A new line of attack bypasses all current Spectre protections built into the chips. The new attack method exploits what’s called a micro-operations cache, an on-chip component that decomposes machine instructions into simpler commands and speeds up computing, as a side-channel to divulge secret information. To safeguard from the new attack, the researchers propose flushing the micro-ops cache, a technique that offsets the performance benefits gained by using the cache in the first place, and leverage performance counters to detect anomalies.
Source: https://thehackernews.com/2021/05/new-spectre-flaws-in-intel-and-amd-cpus.html