On Fri, May 8, 2020 at 8:03 PM Xiaoyao Li <xiaoyao.li@xxxxxxxxx> wrote: > > Introduce a synthetic feature flag X86_FEATURE_SLD_FATAL, which means > kernel is in sld_fatal mode if set. > > Now sld_state is not needed any more that the state of SLD can be > inferred from X86_FEATURE_SPLIT_LOCK_DETECT and X86_FEATURE_SLD_FATAL. Is it too much to ask for Intel to actually allocate and define a CPUID bit that means "this CPU *always* sends #AC on a split lock"? This would be a pure documentation change, but it would make this architectural rather than something that each hypervisor needs to hack up. Meanwhile, I don't see why adding a cpufeature flag is worthwhile to avoid a less bizarre global variable. There's no performance issue here, and the old code looked a lot more comprehensible than the new code.
