[Bug 1987541] Re: shim executes GRUB w/ dirty instruction cache on arm64

[Steve Langasek]

Hello dann, or anyone else affected,

Accepted shim into kinetic-proposed. The package will build now and be
available at https://launchpad.net/ubuntu/+source/shim/15.7-0ubuntu1 in
a few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.  Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, what testing has been
performed on the package and change the tag from verification-needed-
kinetic to verification-done-kinetic. If it does not fix the bug for
you, please add a comment stating that, and change the tag to
verification-failed-kinetic. In either case, without details of your
testing we will not be able to proceed.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance for helping!

N.B. The updated package will be released to -updates after the bug(s)
fixed by this package have been verified and the package has been in
-proposed for a minimum of 7 days.

** Changed in: shim (Ubuntu Kinetic)
       Status: New => Fix Committed

** Tags added: verification-needed verification-needed-kinetic

** Changed in: shim (Ubuntu Jammy)
       Status: New => Fix Committed

** Tags added: verification-needed-jammy

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https://bugs.launchpad.net/bugs/1987541

Title:
  shim executes GRUB w/ dirty instruction cache on arm64

Status in shim package in Ubuntu:
  Fix Released
Status in shim source package in Bionic:
  Fix Committed
Status in shim source package in Focal:
  Fix Committed
Status in shim source package in Jammy:
  Fix Committed
Status in shim source package in Kinetic:
  Fix Committed

Bug description:
  [Impact]
  On arm64 platforms, GRUB may occasionally crash after being executed by shim. We're seeing it on the order of 1/100 boots.

  [Test Case]
  Put an arm64 server in a reboot loop. We're seeing this w/ a Cortex A72-based system (Nvidia Bluefield).

  [Fix]
  https://github.com/rhboot/shim/commit/5c537b3d0cf8c393dad2e61d49aade68f3af1401

  [What could go wrong]
  The only negative here would seem to be the performance impact of flushing the cache, which is unlikely to be noticeable.

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