IOMMU groups - ACS patch

[kliment.toshkov]

Hi,

I have enabled IOMMU:

intel_iommu=on iommu=pt pcie_acs_override=downstream,multifunction

Tried with "downstream","multifunction" and "downstream,multifunction"

Added necessary module options

echo "options vfio_iommu_type1 allow_unsafe_interrupts=1" > /etc/modprobe.d/iommu_unsafe_interrupts.conf
echo "options kvm ignore_msrs=1" > /etc/modprobe.d/kvm.conf

Kernel:

Linux ic1 5.4.106-1-pve #1 SMP PVE 5.4.106-1 (Fri, 19 Mar 2021 11:08:47 +0100) x86_64 GNU/Linux

Trying to break those groups in order to use them in separate VMs, but they stay in the same group.

IOMMU Group 70:
    81:00.0 PCI bridge [0604]: ASMedia Technology Inc. ASM1083/1085 PCIe to PCI Bridge [1b21:1080] (rev 04)
    82:01.0 Network controller [0280]: Digium, Inc. Wildcard TE820 octal-span T1/E1/J1 card 3.3V (PCI-Express) [d161:1820] (rev 15)
    82:02.0 Network controller [0280]: Digium, Inc. Wildcard TE820 octal-span T1/E1/J1 card 3.3V (PCI-Express) [d161:1820] (rev 15)
IOMMU Group 71:
    84:00.0 PCI bridge [0604]: ASMedia Technology Inc. ASM1083/1085 PCIe to PCI Bridge [1b21:1080] (rev 04)
    85:01.0 Network controller [0280]: Digium, Inc. Wildcard TE820 octal-span T1/E1/J1 card 3.3V (PCI-Express) [d161:1820] (rev 15)
    85:02.0 Network controller [0280]: Digium, Inc. Wildcard TE820 octal-span T1/E1/J1 card 3.3V (PCI-Express) [d161:1820] (rev 15)

Please advise.

 

[leesteken]

Trying to break those groups in order to use them in separate VMs, but they stay in the same group.

Try putting one of them in another PCI(e) slot, until you find one that has a different IOMMU group. Maybe try a M.2 slot riser or OCulink or similar to x4 PCIe slot, if there are no other PCIe slots available. The PCIe lanes connected to the CPU are always the best bet for separate IOMMU groups.
The IOMMU groups are determined by the motherboard (and CPU) PCIe layout/chips and the motherboard BIOS/UEFI. Try a different BIOS/UEFI version or use a different motherboard.