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> Reviewed-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com> --- Changelog: Resend: * Added ack by Aneesh. * Minor fix to changelog of v2 patch v2: * Rebased the patch on latest ppc-next tree * s/psdm/pdsm/g [ Santosh ] --- 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..eb8be0eb6119 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_pdsm_dsc(struct papr_scm_priv *p, + 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_pdsm_dsc(p, payload); 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
