AMD releases Linux patches to disable vulnerable PSF prediction engine
Last week it became known that AMD processors based on Zen 3 architecture are susceptible to side-channel attacks. Specter and Meltdown, which are mainly inherent in Intel processors, are prominent representatives of this vulnerability type. Later, AMD promised to provide patches for Linux that would disable the PSF prediction engine, which is exactly the subject of the vulnerability. The distribution of these fixes started today.
The journalists Phoronix found that the Linux kernel has appeared five new patches, which allow you to disable the Predictive Store Forwarding system (PSF) in the processors Ryzen 5000th and 7003rd EPYC series. After installing the patch, the PSF mechanism remains enabled, but the user gets the opportunity to disable it if necessary. To do this, you need to set nopsfd in the boot parameters.
AMD itself does not believe that the new vulnerability poses a real threat. The company warns that disabling the prediction engine could degrade processor performance. However, tests have shown that disabling PSF has a minimal performance impact. Users have found that the difference is only visible in long-term workloads, and even in those workloads, there is only a 1-2 percent drop in performance or less.
