USN-4628-2: Intel Microcode regression

USN-4628-1 provided updated Intel Processor Microcode. Unfortunately,
that update prevented certain processors in the Intel Tiger Lake family
from booting successfully. This update reverts the microcode update for
the Tiger Lake processor family.

Please note that the ‘dis_ucode_ldr’ kernel command line option can be
added in the boot menu to disable microcode loading for system recovery.

We apologize for the inconvenience.

Original advisory details:

Moritz Lipp, Michael Schwarz, Andreas Kogler, David Oswald, Catherine
Easdon, Claudio Canella, and Daniel Gruss discovered that the Intel Running
Average Power Limit (RAPL) feature of some Intel processors allowed a side-
channel attack based on power consumption measurements. A local attacker
could possibly use this to expose sensitive information. (CVE-2020-8695)

Ezra Caltum, Joseph Nuzman, Nir Shildan and Ofir Joseff discovered that
some Intel(R) Processors did not properly remove sensitive information
before storage or transfer in some situations. A local attacker could
possibly use this to expose sensitive information. (CVE-2020-8696)

Ezra Caltum, Joseph Nuzman, Nir Shildan and Ofir Joseff discovered that
some Intel(R) Processors did not properly isolate shared resources in some
situations. A local attacker could possibly use this to expose sensitive
information. (CVE-2020-8698)