Critical Flaw In Intel Skylake And Kaby Lake HyperThreading Discovered Requiring BIOS Microcode Fix

[LASER_oneXM]

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Unpredictable system behavior is seldom a desired state of operation, obviously. These errors can cause anything from system lockups to data corruption or loss. Before we get too apocalyptic on this issue, however, the replication conditions are very specific and are unlikely to be encountered by most users in the wild. Still, the report from Linux-distro Debian does recommend disabling HyperThreading until a relevant microcode update is applied as a precaution.

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A new flaw has been disclosed that impacts most Intel 6th and 7th Generation Skylake and Kaby Lake-based processors that support HyperThreading, and reportedly exists across all operating systems. The issue was just disclosed on the Debian Linux user list and sent out with a warning notification, but again, this issue affects all OSes beyond just Linux.

The flaw is detailed by Intel errata documentation as follows:

Errata: SKZ7/SKW144/SKL150/SKX150/SKZ7/KBL095/KBW095
"Short Loops Which Use AH/BH/CH/DH Registers May Cause Unpredictable System Behavior."

Problem: "Under complex micro-architectural conditions, short loops of less than 64 instructions that use AH, BH, CH or DH registers as well as their corresponding wider register (e.g. RAX, EAX or AX for AH) may cause unpredictable system behavior. This can only happen when both logical processors on the same physical processor are active."

Implication: "Due to this erratum, the system may experience unpredictable system behavior."

 

[Dean Winchestere]

AMD put intel to shame!