This is *not* fixed for Xenial. I had originally applied the workaround in the bug description to get my computer to boot again. After seeing a "fixed" status for this bug, I updated intel-microcode. After I rebooted, my computer would not boot to the kernel which had the microcode applied (4.4.0-122). It would only boot to the previous kernel without the microcode (4.4.0-119).
$ tail -n 5 /var/log/apt/history.log Start-Date: 2018-05-05 06:06:43 Commandline: apt install intel-microcode Upgrade: intel-microcode:amd64 (3.20180108.0+really20170707ubuntu16.04.1, 3.20180312.0~ubuntu16.04.1) End-Date: 2018-05-05 06:06:57 $ uname -a Linux thinkpad 4.4.0-119-generic #143-Ubuntu SMP Mon Apr 2 16:08:24 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux $ dpkg -l | grep linux-image-4 | grep ^i ii linux-image-4.4.0-112-generic 4.4.0-112.135 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP ii linux-image-4.4.0-119-generic 4.4.0-119.143 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP ii linux-image-4.4.0-122-generic 4.4.0-122.146 amd64 Linux kernel image for version 4.4.0 on 64 bit x86 SMP $ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 16.04.4 LTS Release: 16.04 Codename: xenial $ cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 58 model name : Intel(R) Core(TM) i5-3317U CPU @ 1.70GHz stepping : 9 microcode : 0x1c cpu MHz : 893.761 cache size : 3072 KB physical id : 0 siblings : 4 core id : 0 cpu cores : 2 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm epb retpoline kaiser tpr_shadow vnmi flexpriority ept vpid fsgsbase smep erms xsaveopt dtherm ida arat pln pts bugs : cpu_meltdown spectre_v1 spectre_v2 bogomips : 3391.94 clflush size : 64 cache_alignment : 64 address sizes : 36 bits physical, 48 bits virtual power management: -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1759920 Title: intel-microcode 3.20180312.0 causes lockup at login screen Status in intel-microcode package in Ubuntu: Invalid Status in linux package in Ubuntu: Invalid Status in intel-microcode source package in Trusty: Invalid Status in linux source package in Trusty: Fix Released Status in intel-microcode source package in Xenial: Invalid Status in linux source package in Xenial: Fix Released Status in intel-microcode source package in Artful: Invalid Status in linux source package in Artful: Fix Released Bug description: [Impact] * Some systems experience kernel lockups after updating to the latest intel-microcode package or when receiving updated microcode from a BIOS update. * In many cases, the lockups occur before users can reach the login screen which makes it very difficult to debug/workaround. [Test Case] * The most reliable test case currently known is to install the sssd package. Lockups may occur during package installation (disable IBPB by writing 0 to /proc/sys/kernel/ibpb_enabled to prevent this from happening). A lockup will most likely occur just after booting the system up as the lock screen is displayed. [Regression Potential] * The fix is in the task switching code of the kernel so complexity of the change is relatively high. [Original Report] 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 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/intel-microcode/+bug/1759920/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp