** Changed in: linux (Ubuntu Trusty)
       Status: New => Fix Committed

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https://bugs.launchpad.net/bugs/1697053

Title:
  Missing IOTLB flush causes DMAR errors with SR-IOV

Status in linux package in Ubuntu:
  Confirmed
Status in linux source package in Trusty:
  Fix Committed

Bug description:
  SRU Justification:

  Impact:

          Using SR-IOV with Intel IOMMUs can observe DMAR errors of the
  following type:

  [606483.223009] DMAR:[fault reason 05] PTE Write access is not set 
  [606484.071974] dmar: DRHD: handling fault status reg 402 
  [606484.077121] dmar: DMAR:[DMA Write] Request device [d8:0a.1] fault addr 
35c6e000 

          The DMAR error causes, at a minimum, loss of network traffic
  because the request being serviced is lost.  Network cards were also
  observed to experience transmit timeouts after a DMAR fault.

          In this case, these errors arise from a race condition in
  the IOTLB management; this race is described (and fixed) in upstream
  commit:

  commit ea8ea460c9ace60bbb5ac6e5521d637d5c15293d
  Author: David Woodhouse <david.woodho...@intel.com>
  Date:   Wed Mar 5 17:09:32 2014 +0000

      iommu/vt-d: Clean up and fix page table clear/free behaviour

          This commit first appeared in mainline 3.15.  This issue
  affects only the Ubuntu 3.13 kernel series.

  Fix:

          The race avoidance portion of the above was backported to
  3.14-stable, but was never incorporated into the Ubuntu 3.13
  kernel series.

  commit 51d20e1096a711f8cfa9d98a3ac2dd2c7c0fc20c
  Author: David Woodhouse <dw...@infradead.org>
  Date:   Mon Jun 9 14:09:53 2014 +0100

      iommu/vt-d: Fix missing IOTLB flush in intel_iommu_unmap()
      
      Based on commit ea8ea460c9ace60bbb5ac6e5521d637d5c15293d upstream

          This 3.14-stable patch was tested by the customer and observed
  to resolve the issue in their environment.

  Testcase:

          In this case, the issue occurs on very recent Intel based
  servers using two different SR-IOV network cards (i40e and bnxt) at a
  customer site.  The customer has tested the patch in their environment
  and confirmed that it resolves the issue.

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