Public bug reported:

== Comment: #0 - Ranjal G. Shenoy <[email protected]> - 2017-04-20 08:29:13 ==
Power9 DD1 has a hardware issue due to which  in core whose all threads are 
offlined , when any of the CPUs are onlined, they come online with an incorrect 
PACA thereby resulting in a crash.

The following fixes sent upstream need to applied to the 17.04 kernel to
get CPU-Hotplug working correctly on a Power9 DD1 system.

1) powerpc/linux.git next, commit a7cd88da9704 ("powernv: Move CPU-
Offline idle state invocation from smp.c to idle.c").

2) powerpc/linux.git next, the commit 900612315788
("powerpc/powernv/smp: Add busy-wait loop as fall back for CPU-
Hotplug").

3) powerpc/linux.git, commit f3b3f28493d932 ("powerpc/powernv/idle:
Don't override default/deepest directly in kernel").

4) powerpc/linux.git next, commit 17ed4c8f81da ("powerpc/powernv:
Recover correct PACA on wakeup from a stop on P9 DD1").

These patches have been backported onto the 17.04 Kernel tagged
Ubuntu-4.10.0-19.21.

== Comment: #1 - Ranjal G. Shenoy <[email protected]> - 2017-04-20
08:29:54 ==


== Comment: #2 - Ranjal G. Shenoy <[email protected]> - 2017-04-20 08:30:37 ==


== Comment: #3 - Ranjal G. Shenoy <[email protected]> - 2017-04-20 08:31:15 ==

** Affects: linux (Ubuntu)
     Importance: Undecided
     Assignee: Taco Screen team (taco-screen-team)
         Status: New


** Tags: architecture-ppc64le bugnameltc-153589 severity-high 
targetmilestone-inin1704

** Tags added: architecture-ppc64le bugnameltc-153589 severity-high
targetmilestone-inin1704

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https://bugs.launchpad.net/bugs/1685792

Title:
  Offlined CPUs of a core fail to come up online on POWER9 DD1 (Ubuntu
  17.04)

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