To properly protect your IBM i systems, you need to install patches to both the OS and the firmware to address the Spectre and Meltdown security exposures. Below are the required fixes depending on your OS level:
Release 7.1 – MF64553
Release 7.2 – MF64552
Release 7.3 – MF64551
Details can be found here: http://www-01.ibm.com/support/docview.wss?uid=nas8N1022433
The OS fix can be applied independently of the firmeware fix. Keep in mind that BOTH the OS and firmware fixes are required to mitigate the security vulnerabilities presented by Spectre and Meltdown.
The firmware update can be obtained from FixCentral. Download one of the following depending on your Power Systems firmware:
770.91 (01AL770_120_032, 01AM770_120_032)
780.81 (01AM780_094_040)
783.51 (01AF783_039_021)
860.42 (01SV860_138_056, 01SC860_138_056)
Details on the firmware updates can be found here: http://www-01.ibm.com/support/docview.wss?uid=isg3T1026811