netdev - Re: Rx issues with Linux Bridge and thunderbolt-net

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <4E2F8965-E609-44F2-A361-270082367DC9@gmail.com>
Date: Fri, 8 Dec 2023 10:30:39 -0700
From: Arjun Mehta <arjunmeht@...il.com>
To: Stephen Hemminger <stephen@...workplumber.org>
Cc: netdev@...r.kernel.org
Subject: Re: Rx issues with Linux Bridge and thunderbolt-net

Hi Stephen, thank you for the reply.

Proxmox does use a kernel derived from Ubuntu I believe (eg. kernel for Proxmox 8.1 which is what I'm using is 6.5.11-6-pve derived from Ubuntu 23.10). Not sure if there have been any modifications to the Linux Bridge in it.
https://pve.proxmox.com/wiki/Proxmox_VE_Kernel#Proxmox_VE_8.x

Long shot, but do you happen to know of any workarounds with the Wifi interface issue you mentioned that would mitigate this issue? Maybe they would apply here.

I will also post to the Proxmox forums about this issue to flag for them.

Arjun


> On Dec 7, 2023, at 3:37 PM, Stephen Hemminger <stephen@...workplumber.org> wrote:
> 
> On Thu, 7 Dec 2023 12:57:08 -0700
> Arjun Mehta <arjunmeht@...il.com> wrote:
> 
>> Hi there, I’d like to report what I believe to be a bug with either Linux Bridge (maybe and/or thunderbolt-net as well).
>> 
>> Problem: Rx on bridged Thunderbolt interface are blocked
>> 
>> Reported Behavior:
>> Tested on Proxmox host via iperf3, between B550 Vision D-P and MacBook Pro (2019 intel). On a direct interface, thunderbolt bridge Tx and Rx speeds are equal and full speed (in my case 9GB/s each). However, when a thunderbolt bridge is passed through via Linux Bridge to a VM or container (in my case a Proxmox LXC container or VM) the bridge achieves full Tx speeds, but Rx speeds are reporting limited to ~30kb/s
>> 
>> Expected:
>> The VM/CT should have the same general performance for Tx AND Rx as the host
>> 
>> Reproducing:
>> - Setup for the bridge was done by following this guide: https://gist.github.com/scyto/67fdc9a517faefa68f730f82d7fa3570
>> - Both devices on Thunderbolt interfaces have static IPs
>> - VM is given the same IP, but unique MAC address
>> - BIOS has Thunderbolt security mode set to “No security”
>> 
>> Further reading:
>> The problem is outlined more with screenshots and further details in this Reddit post: https://www.reddit.com/r/Proxmox/comments/17kq5st/slow_rx_speed_from_thunderbolt_3_port_to_vm_over/.
>> 
>> Please let me know if there is any further action I can do to help investigate or where else I can direct the bug/concern
> 
> Most likely this is a hardware issue on the thunderbolt interface where it will not
> allow sending with a different source MAC address.  Some Wifi interfaces have this
> problem.
> 
> Is Promox using a kernel from upstream Linux repository directly.
> Netdev developers are unwilling to assist if there are any non-upstream kernel modules in use.