On Fri, Nov 03 2023 at 19:58, Andrew Cooper wrote: > On 02/11/2023 12:26 pm, Andrew Cooper wrote: > Another dodgy construct spotted while doing this work is > > #ifdef CONFIG_X86_32 > #define BAD_APICID 0xFFu > #else > #define BAD_APICID 0xFFFFu > #endif > > considering that both of those "bad" values are legal APIC IDs in an > x2APIC system. > > The majority use is as a sentential (of varying types - int, u16 > mostly), although the uses for NUM_APIC_CLUSTERS, and > safe_smp_processor_id() look suspect. > > In particular, safe_smp_processor_id() *will* malfunction on some legal > CPUs, and needs to use -1 (32 bits wide) to spot the intended error case > of a bad xAPIC mapping. > > However, it's use in amd_pmu_cpu_starting() from topology_die_id() looks > broken. Partly because the error handling is (only) a WARN_ON_ONCE(), > and also because nb->nb_id's sentinel value is -1 of type int. > > I suspect there's a lot of cleaning to be done here too. Sigh...
