[PATCH v9 0/5] powerpc/papr_scm: Add support for reporting nvdimm health

[PATCH v9 0/5] powerpc/papr_scm: Add support for reporting nvdimm health

[Vaibhav Jain]

Changes since v8 [1]:

* Updated proposed changes to remove usage of term 'SCM' due to
  ambiguity with 'PMEM' and 'NVDIMM'. [ Dan Williams ]
* Replaced the usage of term 'SCM' with 'PMEM' in most contexts.
  [ Aneesh ]
* Renamed NVDIMM health defines from PAPR_SCM_DIMM_* to PAPR_PMEM_* .
* Updates to various newly introduced identifiers in 'papr_scm.c'
  removing the 'SCM' prefix from their names.
* Renamed NVDIMM_FAMILY_PAPR_SCM to NVDIMM_FAMILY_PAPR
* Renamed PAPR_SCM_PDSM_HEALTH PAPR_PDSM_HEALTH
* Renamed uapi header 'papr_scm_pdsm.h' to 'papr_pdsm.h'.
* Renamed sysfs ABI document from sysfs-bus-papr-scm to
  sysfs-bus-papr-pmem.
* No behavioural changes from v8 [1].

[1] https://lore.kernel.org/linux-nvdimm/20200527041244.37821-1-vaibhav@linux.ibm.com/
---

The PAPR standard[2][4] provides mechanisms to query the health and
performance stats of an NVDIMM via various hcalls as described in
Ref[3].  Until now these stats were never available nor exposed to the
user-space tools like 'ndctl'. This is partly due to PAPR platform not
having support for ACPI and NFIT. Hence 'ndctl' is unable to query and
report the dimm health status and a user had no way to determine the
current health status of a NDVIMM.

To overcome this limitation, this patch-set updates papr_scm kernel
module to query and fetch NVDIMM health stats using hcalls described
in Ref[3].  This health and performance stats are then exposed to
userspace via sysfs and PAPR-NVDIMM-Specific-Methods(PDSM) issued by
libndctl.

These changes coupled with proposed ndtcl changes located at Ref[5]
should provide a way for the user to retrieve NVDIMM health status
using ndtcl.

Below is a sample output using proposed kernel + ndctl for PAPR NVDIMM
in a emulation environment:

 # ndctl list -DH
[
  {
    "dev":"nmem0",
    "health":{
      "health_state":"fatal",
      "shutdown_state":"dirty"
    }
  }
]

Dimm health report output on a pseries guest lpar with vPMEM or HMS
based NVDIMMs that are in perfectly healthy conditions:

 # ndctl list -d nmem0 -H
[
  {
    "dev":"nmem0",
    "health":{
      "health_state":"ok",
      "shutdown_state":"clean"
    }
  }
]

PAPR NVDIMM-Specific-Methods(PDSM)
==================================

PDSM requests are issued by vendor specific code in libndctl to
execute certain operations or fetch information from NVDIMMS. PDSMs
requests can be sent to papr_scm module via libndctl(userspace) and
libnvdimm (kernel) using the ND_CMD_CALL ioctl command which can be
handled in the dimm control function papr_scm_ndctl(). Current
patchset proposes a single PDSM to retrieve NVDIMM health, defined in
the newly introduced uapi header named 'papr_pdsm.h'. Support for
more PDSMs will be added in future.

Structure of the patch-set
==========================

The patch-set starts with a doc patch documenting details of hcall
H_SCM_HEALTH. Second patch exports kernel symbol seq_buf_printf()
thats used in subsequent patches to generate sysfs attribute content.

Third patch implements support for fetching NVDIMM health information
from PHYP and partially exposing it to user-space via a NVDIMM sysfs
flag.

Fourth patches deal with implementing support for servicing PDSM
commands in papr_scm module.

Finally the last patch implements support for servicing PDSM
'PAPR_PDSM_HEALTH' that returns the NVDIMM health information to
libndctl.

