This patch implements support for PDSM request 'PAPR_PDSM_HEALTH'
that returns a newly introduced 'struct nd_papr_pdsm_health' instance
containing dimm health information back to user space in response to
ND_CMD_CALL. This functionality is implemented in newly introduced
papr_pdsm_health() that queries the nvdimm health information and
then copies this information to the package payload whose layout is
defined by 'struct nd_papr_pdsm_health'.

Cc: "Aneesh Kumar K . V" <aneesh.ku...@linux.ibm.com>
Cc: Dan Williams <dan.j.willi...@intel.com>
Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Ira Weiny <ira.we...@intel.com>
Signed-off-by: Vaibhav Jain <vaib...@linux.ibm.com>
---
Changelog:
v12..v13:
* Added the 'struct nd_papr_pdsm_health' to 'union nd_pdsm_payload'
* Added pdsm descriptor of 'PAPR_PDSM_HEALTH' to
  __pdsm_cmd_descriptors[].
* Updated papr_pdsm_health() to copy the dimm health information
  directly into PDSM payload rather then copying it to an intermediate
  struct and then memcpy it to the PDSM payload area.

v11..v12:
* Minor: Reodered the initialization of 'struct nd_papr_pdsm_health'
  fields to match order present in its definition. [ Ira ]
* Added ack from Ira

v10..v11:
* Changed the definition of 'struct nd_papr_pdsm_health' to a maximal
  struct 184 bytes in size [ Dan Williams ]
* Added new field 'extension_flags' to 'struct nd_papr_pdsm_health'
  [ Dan Williams ]
* Updated papr_pdsm_health() to set field 'extension_flags' to 0.
* Introduced a define ND_PDSM_PAYLOAD_MAX_SIZE that indicates the
  maximum size of a payload.
* Fixed a suspicious conversion from u64 to u8 in papr_pdsm_health
  that was preventing correct initialization of 'struct
  nd_papr_pdsm_health'. [ Ira ]

v9..v10:
* Removed code in papr_pdsm_health that performed validation on pdsm
  payload version and corrosponding struct and defines used for
  validation of payload version.
* Dropped usage of struct papr_pdsm_health in 'struct
  papr_scm_priv'. Instead papr_psdm_health() now uses
  'papr_scm_priv.health_bitmap' to populate the pdsm payload.
* Above change also fixes the problem where this patch was removing
  the code that was previously introduced in this patch-series.
  [ Ira ]
* Introduced a new def ND_PDSM_ENVELOPE_HDR_SIZE that indicates the
  space allocated to 'struct nd_pdsm_cmd_pkg' fields except 'struct
  nd_cmd_pkg'. This def is useful in validating payload sizes.
* Reworked papr_pdsm_health() to enforce a specific payload size for
  'PAPR_PDSM_HEALTH' pdsm request.

Resend:
* Added ack from Aneesh.

v8..v9:
* s/PAPR_SCM_PDSM_HEALTH/PAPR_PDSM_HEALTH/g  [ Dan , Aneesh ]
* s/PAPR_SCM_PSDM_DIMM_*/PAPR_PDSM_DIMM_*/g
* Renamed papr_scm_get_health() to papr_psdm_health()
* Updated patch description to replace papr-scm dimm with nvdimm.

v7..v8:
* None

Resend:
* None

v6..v7:
* Updated flags_show() to use seq_buf_printf(). [Mpe]
* Updated papr_scm_get_health() to use newly introduced
  __drc_pmem_query_health() bypassing the cache [Mpe].

v5..v6:
* Added attribute '__packed' to 'struct nd_papr_pdsm_health_v1' to
  gaurd against possibility of different compilers adding different
  paddings to the struct [ Dan Williams ]

* Updated 'struct nd_papr_pdsm_health_v1' to use __u8 instead of
  'bool' and also updated drc_pmem_query_health() to take this into
  account. [ Dan Williams ]

v4..v5:
* None

v3..v4:
* Call the DSM_PAPR_SCM_HEALTH service function from
  papr_scm_service_dsm() instead of papr_scm_ndctl(). [Aneesh]

v2..v3:
* Updated struct nd_papr_scm_dimm_health_stat_v1 to use '__xx' types
  as its exported to the userspace [Aneesh]
* Changed the constants DSM_PAPR_SCM_DIMM_XX indicating dimm health
  from enum to #defines [Aneesh]

v1..v2:
* New patch in the series
---
 arch/powerpc/include/uapi/asm/papr_pdsm.h | 37 ++++++++++++++++
 arch/powerpc/platforms/pseries/papr_scm.c | 51 +++++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/arch/powerpc/include/uapi/asm/papr_pdsm.h 
b/arch/powerpc/include/uapi/asm/papr_pdsm.h
index 28115152aa4e..9ccecc1d6840 100644
--- a/arch/powerpc/include/uapi/asm/papr_pdsm.h
+++ b/arch/powerpc/include/uapi/asm/papr_pdsm.h
@@ -66,17 +66,54 @@
 #define ND_PDSM_HDR_SIZE \
        (sizeof(struct nd_pkg_pdsm) - ND_PDSM_PAYLOAD_MAX_SIZE)
 
