Date: Mon, 29 Sep 2025 18:14:02 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 289907] cxlv: problem with receive checksum offload Message-ID: <bug-289907-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=289907 Bug ID: 289907 Summary: cxlv: problem with receive checksum offload Product: Base System Version: CURRENT Hardware: Any OS: Any Status: New Severity: Affects Some People Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: tuexen@freebsd.org John reported a problem related to using a cxgbe VF on a Linux host with with KVM, Qemu and libvirtd and running a FreeBSD guest. It turns out that incoming TCP packets are received with the correct csum_flags, but unexpected csum_data data. This is from instrumented code: 7 Dropping TCP/IPv4 packet with csum_flags 0xf000000<CSUM_L3_CALC,CSUM_L3_VALID,CSUM_L4_CALC,CSUM_L4_VALID>, csum_data 0x00001d1e and SEG.CSUM e2e1 10 Dropping TCP/IPv4 packet with csum_flags 0xf000000<CSUM_L3_CALC,CSUM_L3_VALID,CSUM_L4_CALC,CSUM_L4_VALID>, csum_data 0x000079a6 and SEG.CSUM 8659 3 Dropping TCP/IPv4 packet with csum_flags 0xf000000<CSUM_L3_CALC,CSUM_L3_VALID,CSUM_L4_CALC,CSUM_L4_VALID>, csum_data 0x000079b6 and SEG.CSUM 8649 11 Dropping TCP/IPv4 packet with csum_flags 0xf000000<CSUM_L3_CALC,CSUM_L3_VALID,CSUM_L4_CALC,CSUM_L4_VALID>, csum_data 0x00007a67 and SEG.CSUM 8598 21 Dropping TCP/IPv4 packet with csum_flags 0xf000000<CSUM_L3_CALC,CSUM_L3_VALID,CSUM_L4_CALC,CSUM_L4_VALID>, csum_data 0x00007a6f and SEG.CSUM 8590 1 Dropping TCP/IPv4 packet with csum_flags 0xf000000<CSUM_L3_CALC,CSUM_L3_VALID,CSUM_L4_CALC,CSUM_L4_VALID>, csum_data 0x00007a7b and SEG.CSUM 8584 Wireshark shows that packet as correct, in particular the checksums. Changing in https://cgit.freebsd.org/src/tree/sys/dev/cxgbe/t4_sge.c#n2043 m0->m_pkthdr.csum_data = be16toh(cpl->csum); to m0->m_pkthdr.csum_data = 0xffff makes the issue disappear. John also reports that the problem does NOT occur when using a FreeBSD host and bhyve and a FreeBSD guest. -- You are receiving this mail because: You are the assignee for the bug.home | help
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