Intel Skylake/Kaby Lake Hyper-threading bug update
TL;DR: Intel has issued public microcode updates in 2017-07-07, fixing
the hyper-threading errata on every affected processor. These updates
have been included in the stable and oldstable point releases from
2017-07-22.
The microcode updates in the "intel-microcode" packages with the base
version of 3.20170707.1 fix the hyper-threading defect on every known-
affected Intel processor, including Kaby Lake and all variants of
Skylake.
Updated intel-microcode packages are already available for oldstable,
stable, testing, unstable, jessie-backports-sloppy and
stretch-backports.
For more details and instructions, please refer to:
https://wiki.debian.org/Microcode
FAQ about the "hyper-threading defect":
Q. Does the Intel "microcode update" that fixes the defect remove
hyper-threading support?
A. The updated microcode *fixes* hyper-threading, it does *not* remove
hyper-threading support.
Upgraded microcode information related to these errata:
Skylake D0/R0 (mobile/desktop), signatures 0x406e3, 0x506e3:
Known to be fixed in microcode revision 0xb9/0xba and later. Public fix
available in linux microcode 20170511 and later.
Skylake H0 (server/HEDT/X-series), signature 0x50654:
Known to be fixed in microcode revision 0x2000022 and later, and it
might have been fixed since revision 0x200001a. Public fix available in
linux microcode 20170707 and later.
Kaby Lake H0/B0 (mobile/desktop), signatures 0x806e9, 0x906e9 (pf mask 0x22):
Known to be fixed in microcode revision 0x5d/0x5e and later. Public fix
available in linux microcode 20170707 and later.
Kaby Lake X-series, signature 0x906e9 (pf mask 0x08):
These processors are *NOT* affected when installed in a *supported*
motherboard configuration (i.e. one that had its firmware updated to be
compatible with Kaby Lake X-series). The launch production microcode
already has the fix (believed to be microcode revision 0x5d or later
based on the processor flags mask).
Kaby Lake Y0: signature 0x806ea:
Known to be fixed in microcode revision 0x65/0x66 and later, and it
might have been fixed since revision 0x5d/0x5e. Public fix available in
linux microcode 20170707 and later.
References from the original advisory:
https://caml.inria.fr/mantis/view.php?id=7452
http://metadata.ftp-master.debian.org/changelogs/non-free/i/intel-microcode/unstable_changelog
https://www.intel.com/content/www/us/en/processors/core/desktop-6th-gen-core-family-spec-update.html
https://www.intel.com/content/www/us/en/processors/core/7th-gen-core-family-spec-update.html
https://www.intel.com/content/www/us/en/processors/xeon/xeon-e3-1200v6-spec-update.html
https://www.intel.com/content/www/us/en/processors/xeon/xeon-e3-1200v5-spec-update.html
https://www.intel.com/content/www/us/en/products/processors/core/6th-gen-x-series-spec-update.html
New references:
The two new references below contain material that was not known to the
Debian maintainers or to the Debian project:
https://medium.com/ahrefs/skylake-bug-a-detective-story-ab1ad2beddcd
http://gallium.inria.fr/blog/intel-skylake-bug/
--
Henrique Holschuh
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