 3D controller: NVIDIA Corporation GA100 [A100 PCIe 80GB] (rev a1)

• Once you have installed the Nvidia driver almost all operations over the GPU card are performed using the command nvidia-smi.

• In Linux-kvm distros is necessary to enable virtual functions using the command /usr/lib/nvidia/sriov-manage. In Citrix this file does not exists and the vGPU profiles are magically selectable from the GPU tab in Xen Center.

Test 1. Driver for Citrix Hypervisor “NVIDIA-GRID-XenServer-8.2-450.236.03-450.236.01-454.14” (version 11.2 in the Nvidia licensing portal).

• Install driver “NVIDIA-GRID-XenServer-8.2-450.236.03-450.236.01-454.14”. Is a rpm file you can install with “yum install NVIDIA-….rpm”

• Reboot

• XCP-ng Center only detect the whole GPU, not the vGPU profiles.

• The script sriov-manage is not present, so we can’t enable virtual functions in Ubuntu-like way.

• The command nvidia-smi detects the Nvidia A100, even with its correct name, but if we query GPU info with “nvidia-smi -q” it tells us is in mode “non SR-IOV”:

GPU Virtualization Mode
        Virtualization Mode: Host VGPU
        Host VGPU Mode: Non SR-IOV <-- BAD THING

• If we list kernel modules loaded related to Nvidia we can see only the first, but we should see also the i2c module.

# lsmod | grep nvidia
nvidia 19795968 0
i2c_core 20294 2 nvidia,i2c_  <-- NOT PRESENT

• dmesg| grep -E "NVRM|nvidia"
  No output. We should see some Nvidia related messages. Again a bad thing.

• We can manipulate the GPU, create MIG instances and change between MIG and time-sliced modes, but we can’t virtualize them because we don’t have virtual functions and XCP-ng Center doesn't detect vGPU types.

Result of the test: FAIL.

Test 2. Driver for Citrix Hypervisor “NVIDIA-GRID-XenServer-8.2-450.236.03-450.236.01-454.14” (version 11.2 in the Nvidia Licensing portal) installed as a supplemental pack.

In the driver zip file, Nvidia provides the host driver in two formats: RPM file (test 1) and an ISO file for installing as a supplemental pack. In this test we are using the second one, so we can check if there is any difference.

• Install driver

# xe-install-supplemental-pack NVIDIA-vGPU-xenserver-8.2-450.236.03.x86_64.iso

• No output messages. Reboot.

• dmesg| grep -E "NVRM|nvidia"
  Now we have some output so maybe we are in the right direction.

[    4.210201] nvidia: module license 'NVIDIA' taints kernel.
[    4.234741] nvidia-nvlink: Nvlink Core is being initialized, major device number 239
[    4.235330] NVRM: PAT configuration unsupported.
[    4.235400] nvidia 0000:81:00.0: enabling device (0000 -> 0002)
[    4.281760] NVRM: loading NVIDIA UNIX x86_64 Kernel Module  450.236.03  Wed Feb 15 11:28:29 UTC 2023
[    6.806041] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy NONE.

• At this point we are in the same state as in test 1. nvidia-smi works but we don’t have sriov-manage nor virtual functions. XCP-ng Center still not show vGPU types. Result: We can’t assign vGPUs to virtual machines.

• If we check xensource.log there is some warnings about xenopsd-xc failed to find vgpu binary in the path. OK, let’s copy the binary from citrix iso and reboot.

• Open Citrix 8.2 express iso (free to donwload) and get the vgpu-7.4.8-1.x86_64.rpm from the folder “packages”. Install with yum and reboot.
  Now xen is able to find the vgpu binary at startup but we still have the same problems: No virtual functions, no vGPU types in XCP-ng center…

• Try to reinstall the driver with vgpu binary copied: Same problems.

Result of the test: FAIL.

Test 3. Driver for Citrix Hypervisor “NVIDIA-GRID-CitrixHypervisor-8.2-525.105.14-525.105.17-528.89” (version 15.2 in the Nvidia Licensing portal).

• Install driver and reboot.
• nvida-smi -q now reports SR-IOV virtualization mode. Looks good for now.

GPU Virtualization Mode
        Virtualization Mode: Host VGPU
        Host VGPU Mode: SR-IOV <-- GOOD

• lsmod | grep nvidia is still not reporting the i2c module. Bad thing.