References:
[2] "Power Architecture Platform Reference"
      https://en.wikipedia.org/wiki/Power_Architecture_Platform_Reference
[3] commit 58b278f568f0
     ("powerpc: Provide initial documentation for PAPR hcalls")
[4] "Linux on Power Architecture Platform Reference"
     https://members.openpowerfoundation.org/document/dl/469
[5] https://github.com/vaibhav92/ndctl/tree/papr_scm_health_v9

---

Vaibhav Jain (5):
  powerpc: Document details on H_SCM_HEALTH hcall
  seq_buf: Export seq_buf_printf
  powerpc/papr_scm: Fetch nvdimm health information from PHYP
  ndctl/papr_scm,uapi: Add support for PAPR nvdimm specific methods
  powerpc/papr_scm: Implement support for PAPR_PDSM_HEALTH

 Documentation/ABI/testing/sysfs-bus-papr-pmem |  27 ++
 Documentation/powerpc/papr_hcalls.rst         |  46 ++-
 arch/powerpc/include/uapi/asm/papr_pdsm.h     | 175 +++++++++
 arch/powerpc/platforms/pseries/papr_scm.c     | 363 +++++++++++++++++-
 include/uapi/linux/ndctl.h                    |   1 +
 lib/seq_buf.c                                 |   1 +
 6 files changed, 600 insertions(+), 13 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-papr-pmem
 create mode 100644 arch/powerpc/include/uapi/asm/papr_pdsm.h

-- 
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[PATCH v9 1/5] powerpc: Document details on H_SCM_HEALTH hcall

[Vaibhav Jain]

Add documentation to 'papr_hcalls.rst' describing the bitmap flags
that are returned from H_SCM_HEALTH hcall as per the PAPR-SCM
specification.

Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
Changelog:

v8..v9:
* s/SCM/PMEM device. [ Dan Williams, Aneesh ]

v7..v8:
* Added a clarification on bit-ordering of Health Bitmap

Resend:
* None

v6..v7:
* None

v5..v6:
* New patch in the series
---
 Documentation/powerpc/papr_hcalls.rst | 46 ++++++++++++++++++++++++---
 1 file changed, 42 insertions(+), 4 deletions(-)

diff --git a/Documentation/powerpc/papr_hcalls.rst b/Documentation/powerpc/papr_hcalls.rst
index 3493631a60f8..48fcf1255a33 100644
--- a/Documentation/powerpc/papr_hcalls.rst
+++ b/Documentation/powerpc/papr_hcalls.rst
@@ -220,13 +220,51 @@ from the LPAR memory.
 **H_SCM_HEALTH**
 
 | Input: drcIndex
-| Out: *health-bitmap, health-bit-valid-bitmap*
+| Out: *health-bitmap (r4), health-bit-valid-bitmap (r5)*
 | Return Value: *H_Success, H_Parameter, H_Hardware*
 
 Given a DRC Index return the info on predictive failure and overall health of
-the NVDIMM. The asserted bits in the health-bitmap indicate a single predictive
-failure and health-bit-valid-bitmap indicate which bits in health-bitmap are
-valid.
+the PMEM device. The asserted bits in the health-bitmap indicate one or more states
+(described in table below) of the PMEM device and health-bit-valid-bitmap indicate
+which bits in health-bitmap are valid. The bits are reported in
+reverse bit ordering for example a value of 0xC400000000000000
+indicates bits 0, 1, and 5 are valid.
+
+Health Bitmap Flags:
+
++------+-----------------------------------------------------------------------+
+|  Bit |               Definition                                              |
++======+=======================================================================+
+|  00  | PMEM device is unable to persist memory contents.                     |
+|      | If the system is powered down, nothing will be saved.                 |
++------+-----------------------------------------------------------------------+
+|  01  | PMEM device failed to persist memory contents. Either contents were   |
+|      | not saved successfully on power down or were not restored properly on |
+|      | power up.                                                             |
++------+-----------------------------------------------------------------------+
+|  02  | PMEM device contents are persisted from previous IPL. The data from   |
+|      | the last boot were successfully restored.                             |
++------+-----------------------------------------------------------------------+
+|  03  | PMEM device contents are not persisted from previous IPL. There was no|
+|      | data to restore from the last boot.                                   |
++------+-----------------------------------------------------------------------+
+|  04  | PMEM device memory life remaining is critically low                   |
++------+-----------------------------------------------------------------------+
+|  05  | PMEM device will be garded off next IPL due to failure                |
++------+-----------------------------------------------------------------------+
+|  06  | PMEM device contents cannot persist due to current platform health    |
+|      | status. A hardware failure may prevent data from being saved or       |
+|      | restored.                                                             |
++------+-----------------------------------------------------------------------+
+|  07  | PMEM device is unable to persist memory contents in certain conditions|
++------+-----------------------------------------------------------------------+
+|  08  | PMEM device is encrypted                                              |
++------+-----------------------------------------------------------------------+
+|  09  | PMEM device has successfully completed a requested erase or secure    |
+|      | erase procedure.                                                      |
++------+-----------------------------------------------------------------------+
+|10:63 | Reserved / Unused                                                     |
++------+-----------------------------------------------------------------------+
 
