On Sun, Jan 07, 2018 at 12:15:40PM -0800, Dan Williams wrote: > > I'm thinking we should provide the option to at least build the > hot-path nospec_array_ptr() usages without an lfence. > > CONFIG_SPECTRE1_PARANOIA_SAFE > CONFIG_SPECTRE1_PARANOIA_PERF SAFE vs PERF naming is problematic and misleading, since users don't have the data to make a decision they will be forced to go with SAFE. What is not safe about array_access() macro with AND ? How lfence approach makes it safer ? Only because lfence was blessed by intel earlier when they couldn't figure out a different way? How about: CONFIG_SPECTRE1_WORKAROUND_INDEX_MASK CONFIG_SPECTRE1_WORKAROUND_LOAD_FENCE > ...if only for easing performance testing and let the distribution set > its policy. > > Where hot-path usages can do: > > nospec_relax(nospec_array_ptr()) AND approach doesn't prevent speculation hence nospec_ is an incorrect prefix. Alan's "speculation management" terminology fits well here. Can we keep array_access() name and change it underneath to either mask or lfence ?
