@Manoj, this patch looks to be in Bionic as
16735b38aeae1ce2ae21983a7a7440922d6941e4 - can you please double check?

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https://bugs.launchpad.net/bugs/1771344

Title:
  Fix enabling bridge MMIO windows

Status in The Ubuntu-power-systems project:
  In Progress
Status in linux package in Ubuntu:
  In Progress
Status in linux source package in Artful:
  Fix Committed
Status in linux source package in Bionic:
  In Progress
Status in linux source package in Cosmic:
  In Progress

Bug description:
  == SRU Justification ==
  IBM is requesting this patch in Bionic and Artful to fix a regression.  The
  regression was introduced in v3.11-rc1.  The patch fixes enabling bridge
  MMIO windows.  Commit 13a83eac373c was also cc'd to upstream stable, and
  has already landed in Xenial via upstream stable updates.

  == Fix ==
  13a83eac373c ("powerpc/eeh: Fix enabling bridge MMIO windows")

  == Regression Potential ==
  Low.  Limited to powerpc and fixes a current regression.

  == Test Case ==
  A test kernel was built with this patch and tested by the original bug 
reporter.
  The bug reporter states the test kernel resolved the bug.


  == Comment: #0 - Breno Leitao <bren...@br.ibm.com>
  On boot we save the configuration space of PCIe bridges. We do this so
  when we get an EEH event and everything gets reset that we can restore
  them.

  Unfortunately we save this state before we've enabled the MMIO space
  on the bridges. Hence if we have to reset the bridge when we come back
  MMIO is not enabled and we end up taking an PE freeze when the driver
  starts accessing again.

  This patch forces the memory/MMIO and bus mastering on when restoring
  bridges on EEH. Ideally we'd do this correctly by saving the
  configuration space writes later, but that will have to come later in
  a larger EEH rewrite. For now we have this simple fix.

  The original bug can be triggered on a boston machine by doing:
   echo 0x8000000000000000 > 
/sys/kernel/debug/powerpc/PCI0001/err_injct_outbound
  On boston, this PHB has a PCIe switch on it.  Without this patch,
  you'll see two EEH events, 1 expected and 1 the failure we are fixing
  here. The second EEH event causes the anything under the PHB to
  disappear (i.e. the i40e eth).

  With this patch, only 1 EEH event occurs and devices properly recover.

  This is commit id 13a83eac373c49c0a081cbcd137e79210fe78acd and should
  be part of Ubuntu 18.04 kernel.

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