# lsmod | grep nvidia 
nvidia 19795968 0
i2c_core 20294 2 nvidia,i2c_  <-- NOT PRESENT

• The script /usr/lib/nvidia/sriov-manage now is present in the system. Don’t lose the hope.

• XCP-ng Center only detect the whole GPU, not the vGPU profiles.

• If we enable virtual functions with sriov-manage there is no error in the output, but if we check dmesg | grep -E “NVRM|nvidia” there are many errors:

[09:19 gpu01 administracion]# dmesg|grep -E "NVRM|nvidia"
[    4.057501] nvidia: module license 'NVIDIA' taints kernel.
[    4.146715] nvidia-nvlink: Nvlink Core is being initialized, major device number 239
[    4.148611] NVRM: PAT configuration unsupported.
[    4.148740] nvidia 0000:81:00.0: enabling device (0000 -> 0002)
[    4.199270] NVRM: loading NVIDIA UNIX x86_64 Kernel Module  525.105.14  Sat Mar 18 01:14:41 UTC 2023
[    5.106436] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy BEST_EFFORT.
[   89.893828] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy BEST_EFFORT.
[  101.562403] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy BEST_EFFORT.
[  420.977413] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy BEST_EFFORT.
[  426.885197] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy BEST_EFFORT.
[  428.310527] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy BEST_EFFORT.
[  520.759001] NVRM: GPU 0000:81:00.0: UnbindLock acquired
[  521.392111] NVRM: Ignoring probe for VF 0000:81:00.4
[  521.392117] nvidia: probe of 0000:81:00.4 failed with error -1
[  521.392493] NVRM: Ignoring probe for VF 0000:81:00.5
[  521.392496] nvidia: probe of 0000:81:00.5 failed with error -1
[  521.392848] NVRM: Ignoring probe for VF 0000:81:00.6
[  521.392850] nvidia: probe of 0000:81:00.6 failed with error -1
[  521.393207] NVRM: Ignoring probe for VF 0000:81:00.7
[  521.393211] nvidia: probe of 0000:81:00.7 failed with error -1
[  521.393572] NVRM: Ignoring probe for VF 0000:81:01.0
[  521.393575] nvidia: probe of 0000:81:01.0 failed with error -1
[  521.393965] NVRM: Ignoring probe for VF 0000:81:01.1
[  521.393968] nvidia: probe of 0000:81:01.1 failed with error -1
[  521.394318] NVRM: Ignoring probe for VF 0000:81:01.2
[  521.394321] nvidia: probe of 0000:81:01.2 failed with error -1
[  521.394697] NVRM: Ignoring probe for VF 0000:81:01.3
[  521.394700] nvidia: probe of 0000:81:01.3 failed with error -1
[  521.395032] NVRM: Ignoring probe for VF 0000:81:01.4
[  521.395035] nvidia: probe of 0000:81:01.4 failed with error -1
[  521.395489] NVRM: Ignoring probe for VF 0000:81:01.5
[  521.395494] nvidia: probe of 0000:81:01.5 failed with error -1
[  521.395860] NVRM: Ignoring probe for VF 0000:81:01.6
[  521.395863] nvidia: probe of 0000:81:01.6 failed with error -1
[  521.396234] NVRM: Ignoring probe for VF 0000:81:01.7
[  521.396237] nvidia: probe of 0000:81:01.7 failed with error -1
[  521.396587] NVRM: Ignoring probe for VF 0000:81:02.0
[  521.396589] nvidia: probe of 0000:81:02.0 failed with error -1
[  521.396951] NVRM: Ignoring probe for VF 0000:81:02.1
[  521.396954] nvidia: probe of 0000:81:02.1 failed with error -1
[  521.397337] NVRM: Ignoring probe for VF 0000:81:02.2
[  521.397339] nvidia: probe of 0000:81:02.2 failed with error -1
[  521.397690] NVRM: Ignoring probe for VF 0000:81:02.3
[  521.397693] nvidia: probe of 0000:81:02.3 failed with error -1
[  521.398085] NVRM: Ignoring probe for VF 0000:81:02.4
[  521.398088] nvidia: probe of 0000:81:02.4 failed with error -1
[  521.398432] NVRM: Ignoring probe for VF 0000:81:02.5
[  521.398439] nvidia: probe of 0000:81:02.5 failed with error -1
[  521.398809] NVRM: Ignoring probe for VF 0000:81:02.6
[  521.398812] nvidia: probe of 0000:81:02.6 failed with error -1
[  521.399151] NVRM: Ignoring probe for VF 0000:81:02.7
[  521.399154] nvidia: probe of 0000:81:02.7 failed with error -1
[  521.483491] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy BEST_EFFORT.

