group.of.nepali.translators team mailing list archive

[Chloé Smith <1913739@xxxxxxxxxxxxxxxxxx>]

Linking this bug to `linux-gcp-fips` as well as the bionic
(4.15.0.1001.3) and focal (5.4.0.1021.20) versions are also missing
upstream commit c40aaaac1018. However these are certified kernels and
will not be updated, so I'm marking as "Invalid" and using this as a
paper trail should we need it :)

** Also affects: linux-gcp (Ubuntu)
   Importance: Undecided
       Status: New

** Changed in: linux-gcp (Ubuntu)
       Status: New => Invalid

** Changed in: linux-gcp (Ubuntu)
     Assignee: (unassigned) => Chloé Smith (kajiya)

** Changed in: linux-gcp (Ubuntu Xenial)
       Status: New => Invalid

** Changed in: linux-gcp (Ubuntu Xenial)
     Assignee: (unassigned) => Chloé Smith (kajiya)

** Changed in: linux-gcp (Ubuntu Bionic)
       Status: New => Invalid

** Changed in: linux-gcp (Ubuntu Bionic)
     Assignee: (unassigned) => Chloé Smith (kajiya)

** Changed in: linux-gcp (Ubuntu Focal)
       Status: New => Invalid

** Changed in: linux-gcp (Ubuntu Focal)
     Assignee: (unassigned) => Chloé Smith (kajiya)

** Changed in: linux-gcp (Ubuntu Groovy)
       Status: New => Invalid

** No longer affects: linux-gcp (Ubuntu Groovy)

** No longer affects: linux-gcp (Ubuntu Xenial)

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https://bugs.launchpad.net/bugs/1913739

Title:
  aws: properly support instance types with > 255 cpu cores

Status in linux-aws package in Ubuntu:
  Fix Released
Status in linux-gcp package in Ubuntu:
  Invalid
Status in linux-aws source package in Xenial:
  Fix Released
Status in linux-aws source package in Bionic:
  Fix Released
Status in linux-gcp source package in Bionic:
  Invalid
Status in linux-aws source package in Focal:
  Fix Released
Status in linux-gcp source package in Focal:
  Invalid
Status in linux-aws source package in Groovy:
  Fix Released

Bug description:
  [Impact]

  To properly support instance types in AWS with > 255 cores we need to
  make sure that commit c40aaaac1018ff1382f2d35df5129a6bcea3df6b
  ("iommu/vt-d: Gracefully handle DMAR units with no supported address
  widths") is applied across all our linux-aws kernels.

  [Test Case]

  Tests performed by AWS.

  [Fix]

  Apply/backport commit c40aaaac1018ff1382f2d35df5129a6bcea3df6b.

  For groovy it's a clean cherry pick.

  For Focal/Bionic the backport activity is to simply rename the patched
  file.

  Only Xenial requires a little more backporting activity, in particular
  we need to change the condition in free_iommu() checking if
  iommu->iommu_dev is defined (instead of checking for iommu->iommu.ops,
  that is not available in the 4.4 kernel).

  [Regression potential]

  This change allows to use DMAR units that were not used before (for
  interrupt remapping). Theoretically this should provide a performance
  improvement, but we should keep an eye about potential performance
  regressions of drivers that are using IOMMU, in case they're using
  this new behavior incorrectly.

  Moreover, the Xenial backport required an adjustment in free_iommu()
  to check when we need to call iommu_device_destroy(), if the
  adjustment is not 100% correct we could introduce a potential memory
  leak.

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