 **H_SCM_PERFORMANCE_STATS**
 
-- 
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[PATCH v9 2/5] seq_buf: Export seq_buf_printf

[Vaibhav Jain]

'seq_buf' provides a very useful abstraction for writing to a string
buffer without needing to worry about it over-flowing. However even
though the API has been stable for couple of years now its still not
exported to kernel loadable modules limiting its usage.

Hence this patch proposes update to 'seq_buf.c' to mark
seq_buf_printf() which is part of the seq_buf API to be exported to
kernel loadable GPL modules. This symbol will be used in later parts
of this patch-set to simplify content creation for a sysfs attribute.

Cc: Piotr Maziarz <piotrx.maziarz@linux.intel.com>
Cc: Cezary Rojewski <cezary.rojewski@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@alien8.de>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
Changelog:

v8..v9:
* None

v7..v8:
* Updated the patch title [ Christoph Hellwig ]
* Updated patch description to replace confusing term 'external kernel
  modules' to 'kernel lodable modules'.

Resend:
* Added ack from Steven Rostedt

v6..v7:
* New patch in the series
---
 lib/seq_buf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/seq_buf.c b/lib/seq_buf.c
index 4e865d42ab03..707453f5d58e 100644
--- a/lib/seq_buf.c
+++ b/lib/seq_buf.c
@@ -91,6 +91,7 @@ int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(seq_buf_printf);
 
 #ifdef CONFIG_BINARY_PRINTF
 /**
-- 
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[PATCH v9 3/5] powerpc/papr_scm: Fetch nvdimm health information from PHYP

[Vaibhav Jain]

Implement support for fetching nvdimm health information via
H_SCM_HEALTH hcall as documented in Ref[1]. The hcall returns a pair
of 64-bit bitmap, bitwise-and of which is then stored in
'struct papr_scm_priv' and subsequently partially exposed to
user-space via newly introduced dimm specific attribute
'papr/flags'. Since the hcall is costly, the health information is
cached and only re-queried, 60s after the previous successful hcall.

The patch also adds a  documentation text describing flags reported by
the the new sysfs attribute 'papr/flags' is also introduced at
Documentation/ABI/testing/sysfs-bus-papr-pmem.

[1] commit 58b278f568f0 ("powerpc: Provide initial documentation for
PAPR hcalls")

Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
Changelog:

v8..v9:
* Rename some variables and defines to reduce usage of term SCM
  replacing it with PMEM [Dan Williams, Aneesh]
* s/PAPR_SCM_DIMM/PAPR_PMEM/g
* s/papr_scm_nd_attributes/papr_nd_attributes/g
* s/papr_scm_nd_attribute_group/papr_nd_attribute_group/g
* s/papr_scm_dimm_attr_groups/papr_nd_attribute_groups/g
* Renamed file sysfs-bus-papr-scm to sysfs-bus-papr-pmem

v7..v8:
* Update type of variable 'rc' in __drc_pmem_query_health() and
  drc_pmem_query_health() to long and int respectively. [ Ira ]
* Updated the patch description to s/64 bit Big Endian Number/64-bit
  bitmap/ [ Ira, Aneesh ].

