Question about using downstream and multifunction IOMMU groups


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Hello,

 

I just wanted to use my HD Audio from the mainboard in a Windows VM.

Sadly I got an error everytime because of the IOMMU groups. (Attached my IOMMU groups without override)

I tried both pcie_acs_override and vfio-pci.ids parameter with modprobe.blacklist=i2c_i801,i2c_smbus.

 

So now I have both pcie_acs_override=downstream, multifunction enabled.

Only way I got it to work by now.

 

I heard that it is not recommended using both or and have almost every device in an own IOMMU group.

So what is the worst thing that can happen? Or what else can I try to get the mainboard audio to work?

Also I'm interested if it affects the performance and secruity of the VM or the whole system?

 

Thx for your time

iommu_groups.txt

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