• Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

Critical Flaw in HyperThreading Discovered in "Skylake" and "Kaby Lake" CPUs

btarunr

Editor & Senior Moderator
Staff member
Joined
Oct 9, 2007
Messages
38,102 (8.42/day)
Location
Hyderabad, India
Processor AMD Ryzen 7 2700X
Motherboard ASUS ROG Strix B450-E Gaming
Cooling AMD Wraith Prism
Memory 2x 16GB Corsair Vengeance LPX DDR4-3000
Video Card(s) Palit GeForce RTX 2080 SUPER GameRock
Storage Western Digital Black NVMe 512GB
Display(s) Samsung U28D590 28-inch 4K UHD
Case Corsair Carbide 100R
Audio Device(s) Creative Sound Blaster Recon3D PCIe
Power Supply Cooler Master MWE Gold 650W
Mouse ASUS ROG Strix Impact
Keyboard Microsoft Sidewinder X4
Software Windows 10 Pro
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.

View at TechPowerUp Main Site
 
Last edited by a moderator:
Joined
Oct 2, 2004
Messages
13,791 (2.45/day)
Intel is really getting a shitstorm shoved straight in their face. I bet AMD is chuckling evilishly in the corner :D
 

Frick

Fishfaced Nincompoop
Joined
Feb 27, 2006
Messages
16,080 (3.15/day)
Location
Piteå
System Name Black MC in Tokyo
Processor Ryzen 5 2600x
Motherboard Asrock B450M-HDV
Cooling AMD Wraith Spire I think
Memory 2 x 8GB G-skill Aegis 3000 or somesuch
Video Card(s) Asus GTX 760 DCU2OC 2GB
Storage Kingston A400 240GB | WD Blue 1TB x 2
Display(s) BenQ GL2450HT
Case Some old Antec
Audio Device(s) Line6 UX1 + slightly modded Sony DR-ZX302
Power Supply Fractal Design Effekt 400W
Mouse Logitech G602
Keyboard Cherry MX-Board 3.0
Software Windows 10 Pro
Benchmark Scores I once had +100 dorfs in DF, so yeah pretty great
Joined
Apr 10, 2013
Messages
285 (0.11/day)
Location
Michigan, USA
Processor AMD 1700X
Motherboard Crosshair VI Hero
Memory F4-3200C14D-16GFX
Video Card(s) GTX 1070
Storage 960 Pro
Display(s) PG279Q
Case HAF X
Power Supply Silencer MK III 850
Mouse Logitech G700s
Keyboard Logitech G105
Software Windows 10
Do we have any cases of anything negative happening related to this? I can't believe we should really disable functionality based on nameless "Debian support groups" rather than Intel's specification update errata. Skylake has been around a long time now and forums show remarkable stability with CPU related tasks.
 
Joined
Jan 5, 2006
Messages
10,177 (1.97/day)
System Name Desktop / Laptop
Processor Intel i7 6700K @ 4.3GHz (1.180 V) / Intel i3 7100U
Motherboard Asus Z170 Pro Gaming / HP 83A3 (U3E1)
Cooling Noctua NH-U12A 2 fans + Thermal Grizzly Kryonaut + 5 case fans / Fan
Memory 16GB DDR4 Corsair Vengeance LPX 3000MHz CL15 / 8GB DDR4 HyperX CL13
Video Card(s) MSI RTX 2070 Super Gaming X Trio / Intel HD620
Storage Samsung 970 Evo 500GB + Samsung 850 Pro 512GB + Samsung 860 Evo 1TB / Samsung 256GB M.2 SSD
Display(s) 23.8" Dell S2417DG 165Hz G-Sync 1440p + 21.5" LG 22MP67VQ IPS 60Hz 1080p / 14" 1080p IPS Glossy
Case Be quiet! Silent Base 600 - Window / HP Pavilion
Audio Device(s) SupremeFX Onboard / Realtek onboard + B&O speaker system
Power Supply Seasonic Focus Plus Gold 750W / Powerbrick
Mouse Logitech MX Anywhere 2 Laser wireless / Logitech M330 wireless
Keyboard RAPOO E9270P Black 5GHz wireless / HP backlit
Software Windows 10 / Windows 10
Glad I'm fine then with my i5 with no hyper threading.:)
 
