On 09/01/2018 17:13, Liran Alon wrote: >>> Why are you doing here "has_spec_ctrl() ||" and not just checking >> "cpuid(0x80000008).b & (1 << 12)"? >> >> Because Intel's recent microcode updates do not expose >> CPUID[EAX=0x80000008].EBX[12], but they do add PRED_CMD MSR. > > OK that's weird... :) > So doesn't it make sense to also have same logic in cpu_has_ibpb_support() in KVM? Note that cpu_has_ibpb_support() is not going to exist in the final committed version of the series. It's just a hack for testing before the bare metal IBRS/IBPB patches are in. > Also, I would add an appropriate comment above those lines as this is not trivial. Ok, will do. Paolo
