Hi,

Le 08/11/2020 à 22:15, Vaibhav Jain a écrit :
Add support for reporting papr-scm supported generic nvdimm stats by
implementing support for handling ND_CMD_GET_STAT in
'papr_scm_ndctl().

The mapping between libnvdimm generic nvdimm-stats and papr-scm
specific performance-stats is embedded inside 'dimm_stats_map[]'. This
array is queried by newly introduced 'papr_scm_get_stat()' that
verifies if the requested nvdimm-stat is supported and if yes does an
hcall via 'drc_pmem_query_stat()' to request the performance-stat and
return it back to libnvdimm.

Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com>

I see this series is still flagged as 'new' in patchwork.

I saw some patches providing stats to nvdimm are in a pull request for 5.18.

I imagine this is the same subject, so I'm going to change the status of this series. Let me know if I'm wrong.

Thanks
Christophe

---
  arch/powerpc/platforms/pseries/papr_scm.c | 66 ++++++++++++++++++++++-
  1 file changed, 65 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/papr_scm.c 
b/arch/powerpc/platforms/pseries/papr_scm.c
index 835163f54244..51eeab3376fd 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -25,7 +25,8 @@
        ((1ul << ND_CMD_GET_CONFIG_SIZE) | \
         (1ul << ND_CMD_GET_CONFIG_DATA) | \
         (1ul << ND_CMD_SET_CONFIG_DATA) | \
-        (1ul << ND_CMD_CALL))
+        (1ul << ND_CMD_CALL) |              \
+        (1ul << ND_CMD_GET_STAT))
/* DIMM health bitmap bitmap indicators */
  /* SCM device is unable to persist memory contents */
@@ -120,6 +121,16 @@ struct papr_scm_priv {
  static LIST_HEAD(papr_nd_regions);
  static DEFINE_MUTEX(papr_ndr_lock);
+/* Map generic nvdimm stats to papr-scm stats */
+static const char * const dimm_stat_map[] = {
+       [ND_DIMM_STAT_INVALID] = NULL,
+       [ND_DIMM_STAT_MEDIA_READS] = "MedRCnt ",
+       [ND_DIMM_STAT_MEDIA_WRITES] = "MedWCnt ",
+       [ND_DIMM_STAT_READ_REQUESTS] = "HostLCnt",
+       [ND_DIMM_STAT_WRITE_REQUESTS] = "HostSCnt",
+       [ND_DIMM_STAT_MAX] = NULL,
+};
+
  static int drc_pmem_bind(struct papr_scm_priv *p)
  {
        unsigned long ret[PLPAR_HCALL_BUFSIZE];
@@ -728,6 +739,54 @@ static int papr_scm_service_pdsm(struct papr_scm_priv *p,
        return pdsm_pkg->cmd_status;
  }
+/*
+ * For a given pdsm request call an appropriate service function.
+ * Returns errors if any while handling the pdsm command package.
+ */
+static int papr_scm_get_stat(struct papr_scm_priv *p,
+                            struct nd_cmd_get_dimm_stat *dimm_stat)
+
+{
+       int rc;
+       ssize_t size;
+       struct papr_scm_perf_stat *stat;
+       struct papr_scm_perf_stats *stats;
+
+       /* Check if the requested stat-id is supported */
+       if (dimm_stat->stat_id >= ARRAY_SIZE(dimm_stat_map) ||
+           !dimm_stat_map[dimm_stat->stat_id]) {
+               dev_dbg(&p->pdev->dev, "Invalid stat-id %lld\n", 
dimm_stat->stat_id);
+               return -ENOSPC;
+       }
+
+       /* Allocate request buffer enough to hold single performance stat */
+       size = sizeof(struct papr_scm_perf_stats) +
+               sizeof(struct papr_scm_perf_stat);
+
+       stats = kzalloc(size, GFP_KERNEL);
+       if (!stats)
+               return -ENOMEM;
+
+       stat = &stats->scm_statistic[0];
+       memcpy(&stat->stat_id, dimm_stat_map[dimm_stat->stat_id],
+              sizeof(stat->stat_id));
+       stat->stat_val = 0;
+
+       /* Fetch the statistic from PHYP and copy it to provided payload */
+       rc = drc_pmem_query_stats(p, stats, 1);
+       if (rc < 0) {
+               dev_dbg(&p->pdev->dev, "Err(%d) fetching stat '%.8s'\n",
+                       rc, stat->stat_id);
+               kfree(stats);
+               return rc;
+       }
+
+       dimm_stat->int_val = be64_to_cpu(stat->stat_val);
+
+       kfree(stats);
+       return 0;
+}
+
  static int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc,
                          struct nvdimm *nvdimm, unsigned int cmd, void *buf,
                          unsigned int buf_len, int *cmd_rc)
@@ -772,6 +831,11 @@ static int papr_scm_ndctl(struct nvdimm_bus_descriptor 
*nd_desc,
                *cmd_rc = papr_scm_service_pdsm(p, call_pkg);
                break;
+ case ND_CMD_GET_STAT:
+               *cmd_rc = papr_scm_get_stat(p,
+                                           (struct nd_cmd_get_dimm_stat *)buf);
+               break;
+
        default:
                dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd);
                return -EINVAL;

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