Fixup tlbie vs store ordering issue on POWER9
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
The Ubuntu-power-systems project |
Fix Released
|
Medium
|
Canonical Kernel Team | ||
linux (Ubuntu) |
Fix Released
|
Medium
|
Manoj Iyer | ||
Eoan |
Fix Released
|
Medium
|
Unassigned |
Bug Description
== Comment: #0 - Michael Ranweiler - 2019-10-07 01:52:38 ==
On POWER9, under some circumstances, a broadcast TLB invalidation will fail to invalidate the ERAT cache on some threads when there are parallel mtpidr/mtlpidr happening on other threads of the same core. This can cause stores to continue to go to a page after it's unmapped.
The workaround is to force an ERAT flush using PID=0 or LPID=0 tlbie flush. This additional TLB flush will cause the ERAT cache invalidation. Since we are using PID=0 or LPID=0, we don't get filtered out by the TLB snoop filtering logic.
We need to still follow this up with another tlbie to take care of store vs tlbie ordering issue explained in commit: a5d4b5891c2f ("powerpc/mm: Fixup tlbie vs store ordering issue on POWER9"). The presence of ERAT cache implies we can still get new stores and they may miss store queue marking flush.
The upstream git commits to resolve the problem:
tags: | added: architecture-ppc64le bugnameltc-181791 severity-medium targetmilestone-inin--- |
Changed in ubuntu: | |
assignee: | nobody → Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage) |
affects: | ubuntu → linux (Ubuntu) |
Changed in ubuntu-power-systems: | |
assignee: | nobody → Canonical Kernel Team (canonical-kernel-team) |
importance: | Undecided → Medium |
Changed in linux (Ubuntu): | |
assignee: | Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage) → Manoj Iyer (manjo) |
importance: | Undecided → Medium |
Changed in linux (Ubuntu): | |
status: | New → In Progress |
Changed in ubuntu-power-systems: | |
status: | New → In Progress |
Changed in linux (Ubuntu): | |
status: | In Progress → Incomplete |
Changed in ubuntu-power-systems: | |
status: | In Progress → Incomplete |
Changed in linux (Ubuntu): | |
status: | Incomplete → Triaged |
tags: |
added: targetmilestone-inin1910 removed: targetmilestone-inin--- |
IBM can you please test the Eoan kernel in this PPA: https:/ /launchpad. net/~ubuntu- power-triage/ +archive/ ubuntu/ lp1848193/
Also, please share the following information with us:
1. Your testcase, and instructions on how to run the test cases.
2. Your system config information and firmware levels.
3. Is there any significant customer impact if this is not backported to earlier releases?