Joined
Mar 6, 2017
Messages
1,809 (1.67/day)
Location
North East Ohio, USA
System Name My Super Computer
Processor Intel Core i7 8700K
Motherboard Gigabyte Z370 AORUS Ultra Gaming
Cooling Corsair H55 AIO
Memory 2x8GB Crucial/Micron Ballistix Sport DDR4-2400
Video Card(s) ASUS GeForce GTX1060 6GB
Storage Samsung 970 EVO 500 GB NVMe SSD (System Drive), Samsung 860 EVO 500 GB SATA SSD (Game Drive)
Display(s) HP 2311x and Acer G206HQL
Case CoolerMaster MasterBox Lite 5 RGB
Audio Device(s) On-Board Sound
Power Supply EVGA Supernova 650 G3 Gold
Mouse Logitech M705
Keyboard Logitech Wave K350
Software Windows 10 Pro 64-bit
Benchmark Scores https://valid.x86.fr/liwjs3
Microsoft will probably issue a patch to the OS itself that loads new microcode at load time. It's not the first time Microsoft has done such a thing. It's happened before (example).
 

Frick

Fishfaced Nincompoop
Joined
Feb 27, 2006
Messages
16,080 (3.15/day)
Location
Piteå
System Name Black MC in Tokyo
Processor Ryzen 5 2600x
Motherboard Asrock B450M-HDV
Cooling AMD Wraith Spire I think
Memory 2 x 8GB G-skill Aegis 3000 or somesuch
Video Card(s) Asus GTX 760 DCU2OC 2GB
Storage Kingston A400 240GB | WD Blue 1TB x 2
Display(s) BenQ GL2450HT
Case Some old Antec
Audio Device(s) Line6 UX1 + slightly modded Sony DR-ZX302
Power Supply Fractal Design Effekt 400W
Mouse Logitech G602
Keyboard Cherry MX-Board 3.0
Software Windows 10 Pro
Benchmark Scores I once had +100 dorfs in DF, so yeah pretty great
Do we have any cases of anything negative happening related to this? I can't believe we should really disable functionality based on nameless "Debian support groups" rather than Intel's specification update errata. Skylake has been around a long time now and forums show remarkable stability with CPU related tasks.
https://caml.inria.fr/mantis/view.php?id=7452

I don't pretend to understand it, but well.
 

Solaris17

Dainty Moderator
Staff member
Joined
Aug 16, 2005
Messages
21,282 (4.01/day)
Location
Florida
System Name Venslar
Processor I9 7980XE
Motherboard MSI x299 Tomahawk Arctic
Cooling EK Custom
Memory 32GB Corsair DDR4 3000mhz
Video Card(s) Nvidia Titan RTX
Storage 2x Micron 500GB SSD | 1x 1TB 850 EVO | 1x 250GB 960 EVO | 32TB SAN
Display(s) 3x AOC Q2577PWQ (2k IPS)
Case Inwin 303 White (Thermaltake Ring 120mm Purple accent)
Audio Device(s) Focusrite Scarlett Solo on beyerdynamic DT 990 Pros
Power Supply Seasonic 1050W Snow
Mouse Roccat Kone Aimo White
Keyboard Ducky Shine 6 Snow White
Software Windows 10 x64 Pro
Do we have any cases of anything negative happening related to this? I can't believe we should really disable functionality based on nameless "Debian support groups" rather than Intel's specification update errata. Skylake has been around a long time now and forums show remarkable stability with CPU related tasks.
then lets look where the well trusted debian group got it.

https://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/7th-gen-core-family-spec-update.pdf
 

CAPSLOCKSTUCK

Spaced Out Lunar Tick
Joined
Feb 26, 2013
Messages
8,579 (3.36/day)
Location
llaregguB...WALES
System Name Party On
Processor Xeon w 3520
Motherboard DFI Lanparty
Cooling Big tower thing
Memory 6 gb Ballistix Tracer
Video Card(s) HD 7970
Case a plank of wood
Audio Device(s) seperate amp and 6 big speakers
Power Supply Corsair
Mouse cheap
Keyboard under going restoration
No problems here


Long live socket 1366..........:peace:
 
Joined
Apr 1, 2010
Messages
220 (0.06/day)
why now?
skylake and kaby lake are out for a long time ,so how was it not found before?
 
Joined
Dec 31, 2009
Messages
16,647 (4.49/day)
Its so critical, yet, what is actually wrong? The article here doesn't say much at all, sadly. Thank you, Frick, for taking the time to do that, for free...

Microsoft will probably issue a patch to the OS itself that loads new microcode at load time. It's not the first time Microsoft has done such a thing. It's happened before (example).
Or, as was said, they will do it in a microcode update in the form of a new bios from AIBs/OEMs...
 
Joined
Mar 6, 2017
Messages
1,809 (1.67/day)
Location
North East Ohio, USA
System Name My Super Computer
Processor Intel Core i7 8700K
Motherboard Gigabyte Z370 AORUS Ultra Gaming
Cooling Corsair H55 AIO
Memory 2x8GB Crucial/Micron Ballistix Sport DDR4-2400
Video Card(s) ASUS GeForce GTX1060 6GB
Storage Samsung 970 EVO 500 GB NVMe SSD (System Drive), Samsung 860 EVO 500 GB SATA SSD (Game Drive)
Display(s) HP 2311x and Acer G206HQL
Case CoolerMaster MasterBox Lite 5 RGB
Audio Device(s) On-Board Sound
Power Supply EVGA Supernova 650 G3 Gold
Mouse Logitech M705
Keyboard Logitech Wave K350
Software Windows 10 Pro 64-bit
Benchmark Scores https://valid.x86.fr/liwjs3
Enthusiast motherboards may get the BIOS/UEFI update to fix it but as for the OEMs like HP, Dell, etc.? Fat chance!
 
Joined
Mar 6, 2017
Messages
1,809 (1.67/day)
Location
North East Ohio, USA
System Name My Super Computer
Processor Intel Core i7 8700K
Motherboard Gigabyte Z370 AORUS Ultra Gaming
Cooling Corsair H55 AIO
Memory 2x8GB Crucial/Micron Ballistix Sport DDR4-2400
Video Card(s) ASUS GeForce GTX1060 6GB
Storage Samsung 970 EVO 500 GB NVMe SSD (System Drive), Samsung 860 EVO 500 GB SATA SSD (Game Drive)
Display(s) HP 2311x and Acer G206HQL
Case CoolerMaster MasterBox Lite 5 RGB
Audio Device(s) On-Board Sound
Power Supply EVGA Supernova 650 G3 Gold
Mouse Logitech M705
Keyboard Logitech Wave K350
Software Windows 10 Pro 64-bit
Benchmark Scores https://valid.x86.fr/liwjs3
Apparently you have more faith in the OEMs than I do, which is none.
 
Joined
Mar 6, 2017
Messages
1,809 (1.67/day)
Location
North East Ohio, USA
System Name My Super Computer
Processor Intel Core i7 8700K
Motherboard Gigabyte Z370 AORUS Ultra Gaming
Cooling Corsair H55 AIO
Memory 2x8GB Crucial/Micron Ballistix Sport DDR4-2400
Video Card(s) ASUS GeForce GTX1060 6GB
Storage Samsung 970 EVO 500 GB NVMe SSD (System Drive), Samsung 860 EVO 500 GB SATA SSD (Game Drive)
Display(s) HP 2311x and Acer G206HQL
Case CoolerMaster MasterBox Lite 5 RGB
Audio Device(s) On-Board Sound
Power Supply EVGA Supernova 650 G3 Gold
Mouse Logitech M705
Keyboard Logitech Wave K350
Software Windows 10 Pro 64-bit
Benchmark Scores https://valid.x86.fr/liwjs3
Most OEM hardware is less than shit. There's a reason why I built my own PCs.
 
Joined
Mar 18, 2008
Messages
4,821 (1.11/day)
System Name Virtual Reality / Bioinformatics
Processor Undead CPU
Motherboard Undead TUF X99
Cooling Noctua NH-D15
Memory GSkill 128GB DDR4-3000
Video Card(s) EVGA 2080Ti
Storage Samsung 960 Pro 1TB + 860 EVO 2TB + WD Black 5TB
Display(s) Acer K272HUL, HTC Vive
Case Fractal Design R5
Audio Device(s) BOSE 2.0
Power Supply Seasonic 850watt
Mouse Logitech Master MX
Keyboard Corsair K70 Cherry MX Blue
Software Windows 10 Professional/Linux Mint
This should affect the new Core I9 X processors as well. Oops.
 

Frick

Fishfaced Nincompoop
Joined
Feb 27, 2006
Messages
16,080 (3.15/day)
Location
Piteå
System Name Black MC in Tokyo
Processor Ryzen 5 2600x
Motherboard Asrock B450M-HDV
Cooling AMD Wraith Spire I think
Memory 2 x 8GB G-skill Aegis 3000 or somesuch
Video Card(s) Asus GTX 760 DCU2OC 2GB
Storage Kingston A400 240GB | WD Blue 1TB x 2
Display(s) BenQ GL2450HT
Case Some old Antec
Audio Device(s) Line6 UX1 + slightly modded Sony DR-ZX302
Power Supply Fractal Design Effekt 400W
Mouse Logitech G602
Keyboard Cherry MX-Board 3.0
Software Windows 10 Pro
Benchmark Scores I once had +100 dorfs in DF, so yeah pretty great
Joined
Jan 3, 2015
Messages
1,501 (0.80/day)
System Name Suffering from random access memory loss.
Processor Intel Core i7 980X @ 4.42 GHz (when becnching op to 4.77 GHz)
Motherboard ASUS P6X58D Premium
Cooling Noctua NH-D14 CPU cooler with 3 x noctua nf-f12 industrialppc-3000 pwm 120 MM fans
Memory 12 GB DDR3 CORSAIR 1600 MHz TIMMINGS 9-9-9-24
Video Card(s) EVGA GeForce GTX 1080 Ti SC2 GAMING
Storage 2 x Samsung 950 PRO 256 GB M.2 NVME SSD, Crucial MX300 2 TB SSD, WD RED 4 TB + WD AV-GP 2 TB HDD.
Display(s) 24" SAMSUNG
Case ANTEC TWELVE HUNDRED
Audio Device(s) ONBOARD realtek sound card.
Power Supply THERMALTAKE TOUGHPOWER 1500 WATT
Mouse Logitech G903 Lightspeed Wireless Gaming Mouse
Keyboard LOGITECH G19s
Software WINDOWS 10 PRO 64 BITS
Benchmark Scores https://www.3dmark.com/fs/13514527 https://www.3dmark.com/spy/2333033
Just another good reason to stay on X58 for a while longer. X58 never failed or been a pain in the ass and its not like X58 lagging features i need.

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.
 
Last edited:
Joined
Nov 4, 2005
Messages
10,499 (2.01/day)
System Name MoFo 2
Processor AMD PhenomII 1100T @ 4.2Ghz
Motherboard Asus Crosshair IV
Cooling Swiftec 655 pump, Apogee GT,, MCR360mm Rad, 1/2 loop.
Memory 8GB DDR3-2133 @ 1900 8.9.9.24 1T
Video Card(s) HD7970 1250/1750
Storage Agility 3 SSD 6TB RAID 0 on RAID Card
Display(s) 46" 1080P Toshiba LCD
Case Rosewill R6A34-BK modded (thanks to MKmods)
Audio Device(s) ATI HDMI
Power Supply 750W PC Power & Cooling modded (thanks to MKmods)
Software A lot.
Benchmark Scores Its fast. Enough.
AMD "We are making a new Ryzen spin to fix minor bugs, also have this BIOS to push performance up to help close that 5% gap at half the price and noob level overclocking with power savings too"

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.
 
