[PATCH v10 6/6] powerpc/papr_scm: Implement support for PAPR_PDSM_HEALTH

[Vaibhav Jain]

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.kumar@xxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Ira Weiny <ira.weiny@xxxxxxxxx>
Signed-off-by: Vaibhav Jain <vaibhav@xxxxxxxxxxxxx>
---
Changelog:

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 | 33 +++++++++++
 arch/powerpc/platforms/pseries/papr_scm.c | 70 +++++++++++++++++++++++
 2 files changed, 103 insertions(+)

diff --git a/arch/powerpc/include/uapi/asm/papr_pdsm.h b/arch/powerpc/include/uapi/asm/papr_pdsm.h
index 8b1a4f8fa316..c4c990ede5d4 100644
--- a/arch/powerpc/include/uapi/asm/papr_pdsm.h
+++ b/arch/powerpc/include/uapi/asm/papr_pdsm.h
@@ -71,12 +71,17 @@ struct nd_pdsm_cmd_pkg {
 	__u8 payload[];		/* In/Out: Sub-cmd data buffer */
 } __packed;
 
+/* Calculate size used by the pdsm header fields minus 'struct nd_cmd_pkg' */
+#define ND_PDSM_ENVELOPE_HDR_SIZE \
+	(sizeof(struct nd_pdsm_cmd_pkg) - sizeof(struct nd_cmd_pkg))
+
 /*
  * Methods to be embedded in ND_CMD_CALL request. These are sent to the kernel
  * via 'nd_pdsm_cmd_pkg.hdr.nd_command' member of the ioctl struct
  */
 enum papr_pdsm {
 	PAPR_PDSM_MIN = 0x0,
+	PAPR_PDSM_HEALTH,
 	PAPR_PDSM_MAX,
 };
 
@@ -95,4 +100,32 @@ static inline void *pdsm_cmd_to_payload(struct nd_pdsm_cmd_pkg *pcmd)
 		return (void *)(pcmd->payload);
 }
 
+/* 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.
+ *
+ * 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 {
+	__u8 dimm_unarmed;
+	__u8 dimm_bad_shutdown;
+	__u8 dimm_bad_restore;
+	__u8 dimm_scrubbed;
+	__u8 dimm_locked;
+	__u8 dimm_encrypted;
+	__u16 dimm_health;
+} __packed;
+
 #endif /* _UAPI_ASM_POWERPC_PAPR_PDSM_H_ */
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 05eb56ecab5e..984942be24c1 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -421,6 +421,72 @@ 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,
+			    struct nd_pdsm_cmd_pkg *pkg)
+{
+	int rc;
+	struct nd_papr_pdsm_health health = { 0 };
+	u16 copysize = sizeof(struct nd_papr_pdsm_health);
+	u16 payload_size = pkg->hdr.nd_size_out - ND_PDSM_ENVELOPE_HDR_SIZE;
+
+	/* Ensure correct payload size that can hold struct nd_papr_pdsm_health */
+	if (payload_size != copysize) {
+		dev_dbg(&p->pdev->dev,
+			"Unexpected payload-size (%u). Expected (%u)",
+			pkg->hdr.nd_size_out, copysize);
+		rc = -ENOSPC;
+		goto out;
+	}
+
+	/* 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 */
+	health = (struct nd_papr_pdsm_health) {
+		.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_encrypted = p->health_bitmap & PAPR_PMEM_ENCRYPTED,
+		.dimm_locked = p->health_bitmap & PAPR_PMEM_SCRUBBED_AND_LOCKED,
+		.dimm_scrubbed = p->health_bitmap & PAPR_PMEM_SCRUBBED_AND_LOCKED,
+		.dimm_health = PAPR_PDSM_DIMM_HEALTHY,
+	};
+
+	/* Update field dimm_health based on health_bitmap flags */
+	if (p->health_bitmap & PAPR_PMEM_HEALTH_FATAL)
+		health.dimm_health = PAPR_PDSM_DIMM_FATAL;
+	else if (p->health_bitmap & PAPR_PMEM_HEALTH_CRITICAL)
+		health.dimm_health = PAPR_PDSM_DIMM_CRITICAL;
+	else if (p->health_bitmap & PAPR_PMEM_HEALTH_UNHEALTHY)
+		health.dimm_health = PAPR_PDSM_DIMM_UNHEALTHY;
+
+	/* struct populated hence can release the mutex now */
+	mutex_unlock(&p->health_mutex);
+
+	dev_dbg(&p->pdev->dev, "Copying payload size=%u\n", copysize);
+
+	/* Copy the health struct to the payload */
+	memcpy(pdsm_cmd_to_payload(pkg), &health, copysize);
+
+	/* Update fw size including size of struct nd_pdsm_cmd_pkg fields */
+	pkg->hdr.nd_fw_size = copysize + ND_PDSM_ENVELOPE_HDR_SIZE;
+
+out:
+	dev_dbg(&p->pdev->dev, "completion code = %d\n", rc);
+
+	return rc;
+}
+
 /*
  * For a given pdsm request call an appropriate service function.
  * Note: Use 'nd_pdsm_cmd_pkg.cmd_status to report psdm servicing errors. Hence
@@ -435,6 +501,10 @@ static void papr_scm_service_pdsm(struct papr_scm_priv *p,
 
 	/* Call pdsm service function */
 	switch (pdsm) {
+	case PAPR_PDSM_HEALTH:
+		pkg->cmd_status = papr_pdsm_health(p, pkg);
+		break;
+
 	default:
 		dev_dbg(&p->pdev->dev, "PDSM[0x%x]: Unsupported PDSM request\n",
 			pdsm);
-- 
2.26.2