Am I correct in understanding that any memory access to a previously unaccessed (therefore uncached) region will be counted as a cache miss?
I would like to understand when an access is eligible to be a cache miss and how modern memory caching works.
That’s correct. A cache miss happens whenever data you’re trying to access is not in the cache.
Rowhammer happens when you write to the same location over and over again, which might make it possible to distinguish the attack from normal usage.