Joined
Jan 10, 2011
Messages
830 (0.25/day)
Location
Sudan, the lesser known, bigger home of the Nile.
System Name 192.168.1.1~192.16.1.100
Processor Intel Core i7 4770k
Motherboard Asus B85M-G
Cooling Corsair H60
Memory 20GB mixed sticks (because screw best practices)
Video Card(s) Gigabyte GTX 1080 OC (Underclocked, underpowered)
Storage Samsung 850 Evo + lots of TBs of HDD storage.
Display(s) LG 24MK430 Primary + Samsung S24D590 secondary
Case Corsair Graphite 780T
Audio Device(s) On-Board
Power Supply Coolermaster 850V
Mouse Coolermaster MM530
Keyboard Kingston HyperX Alloy FPS
Software Windows 10 Pro
Benchmark Scores Me no know English. What bench mean? Bench like one sit on?
Just another good reason to stay on X58 for a while longer. X58 never failed or been a pain in the ass and its not like X58 lagging features i need.

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.

At the risk of sounding an Intel apologist, bugs happen, we can't really fault intel much here. Sure, someone was sloppy with their work, but it doesn't really have that much an effect to drive this negative a reaction. If intel bugs has been considerably frequent, it would've been a different story, but it isn't. Moreover, according to Frick's link, the fix for this issue is already out there.
 
Joined
Feb 17, 2017
Messages
806 (0.73/day)
Location
Italy
Processor i7 2600K @4.5GHz
Motherboard Asus P8Z68-V PRO/Gen 3
Cooling ZeroTherm FZ120
Memory G.Skill Ripjaws 4x4GB DDR3
Video Card(s) MSI GTX 1060 6G Gaming X
Storage Samsung 830 Pro 256GB + WD Caviar Blue 1TB
Display(s) Samsung PX2370 + Acer AL1717
Case Antec 1200 v1
Audio Device(s) aune x1s
Power Supply Enermax Modu87+ 800W
Mouse Logitech G403
Keyboard Qpad MK80
Intel is really getting a shitstorm shoved straight in their face. I bet AMD is chuckling evilishly in the corner :D
And you're happy, are you not? :):):)
 
Joined
Dec 12, 2011
Messages
79 (0.03/day)
It is called Debian GNU/Linux, not Debian Linux. It is not a Linux made by Debian, but a GNU/Linux operating system put together by Debian.
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.
 
Last edited:

Solaris17

Dainty Moderator
Staff member
Joined
Aug 16, 2005
Messages
21,282 (4.01/day)
Location
Florida
System Name Venslar
Processor I9 7980XE
Motherboard MSI x299 Tomahawk Arctic
Cooling EK Custom
Memory 32GB Corsair DDR4 3000mhz
Video Card(s) Nvidia Titan RTX
Storage 2x Micron 500GB SSD | 1x 1TB 850 EVO | 1x 250GB 960 EVO | 32TB SAN
Display(s) 3x AOC Q2577PWQ (2k IPS)
Case Inwin 303 White (Thermaltake Ring 120mm Purple accent)
Audio Device(s) Focusrite Scarlett Solo on beyerdynamic DT 990 Pros
Power Supply Seasonic 1050W Snow
Mouse Roccat Kone Aimo White
Keyboard Ducky Shine 6 Snow White
Software Windows 10 x64 Pro
Intel has been shoddy here. Not talking about this bug nor contacting with those who discovered it. The microcode was released silently.
lol?

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

http://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.

http://support.amd.com/en-us/search/tech-docs#k=errata
 
Last edited:
Top