Date: Fri, 26 Sep 2025 12:52:41 -0600 From: John Nielsen <lists@jnielsen.net> To: Michael Tuexen <michael.tuexen@lurchi.franken.de> Cc: net@freebsd.org, virtualization@freebsd.org, np@freebsd.org Subject: Re: Chelsio (cxgbe) VF on FreeBSD guest under KVM requires -rxcsum Message-ID: <B648CE12-8D42-4978-A50B-DE5E7F39A512@jnielsen.net> In-Reply-To: <CF7D677F-2D3A-41B5-A3F1-0FCA844D206F@lurchi.franken.de> References: <CF7D677F-2D3A-41B5-A3F1-0FCA844D206F@lurchi.franken.de>
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> On Sep 26, 2025, at 1:46=E2=80=AFAM, Michael Tuexen <michael.tuexen@lurchi= .franken.de> wrote: > =EF=BB=BF >>=20 >> On 26. Sep 2025, at 02:58, John Nielsen <lists@jnielsen.net> wrote: >>=20 >> Not sure if this is a known issue or even an issue on the FreeBSD side bu= t decided to ask here first. I=E2=80=99m happy to put in a bug report if app= ropriate. >>=20 >> I have a hypervisor machine running Arch Linux with KVM, Qemu and libvirt= d. The machine has a Chelsio T520-CR adapter. I recently began passing throu= gh virtual functions of the NIC to several of the guests I run on the hyperv= isor. 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 r= eadily identified and configured (using DHCP in one case), and ping and ARP a= ppeared to work fine. However, TCP and UDP traffic to the guests never recei= ved a response. After some head-scratching and troubleshooting I discovered t= hat running =E2=80=9Cifconfig cxlv0 -rxcsum=E2=80=9D immediately allowed tra= ffic to flow as expected. >=20 > I don't have access to such a network card. Just to be clear: you are runn= ing the =E2=80=9Cifconfig cxlv0 -rxcsum=E2=80=9D command inside the guest ru= nning FreeBSD, right? Yes. > 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? My laptop on the same subnet primarily, but. Also tested from another physic= al machine running FreeBSD. >> As workarounds go that isn=E2=80=99t terrible, but I was surprised that t= he FreeBSD guests required this adjustment while the Windows one did not. >>=20 >> As a point of reference I have another hypervisor machine that runs FreeB= SD 14-STABLE. It also has a > So the host runs FreeBSD and you use bhyve to run some VM? Yes >> 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? FreeBSD 14-STABLE circa 14.3 Multiple off-box same-subnet peers in this scenario as well including my lap= top. I=E2=80=99m aware that VF-to-PF communication is a special case. JN=
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