Fedora 27 Repository for Patched QEMU and Linux 4.15.15

mechanoid · April 1, 2018, 7:15pm

… sorry for too many questions

… I installed kernel-devel-4.15.9-300.acs.fc27.x86_64

akmods wrote me that no akmod packages found

I try Xorg -configure , but - no result
… tried to remove xorg.conf - the same result

“…no screens found…”

MichaelLindman · April 1, 2018, 7:45pm

beause akmods can’t find the packages mustn’t be using the proprietary nvidia drivers, what does /var/log/Xorg.0.log say when you run startx?

SgtAwesomesauce · April 1, 2018, 10:11pm

You should never use pci-stub. that’s been replaced by vfio.

pcie_acs_override is the correct parameter.

Looks like I need to update my package.

mechanoid · April 1, 2018, 10:12pm

Thank you!!!

mechanoid · April 1, 2018, 11:35pm

… there in the log: “failed to initialize the nvidia kernel module”

SgtAwesomesauce · April 2, 2018, 12:18am

How did you install nvidia drivers?

mechanoid · April 2, 2018, 3:03am

… I have nvidia drivers installed during installation virtualization package …

UPD: I uninstalled nvidia driver now and then x-windows starts with nouveau

I am happy now ))
I started win10 with my new usb-hub card - so I don’t need passthrough usb ports any more)

Thank all of you !!!
It’s a big deal for me )

SgtAwesomesauce · April 4, 2018, 6:21pm

Update: I’m currently building the ACS patch into the latest Fedora kernel.

https://copr.fedorainfracloud.org/coprs/kebrx/QEMU-Patched/build/736944/

Update should land this evening.

SgtAwesomesauce · April 5, 2018, 6:01pm

So, 4.15.14 was released. Working on the package now.

SgtAwesomesauce · April 11, 2018, 7:56pm

I’m aware that the packages are out of date. I’ll be updating them in the next 48 hours. I’ve got a lot going on at work right now.

I need to update both QEMU and Linux.

EDIT: the new version of QEMU will will include looking glass ivshmem patches and side-button support for the virtual mouse device.

SgtAwesomesauce · April 12, 2018, 12:15am

Lots of builds in the queue right now, probably not going to be ready until tomorrow. (Too bad I can’t upload my own binaries)

QEMU Build: ~~https://copr.fedorainfracloud.org/coprs/kebrx/QEMU-Patched/build/740070/~~ Failed.

Kernel Build: https://copr.fedorainfracloud.org/coprs/kebrx/QEMU-Patched/build/740071/

EDIT: QEMU build failed. Here’s the new one: https://copr.fedorainfracloud.org/coprs/kebrx/QEMU-Patched/build/740110/

boistordu · July 20, 2018, 2:24pm

@SgtAwesomesauce I guess your repo is the only one that currently exist? it’s for intel under fedora 28 ?

By the way does anyone of you have a wiki page or something that explain what’s an ACS patch and what’s the acronym for and what’s the same thing about npt?

SgtAwesomesauce · July 20, 2018, 4:25pm

I’ve stopped maintaining the repo. I simply don’t have time to maintain a passthrough VM and I sure don’t have time to maintain the kernel patches with proper testing.

That said, this is another repo to sort that out:

https://copr.fedorainfracloud.org/coprs/jlay/kernel-acspatch/

NPT stands for Nested Page Tables. Here’s a whitepaper on it. It’s a bit dry, but you’ll fully understand it after you read through:

ACS stands for Access Control Services. What’s important to you is that ACS is how the kernel builds IOMMU groups. Using the ACS override, you can separate all the PCI devices out into their own IOMMU group, allowing you to pass a single device to a single VM.

I wrote about ACS briefly in this article:

The Pragmatic Neckbeard 3: VFIO, IOMMU and PCIe Linux

Intro In this installation we are going to be discussing the technology behind PCI Passthrough to VMs. The concept of passthrough is relatively simple. You take a physical device and forward it’s memory registers to the VM. A simple idea, however, doesn’t make an implementation simple. There’s a lot that goes into passthrough, and a bunch of extremely talented people have put a lot of time into software to bring passthrough to the point where it’s a lot easier than it was before, but still not quite plug ‘n’ play. Conceptual Discussion Now, what goes into it exactly? To give a brief overview, we’ve got the hardware support for passthrough, the IOMMU or Input-Output Memory Management Unit, supported by both the motherboard and CPU. (more info on that here) The Linux driver, VFIO, is assigned to the device at boot, preventing the device from being initialized. This will help us when it comes to passing our GPU into the vm. If we’ve got the GPU bound to another driver, we won’t achieve successful passthrough, because you won’t be able to exclusively lock the GPU’s resources to the QEMU vm. Now, let’s talk about the PCIe bus. The machine I’m going to be using as a reference has an ASUS Z170-a and a 6700k. This gives me 16 PCIe lanes on the CPU to play with. Most GPU’s will be happy with 8 lanes, so we shouldn’t have bandwith issues here. I am going to be passing two devices to my VM: GPU and USB-3 controller. The passthrough GPU will be using an 8x connection on the PCH and the USB controller will be using a 4x connection on the CPU. This will allow the GPU I’m using for Linux output to be connected by an 8x connection as well. Handling PCIe passthrough isn’t 100% straightforward. There are limitations and rules about how the IOMMU sees a device and its IO Virtual Addresses (IOVA). Some devices will alias to the same IOVA space which makes the IOMMU unable to destinguish between the two devices. This becomes problematic when dealing with transaction…