Problems with IOMMU pass-throughs

[keige369]

Hi, I am a user with Proxmox 8.1.3 installed on an HP Microserver N40L (Turion II Neo). When I create a VM and try to pass through the SAS Controller, I get No IOMMU detected, please activate it.See Documentation for further information. I followed the instructions on the internet and configured it as written below.

# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
#   info -f grub -n 'Simple configuration'

GRUB_DEFAULT=0
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet amd_iommu=on iommu=pt pcie_acs_override=downstream,multifunction nofb nomodeset video=vesafb:off,efifb:off"
GRUB_CMDLINE_LINUX=""

With the above setup, I ran update-grub as a matter of course, and also ran proxmox-boot-tool refresh, which I found somewhere on the internet.

# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.
# Parameters can be specified after the module name.

vfio
vfio_iommu_type1
vfio_pci
vfio_virqfd

I also modified the /etc/modules file, but that didn't work.

[    0.000000] Warning: PCIe ACS overrides enabled; This may allow non-IOMMU protected peer-to-peer DMA
[    0.094986] AGP: Please enable the IOMMU option in the BIOS setup
[    1.424958] PCI-DMA: using GART IOMMU.
[    1.424961] PCI-DMA: Reserving 64MB of IOMMU area in the AGP aperture
[   23.582908] AMD-Vi: AMD IOMMUv2 functionality not available on this system - This is not a bug.

How can I resolve this error? I apologize for the lack of context in the translator.

Additionally, no /etc/kernel/cmdline files not found.

 

[leesteken]

GRUB_CMDLINE_LINUX_DEFAULT="quiet amd_iommu=on iommu=pt pcie_acs_override=downstream,multifunction nofb nomodeset video=vesafb:off,efifb:off"

amd_iommu=on does nothing because it is enabled by default. video=vesafb:off,efifb:off" is wrong and even when you write it correctly, it does nothing on modern Proxmox. Please don't use pcie_acs_override unless you really need it and know the security risks. iommu=pt does mostly nothing and what do you expect nofb nomodeset to do for your system?

When I create a VM and try to pass through the SAS Controller, I get No IOMMU detected, please activate it

You only need to enabled IOMMU in the motherboard BiOS settings (Auto is not enough, it needs to be Enabled). This is the only reason that would explain the message on AMD; it's not enabled by the motherboard BIOS. Even though it's 12 years old, It looks like AMD Turion II Neo CPUs support IOMMU (AMD-Vi). Maybe this is a HP limitation and their support can help you?

 

[keige369]

amd_iommu=on does nothing because it is enabled by default. video=vesafb:off,efifb:off" is wrong and even when you write it correctly, it does nothing on modern Proxmox. Please don't use pcie_acs_override unless you really need it and know the security risks. iommu=pt does mostly nothing and what do you expect nofb nomodeset to do for your system?

You only need to enabled IOMMU in the motherboard BiOS settings (Auto is not enough, it needs to be Enabled). This is the only reason that would explain the message on AMD; it's not enabled by the motherboard BIOS. Even though it's 12 years old, It looks like AMD Turion II Neo CPUs support IOMMU (AMD-Vi). Maybe this is a HP limitation and their support can help you?

After a little more research, I found that the N40L does not support IOMMU... The CPU says that IOMMU is supported, so I think I was wrong to think that it would be supported of course. Thank you for your answer.

 

[leesteken]

After a little more research, I found that the N40L does not support IOMMU... The CPU says that IOMMU is supported, so I think I was wrong to think that it would be supported of course. Thank you for your answer.

Ah right, those motherboards still had a "north bridge chip" for connecting to memory and the RS785E probably does not support IOMMU/AMD-Vi.