Hello,
I have the High Point RocketU 1144C 4-port USB3 PCIe card and I am trying to do exactly the same as you.
I have in the Syslinux configuration this: "append pcie_acs_override=downstream,id:10b5:8609 initrd=/bzroot"
Now it seems that each port belongs to it's own IOMMU group like:
IOMMU group 23
[1b21:1142] 05:00.0 USB controller: ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller
IOMMU group 24
[1b21:1142] 06:00.0 USB controller: ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller
IOMMU group 25
[1b21:1142] 07:00.0 USB controller: ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller
IOMMU group 26
[1b21:1142] 08:00.0 USB controller: ASMedia Technology Inc. ASM1042A USB 3.0 Host Controller
What is the next step to pass through each one of them into a VM ?
Thanks,
Alex