GRUB_CMDLINE_LINUX_DEFAULT="quiet splash kvm.ignore_msrs=1 amd_iommu=on vfio-pci.ids=1002:67df:1682:9587,1002:aaf0:1682:aaf0,10ec:8168:1462:7b79 pcie_acs_override=downstream,multifunction"

Under 5.4.0-107-generic, the line above functions to isolate the devices desired in grub. However when I switch over to the Liqorix Kernel the isolation breaks down. Hence I am left with the question how does one fix this problem and allow isolation of these pci-e devices.
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ACS override support is included with Liquorix and Zen Kernel. It appears that the patch we apply no longer works and needs changes:

github.com/zen-kernel/zen-kernel/commit/733b70b1a0747215a152e88073b7f49330d09296

Unfortunately, the original developer of the patch hasn't rebased the patch since 5.10.4: gitlab.com/Queuecumber/linux-acs-override/-/blob/master/workspaces/5.10.4/acso.patch
gitlab.com/Queuecumber/linux-acs-override/-/commit/142cdc461be35ed351fa00faa11492abc918347f

If you have a newer source for this patch, maybe a modified version by Ubuntu or Fedora, we can update our patch to a working version.

EDIT: It appears that this patch is only needed on hardware that doesn't support ACS properly: www.reddit.com/r/VFIO/comments/bvif8d/official_reason_why_acs_override_patch_is_not_in/

Maybe a new motherboard, bios update, or configuration can allow what you're trying to do without this patch?
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And finally, it looks like I might be right. A good motherboard doesn't require the ACS override patch: www.reddit.com/r/VFIO/comments/ios4dx/can_i_use_amd_without_acs_override_patch/
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"IMPORTANT NOTICE It has come to my attention that the patches maintained here have been included in the Zen/Liquorix kernel. This project has more resources than myself and the kernel itself has more features which would be of interest to ACSO users. In light of this I am retiring this project. If something should change with the status of the ACSO patch in that kernel, please use #12 to let me know and I will consider reviving the project."
https://queuecumber.gitlab.io/linux-acs-override/
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Yes, I'm not sure why he retired the project. He's the author of the patch, we just included it. Without a patch maintainer, the patch will probably stop working due to changes in newer kernels, so we'll probably need to pull it out.

EDIT: He's not the author but was forward porting the patches, probably testing. This looks like the best source for the latest version of the patch: aur.archlinux.org/cgit/aur.git/tree/add-acs-overrides.patch?h=linux-vfio. It is identical to what's already in Zen Kernel, but with a good commit message.

< Edited by damentz :: May 1, 22, 8:42 >
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atton, can you confirm if any other kernel with the ACS override patch works? In the AUR, there's the linux-vfio package with the identical patch we're using in Zen Kernel.

I see that you're using Ubuntu though so you'd need to reinstall in order to test. I'm not aware of any other kernels for Ubuntu with this patch added.
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https://queuecumber.gitlab.io/linux-acs-override/
It would appear they still release kernels
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The last kernel released is for 5.12.2, about a year ago.
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