[SOLVED] Proxmox 8.0.3 & 7.4.3: Host Network Issues with PCI Passthrough Setup


New Member
Aug 6, 2023
Hello, I'm using Proxmox and trying to pass through a specific PCI device (Multimedia controller: Altera Corporation Device 4c15) to a VM. I've encountered a phenomenon where after attempting this setup, the host's other PCI devices start having issues, and the VM itself also appears to fail to boot.

Situation and Issues:

  • After setting up the PCI device passthrough, the entire host is affected when starting the VM.
  • The host's onboard NIC and additional HDDs behave as if they have been disconnected.
  • Other issues, such as the host's network card ceasing to function, also occur.
  • The VM itself also appears to fail to boot.
  • This problem has been reproduced in both Proxmox version 8.0.3 and 7.4.3.

  • I've added the target driver to the blacklist and bound it to vfio-pci with the following steps:
    lspci -k -s 06:00.0
    Kernel driver in use: vfio-pci
    Kernel modules: earth_pt3, altera_cvp

  • The following are added to /etc/modules:

I've been following the Proxmox official PCI(e) Passthrough guide (https://pve.proxmox.com/wiki/PCI(e)_Passthrough) for these configurations.

If anyone knows a solution to this problem, or has any clue to identify what might be causing it, I would really appreciate your help. Thank you in advance.

Postscript. Apparently, devices in the same IOMMU group as the PCI device I tried to pass through are disabled.
Last edited:
Self resolved. I don't know if this was the essential problem, but what I am sure of is that the IOMMU group of the device I wanted to pass through included NICs and other devices.
I had added the option to split it as documented, but that was not enough. I don't know which ones were valid, but in my environment, I changed the grub settings to the following, and it split the devices successfully.
GRUB_CMDLINE_LINUX_DEFAULT="quiet amd_iommu=on iommu=pt pcie_acs_override=downstream,multifunction video=efifb:off video=vesa:off vfio_ iommu_type1.allow_unsafe_interrupts=1 kvm.ignore_msrs=1"


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