[Bug 219129] New: virtio net performance degradation between Windows and Linux guest in kernel 6.10.3

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=219129

            Bug ID: 219129
           Summary: virtio net performance degradation between Windows and
                    Linux guest in kernel 6.10.3
           Product: Virtualization
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: anton.wd@gmail.com
        Regression: No

After kernel upgrade from 6.10.2 to 6.10.3 network performance has become very
low between Windows and Linux guest.

Steps to reproduce:
MTU 9000 for all adapters and bridge (Jumbo frame 9014 in Windows)
KVM host, qemu 9.0.2, bridge (e.g. br0)
Linux guest, virtio net adapter bridged to host br0, address e.g. 192.168.0.1
Windows 11 guest, virtio net adapter, bridged to host br0, address e.g.
192.168.0.2

When accessing Linux guest from Windows 11 and if kvm host OR Linux guest has
kernel version 6.10.3 then network performance is poor.

iperf3 for example:

$ iperf3.exe --client 192.168.0.1
Connecting to host 192.168.0.1, port 5201
[  5] local 192.168.0.2 port 49849 connected to 192.168.0.1 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.01   sec   256 KBytes  2.08 Mbits/sec
[  5]   1.01-2.01   sec   128 KBytes  1.04 Mbits/sec
[  5]   2.01-3.01   sec  0.00 Bytes  0.00 bits/sec
[  5]   3.01-4.01   sec   128 KBytes  1.05 Mbits/sec
[  5]   4.01-5.00   sec  0.00 Bytes  0.00 bits/sec
[  5]   5.00-6.01   sec  0.00 Bytes  0.00 bits/sec
[  5]   6.01-7.01   sec  0.00 Bytes  0.00 bits/sec
[  5]   7.01-8.01   sec   128 KBytes  1.05 Mbits/sec
[  5]   8.01-9.01   sec  0.00 Bytes  0.00 bits/sec
[  5]   9.01-10.01  sec  0.00 Bytes  0.00 bits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-10.01  sec   640 KBytes   524 Kbits/sec                  sender
[  5]   0.00-10.02  sec   384 KBytes   314 Kbits/sec                  receiver

iperf Done.


If kvm host AND Linux guest has kernel version 6.10.2 then performance seems ok

$ iperf3.exe --client 192.168.0.1
Connecting to host 192.168.0.1, port 5201
[  5] local 192.168.0.2 port 50092 connected to 192.168.0.1 port 5201
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-1.01   sec  3.86 GBytes  33.0 Gbits/sec
[  5]   1.01-2.01   sec  3.78 GBytes  32.4 Gbits/sec
[  5]   2.01-3.02   sec  3.72 GBytes  31.6 Gbits/sec
[  5]   3.02-4.01   sec  3.75 GBytes  32.2 Gbits/sec
[  5]   4.01-5.01   sec  3.80 GBytes  32.8 Gbits/sec
[  5]   5.01-6.01   sec  3.64 GBytes  31.3 Gbits/sec
[  5]   6.01-7.01   sec  3.90 GBytes  33.6 Gbits/sec
[  5]   7.01-8.00   sec  3.94 GBytes  33.9 Gbits/sec
[  5]   8.00-9.00   sec  3.83 GBytes  32.9 Gbits/sec
[  5]   9.00-10.00  sec  3.87 GBytes  33.3 Gbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate
[  5]   0.00-10.00  sec  38.1 GBytes  32.7 Gbits/sec                  sender
[  5]   0.00-10.01  sec  38.1 GBytes  32.7 Gbits/sec                  receiver

iperf Done.

The following entries appear in the kernel logs on Linux guest:
[  157.294081] enp3s0: bad gso: type: 1, size: 8960
[  157.294298] enp3s0: bad gso: type: 1, size: 8960
[  157.623938] enp3s0: bad gso: type: 1, size: 8960
[  157.938094] enp3s0: bad gso: type: 1, size: 8960
[  158.249957] enp3s0: bad gso: type: 1, size: 8960
[  158.593349] enp3s0: bad gso: type: 1, size: 8960
[  158.909346] enp3s0: bad gso: type: 1, size: 8960
[  159.236646] enp3s0: bad gso: type: 1, size: 8960
[  159.236721] enp3s0: bad gso: type: 1, size: 8960
[  159.236745] enp3s0: bad gso: type: 1, size: 8960

This is also reproduced for bare metal Windows 11 PC with bridged physical
network adapter to br0 on kvm host.

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