Public bug reported:
SRU Justification:
[Impact]
On BlueField 2 and BlueField 3 the MAC HW is designed to repeatedly send
pause frames to its link partner when the RX FIFO is full. The internal
Ethernet switch on BlueField that is connected to this port is also
designed to stop traffic on all ports when it receives a high number of
continuous pause frames from one of the ports.
What this means is that when the MAC RX FIFO cannot be drained (e.g. due
to panic), it is possible to reproduce a scenario under steady and high
network load where the network becomes inaccessible for other devices
connected to the 3-port switch, namely the OOB host and DPU-BMC.
[Fix]
Register a panic notifier at highest priority that disables MAC RX and
clears the RX FIFO to ensure that the MAC can no longer receive packets
or send pause frames after a kernel panic.
Add protection in the mlxbf_gige driver for the case when firmware
disables the MAC after handling a fatal error or panic that the kernel
could not detect.
[Test Case]
The following testing was done:
* Verified no performance difference when testing with iperf.
* No regressions found when copying large files to and from DUT.
* Module load/unload succeeds.
* Bringing interface down and up repeatedly succeeds.
* Flooded the interface with broadcast packets to keep MAC RX FIFO full
while monitoring pause frames received on the internal 3 port switch.
With this test setup verified pause frames stopped after:
* ATF FW panic
* kernel panic triggered with sysrq
* power off
* reboot
* module unload
* No unexpected kernel Oops or warnings when implementing custom ATF FW
to disable OOB MAC while mlxbf_gige is actively draining the RX queue.
[Regression Potential]
Low regression potential because the changes are mostly isolated to OOB
port cleanup and kernel panic.
** Affects: linux-bluefield (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2172611
Title:
mlxbf_gige: disable MAC after panic
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