Public bug reported:

== Comment: #0 - Breno Leitao <[email protected]> - 2018-08-23 17:52:30 ==
Please apply the following kernel patch into Bionic  4.15 kernel, and Xenial 
4.4 kernel.

https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=next&id=db2173198b9513f7add8009f225afa1f1c79bcc6

powerpc/powernv/pci: Work around races in PCI bridge enabling

The generic code is racy when multiple children of a PCI bridge try to
enable it simultaneously.

This leads to drivers trying to access a device through a
not-yet-enabled bridge, and this EEH errors under various
circumstances when using parallel driver probing.

There is work going on to fix that properly in the PCI core but it
will take some time.

x86 gets away with it because (outside of hotplug), the BIOS enables
all the bridges at boot time.

This patch does the same thing on powernv by enabling all bridges that
have child devices at boot time, thus avoiding subsequent races. It's
suitable for backporting to stable and distros, while the proper PCI
fix will probably be significantly more invasive.

Signed-off-by: Benjamin Herrenschmidt <[email protected]>
Cc: [email protected]
Signed-off-by: Michael Ellerman <[email protected]>

** Affects: kernel-package (Ubuntu)
     Importance: Undecided
     Assignee: Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage)
         Status: New


** Tags: architecture-ppc64le bugnameltc-170843 severity-high 
targetmilestone-inin---

** Tags added: architecture-ppc64le bugnameltc-170843 severity-high
targetmilestone-inin---

** Changed in: ubuntu
     Assignee: (unassigned) => Ubuntu on IBM Power Systems Bug Triage 
(ubuntu-power-triage)

** Package changed: ubuntu => kernel-package (Ubuntu)

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https://bugs.launchpad.net/bugs/1788850

Title:
  [Bionic, Xenial] powerpc/powernv/pci: Work around races in PCI bridge
  enabling

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