IOMMU group isolation check for 1851 motherboards (recommendation needed)

Hi there,

I’m looking for a 1851 socket motherboard that will have a good IOMMU group isolation / ACS.

My primary goal is to have adequate isolation for main things, e.g. USBs, GPU(pcie 5.0, and possibly 4.0), m.2, thunderbolt, display port, hdmi, audio, networking etc.

I thought of the MSI PRO Z890-P WIFI(msi com/Motherboard/PRO-Z890-P-WIFI/Specification), but there’s no info regarding this motherboard’s IOMMU groups anywhere.
In case you have this board or have an access to it, I would really appreciate if you could check the IOMMU groups of it. It’s fairly easy to do, all you need is to boot the system with a live linux distribution with iommu=on intel_iommu=on in the kernel command line. and then run this script to see the full group layout:

#!/bin/bash shopt -s nullglob for g in /sys/kernel/iommu_groups/*; do echo "IOMMU Group ${g##*/}:" for d in "$g"/devices/*; do # added quotes for safety lspci -nns "${d##*/}" | sed 's/^/ /' done done

Would appreciate any relevant suggestions or recommendations or whatever you think may help me out.

Can’t edit the post. here’s the properly formated script:
#!/bin/bash
shopt -s nullglob
for g in /sys/kernel/iommu_groups/*; do
echo “IOMMU Group ${g##*/}:”
for d in “$g”/devices/*; do # added quotes for safety
lspci -nns “${d##*/}” | sed ‘s/^/ /’
done
done

You might wanna check with MSI. They recently changed IOMMU groups on my MSI Z890 tomahawk motherboard (original not the new downgrade) and it broke my proxmox when I updated the bios. Not sure if they actually changed the number of groups/how they are separated.

Once I get the system running again I can check this weekend, but I recall all the pcie slots are seperate, I believe thunderbolt could be split as well. Some USB were together, and HDMI and DP were seperate. I think 30 something groups in total so pretty good

But that also is the original and I saw a new version of this board in stores missing a ton of stuff so i think that might be entirely different model so be careful if you go that way

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Yes, I was actually almost selected the tomahawk motherboard myself and just couple of days ago I found it has(had?) issues with USB/thunderbolt/display port grouping.

And this is despite the board is not that cheap.

I was vey much optimistic regarding MSI in general, especially about MSI PRO Z890-P WIFI, as they offer a budget yet highly featured board, but since my journey to find out the IOMMU group isolation of this board, I probably will never buy MSI again.

They have one of the worst costumer experiences I ever encountered in computer world: they have one of the most idiotic anti-bot detection systems ever. And there’s no way around it. I first tried to use to register with them through tor and failed. Then with clearnet. I registered and now each time I try to submit the contact form web ticket, the system blocks me with an “Access Denied” server message.
So stupid.

I did messaged Asus with no issue, but Asus for whatever reason, use limited real features for the sake of some funky gaming things. Like instead of giving the good LAN (intel’s killer 5Gb), they provide some 2.5Gb ethernet with a bit unknown to me “ASUS LANGuard”. And this is for not budget boards.

I can only imagine the pain.
Why don’t you want to downgrade though?

That’s the plan. I meant there is a Z890 Tomahawk 2 which is a downgrade. Missing thunderbolt and I think the lan is only 2.5g, and I think more downgrades. Like its a significantly different board

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No, I meant why won’t you downgrade BIOS, so the IOMMU grouping will work again for your current tomahawk board.

I have an ASUS ROG Strix Z890-A and it has good IOMMU Groups.

Overall a very solid Board I’d recommend, it’s a lot cheaper now than when it went into the market so you get a very high-end board for your money.

1 Like

What do you mean by good IOMMU groups exactly please? Did you check the groups or just maybe tried it on some type 1 hypervisor like Xen?

I’m a bit skeptical regarding the HDMI

I’m not sure what the price was for it(it also depends on location etc), but it costs around 550 USD in my area.
The Asus ROG STRIX Z890-H GAMING WiFi for example costs like 35 bucks less.
I wouldn’t even mention the Asus ROG STRIX Z890-H GAMING WiFi if the ASUS ROG Strix Z890-A would have 5GB ethernet, but it has 2.5…
Why would they cut 5gb ethernet for such board is a mystery to me.

It cost me around 250 EUR. So for 550 I wouldn’t consider it a good deal.

I’m using QEMU/KVM on Fedora on my Desktop.

Did you have to use the pcie_acs_override kernel parameter to get your passthrough working? Or maybe some other workaround etc?

I never used KVM, but afaik KVM uses the standard kernel to talk to the motherboard firmware(UEFI/ACPI) and Xen for example sits under linux.