TLBleed is a new side channel attack that has been proven to work on Intel CPU’s with Hyperthreading (generally Simultaneous Multi-threading, or SMT, or HT on Intel) enabled. It relies on concurrent access to the TLB, and it being shared between threads. We find that the L1dtlb and the STLB (L2 TLB) is shared between threads on Intel CPU cores.

source: L