• We can manipulate the GPU, create MIG instances and change between MIG and time-sliced modes, but we can’t virtualize them because we don’t have virtual functions.
  The directory /sys/class/mdevbus doesn’t exists so there is no mediated devices.
  Looks like virtio module is not loaded in the kernel. In fact I think it’s not installed at all but I don’t know how to install it nor even if it is possible.

Result of the test: FAIL.

Test 4. Driver for RHEL 7.9

XCP-ng is based on CentOS 7.5: https://xcp-ng.org/docs/release-8-2.html
Looking in the Nvidia licensing portal there is a driver for RHEL 7.9. This is the closest driver to XCP-ng version so let’s try it.

• Install driver

# yum install NVIDIA-vGPU-rhel-7.9-525.105.14.x86_64.rpm

• Reboot

• lsmod |grep nvidia
  No output.

• lsmod |grep vfio
  No output.

• dmesg |grep nvidia
  No output.

• nvidia-smi

Error: NVIDIA-SMI has failed because it couldn't communicate with the NVIDIA driver. Make sure that the latest NVIDIA driver is installed and running

• Looks very bad for now. Let’s check XCP-ng Center:
  Surprise! In the GPU tab we can see the vGPU types, named by its subsystem id (“Device <hex_number>”). All this vGPU types correspond to the MIG types and time-sliced types supported by the A100.
  If we navigate the file system to /usr/share/nvidia/vgpu/ there is a xml file called vgpuConfig.xml in which we can found the mappings between the hex subsystem ids and the names of the profiles. For example, the id 1591 corresponds to the profile GRID A100D-1-10C.
  

• If we list supported vGPU types with the xen command we can see all of them and its uuids:
  xe pgpu-param-list uuid=<uuid-of-your-pgpu>

• Ok. Let’s try to create a virtual machine and assign one of this vGPU to it:

Internal error: Can’t rebind PCI 0000:81:00.0 driver

• I think XCP-ng is trying to assign the vGPU using the PCI ID of the whole card, not the PCI ID of the vGPU, wich makes sense because we still don’t have virtual functions nor mdev devices.

• At this time the vGPUs detected by XCP-ng Center don’t work and the Nvidia driver is not loaded so we are stuck.

Result of the test: FAIL.

Test 5. From the end of test 4, go back to test 3 (Citrix driver) and try to get a hybrid.

We are at the end of test 4, vGPU types are in XCP-ng Center and the driver can’t load. Well, lets install the Citrix driver over the RHEL driver and see what happens.

• Install driver
  yum install NVIDIA-vGPU-CitrixHypervisor-8.2-525.105.14.x86_64.rpm

• Error. Yum complains about transaction check errors with some packet conflicts.
  We have to uninstall first the RHEL driver. Ok, nothing to lose right now, so here we go.

# yum remove NVIDIA-vGPU-rhel.x86_64
# yum install NVIDIA-vGPU-CitrixHypervisor-8.2-525.105.14.x86_64.rpm

• Reboot

• The vGPU profiles have gone from XCP-ng Center. We are at the same point as in the test 3.

Result of the test: FAIL.

[olivierlambert]

Adding @andSmv in the loop, some of this is somehow familiar

@Dani could you experiment with Citrix Hypervisor and see if it works as it should?

[Dani]

@splastunov
The license server is needed for the virtual machines to work, but the host driver has to work first. Once you have setup the hypervisor with the driver then you have to deploy the license server, wich can run in a virtual machine in the same hypervisor, and then bind the virtual machines with it using some tokens (is a complicated process, by the way. I think Nvidia made it too difficult).

I've spent almost two days with this, so maybe trees don't let me see the forest

[splastunov]

Do you have vgpu binary file at /usr/lib64/xen/bin/vgpu?

[Dani]

@olivierlambert I don't have a commercial license of Citrix and I don't know if exists an evaluation one.
Tomorrow I'll try to get some time and install Citrix 8.2 Express, wich is free, but they say vGPU are only available in Premium edition. We'll see.

[olivierlambert]

@Dani when you have the express version installed, please contact me in the chat, I might be able to help you on that

[Dani]

@splastunov Yes I do, but it doesn't work

[splastunov]

@Dani Strange. Is it executable? Did you tried to follow step by step my instruction to make vGPU work?

