Hey Jon from Nutanix AHV R&D here - We also see this issue on RHEL,
SLE15, and vanilla kernels. In all three of those cases, the problem
wasn't with AHV, but with a problematic set of backport that was tagged
as a CVE, but caused a GSO-based performance regression. This can be
reproduced on non-Nutanix AHV hosts too.

Cross-referencing:
RHEL bugs:
https://issues.redhat.com/browse/RHEL-62411
https://issues.redhat.com/browse/RHEL-67427

CentOS stream PR to fix this: 
https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9/-/merge_requests/5623

Generic reproduction from the Tailscale community, lot of great info in this 
thread:
https://github.com/tailscale/tailscale/issues/13041#issuecomment-2294011607

Cross reference for SUSE SLES15 SP6:
- broken in SLE15 SP6 with kernel 6.4.0-150600.23.22.1 (Sep-23-2024)
- fixed in SLE15 SP6 with kernel 6.4.0-150600.23.25.1 (Oct-09-2024)
- Versions are tracked here https://www.suse.com/support/kb/doc/?id=000019587 
and aligned to the commit tags here:
- bad commit: 
https://github.com/SUSE/kernel/commit/25229b4457540a2da59598839f39f8fbe3dfaa64
- good commit: 
https://github.com/SUSE/kernel/commit/e5010362f58efcc32c223cae45c7939ed3d04399

TLDR, the breaking commit is:
net: drop bad gso csum_start and offset in virtio_net_hdr

See commits with Fixes tag:
Fixes: 89add40066f9 ("net: drop bad gso csum_start and offset in 
virtio_net_hdr")

Fixing commits in our other cases with RHEL, SLE15, and generic vanilla 
upstream kernels:
udp: fix receiving fraglist GSO packets
net: tighten bad gso csum offset check in virtio_net_hdr

Any chance this specific ubuntu kernel has "net: drop bad gso csum_start
and offset in virtio_net_hdr" and not "net: tighten bad gso csum offset
check in virtio_net_hdr"?


** Bug watch added: github.com/tailscale/tailscale/issues #13041
   https://github.com/tailscale/tailscale/issues/13041

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https://bugs.launchpad.net/bugs/2089012

Title:
  virtio-net slowdown and error message ens3: bad gso: type: 1, size:
  1448

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