Hi Vaibhav,
Vaibhav Jain <vaib...@linux.ibm.com> writes: > Persistent memory devices like NVDIMMs can loose cached writes in case > something prevents flush on power-fail. Such situations are termed as > dirty shutdown and are exposed to applications as > last-shutdown-state (LSS) flag and a dirty-shutdown-counter(DSC) as > described at [1]. The latter being useful in conditions where multiple > applications want to detect a dirty shutdown event without racing with > one another. > > PAPR-NVDIMMs have so far only exposed LSS style flags to indicate a > dirty-shutdown-state. This patch further adds support for DSC via the > "ibm,persistence-failed-count" device tree property of an NVDIMM. This > property is a monotonic increasing 64-bit counter thats an indication > of number of times an NVDIMM has encountered a dirty-shutdown event > causing persistence loss. > > Since this value is not expected to change after system-boot hence > papr_scm reads & caches its value during NVDIMM probe and exposes it > as a PAPR sysfs attributed named 'dirty_shutdown' to match the name of > similarly named NFIT sysfs attribute. Also this value is available to > libnvdimm via PAPR_PDSM_HEALTH payload. 'struct nd_papr_pdsm_health' > has been extended to add a new member called 'dimm_dsc' presence of > which is indicated by the newly introduced PDSM_DIMM_DSC_VALID flag. > > References: > [1] https://pmem.io/documents/Dirty_Shutdown_Handling-V1.0.pdf > > Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com> > --- > arch/powerpc/include/uapi/asm/papr_pdsm.h | 6 +++++ > arch/powerpc/platforms/pseries/papr_scm.c | 30 +++++++++++++++++++++++ > 2 files changed, 36 insertions(+) > > diff --git a/arch/powerpc/include/uapi/asm/papr_pdsm.h > b/arch/powerpc/include/uapi/asm/papr_pdsm.h > index 50ef95e2f5b1..82488b1e7276 100644 > --- a/arch/powerpc/include/uapi/asm/papr_pdsm.h > +++ b/arch/powerpc/include/uapi/asm/papr_pdsm.h > @@ -77,6 +77,9 @@ > /* Indicate that the 'dimm_fuel_gauge' field is valid */ > #define PDSM_DIMM_HEALTH_RUN_GAUGE_VALID 1 > > +/* Indicate that the 'dimm_dsc' field is valid */ > +#define PDSM_DIMM_DSC_VALID 2 > + > /* > * Struct exchanged between kernel & ndctl in for PAPR_PDSM_HEALTH > * Various flags indicate the health status of the dimm. > @@ -105,6 +108,9 @@ struct nd_papr_pdsm_health { > > /* Extension flag PDSM_DIMM_HEALTH_RUN_GAUGE_VALID */ > __u16 dimm_fuel_gauge; > + > + /* Extension flag PDSM_DIMM_DSC_VALID */ > + __u64 dimm_dsc; > }; > __u8 buf[ND_PDSM_PAYLOAD_MAX_SIZE]; > }; > diff --git a/arch/powerpc/platforms/pseries/papr_scm.c > b/arch/powerpc/platforms/pseries/papr_scm.c > index 11e7b90a3360..68f0d3d5e899 100644 > --- a/arch/powerpc/platforms/pseries/papr_scm.c > +++ b/arch/powerpc/platforms/pseries/papr_scm.c > @@ -114,6 +114,9 @@ struct papr_scm_priv { > /* Health information for the dimm */ > u64 health_bitmap; > > + /* Holds the last known dirty shutdown counter value */ > + u64 dirty_shutdown_counter; > + > /* length of the stat buffer as expected by phyp */ > size_t stat_buffer_len; > }; > @@ -603,6 +606,16 @@ static int papr_pdsm_fuel_gauge(struct papr_scm_priv *p, > return rc; > } > > +/* Add the dirty-shutdown-counter value to the pdsm */ > +static int papr_psdm_dsc(struct papr_scm_priv *p, ^^^^ should be pdsm > + union nd_pdsm_payload *payload) > +{ > + payload->health.extension_flags |= PDSM_DIMM_DSC_VALID; > + payload->health.dimm_dsc = p->dirty_shutdown_counter; > + > + return sizeof(struct nd_papr_pdsm_health); > +} > + > /* Fetch the DIMM health info and populate it in provided package. */ > static int papr_pdsm_health(struct papr_scm_priv *p, > union nd_pdsm_payload *payload) > @@ -646,6 +659,8 @@ static int papr_pdsm_health(struct papr_scm_priv *p, > > /* Populate the fuel gauge meter in the payload */ > papr_pdsm_fuel_gauge(p, payload); > + /* Populate the dirty-shutdown-counter field */ > + papr_psdm_dsc(p, payload); ^^^^ same typo Thanks, Santosh > > rc = sizeof(struct nd_papr_pdsm_health); > > @@ -907,6 +922,16 @@ static ssize_t flags_show(struct device *dev, > } > DEVICE_ATTR_RO(flags); > > +static ssize_t dirty_shutdown_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct nvdimm *dimm = to_nvdimm(dev); > + struct papr_scm_priv *p = nvdimm_provider_data(dimm); > + > + return sysfs_emit(buf, "%llu\n", p->dirty_shutdown_counter); > +} > +DEVICE_ATTR_RO(dirty_shutdown); > + > static umode_t papr_nd_attribute_visible(struct kobject *kobj, > struct attribute *attr, int n) > { > @@ -925,6 +950,7 @@ static umode_t papr_nd_attribute_visible(struct kobject > *kobj, > static struct attribute *papr_nd_attributes[] = { > &dev_attr_flags.attr, > &dev_attr_perf_stats.attr, > + &dev_attr_dirty_shutdown.attr, > NULL, > }; > > @@ -1149,6 +1175,10 @@ static int papr_scm_probe(struct platform_device *pdev) > p->is_volatile = !of_property_read_bool(dn, "ibm,cache-flush-required"); > p->hcall_flush_required = of_property_read_bool(dn, > "ibm,hcall-flush-required"); > > + if (of_property_read_u64(dn, "ibm,persistence-failed-count", > + &p->dirty_shutdown_counter)) > + p->dirty_shutdown_counter = 0; > + > /* We just need to ensure that set cookies are unique across */ > uuid_parse(uuid_str, (uuid_t *) uuid); > /* > -- > 2.31.1
