On Thu, Jun 21, 2018 at 11:37:24AM +1200, Peter Reutemann wrote:
Hyper-threading (HT) is Intel's proprietary implementation of Simultaneous Multithreading (SMT), a technology that allows processors to run parallel operations on different cores of the same multi-core CPU.
I thought hyper-threading is about having two threads running on one CPU pipeline, thus within one core. Only just enough CPU resources (such as the register file) are duplicated so that the state of each thread can be separately maintained. By putting two threads on the one pipeline better utilisation is made of the pipeline. I suspect this will be why they are so vulnerable to the new attacks. The two threads share certain CPU resources such as the L1 cache so one can potentially perform a timing attack on the other to get an idea of what it is up to. Cheers Michael.