Resend:
* None

v6..v7 :
* Used the exported buf_seq_printf() function to generate content for
  'papr/flags'
* Moved the PAPR_SCM_DIMM_* bit-flags macro definitions to papr_scm.c
  and removed the papr_scm.h file [Mpe]
* Some minor consistency issued in sysfs-bus-papr-scm
  documentation. [Mpe]
* s/dimm_mutex/health_mutex/g [Mpe]
* Split drc_pmem_query_health() into two function one of which takes
  care of caching and locking. [Mpe]
* Fixed a local copy creation of dimm health information using
  READ_ONCE(). [Mpe]

v5..v6 :
* Change the flags sysfs attribute from 'papr_flags' to 'papr/flags'
  [Dan Williams]
* Include documentation for 'papr/flags' attr [Dan Williams]
* Change flag 'save_fail' to 'flush_fail' [Dan Williams]
* Caching of health bitmap to reduce expensive hcalls [Dan Williams]
* Removed usage of PPC_BIT from 'papr-scm.h' header [Mpe]
* Replaced two __be64 integers from papr_scm_priv to a single u64
  integer [Mpe]
* Updated patch description to reflect the changes made in this
  version.
* Removed avoidable usage of 'papr_scm_priv.dimm_mutex' from
  flags_show() [Dan Williams]

v4..v5 :
* None

v3..v4 :
* None

v2..v3 :
* Removed PAPR_SCM_DIMM_HEALTH_NON_CRITICAL as a condition for
       	 NVDIMM unarmed [Aneesh]

v1..v2 :
* New patch in the series.
---
 Documentation/ABI/testing/sysfs-bus-papr-pmem |  27 +++
 arch/powerpc/platforms/pseries/papr_scm.c     | 169 +++++++++++++++++-
 2 files changed, 194 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-papr-pmem

diff --git a/Documentation/ABI/testing/sysfs-bus-papr-pmem b/Documentation/ABI/testing/sysfs-bus-papr-pmem
new file mode 100644
index 000000000000..5b10d036a8d4
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-papr-pmem
@@ -0,0 +1,27 @@
+What:		/sys/bus/nd/devices/nmemX/papr/flags
+Date:		Apr, 2020
+KernelVersion:	v5.8
+Contact:	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, linux-nvdimm@lists.01.org,
+Description:
+		(RO) Report flags indicating various states of a
+		papr-pmem NVDIMM device. Each flag maps to a one or
+		more bits set in the dimm-health-bitmap retrieved in
+		response to H_SCM_HEALTH hcall. The details of the bit
+		flags returned in response to this hcall is available
+		at 'Documentation/powerpc/papr_hcalls.rst' . Below are
+		the flags reported in this sysfs file:
+
+		* "not_armed"	: Indicates that NVDIMM contents will not
+				  survive a power cycle.
+		* "flush_fail"	: Indicates that NVDIMM contents
+				  couldn't be flushed during last
+				  shut-down event.
+		* "restore_fail": Indicates that NVDIMM contents
+				  couldn't be restored during NVDIMM
+				  initialization.
+		* "encrypted"	: NVDIMM contents are encrypted.
+		* "smart_notify": There is health event for the NVDIMM.
+		* "scrubbed"	: Indicating that contents of the
+				  NVDIMM have been scrubbed.
+		* "locked"	: Indicating that NVDIMM contents cant
+				  be modified until next power cycle.
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index f35592423380..149431594839 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -12,6 +12,7 @@
 #include <linux/libnvdimm.h>
 #include <linux/platform_device.h>
 #include <linux/delay.h>
+#include <linux/seq_buf.h>
 
 #include <asm/plpar_wrappers.h>
 
@@ -22,6 +23,44 @@
 	 (1ul << ND_CMD_GET_CONFIG_DATA) | \
 	 (1ul << ND_CMD_SET_CONFIG_DATA))
 
