On 10/01/2018 18:14, Jim Mattson wrote: >>> If (a) is true, does "IBRS ALL THE TIME" usage is basically a CPU >>> change to just create all BTB/BHB entries to be tagged with >>> prediction-mode at creation-time and that tag to be compared to current >>> prediction-mode when CPU attempts to use BTB/BHB? >> >> I hope so, and I hope said prediction mode includes PCID/VPID too. > > Branch prediction entries should probably be tagged with PCID, VPID, > EP4TA, and thread ID...the same things used to tag TLB contexts. But if so, I don't see the need for IBPB. Paolo
