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> @@ -612,6 +622,10 @@ static void init_intel(struct cpuinfo_x86 *c) > if (x86_match_cpu(zmm_exclusion_list)) > set_cpu_cap(c, X86_FEATURE_PREFER_YMM); > > + if (x86_match_cpu(implicit_rfds_list) && > + !boot_cpu_has_bug(X86_BUG_OLD_MICROCODE)) > + setup_force_cpu_cap(X86_FEATURE_RFDS_CLEAR); > + I do not understand the usage of X86_BUG_OLD_MICROCODE over here. "old_microcode" by design is a moving target. That would imply that this feature/mitigation would depend on keeping the microcode up-to-date. Let's say for example that a new microcode blob gets released for INTEL_ATOM_GOLDMONT for some unrelated reason. Do we want the kernel behavior for RFDS_CLEAR feature to change just because someone didn't perform the update? If this is intentional, we should probably add a comment here or near "struct x86_cpu_id implicit_rfds_list" to describe this choice. I see that Dave suggested this in the previous review to avoid checks such as (c->microcode >= 0x4c000026). But, that seems redundant in some sense. You could simply do: if (x86_match_cpu(implicit_rfds_list) setup_force_cpu_cap(X86_FEATURE_RFDS_CLEAR); The old microcode mechanism will work independently and complain separately about the user not running with the latest microcode. Old microcode by definition means: "CPU has old microcode, it is surely vulnerable to something." This way Linux behavior for this feature doesn't vary from one kernel to another.