Issue Description

When adding PCI devices to OpenWrt or Ikuai virtual machines, you may experience a hang. If you are facing this problem and have already grouped the IOMMU network card devices, you might want to try this solution.

Solution

Edit the file by running:

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nano /etc/default/grub

Modify the line to change:

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GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt"

to:

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GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on pcie_port_pm=off iommu=pt"

After making this change, run:

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update-grub

Explanation of the Content

Adding the pcie_port_pm=off command when passing through network cards in PVE virtual machines can disable PCIe port power management.

Specifically, this command can:

• Prevent PCIe ports from entering low power states, thereby enhancing the performance of the virtual machine’s network card.
• Avoid instability in PCIe ports when in low power states.

Scenarios for Adding This Command:

• Virtual machines using NVIDIA graphics cards might encounter issues with GPU drivers due to PCIe port power management.
• Situations where maximum virtual machine network performance is required, such as network servers or virtualization firewalls.

How to Add This Command:

• Add pcie_port_pm=off to the boot parameters of the PVE host.
• Add pcie_port_pm=off to the configuration file of the virtual machine.

Cautions:

• Adding this command may slightly increase the power consumption of the virtual machine.
• If you are unsure whether you need to add this command, it is recommended to leave it out initially and add it only if necessary.