+/* DIMM health bitmap bitmap indicators */
+/* SCM device is unable to persist memory contents */
+#define PAPR_PMEM_UNARMED                   (1ULL << (63 - 0))
+/* SCM device failed to persist memory contents */
+#define PAPR_PMEM_SHUTDOWN_DIRTY            (1ULL << (63 - 1))
+/* SCM device contents are persisted from previous IPL */
+#define PAPR_PMEM_SHUTDOWN_CLEAN            (1ULL << (63 - 2))
+/* SCM device contents are not persisted from previous IPL */
+#define PAPR_PMEM_EMPTY                     (1ULL << (63 - 3))
+/* SCM device memory life remaining is critically low */
+#define PAPR_PMEM_HEALTH_CRITICAL           (1ULL << (63 - 4))
+/* SCM device will be garded off next IPL due to failure */
+#define PAPR_PMEM_HEALTH_FATAL              (1ULL << (63 - 5))
+/* SCM contents cannot persist due to current platform health status */
+#define PAPR_PMEM_HEALTH_UNHEALTHY          (1ULL << (63 - 6))
+/* SCM device is unable to persist memory contents in certain conditions */
+#define PAPR_PMEM_HEALTH_NON_CRITICAL       (1ULL << (63 - 7))
+/* SCM device is encrypted */
+#define PAPR_PMEM_ENCRYPTED                 (1ULL << (63 - 8))
+/* SCM device has been scrubbed and locked */
+#define PAPR_PMEM_SCRUBBED_AND_LOCKED       (1ULL << (63 - 9))
+
+/* Bits status indicators for health bitmap indicating unarmed dimm */
+#define PAPR_PMEM_UNARMED_MASK (PAPR_PMEM_UNARMED |		\
+				PAPR_PMEM_HEALTH_UNHEALTHY)
+
+/* Bits status indicators for health bitmap indicating unflushed dimm */
+#define PAPR_PMEM_BAD_SHUTDOWN_MASK (PAPR_PMEM_SHUTDOWN_DIRTY)
+
+/* Bits status indicators for health bitmap indicating unrestored dimm */
+#define PAPR_PMEM_BAD_RESTORE_MASK  (PAPR_PMEM_EMPTY)
+
+/* Bit status indicators for smart event notification */
+#define PAPR_PMEM_SMART_EVENT_MASK (PAPR_PMEM_HEALTH_CRITICAL | \
+				    PAPR_PMEM_HEALTH_FATAL |	\
+				    PAPR_PMEM_HEALTH_UNHEALTHY)
+
+/* private struct associated with each region */
 struct papr_scm_priv {
 	struct platform_device *pdev;
 	struct device_node *dn;
@@ -39,6 +78,15 @@ struct papr_scm_priv {
 	struct resource res;
 	struct nd_region *region;
 	struct nd_interleave_set nd_set;
+
+	/* Protect dimm health data from concurrent read/writes */
+	struct mutex health_mutex;
+
+	/* Last time the health information of the dimm was updated */
+	unsigned long lasthealth_jiffies;
+
+	/* Health information for the dimm */
+	u64 health_bitmap;
 };
 
 static int drc_pmem_bind(struct papr_scm_priv *p)
@@ -144,6 +192,62 @@ static int drc_pmem_query_n_bind(struct papr_scm_priv *p)
 	return drc_pmem_bind(p);
 }
 
+/*
+ * Issue hcall to retrieve dimm health info and populate papr_scm_priv with the
+ * health information.
+ */
+static int __drc_pmem_query_health(struct papr_scm_priv *p)
+{
+	unsigned long ret[PLPAR_HCALL_BUFSIZE];
+	long rc;
+
+	/* issue the hcall */
+	rc = plpar_hcall(H_SCM_HEALTH, ret, p->drc_index);
+	if (rc != H_SUCCESS) {
+		dev_err(&p->pdev->dev,
+			 "Failed to query health information, Err:%ld\n", rc);
+		rc = -ENXIO;
+		goto out;
+	}
+
+	p->lasthealth_jiffies = jiffies;
+	p->health_bitmap = ret[0] & ret[1];
+
+	dev_dbg(&p->pdev->dev,
+		"Queried dimm health info. Bitmap:0x%016lx Mask:0x%016lx\n",
+		ret[0], ret[1]);
+out:
+	return rc;
+}
+
+/* Min interval in seconds for assuming stable dimm health */
+#define MIN_HEALTH_QUERY_INTERVAL 60
+
+/* Query cached health info and if needed call drc_pmem_query_health */
+static int drc_pmem_query_health(struct papr_scm_priv *p)
+{
+	unsigned long cache_timeout;
+	int rc;
+
+	/* Protect concurrent modifications to papr_scm_priv */
+	rc = mutex_lock_interruptible(&p->health_mutex);
+	if (rc)
+		return rc;
+
+	/* Jiffies offset for which the health data is assumed to be same */
+	cache_timeout = p->lasthealth_jiffies +
+		msecs_to_jiffies(MIN_HEALTH_QUERY_INTERVAL * 1000);
+
+	/* Fetch new health info is its older than MIN_HEALTH_QUERY_INTERVAL */
+	if (time_after(jiffies, cache_timeout))
+		rc = __drc_pmem_query_health(p);
+	else
+		/* Assume cached health data is valid */
+		rc = 0;
+
+	mutex_unlock(&p->health_mutex);
+	return rc;
+}
 
 static int papr_scm_meta_get(struct papr_scm_priv *p,
 			     struct nd_cmd_get_config_data_hdr *hdr)
@@ -286,6 +390,64 @@ static int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc,
 	return 0;
 }
 
