[Bug 1759920] Re: intel-microcode 3.20180312.0 causes lockup at login screen(w/ linux-image-4.13.0-37-generic)

[Gordon Lack]

> Define *old* microcode

The microcode from 3.20180108.0+really20170707ubuntu17.10.1:
 [parent]: dmesg -t | grep -i microcode
 microcode: microcode updated early to revision 0x29, date = 2013-06-12
 microcode: sig=0x206a7, pf=0x2, revision=0x29
 microcode: Microcode Update Driver: v2.2.

If Intel were fixing this in microcode in 2013 then there's something
about which they haven't been letting on.  This is an Intel(R) Core(TM)
i5-2500K(family 6, model 42, stepping 7).

Similarly running this on my laptop (Intel(R) Core(TM) i5-4330M with
microcode from that same deb package (microcode revision 0x22, date =
2017-01-27) reports that it is not vulnerable.

Both of these systems hang using the new ("current") microcode (their
reports only differs in the CPU type).

One difference I can see on the report for my system running 18.04beta
which is OK with the new microcode is that it says NO "Kernel has the
Red Hat/Ubuntu patch", but the two systems above, which both suffer with
the new microcode, have YES.

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https://bugs.launchpad.net/bugs/1759920

Title:
  intel-microcode 3.20180312.0 causes lockup at login screen(w/ linux-
  image-4.13.0-37-generic)

Status in intel-microcode package in Ubuntu:
  Confirmed
Status in linux package in Ubuntu:
  Confirmed
Status in intel-microcode source package in Xenial:
  Confirmed
Status in linux source package in Xenial:
  Confirmed
Status in intel-microcode source package in Artful:
  Confirmed
Status in linux source package in Artful:
  Confirmed

Bug description:
  I don't know if this is a problem with the kernel or the microcode,
  but we have a significant number of computers in our organization (on
  both 16.04 and 17.10) that fail if they have both updated.  Booting
  with either linux-image-4.13.0-36-generic or intel-microcode
  3.20180108.0+really20170707ubuntu17.10.1 allows all these computers to
  boot.

  ## Workaround ##
  1. Boot the system with the dis_ucode_ldr kernel boot parameter to temporary avoid the problem:
     https://wiki.ubuntu.com/Kernel/KernelBootParameters
  2. Install the previous version of package from
     https://launchpad.net/~ubuntu-security-proposed/+archive/ubuntu/ppa/+build/14261530/+files/intel-microcode_3.20180108.0+really20170707ubuntu16.04.1_amd64.deb
  3. (Optional) Hold the package so that it won't be upgraded accidentally
     sudo apt-mark hold intel-microcode

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