Intel has disclosed vulnerabilities called Microarchitectural Data Sampling (MDS) that apply to desktop and notebook computers with Intel CPUs, including all modern Mac computers.
You can check if hyper-threading is enabled or disabled in the System Information app. Just choose Apple menu > About This Mac, then click the System Report button. Then select Hardware in the sidebar. If the processor in your Mac supports hyper-threading, Hyper-Threading Technology is shown as either Enabled or Disabled.
Although there are no known exploits affecting customers at the time of this writing, customers who believe their computer is at heightened risk of attack can use the Terminal app to enable an additional CPU instruction and disable hyper-threading processing technology, which provides full protection from these security issues.
This option is available for macOS Mojave, High Sierra and Sierra and may have a significant impact on the performance of your computer.
The full mitigation, which includes disabling hyper-threading, prevents information leakage across threads and when transitioning between kernel and user space, which is associated with the MDS vulnerabilities for both local and remote (web) attacks.
Testing conducted by Apple in May 2019 showed as much as a 40 percent reduction in performance with tests that include multithreaded workloads and public benchmarks. Performance tests are conducted using specific Mac computers. Actual results will vary based on model, configuration, usage, and other factors.
How to enable full mitigation for MDS in macOS and how to revert the mitigation and reenable hyper-threading via Apple Support here.
MacDailyNews Take: Apple can’t begin to dump feckless Intel’s defective chips soon enough! It’s time to start moving Macs to vastly more efficient and secure Apple-designed solutions.
When flawed, insecure, and therefore defective products are sold to consumers, recalls and/or recompense are the proper responses. — MacDailyNews, January 4, 2018
CERT: The only way to fix the Meltdown and Spectre vulnerabilities is to replace the CPU. Intel et al. are going to try to sell us on a software bandaid instead of really fixing the problem properly. Watch and see. https://t.co/OeC2AoPdlK #Intel #AMD #ARM
— MacDailyNews (@MacDailyNews) January 4, 2018
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