+static ssize_t flags_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);
+	struct seq_buf s;
+	u64 health;
+	int rc;
+
+	rc = drc_pmem_query_health(p);
+	if (rc)
+		return rc;
+
+	/* Copy health_bitmap locally, check masks & update out buffer */
+	health = READ_ONCE(p->health_bitmap);
+
+	seq_buf_init(&s, buf, PAGE_SIZE);
+	if (health & PAPR_PMEM_UNARMED_MASK)
+		seq_buf_printf(&s, "not_armed ");
+
+	if (health & PAPR_PMEM_BAD_SHUTDOWN_MASK)
+		seq_buf_printf(&s, "flush_fail ");
+
+	if (health & PAPR_PMEM_BAD_RESTORE_MASK)
+		seq_buf_printf(&s, "restore_fail ");
+
+	if (health & PAPR_PMEM_ENCRYPTED)
+		seq_buf_printf(&s, "encrypted ");
+
+	if (health & PAPR_PMEM_SMART_EVENT_MASK)
+		seq_buf_printf(&s, "smart_notify ");
+
+	if (health & PAPR_PMEM_SCRUBBED_AND_LOCKED)
+		seq_buf_printf(&s, "scrubbed locked ");
+
+	if (seq_buf_used(&s))
+		seq_buf_printf(&s, "\n");
+
+	return seq_buf_used(&s);
+}
+DEVICE_ATTR_RO(flags);
+
+/* papr_scm specific dimm attributes */
+static struct attribute *papr_nd_attributes[] = {
+	&dev_attr_flags.attr,
+	NULL,
+};
+
+static struct attribute_group papr_nd_attribute_group = {
+	.name = "papr",
+	.attrs = papr_nd_attributes,
+};
+
+static const struct attribute_group *papr_nd_attr_groups[] = {
+	&papr_nd_attribute_group,
+	NULL,
+};
+
 static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 {
 	struct device *dev = &p->pdev->dev;
@@ -312,8 +474,8 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 	dimm_flags = 0;
 	set_bit(NDD_LABELING, &dimm_flags);
 
-	p->nvdimm = nvdimm_create(p->bus, p, NULL, dimm_flags,
-				  PAPR_SCM_DIMM_CMD_MASK, 0, NULL);
+	p->nvdimm = nvdimm_create(p->bus, p, papr_nd_attr_groups,
+				  dimm_flags, PAPR_SCM_DIMM_CMD_MASK, 0, NULL);
 	if (!p->nvdimm) {
 		dev_err(dev, "Error creating DIMM object for %pOF\n", p->dn);
 		goto err;
@@ -399,6 +561,9 @@ static int papr_scm_probe(struct platform_device *pdev)
 	if (!p)
 		return -ENOMEM;
 
+	/* Initialize the dimm mutex */
+	mutex_init(&p->health_mutex);
+
 	/* optional DT properties */
 	of_property_read_u32(dn, "ibm,metadata-size", &metadata_size);
 
-- 
2.26.2
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[PATCH v9 4/5] ndctl/papr_scm,uapi: Add support for PAPR nvdimm specific methods

[Vaibhav Jain]

Introduce support for PAPR NVDIMM Specific Methods (PDSM) in papr_scm
module and add the command family NVDIMM_FAMILY_PAPR to the white list
of NVDIMM command sets. Also advertise support for ND_CMD_CALL for the
nvdimm command mask and implement necessary scaffolding in the module
to handle ND_CMD_CALL ioctl and PDSM requests that we receive.

The layout of the PDSM request as we expect from libnvdimm/libndctl is
described in newly introduced uapi header 'papr_pdsm.h' which
defines a new 'struct nd_pdsm_cmd_pkg' header. This header is used
to communicate the PDSM request via member
'nd_cmd_pkg.nd_command' and size of payload that need to be
sent/received for servicing the PDSM.

