Kernel page-table isolation merged

There can be - for example any code that tries to exploit this vulnerability will 'work' on Intel hardware and not AMD. But if you exclude code that has been specifically designed to exploit it, it seems unlikely.

CPUs are usually allowed to fetch whatever memory they fancy whenever they fancy (which gives them freedom to continually improve caches, prefetchers, speculative execution, etc), which is safe because it has no effect on application behaviour except in terms of instruction timing (and performance counters etc). Intel and AMD fetch memory quite differently, and different generations and models of CPUs by a single vendor fetch memory quite differently, so nobody writes applications that depend precisely on instruction timing. Except for people intentionally using timing attacks to extract information that exists inside the CPU pipeline but that wasn't meant to be observable to applications, which is presumably the problem here. (And except for buggy code with race conditions that get triggered by these timing changes, but that's so broken anyway that it doesn't really matter.)