[Bug 1674399] Re: OpenSSL CPU detection for AMD Ryzen CPUs

[Eric Desrochers]

Here's some context after a conversation about this bug on channel :
#ubuntu-release

...
[10:01:50] <slashd> hi SRU, I'm currently working on a case (no LP bug yet).... about an OpenSSL bug on new AMD CPU (Ryzen) released last Feb ... where the SHA Extension routine is not called on AMD Ryzen cores. My question is since this look like H/W enablement ... do you think this could be eligible for SRU in stable release such like Xenial ? or this will only be accepted for devel release ? This is a new CPU but Xenial is there for a couple of years still so maybe future Xenial user running Ryzen CPU may benefit on this eventually...
[10:03:20] <apw> slashd, for me some new functionality like that is ok as long as it is very self-contained so easy to review and confirm is only used on the new h/w
[10:03:52] <apw>one of our main goals is to avoid regressions
[10:04:41] <slashd>apw, make sense, thanks for your input
[10:12:24] <rbasak> The SRU policy does explicitly permit hardware enablement in an LTS IIRC, though I'd expect ~ubuntu-sru to be involved in mitigating risk and making the final risk decision, FWIW.
[10:16:11] <apw> rbasak, right, it would have to be carefully considered once we can see what the diff actually is
[10:16:34] <slashd> rbasak, apw ack, will communite the info with the proper group
[10:16:50] <apw> with a much greater level of testing and scrutiny than a regular fix only sru
[10:17:12] <slashd> apw, rbasak, FYI I have requested the new CPU from our partner to test in deep
...

** Changed in: openssl (Ubuntu)
    Milestone: ubuntu-16.04.2 => None

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https://bugs.launchpad.net/bugs/1674399

Title:
  OpenSSL CPU detection for AMD Ryzen CPUs

Status in openssl package in Ubuntu:
  Triaged

Bug description:
  It has been brought to my attention that :
  "CPUID detection in OpenSSL does not properly detect potential optimizations for AMD processors."

  After further verification on my side :

  Extended feature flags were not pulled on AMD processors, as result a
  number of extensions were effectively masked on Ryzen CPUs. It should
  have been reported for Excavator since it implements AVX2 extension,
  but apparently nobody noticed ...

  The GitHub PR:
  https://github.com/openssl/openssl/pull/2849

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