A Quick Look At The Spectre Mitigation State For AMD Zen 3 On Windows 10

[phoronix]

Phoronix: A Quick Look At The Spectre Mitigation State For AMD Zen 3 On Windows 10

Earlier this week I looked at the Spectre mitigation performance impact on AMD Zen+ / Zen 2 / Zen 3 processors given the recent launch of the Ryzen 5000 series and those newest CPUs still requiring some mitigation handling. Questions were raised about the Spectre mitigation handling on Windows, so I ran some quick tests there as I happened to have a Windows 10 install on the Ryzen 9 5900X test box at the moment for some unrelated Windows vs. Linux gaming...

http://www.phoronix.com/scan.php?page=news_item&px=AMD-5900X-Zen-3-Spectre-Windows

[ms178]

Unfortunately Inspectre was never updated to disable all the other mitigations which came after Spectre and Meltdown. I advise everyone to post the commands you find at this page provided by Microsoft into a Windows Power Shell with administrator rights if you want to get your performance back.

@Michael: Could you try if the following commands change anything?

To disable mitigations for CVE-2018-3639 (Speculative Store Bypass) *and* mitigations for CVE-2017-5715 (Spectre Variant 2) and CVE-2017-5754 (Meltdown)

reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contr ol\Session Manager\Memory Management" /v FeatureSettingsOverride /t REG_DWORD /d 3 /f

reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contr ol\Session Manager\Memory Management" /v FeatureSettingsOverrideMask /t REG_DWORD /d 3 /f

That should disable all the relevant mitigations for AMD systems.

For anyone on Intel systems, use the following to disable them all (they look to be the same though Microsoft lists them seperately):

To disable mitigations for Intel® Transactional Synchronization Extensions (Intel® TSX) Transaction Asynchronous Abort vulnerability (CVE-2019-11135) and Microarchitectural Data Sampling (CVE-2018-11091, CVE-2018-12126, CVE-2018-12127, CVE-2018-12130) along with Spectre (CVE-2017-5753 & CVE-2017-5715) and Meltdown (CVE-2017-5754) variants, including Speculative Store Bypass Disable (SSBD) (CVE-2018-3639) as well as L1 Terminal Fault (L1TF) (CVE-2018-3615, CVE-2018-3620, and CVE-2018-3646):
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contr ol\Session Manager\Memory Management" /v FeatureSettingsOverride /t REG_DWORD /d 3 /f
reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contr ol\Session Manager\Memory Management" /v FeatureSettingsOverrideMask /t REG_DWORD /d 3 /f

[ms178]

Ahhhrgs, you need to delete the white space in \Control\ - I wanted to edit my post to do this but it was flagged as Spam again.

[Bensam123]

Yeah, I've also been looking in a few different spots as a way to disable this in Windows. Apparently this snuck in at some point after I used the inSpectre tool. The above registry fix doesn't work. MDStool is showing the protections are still in place. I also tried Majorgeeks Manage Speculative Execution Protection Settings 3.3, that also doesn't work.

[Royi]

Anyone found anyway to disable them on Windows?