Bug 2004083

Summary:	Incorrectly negotiated feature causes OpenvSwitch upcalls to fail
Product:	Red Hat Enterprise Linux Fast Datapath	Reporter:	Mark Gray <mark.d.gray>
Component:	openvswitch2.16	Assignee:	Open vSwitch development team <ovs-team>
Status:	CLOSED EOL	QA Contact:	Hekai Wang <hewang>
Severity:	urgent	Docs Contact:
Priority:	unspecified
Version:	FDP 20.G	CC:	ctrautma, fleitner, hewang, jhsiao, ralongi
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Last Closed:	2023-06-14 18:05:14 UTC	Type:	Bug
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
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Description Mark Gray 2021-09-14 13:36:24 UTC

Description of problem:
OVS user space component does not correctly negotiate kernel space features on RHEL 7 causing user space to incorrectly detect 'per-cpu-dispatch' mode. This causes upcalls to user space to fail as user space believes it is in 'per-cpu-dispatch' mode whereas kernel space is not.

Version-Release number of selected component (if applicable):
Kernel: 3.10.0-1160.el7.x86_64
OVS: latest master (https://github.com/openvswitch/ovs/commit/00d3d4a7d3750ab1d907d58894ad817febce1cf7)

How reproducible:
Always

Steps to Reproduce:
1. /usr/local/share/openvswitch/scripts/ovs-ctl start
2. ovs-vsctl add-br br0
3. ovs-appctl dpif-netlink/dispatch-mode

Actual results:
ovs-system: per-cpu dispatch mode

Expected results:
ovs-system: per-vport dispatch mode

Additional info:

Comment 1 Mark Gray 2021-09-14 13:41:03 UTC

After investigation, the root-cause appears to be that the RHEL7 openvswitch kernel module does not check for unsupported features.

Comment 2 Mark Gray 2021-09-15 10:05:56 UTC

https://patchwork.ozlabs.org/project/openvswitch/list/?series=262432