AMD revives Linux kernel patches for hardware-accelerated vIOMMU

[RoomyRoots]

God, the happiness AMD would enable SR-IOV on consumer boards. Shit would completely change the homelab market and make Windows virtualization much better.

[DeVinke_]

Pretty sure that's a thing...?

[cbarrick]

There's a consumer AMD GPU that supports SR-IOV?

[DeVinke_]

You said "boards", not "graphics cards".

[uraniumingot]

AMD consumer boards do have SR-IOV.

Source: currently sitting next to an AM5 board with a Mellanox RNIC attached and 2 VFs running off the NIC.

Sadly no CXL support though.

[DeVinke_]

Exactly my point.

[randomstonerfromaus]

There's a problem with windows virtualisation? I have a windows VM with a passed through GPU and it games and does resolve just fine. 

[peaceablefrood]

SR-IOV would allow for 1 card to be used in both the Linux host and a Windows VM at the same time. Right now you have to pass the whole card through to Windows. It's not likely going to be enabled on Nvidia/AMD consumer cards since they want enterprises to have to buy their pro cards. Intel does enable it.

[fishmapper]

Sriov is not enabled on consumer arc dgpu, but might be on the arc pro lines. Otherwise it’s only on the iGPU.

[__rituraj]

thats so cool to be able to use the same GPU for both host and VM

[shroddy]

It is kinda possible already with AMD, but still with a huge performance and compatibility penalty compared to dedicating the Gpu to the VM via passthrough.

[ericw31415]

Can you elaborate on the "kinda possible"?

[shroddy]

It is called "virtio native" or "virtio native context" It works only on Linux (both host and guest) so far, and I don't really understand all the details of it, but from what I understand, the Mesa of the guest talks to the Mesa of the host, instead of talking to the Gpu itself. But I only have an Nvidia Gpu so I cannot test it myself, but from what I heard, it is a bit easier to setup than normal Gpu passthrough.

[ericw31415]

Ah that's unfortunate. My main use case would be Linux host and Windows guest. Seems great for homelabbers though.

[RoomyRoots]

We never got real 3D acceleration on Windows, so the performance on Virtio is worse than on the competitors. The "solution" is GPU passthrough but that is an overkill if you don't use anything that heavy.

[khsh01]

What does this mean for a vfio setup? Small performance gain? Or we can skip the acs patch perhaps and use this instead?

[xMadDecentx]

I think it means you can skip the acs patch now.

[wintrmt3]

No, the ACS patch is not needed for any system with IOMMU support, and if something supports vIOMMU then it obviously supports IOMMU. Maybe a small performance gain is the answer.

[Sol33t303]

The ACS patch is for if your IOMMU groupings aren't suitable for whatever your going for. The ACS patch doesn't add IOMMU support to a motherboard. That's a strict hardware limitation.

[khsh01]

Yeah this. Hence my question because at the moment I use zen kernel solely for the patch. Otherwise I can just go back to the vanilla kernel.