[avianes]

> Or run Linux on ARM, and hope that noone will find similar exploits in the ARM architecure

It's a micro-architecture exploit, nothing specific to the x86 architecture. I highly suspect that some ARM implementations are also vulnerable to this exploit.

As long as return instructions can trick the Branch Preduction Unit (BPU) to produce a speculative return address that is not from the Return Stack Buffer (RSB), then return instructions can potentially be exploited to perform Branch-Target-Injection (Spectre V2). (I simplify it because there are other conditions such as the ability to set the injected branch address produced)