On Wed, 4 Dec 2024 15:46:48 -0700 Dave Jiang <dave.jiang@xxxxxxxxx> wrote: > Add the aliased address of extended linear cache when emitting event > trace for DRAM and general media of CXL events. > > Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx> I wonder if you want to future proof the hpa_alias for potential case of there being more than 1? hpa_alias0 or similar so that we can add more as needed? Otherwise, looks like there is either a null point dereference or overly paranoid existing code. I haven't checked which but changes needed either way. Jonathan > diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c > index 5175138c4fb7..4017b7afa78a 100644 > --- a/drivers/cxl/core/mbox.c > +++ b/drivers/cxl/core/mbox.c > @@ -856,6 +856,24 @@ int cxl_enumerate_cmds(struct cxl_memdev_state *mds) > } > EXPORT_SYMBOL_NS_GPL(cxl_enumerate_cmds, CXL); > > +static u64 cxlr_hpa_cache_alias(struct cxl_region *cxlr, u64 hpa) > +{ > + struct cxl_region_params *p = &cxlr->params; Bad idea to unconditionally dereference I think. See below. > + int nid; > + > + if (!p->cache_size) > + return ~0ULL; > + > + nid = cxl_region_nid(cxlr); > + if (nid == NUMA_NO_NODE) > + nid = 0; > + > + if (hpa >= p->res->start + p->cache_size) > + return hpa - p->cache_size; > + > + return hpa + p->cache_size; > +} > + > void cxl_event_trace_record(const struct cxl_memdev *cxlmd, > enum cxl_event_log_type type, > enum cxl_event_type event_type, > @@ -871,7 +889,7 @@ void cxl_event_trace_record(const struct cxl_memdev *cxlmd, > } > > if (trace_cxl_general_media_enabled() || trace_cxl_dram_enabled()) { > - u64 dpa, hpa = ULLONG_MAX; > + u64 dpa, hpa = ULLONG_MAX, hpa_alias; > struct cxl_region *cxlr; > > /* > @@ -887,11 +905,14 @@ void cxl_event_trace_record(const struct cxl_memdev *cxlmd, > if (cxlr) > hpa = cxl_dpa_to_hpa(cxlr, cxlmd, dpa); > > + hpa_alias = cxlr_hpa_cache_alias(cxlr, hpa); If there is no region, and hence no hpa does it make sense to call this? Particularly as first thing done in this is to dereference cxlr. > + > if (event_type == CXL_CPER_EVENT_GEN_MEDIA) > trace_cxl_general_media(cxlmd, type, cxlr, hpa, > - &evt->gen_media); > + hpa_alias, &evt->gen_media); > else if (event_type == CXL_CPER_EVENT_DRAM) > - trace_cxl_dram(cxlmd, type, cxlr, hpa, &evt->dram); > + trace_cxl_dram(cxlmd, type, cxlr, hpa, hpa_alias, > + &evt->dram); > } > } > EXPORT_SYMBOL_NS_GPL(cxl_event_trace_record, CXL);