Monday, June 26th 2017
Critical Flaw in HyperThreading Discovered in "Skylake" and "Kaby Lake" CPUs
A critical flaw was discovered in the way Intel implemented its simultaneous multi-threading technology, HyperThreading, on "Skylake" and "Kaby Lake" processors. Being a micro-architecture specific flaw, this could affect all implementations, from low-power mobile chips, to mainstream desktop, high-end desktop, and perhaps even enterprise-segment Xeon processors. At this time, there are no security implications of this flaw.
Intel chronicled this flaw in its micro-architecture errata "SKZ7/SKW144/SKL150/SKX150/SKZ7/KBL095/KBW095," and described it as follows: "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." As an implication, Intel goes on to note that Due to this erratum, the system may experience unpredictable system behavior."
The HyperThreading flaw can be fixed through a micro-code update distributed as a UEFI firmware update. Typically, it becomes the responsibility of DIY PC motherboard, pre-built desktop, and notebook manufacturers, to distribute the update. The issue first came to light in a Debian Linux user mailing-list, although it affects all PC operating systems, not just Linux. Support groups of Debian recommend disabling HyperThreading in the UEFI setup programs of your computers as a temporary workaround, till the micro-code patch is applied. Disabling HyperThreading will reduce performance in multi-threaded apps.
Source:
Debian Mailing List
Intel chronicled this flaw in its micro-architecture errata "SKZ7/SKW144/SKL150/SKX150/SKZ7/KBL095/KBW095," and described it as follows: "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." As an implication, Intel goes on to note that Due to this erratum, the system may experience unpredictable system behavior."
98 Comments on Critical Flaw in HyperThreading Discovered in "Skylake" and "Kaby Lake" CPUs
lists.debian.org/debian-devel/2017/06/msg00308.html
Of note is probably how it affects two generations, mostly because that tells you how much of an edge case it is.
I don't pretend to understand it, but well.
www.intel.com/content/dam/www/public/us/en/documents/specification-updates/7th-gen-core-family-spec-update.pdf
Long live socket 1366..........:peace:
skylake and kaby lake are out for a long time ,so how was it not found before?
Intel really messing up one thing after another lately. Some Atom cpu had a flaw, skylake X whas a rushed messed up lauch and now hyper trading is being a pain in the ass, intel else have used HT since the Pentium 4 days so is´t nothing new for them. But thats what you get when you become lazy, greedy and just pissing on customers.
Just waiting for my GTX 1080 TI to come and my X58 system upgrade is now complete for a year or two, then i am properly going on a new system.
Until then you can suck it intel. I am not gonna pay lazy bums then they just fucking things up any way and rips your wallet.
HOLY CRAP THEY ARE SCREWING US ALL HOW ABOUT US BETA TESTERS FOR AMD I CAN'T BELIEVE THEY WOULD DO THIS!!!
Intel "HT is broken for some things, also here is the same processor with MORE CORES and same issues higher power consumption and more thermal limits and no overclocking supported, also make sure you match your CPU to the configuration you want for PCIe lanes and memory or else"
Its OK, they will patch it with BIOS updates, everyone should be OK with BIOS updates and known issues...
Amazing.
Source.
A large part of the basic tools that fill out the operating system come from the GNU project; hence the names: GNU/Linux, GNU/kFreeBSD, and GNU/Hurd. These tools are also free.
Intel has been shoddy here. Not talking about this bug nor contacting with those who reported it to them. The microcode was released silently.
Intel is more transparent with errata than AMD ever has. Its been there motto since forever! You can download the PDF errata documents of any intel CPU product family right from there website?
Silly consumers. This happens all the time. it just doesnt normally affect home users because the software is either IE resilient or it doesnt trigger the issue. Notice how the people that found it were running server teams with large data sets?
Does the forum consensus on TPU actually think CPUs are made without fault other than missing or wanted feature sets by consumers? every single CPU revision has a published errata.
This isnt shady at all. They do it with everything, if you can get your hands on/if the company publishes the documents. from chipsets to hard drive micro-controllers.
EDIT:: Lets take a look
support.amd.com/TechDocs/51810_16h_00h-0Fh_Rev_Guide.pdf
Looks like AMD does it too, and no plan to fix at that. Where is your god now AMD fans?
Here ya go. I took about 35seconds to shatter your delusions of purity.
support.amd.com/en-us/search/tech-docs#k=errata