+/* Various nvdimm health indicators */
+#define PAPR_PDSM_DIMM_HEALTHY       0
+#define PAPR_PDSM_DIMM_UNHEALTHY     1
+#define PAPR_PDSM_DIMM_CRITICAL      2
+#define PAPR_PDSM_DIMM_FATAL         3
+
+/*
+ * Struct exchanged between kernel & ndctl in for PAPR_PDSM_HEALTH
+ * Various flags indicate the health status of the dimm.
+ *
+ * extension_flags     : Any extension fields present in the struct.
+ * dimm_unarmed                : Dimm not armed. So contents wont persist.
+ * dimm_bad_shutdown   : Previous shutdown did not persist contents.
+ * dimm_bad_restore    : Contents from previous shutdown werent restored.
+ * dimm_scrubbed       : Contents of the dimm have been scrubbed.
+ * dimm_locked         : Contents of the dimm cant be modified until CEC reboot
+ * dimm_encrypted      : Contents of dimm are encrypted.
+ * dimm_health         : Dimm health indicator. One of PAPR_PDSM_DIMM_XXXX
+ */
+struct nd_papr_pdsm_health {
+       union {
+               struct {
+                       __u32 extension_flags;
+                       __u8 dimm_unarmed;
+                       __u8 dimm_bad_shutdown;
+                       __u8 dimm_bad_restore;
+                       __u8 dimm_scrubbed;
+                       __u8 dimm_locked;
+                       __u8 dimm_encrypted;
+                       __u16 dimm_health;
+               };
+               __u8 buf[ND_PDSM_PAYLOAD_MAX_SIZE];
+       };
+};
+
 /*
  * Methods to be embedded in ND_CMD_CALL request. These are sent to the kernel
  * via 'nd_cmd_pkg.nd_command' member of the ioctl struct
  */
 enum papr_pdsm {
        PAPR_PDSM_MIN = 0x0,
+       PAPR_PDSM_HEALTH,
        PAPR_PDSM_MAX,
 };
 
 /* Maximal union that can hold all possible payload types */
 union nd_pdsm_payload {
+       struct nd_papr_pdsm_health health;
        __u8 buf[ND_PDSM_PAYLOAD_MAX_SIZE];
 } __packed;
 
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c 
b/arch/powerpc/platforms/pseries/papr_scm.c
index d3bbf9940ba4..9c569078a09f 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -416,6 +416,52 @@ static int is_cmd_valid(struct nvdimm *nvdimm, unsigned 
int cmd, void *buf,
        return 0;
 }
 
+/* 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)
+{
+       int rc;
+
+       /* Ensure dimm health mutex is taken preventing concurrent access */
+       rc = mutex_lock_interruptible(&p->health_mutex);
+       if (rc)
+               goto out;
+
+       /* Always fetch upto date dimm health data ignoring cached values */
+       rc = __drc_pmem_query_health(p);
+       if (rc) {
+               mutex_unlock(&p->health_mutex);
+               goto out;
+       }
+
+       /* update health struct with various flags derived from health bitmap */
+       payload->health = (struct nd_papr_pdsm_health) {
+               .extension_flags = 0,
+               .dimm_unarmed = !!(p->health_bitmap & PAPR_PMEM_UNARMED_MASK),
+               .dimm_bad_shutdown = !!(p->health_bitmap & 
PAPR_PMEM_BAD_SHUTDOWN_MASK),
+               .dimm_bad_restore = !!(p->health_bitmap & 
PAPR_PMEM_BAD_RESTORE_MASK),
+               .dimm_scrubbed = !!(p->health_bitmap & 
PAPR_PMEM_SCRUBBED_AND_LOCKED),
+               .dimm_locked = !!(p->health_bitmap & 
PAPR_PMEM_SCRUBBED_AND_LOCKED),
+               .dimm_encrypted = !!(p->health_bitmap & PAPR_PMEM_ENCRYPTED),
+               .dimm_health = PAPR_PDSM_DIMM_HEALTHY,
+       };
+
+       /* Update field dimm_health based on health_bitmap flags */
+       if (p->health_bitmap & PAPR_PMEM_HEALTH_FATAL)
+               payload->health.dimm_health = PAPR_PDSM_DIMM_FATAL;
+       else if (p->health_bitmap & PAPR_PMEM_HEALTH_CRITICAL)
+               payload->health.dimm_health = PAPR_PDSM_DIMM_CRITICAL;
+       else if (p->health_bitmap & PAPR_PMEM_HEALTH_UNHEALTHY)
+               payload->health.dimm_health = PAPR_PDSM_DIMM_UNHEALTHY;
+
+       /* struct populated hence can release the mutex now */
+       mutex_unlock(&p->health_mutex);
+       rc = sizeof(struct nd_papr_pdsm_health);
+
+out:
+       return rc;
+}
+
 /*
  * 'struct pdsm_cmd_desc'
  * Identifies supported PDSMs' expected length of in/out payloads
@@ -444,6 +490,11 @@ static const struct pdsm_cmd_desc __pdsm_cmd_descriptors[] 
= {
        },
        /* New PDSM command descriptors to be added below */
 
+       [PAPR_PDSM_HEALTH] = {
+               .size_in = 0,
+               .size_out = sizeof(struct nd_papr_pdsm_health),
+               .service = papr_pdsm_health,
+       },
        /* Empty */
        [PAPR_PDSM_MAX] = {
                .size_in = 0,
-- 
2.26.2

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