A new function is_cmd_valid() is implemented that reads the args to
papr_scm_ndctl() and performs sanity tests on them. A new function
papr_scm_service_pdsm() is introduced and is called from
papr_scm_ndctl() in case of a PDSM request is received via ND_CMD_CALL
command from libnvdimm.

Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
Changelog:

v8..v9:
* Reduced the usage of term SCM replacing it with appropriate
  replacement [ Dan Williams, Aneesh ]
* Renamed 'papr_scm_pdsm.h' to 'papr_pdsm.h'
* s/PAPR_SCM_PDSM_*/PAPR_PDSM_*/g
* s/NVDIMM_FAMILY_PAPR_SCM/NVDIMM_FAMILY_PAPR/g
* Minor updates to 'papr_psdm.h' to replace usage of term 'SCM'.
* Minor update to patch description.

v7..v8:
* Removed the 'payload_offset' field from 'struct
  nd_pdsm_cmd_pkg'. Instead command payload is always assumed to start
  at 'nd_pdsm_cmd_pkg.payload'. [ Aneesh ]
* To enable introducing new fields to 'struct nd_pdsm_cmd_pkg',
  'reserved' field of 10-bytes is introduced. [ Aneesh ]
* Fixed a typo in "Backward Compatibility" section of papr_scm_pdsm.h
  [ Ira ]

Resend:
* None

v6..v7 :
* Removed the re-definitions of __packed macro from papr_scm_pdsm.h
  [Mpe].
* Removed the usage of __KERNEL__ macros in papr_scm_pdsm.h [Mpe].
* Removed macros that were unused in papr_scm.c from papr_scm_pdsm.h
  [Mpe].
* Made functions defined in papr_scm_pdsm.h as static inline. [Mpe]

v5..v6 :
* Changed the usage of the term DSM to PDSM to distinguish it from the
  ACPI term [ Dan Williams ]
* Renamed papr_scm_dsm.h to papr_scm_pdsm.h and updated various struct
  to reflect the new terminology.
* Updated the patch description and title to reflect the new terminology.
* Squashed patch to introduce new command family in 'ndctl.h' with
  this patch [ Dan Williams ]
* Updated the papr_scm_pdsm method starting index from 0x10000 to 0x0
  [ Dan Williams ]
* Removed redundant license text from the papr_scm_psdm.h file.
  [ Dan Williams ]
* s/envelop/envelope/ at various places [ Dan Williams ]
* Added '__packed' attribute to command package header to gaurd
  against different compiler adding paddings between the fields.
  [ Dan Williams]
* Converted various pr_debug to dev_debug [ Dan Williams ]

v4..v5 :
* None

v3..v4 :
* None

v2..v3 :
* Updated the patch prefix to 'ndctl/uapi' [Aneesh]

v1..v2 :
* None
---
 arch/powerpc/include/uapi/asm/papr_pdsm.h | 136 ++++++++++++++++++++++
 arch/powerpc/platforms/pseries/papr_scm.c | 101 +++++++++++++++-
 include/uapi/linux/ndctl.h                |   1 +
 3 files changed, 232 insertions(+), 6 deletions(-)
 create mode 100644 arch/powerpc/include/uapi/asm/papr_pdsm.h

