[SOLVED] Attached PCI NIC to VM causes network failure

[bgs]

Hello! I have two NICs enp3s0 and enp2s0 installed on my Proxmox host.

The plan is to attach 0000:02:00.0 (enp2s0) as PCI Device directly to a VM:



But if I start the VM, all network communication to the host is lost

root@mc:~# grep PCI_SLOT_NAME /sys/class/net/enp2s0/device/uevent
PCI_SLOT_NAME=0000:02:00.0
root@mc:~# grep PCI_SLOT_NAME /sys/class/net/enp3s0/device/uevent
PCI_SLOT_NAME=0000:03:00.0

auto lo
iface lo inet loopback

iface enp3s0 inet manual

auto vmbr0
iface vmbr0 inet static
        address 192.168.22.2/24
        gateway 192.168.22.1
        bridge-ports enp3s0
        bridge-stp off
        bridge-fd 0

Thank you all in advance!

 

[VictorSTS]

That's expected because both NIC's share the same IOMMU group (8), so as soon as you passthrough any of them, the other one won't be available to the host. If any of those NIC's are a PCI(e) card try using a different slot and check it's IOMMU group again.

What's your motivation to passthrough a NIC? There may be alternatives.

 

[bgs]

Hello, thank you for your reply!

That's expected because both NIC's share the same IOMMU group (8)

That's what I've thought about.

using a different slot

It's the only one slot.

What's your motivation to passthrough a NIC?

Better performance for the WAN interface of the virtual router instead of adding it as Network Device.

 

[VictorSTS]

I do use plain vNic on VM's with multi gigabit traffic with no issues at all... What kind of performance to you need?

This is a simple iperf among two VMs in the same host using VirtIO NICs

 

[bgs]

Okay, convinced