Nvidia Quadro P400 not working on Ubuntu server via GPU/PCIe passthrough

warriorcookie

@olivierlambert said in Nvidia Quadro P400 not working on Ubuntu server via GPU/PCIe passthrough:

It is, but it doesn't answer how much effort is needed to "solve it". ATM, there's no way to change it in Xen. So the great question is the modification scope required

My Pa always said "don't bring me a dead cat without a shovel..."

Sorry, I'm all cats and no shovel today!

olivierlambert

Maybe a better approach would be to modify Nvidia drivers to change or remove the check. After all, it should be only a kind of grep on the word Xen

And obviously, this would be also against the EULA.

TheFrisianClause

Apparently this seem to be an bigger issue than thought or am I wrong thinking that?

warriorcookie

@olivierlambert said in Nvidia Quadro P400 not working on Ubuntu server via GPU/PCIe passthrough:

Maybe a better approach would be to modify Nvidia drivers to change or remove the check. After all, it should be only a kind of grep on the word Xen

And obviously, this would be also against the EULA.

I've found this but have not had time to play: https://github.com/DualCoder/vgpu_unlock

olivierlambert

So the most advanced discussion within Xen about it, is here: https://lists.archive.carbon60.com/xen/devel/439501

Nothing happened since sadly, but it might be a start. Also, hiding Xen will probably have a lot of consequences regarding performances (no PV drivers and so on)

TheFrisianClause

@olivierlambert hmmm seems something, but why can this so easily be accomplished with Proxmox and even ESXi (Which I thought would be a pain considering the age of the P400). So if I for example would buy an nvidia K4000 I would be able to succesfully passthrough the GPU to Plex? (I don't know if you have done that)

olivierlambert

Because… they are totally different projects? ESXi got thousand engineers working on it. KVM model is different and less isolated than Xen and ESXi, so you can make important modifications in it more easily.

TheFrisianClause

@olivierlambert Yeah that they are different projects is obvious, but my question was more like 'what makes it so hard to do this in Xen?'

olivierlambert

True Type-1 hypervisor (like ESXi, unlike KVM) makes it more isolated but harder to do things in general
It's as hard in ESXi, but resources on the hypervisor are 2 or 3 order of magnitude higher than for the Xen project.

Obviously, we are working hard here at Vates to get more people directly involved in the Xen project. But it takes time and a vast amount of money to reach our target Anyway, I'll try to see what I can do with our resources. The main issue for me now on this feature: it's mainly for non-pro usage, so no company will finance that.

warriorcookie

@olivierlambert said in Nvidia Quadro P400 not working on Ubuntu server via GPU/PCIe passthrough:

True Type-1 hypervisor (like ESXi, unlike KVM) makes it more isolated but harder to do things in general

It's as hard in ESXi, but resources on the hypervisor are 2 or 3 order of magnitude higher than for the Xen project.

Obviously, we are working hard here at Vates to get more people directly involved in the Xen project. But it takes time and a vast amount of money to reach our target Anyway, I'll try to see what I can do with our resources. The main issue for me now on this feature: it's mainly for non-pro usage, so no company will finance that.

I certainly appreciate the challange, and I wish I had something to offer to help development wise.
Perhaps a more "pro" use case could be from the standpoint of nested VM with the likes of HyperV?

olivierlambert

I think I never heard of any company/industry requiring the possibility to hide the hypervisor for now (doesn't mean it doesn't exists, though).

It's all a matter of priorities and limited resources sadly… That's why taking the problem from the other angle (ie drivers that doesn't check it) might be a correct solution.

TheFrisianClause

@olivierlambert
Well I am also looking into a Quadro K2000/M2000 or something similar, I believe those would passthrough without any issues?

olivierlambert

I think we should go back to the main accountable company about all of this: it's Nvidia They probably have the answer on how they decided to artificially segment their product line via their drivers

warriorcookie

@olivierlambert that is a certainty. But no amount of bribery or blackmail seems to make them want to let us in on the secret...

TheFrisianClause

@warriorcookie Well I am at the point on almost giving up on the P400 and just go with an M2000. I currently have an AMD Radeon Pro WX2100 laying around but no luck with this one Plex...

TheFrisianClause

Currently I can get a M4000 for a decent price, I think this one should be able to passthrough in XCP-NG? But I have no idea if this will actually passthrough, has anyone reading this experience with passing through an Quadro M2xxx or M4xxx card to XCP-NG?

olivierlambert

You should ask on Nvidia forum, I assume it will be a safe bet

TheFrisianClause

I will take the bet, an M4000 for 200 euro's is pretty cheap as I have seen M2000 for higher prices.

TheFrisianClause

Well just tested the Quadro M4000 also no luck on this one... Although this GPU is alot more powerfull than the P400 so I will keep in anyway....

EDIT: Well complained to quickly, apparently a host reboot resolved it and I see the GPU now in the Plex VM

XCP-ng-JustGreat

@thefrisianclause Hello, not sure if I missed something from the above thread, but did any of you try to turn off the CPUID "hypervisor present" bit on an Intel-based XCP-ng host VM using this technique from the thread referenced by @warriorcookie above? https://xcp-ng.org/forum/topic/4643/nested-virtualization-of-windows-hyper-v-on-xcp-ng/26

It is the equivalent of the ESXi Hypervisor.CPUID.v0="FALSE" vmx file configuration tweak. It configures the XCP-ng VM to, in effect, lie to the guest OS by saying, "you are not running on a hypervisor."