Intel Sandy Bridge-E/EN/EP CPU models (SNB-EP, family 6, model 45, stepping 7) have issues with MDS-related microcode update that may lead to a system hang after a microcode update[1][2]. In order to address this, microcode update to the MDS-related revision 0x718 has been disabled, and the previously published microcode revision 0x714 is used by default for the OS-driven microcode update. [1] https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files/issues/15 [2] https://access.redhat.com/solutions/4593951 For the reference, SHA1 checksums of 06-2d-07 microcode files containing microcode revisions in question are listed below: * 06-2d-07, revision 0x714: bcf2173cd3dd499c37defbc2533703cfa6ec2430 * 06-2d-07, revision 0x718: 837cfebbfc09b911151dfd179082ad99cf87e85d * 06-2d-07, revision 0x71a: 4512c8149e63e5ed15f45005d7fb5be0041f66f6 Please contact your system vendor for a BIOS/firmware update that contains the latest microcode version. For the information regarding microcode versions required for mitigating specific side-channel cache attacks, please refer to the following knowledge base articles: * CVE-2017-5715 ("Spectre"): https://access.redhat.com/articles/3436091 * CVE-2018-3639 ("Speculative Store Bypass"): https://access.redhat.com/articles/3540901 * CVE-2018-3620, CVE-2018-3646 ("L1 Terminal Fault Attack"): https://access.redhat.com/articles/3562741 * CVE-2018-12130, CVE-2018-12126, CVE-2018-12127, and CVE-2019-11091 ("Microarchitectural Data Sampling"): https://access.redhat.com/articles/4138151 The information regarding enforcing microcode load is provided below. To enforce usage of the 0x718 microcode revision for a specific kernel version, please create file "force-intel-06-2d-07" inside /lib/firmware/ directory, run "/usr/libexec/microcode_ctl/update_ucode" to add it to firmware directory where microcode will be available for late microcode update, and run "dracut -f --kver ", so initramfs for this kernel version is regenerated and the microcode can be loaded early, for example: touch /lib/firmware/3.10.0-862.9.1/force-intel-06-2d-07 /usr/libexec/microcode_ctl/update_ucode dracut -f --kver 3.10.0-862.9.1 After that, it is possible to perform a late microcode update by executing "/usr/libexec/microcode_ctl/reload_microcode" or by writing value "1" to "/sys/devices/system/cpu/microcode/reload" directly. To enforce addition of this microcode for all kernels, please create file "/etc/microcode_ctl/ucode_with_caveats/force-intel-06-2d-07", run "/usr/libexec/microcode_ctl/update_ucode" for enabling late microcode updates, and "dracut -f --regenerate-all" for enabling early microcode updates: mkdir -p /etc/microcode_ctl/ucode_with_caveats touch /etc/microcode_ctl/ucode_with_caveats/force-intel-06-2d-07 /usr/libexec/microcode_ctl/update_ucode dracut -f --regenerate-all Please refer to /usr/share/doc/microcode_ctl/README.caveats for additional information.