[vfio-users] Setting up VFIO Passthrough for LINUX Guests (class room setup)

[Julian Rendell]

Hi-

I’ve been trying to set up a KVM system (ubuntu 15.10 host + guests) for use in a classroom. I’m using Jacob Zimmerman’s PPA for more up-to-date versions of QEMU, libvirt, etc (https://launchpad.net/~jacob/+archive/ubuntu/virtualisation <https://launchpad.net/~jacob/+archive/ubuntu/virtualisation>.)

The test machine is an older AMD based machine with 16Gb of RAM, and I’ve added a couple of G-Force GT-720 GPU cards.

I’ve proved the machine is working, sort of. One instance of windows and things were fine, but I’m trying two instances right now and it’s extremely slow. I’m hoping it’s because one of the instances is still in the process of setting itself up; it’s a clone, but I want to prove it out before buying more windows licenses.

They’re installed using EFI (OVMF) with i440FX chipset.

First problem & question: Is the latest OVMF broken?

I built OVMF from source. No matter what I do (use i440FX & IDE or Q35 & SATA) the ‘fs0’ drive when I boot with any ISO selected is garbled. I can CD to the expected directory but the contents is just ‘$.’ and a few random characters for file names.  Also many more entries than the couple (e.g. grubx64.efi) that I’m expecting.

If I roll back to mid September it works… but only with i440FX & IDE.  No drives are mapped if I use Q35.

Question: anyone else seeing this? Do I need a newer quemu or lbvirt than what’s in the PPA?
Does anyone have a working-for-them git SHA I can try?
What else can I do to get OVMF + Q35 working?

Question 2: Is it possible to have Linux as a guest with GPU passthrough?

This is my preferred solution - much cheaper to setup than a windows license per seat.

I’ve tried legacy bios + VGA passthrough & I think both chipsets. Instantly destroyed; I suspect by VGA arbitration issues: host screen gets some weird updates, and then the screen freezes.  Guest GPU never gets far. I followed http://vfio.blogspot.ca/2015/05/vfio-gpu-how-to-series-part-5-vga-mode.html <http://vfio.blogspot.ca/2015/05/vfio-gpu-how-to-series-part-5-vga-mode.html> 

I’ve tried (older) OVMF + i440: linux guest starts, Tiano/OVMF appears on the external monitor, then garbage, then guest silently shuts down. I read on the KVM website (?) that the linux GPU drivers don’t understand the PCI topology this setup has.

I think I read that this *should* work with the Q35 chipset emulation.

Is this true?
Has anyone got this working?

Some background for the curious-

I’d really like each students ‘workstation’ to be a VM that I can snapshot and easily manage.  The machine is being set up to run some basic 3D applications for beginners, minecraft, and learning to program. The alternative is to buy cheap laptops… but I think sharing an i7 + dedicated GPU should work out better than a bay trail + IGD, not to mention replacing a keyboard and mouse is a lot cheaper! And I’d appreciate the advantages of centralized management.

If I can’t get KVM + vfio to work my next steps are to try LXC + device passthrough, and then a multi-seat setup.

Are there other means of setting up a well isolated multi-seat machine that I’ve missed?

Thanks in advance for any suggestions!

Julian
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