From: Thomas Lamprecht <[email protected]> Sent: Sunday, October 4, 2026 9:37 PM >Since v6.17, X550 adapters without VFs can crash the host on an MDD >event, as reported by Melissa on netdev [0], by Viacheslav on >intel-wired-lan [1], and by Proxmox VE users [2]. > >Patch 1 fixes the NULL pointer dereference, and the out-of-bounds >vfinfo write for events on PF pools with SR-IOV enabled too. Patch 2 >stops enabling MDD without VFs, which is how such setups get MDD events >at all. Why the hardware flags PF queues is still unclear to me, all >reports show tx:80000. > >For completness sake, on E610, the tx hang path in >ixgbe_handle_mdd_event() looks like it can still reach vfinfo for pools >without a VF if VT mode is enabled without VFs, e.g. with macvlan >offload, that's not fixed here. > >Tested on a Supermicro H11DSi-NT with its onboard X550: without this >series RDRXCTL.MDP_EN is set whenever the link is up, also without VFs >or after removing them again. With it, MDD is only enabled while VFs >exist. >Patch 1 is not tested in-depth yet though, as I have no reproducer for >the MDD events themselves, so any testing by the reporters would be more >than welcome.
Hi Thomas great, much thanks for fixing these! Reviewed-by: Jedrzej Jagielski <[email protected]> for both
