From nobody Fri Sep 26 21:44:16 2025 X-Original-To: net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4cYPHs4vhyz68vxh; Fri, 26 Sep 2025 21:44:41 +0000 (UTC) (envelope-from michael.tuexen@lurchi.franken.de) Received: from drew.franken.de (drew.ipv6.franken.de [IPv6:2001:638:a02:a001:20e:cff:fe4a:feaa]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "*.franken.de", Issuer "Certum Domain Validation CA SHA2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4cYPHs236Wz3PbH; Fri, 26 Sep 2025 21:44:41 +0000 (UTC) (envelope-from michael.tuexen@lurchi.franken.de) Authentication-Results: mx1.freebsd.org; none Received: from smtpclient.apple (unknown [IPv6:2a02:8109:1101:be00:4139:486c:e3c3:f4ae]) (Authenticated sender: lurchi) by drew.franken.de (Postfix) with ESMTPSA id 073B6721E280D; Fri, 26 Sep 2025 23:44:16 +0200 (CEST) Content-Type: text/plain; charset=utf-8 List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@FreeBSD.org Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.100.1.1.5\)) Subject: Re: Chelsio (cxgbe) VF on FreeBSD guest under KVM requires -rxcsum From: Michael Tuexen In-Reply-To: Date: Fri, 26 Sep 2025 23:44:16 +0200 Cc: net@freebsd.org, virtualization@freebsd.org, np@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: References: To: John Nielsen X-Mailer: Apple Mail (2.3864.100.1.1.5) X-Spam-Status: No, score=-2.7 required=5.0 tests=ALL_TRUSTED,BAYES_00, URIBL_CSS,URIBL_CSS_A autolearn=disabled version=3.4.1 X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on mail-n.franken.de X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:680, ipnet:2001:638::/32, country:DE] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Queue-Id: 4cYPHs236Wz3PbH > On 26. Sep 2025, at 20:52, John Nielsen wrote: >=20 >> On Sep 26, 2025, at 1:46=E2=80=AFAM, Michael Tuexen = wrote: >> =EF=BB=BF >>>=20 >>> On 26. Sep 2025, at 02:58, John Nielsen wrote: >>>=20 >>> Not sure if this is a known issue or even an issue on the FreeBSD = side but decided to ask here first. I=E2=80=99m happy to put in a bug = report if appropriate. >>>=20 >>> I have a hypervisor machine running Arch Linux with KVM, Qemu and = libvirtd. The machine has a Chelsio T520-CR adapter. I recently began = passing through virtual functions of the NIC to several of the guests I = run on the hypervisor. One of the guests runs Windows 11, and the change = was seamless. Two of the guests are running FreeBSD (14.3 or so). On = each of them the VFs were readily identified and configured (using DHCP = in one case), and ping and ARP appeared to work fine. However, TCP and = UDP traffic to the guests never received a response. After some = head-scratching and troubleshooting I discovered that running = =E2=80=9Cifconfig cxlv0 -rxcsum=E2=80=9D immediately allowed traffic to = flow as expected. >>=20 >> I don't have access to such a network card. Just to be clear: you are = running the =E2=80=9Cifconfig cxlv0 -rxcsum=E2=80=9D command inside the = guest running FreeBSD, right? >=20 > Yes. >=20 >> What is the peer, when you mention TCP and UDP do not work? Is it the = host running Linux? Is it another VM? Is it some external host? >=20 > My laptop on the same subnet primarily, but. Also tested from another = physical machine running FreeBSD. OK. That does not seem to be related to what I initially thought. Could you run tcpdump -i outgoing_interface -w laptop.pcap on your laptop and tcpdump -i cxlv0 -w vm.pcap on your vm at the same time and try to do some TCP based communication. Maybe two times, one time with ifconfig cxlv0 rxcsum and one time with = ifconfig cxlv0 -rxcsum. If you are fine with doing the measurements, you can send the .pcap = files to tuexen@freebsd.org . At least I would like to understand what is going on. Best regards Michael >=20 >>> As workarounds go that isn=E2=80=99t terrible, but I was surprised = that the FreeBSD guests required this adjustment while the Windows one = did not. >>>=20 >>> As a point of reference I have another hypervisor machine that runs = FreeBSD 14-STABLE. It also has a >> So the host runs FreeBSD and you use bhyve to run some VM? >=20 > Yes >=20 >>> Chelsio T520-CR adapter. FreeBSD guests on that machine do not = require =E2=80=9C-rxcsum=E2=80=9D in order to use the Chelsio virtual = functions. >> The guests run FreeBSD-STABLE or Freebsd 14.3? >> What is the peer, when you mention TCP and UDP do not work? Is it the = host running Linux? Is it another VM? Is it some external host? >=20 > FreeBSD 14-STABLE circa 14.3 >=20 > Multiple off-box same-subnet peers in this scenario as well including = my laptop. >=20 > I=E2=80=99m aware that VF-to-PF communication is a special case. >=20 > JN