AMD’s recently published a whitepaper in their security blog detailing PSF or Predictive Store Forwarding. This technique is utilized in their Ryzen 5000 series of CPUs as one of the many architectural techniques the CPU uses to gain its performance.
“PSF is a hardware-based micro-architectural optimization designed to improve the performance of code execution by predicting dependencies between loads and stores.” – AMD
It can be recalled that Spectre, the security exploit on Intel CPUs which abuses the vulnerability found on its prediction technique. This also exposes that techniques for speculative execution are have their owns issues regardless of design.
The post states that AMD CPUs, according to their chip architects, have discovered that isolation-dependent software or those that rely on “sandboxing” are a high risk. When PSF misses, these software become at risk, as an exploit to Spectre can exploit mispredictions of PSF.
If security is an issue, it is advised to disable the PSF on AMD systems. Phoronix has performed tests to show that the CPUs only take a less than a percent performance hit.
Source: AMD Blog
