On Tue, Sep 25, 2018 at 11:58:44PM -0400, Rik van Riel wrote: > @@ -594,8 +628,23 @@ void native_flush_tlb_others(const struct cpumask > *cpumask, > (void *)info, 1); > return; > } > - smp_call_function_many(cpumask, flush_tlb_func_remote, > + > + /* > + * If no page tables were freed, we can skip sending IPIs to > + * CPUs in lazy TLB mode. They will flush the CPU themselves > + * at the next context switch. > + * > + * However, if page tables are getting freed, we need to send the > + * IPI everywhere, to prevent CPUs in lazy TLB mode from tripping > + * up on the new contents of what used to be page tables, while > + * doing a speculative memory access. > + */ > + if (info->freed_tables) > + smp_call_function_many(cpumask, flush_tlb_func_remote, > (void *)info, 1); > + else > + on_each_cpu_cond_mask(tlb_is_not_lazy, flush_tlb_func_remote, > + (void *)info, 1, GFP_ATOMIC, cpumask); > }
And this is safe vs paravirt, because for native we now do _less_ invalidations. That might warrant a mention in the Changelog perhaps.