[Dani]

@splastunov Yes, your steps are the same as I did but I can see some differences.
The big thing is you can see Nvidia GRID vGPU types in XCP-ng center but I can't.
I have two scenarios:

• With Citrix drivers I don't have vGPU types in XCP-ng center, so I can't assign them to virtual machines.
• With RHEL drivers XCP-ng center shows vGPU types (with hex names, no commercial names) but the Nvidia driver doesn't load (no nvidia-smi). If I try to assign one of the vGPUs to a virtual machine it won't start throwing the error "can't rebind 0000:81:00.0 driver", wich is the PCI id of the whole card, not the virtual GPU.

Maybe it's beacause the type of GPU? With the A100 doesn't work but with yours does? I don't know
Looks like a dead end street.

[Dani]

Now I've made another test using Citrix Hypervisor 8.2 Express edition.
Despite Citrix says only Premium edition has support for Nvidia vGPU let’s try it and see what happens.
IMPORTANT: This is only for testing purposes because of this message in Xen Center:
"Citrix Hypervisor 8.2 has reached End of Life for express customers","Citrix Hypervisor 8.2 reached End of Life for express customers on Dec 13, 2021. You are no longer eligible for hotfixes released after this date. Please upgrade to the latest CR."
In fact, Xen Center doesn’t allow you to install updates and throws an error with the license.

Test 6. Install Citrix Hypervisor 8.2 Express and Driver for Citrix Hypervisor “NVIDIA-GRID-CitrixHypervisor-8.2-525.105.14-525.105.17-528.89” (version 15.2 in the Nvidia Licensing portal).

• Install Citrix Hypervisor 8.2 Express

• PCI device detected:

# lspci | grep -i nvidia
81:00.0 3D controller: NVIDIA Corporation Device 20b5 (rev a1)

• xe host-param-get uuid=<uuid-of-your-server> param-name=chipset-info param-key=iommu
  Returns true. Ok.

• Xen Center doens't show Nvidia GPU because there is no “GPU” tab!
  I think that's because this is the express version and it's only available in Premium edition.

• Install Citrix driver and reboot:

rpm -iv NVIDIA-vGPU-CitrixHypervisor-8.2-525.105.14.x86_64.rpm

• List nvidia loaded modules. Missing i2c. Bad thing.

# lsmod |grep nvidia
nvidia              56455168  19

• List vfio loaded modules. Nothing. Bad thing.

# lsmod |grep vfio

• Check dmesg. This looks normal.

# dmesg | grep -E “NVRM|nvidia”
[    4.490920] nvidia: module license 'NVIDIA' taints kernel.
[    4.568618] nvidia-nvlink: Nvlink Core is being initialized, major device number 239
[    4.570625] NVRM: PAT configuration unsupported.
[    4.570702] nvidia 0000:81:00.0: enabling device (0000 -> 0002)
[    4.619948] NVRM: loading NVIDIA UNIX x86_64 Kernel Module  525.105.14  Sat Mar 18 01:14:41 UTC 2023
[    5.511797] NVRM: GPU at 0000:81:00.0 has software scheduler DISABLED with policy BEST_EFFORT.

• nvidia-smi
  Normal output. Correct

• nvidia-smi -q

GPU Virtualization Mode
        Virtualization Mode: Host VGPU
        Host VGPU Mode: SR-IOV <-- GOOD

• The script /usr/lib/nvidia/sriov-manage is present.

• Enable virtual functions with /usr/lib/nvidia/sriov-manage -e ALL
  If we now check dmesg | grep -E “NVRM|nvidia” we have same errors as in test 3. Errors probing the PCI ID of the virtual functions failing with error -1.
  Again I think this is because /sys/class/mdevbus doesn’t exist.

Quick recap: Same problems as with XCP-ng. There is no vfio mdev devices and there is no vGPU types in Xen Center so we can't launch virtual machines with vGPUS.

Result of the test: FAIL.

[Dani]

Looks like we have to use Linux KVM with this server for now, which is not too good for us (and for me as the BOFH ) because we have another cluster with XCP-ng.

The thing is f**king my mind is that in other linux distros, like ubuntu for example, everything is detected ok and working properly but in XCP-ng, which is another linux (with modifications, I know), not. I think it's because the lack of vfio but I don't really know.

[olivierlambert]

It seems that A100 vGPU isn't supported yet: https://hcl.xenserver.com/gpus/?gpusupport__version=20&vendor=50