** Changed in: ubuntu-power-systems
Status: Triaged => Fix Committed
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https://bugs.launchpad.net/bugs/1736145
Title:
Ubuntu16.04.03: ISAv3 initialize MMU registers before setting
partition table
Status in The Ubuntu-power-systems project:
Fix Committed
Status in linux package in Ubuntu:
Fix Committed
Status in linux source package in Artful:
Fix Committed
Status in linux source package in Bionic:
Fix Committed
Bug description:
== SRU Justification ==
Kexec can leave MMU registers set, PIDR in particular, when booting the
new kernel. The boot sequence does not zero PIDR ever, and it only gets
changed as CPUs first switch to userspace processes. This can leave a
window where speculative accesses from a CPU to quadrant 0 can pick up
translations in the partition table that may be set up for processes
running on other CPUs. These cached translations will not be involved in
the invalidation protocol, so we can end with stable TLB and PWC.
This commit was included in mailine as of v4.15-rc5 and fixes commit
7e381c0ff618.
== Fix ==
commit 371b80447ff33ddac392c189cf884a5a3e18faeb
Author: Nicholas Piggin <[email protected]>
Date: Wed Dec 6 18:21:14 2017 +1000
powerpc/64s: Initialize ISAv3 MMU registers before setting
partition table
== Regression Potential ==
Low. This fix is specific to powerpc. It has also been cc'd to upstream
stable,
so it has had additional upstream review.
==Original Bug Description: ==
== Comment: #0 - Breno Leitao <[email protected]> - 2017-12-04 05:50:27 ==
kexec can leave MMU registers set, PIDR in particular, when booting the
new kernel. The boot sequence does not zero PIDR ever, and it only gets
changed as CPUs first switch to userspace processes. This can leave a
window where speculative accesses from a CPU to quadrant 0 can pick up
translations in the partition table that may be set up for processes
running on other CPUs. These cached translations will not be involved in
the invalidation protocol, so we can end with stable TLB and PWC.
We need to have this patch included in Ubuntu kernel.
https://lists.ozlabs.org/pipermail/linuxppc-dev/2017-December/166424.html
We do not have commit id, but once we have, I will post here. There is
no need to include the patch prior to upstream acceptance.
== Comment: #2 - VIPIN K. PARASHAR <[email protected]> - 2017-12-04
06:57:52 ==
(In reply to comment #0)
>
> We need to have this patch included in Ubuntu kernel.
> https://lists.ozlabs.org/pipermail/linuxppc-dev/2017-December/166424.html
>
> We do not have commit id, but once we have, I will post here. There is no
> need to include the patch prior to upstream acceptance.
>
.. Patch subject reads as follows:
[PATCH] powerpc/64s: ISAv3 initialize MMU registers before setting
partition table
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