diff --git a/arch/powerpc/include/uapi/asm/papr_pdsm.h b/arch/powerpc/include/uapi/asm/papr_pdsm.h
new file mode 100644
index 000000000000..6407fefcc007
--- /dev/null
+++ b/arch/powerpc/include/uapi/asm/papr_pdsm.h
@@ -0,0 +1,136 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+/*
+ * PAPR nvDimm Specific Methods (PDSM) and structs for libndctl
+ *
+ * (C) Copyright IBM 2020
+ *
+ * Author: Vaibhav Jain <vaibhav at linux.ibm.com>
+ */
+
+#ifndef _UAPI_ASM_POWERPC_PAPR_PDSM_H_
+#define _UAPI_ASM_POWERPC_PAPR_PDSM_H_
+
+#include <linux/types.h>
+
+/*
+ * PDSM Envelope:
+ *
+ * The ioctl ND_CMD_CALL transfers data between user-space and kernel via
+ * envelope which consists of a header and user-defined payload sections.
+ * The header is described by 'struct nd_pdsm_cmd_pkg' which expects a
+ * payload following it and accessible via 'nd_pdsm_cmd_pkg.payload' field.
+ * There is reserved field that can used to introduce new fields to the
+ * structure in future. It also tries to ensure that 'nd_pdsm_cmd_pkg.payload'
+ * lies at a 8-byte boundary.
+ *
+ *  +-------------+---------------------+---------------------------+
+ *  |   64-Bytes  |       16-Bytes      |       Max 176-Bytes       |
+ *  +-------------+---------------------+---------------------------+
+ *  |               nd_pdsm_cmd_pkg     |                           |
+ *  |-------------+                     |                           |
+ *  |  nd_cmd_pkg |                     |                           |
+ *  +-------------+---------------------+---------------------------+
+ *  | nd_family   |                     |                           |
+ *  | nd_size_out | cmd_status          |                           |
+ *  | nd_size_in  | payload_version     |     payload               |
+ *  | nd_command  | reserved            |                           |
+ *  | nd_fw_size  |                     |                           |
+ *  +-------------+---------------------+---------------------------+
+ *
+ * PDSM Header:
+ *
+ * The header is defined as 'struct nd_pdsm_cmd_pkg' which embeds a
+ * 'struct nd_cmd_pkg' instance. The PDSM command is assigned to member
+ * 'nd_cmd_pkg.nd_command'. Apart from size information of the envelope which is
+ * contained in 'struct nd_cmd_pkg', the header also has members following
+ * members:
+ *
+ * 'cmd_status'		: (Out) Errors if any encountered while servicing PDSM.
+ * 'payload_version'	: (In/Out) Version number associated with the payload.
+ * 'reserved'		: Not used and reserved for future.
+ *
+ * PDSM Payload:
+ *
+ * The layout of the PDSM Payload is defined by various structs shared between
+ * papr_scm and libndctl so that contents of payload can be interpreted. During
+ * servicing of a PDSM the papr_scm module will read input args from the payload
+ * field by casting its contents to an appropriate struct pointer based on the
+ * PDSM command. Similarly the output of servicing the PDSM command will be
+ * copied to the payload field using the same struct.
+ *
+ * 'libnvdimm' enforces a hard limit of 256 bytes on the envelope size, which
+ * leaves around 176 bytes for the envelope payload (ignoring any padding that
+ * the compiler may silently introduce).
+ *
+ * Payload Version:
+ *
+ * A 'payload_version' field is present in PDSM header that indicates a specific
+ * version of the structure present in PDSM Payload for a given PDSM command.
+ * This provides backward compatibility in case the PDSM Payload structure
+ * evolves and different structures are supported by 'papr_scm' and 'libndctl'.
+ *
+ * When sending a PDSM Payload to 'papr_scm', 'libndctl' should send the version
+ * of the payload struct it supports via 'payload_version' field. The 'papr_scm'
+ * module when servicing the PDSM envelope checks the 'payload_version' and then
+ * uses 'payload struct version' == MIN('payload_version field',
+ * 'max payload-struct-version supported by papr_scm') to service the PDSM.
+ * After servicing the PDSM, 'papr_scm' put the negotiated version of payload
+ * struct in returned 'payload_version' field.
+ *
+ * Libndctl on receiving the envelope back from papr_scm again checks the
+ * 'payload_version' field and based on it use the appropriate version dsm
+ * struct to parse the results.
+ *
+ * Backward Compatibility:
+ *
+ * Above scheme of exchanging different versioned PDSM struct between libndctl
+ * and papr_scm should provide backward compatibility until following two
+ * assumptions/conditions when defining new PDSM structs hold:
+ *
+ * Let T(X) = { set of attributes in PDSM struct 'T' versioned X }
+ *
+ * 1. T(X) is a proper subset of T(Y) if Y > X.
+ *    i.e Each new version of PDSM struct should retain existing struct
+ *    attributes from previous version
+ *
+ * 2. If an entity (libndctl or papr_scm) supports a PDSM struct T(X) then
+ *    it should also support T(1), T(2)...T(X - 1).
+ *    i.e When adding support for new version of a PDSM struct, libndctl
+ *    and papr_scm should retain support of the existing PDSM struct
+ *    version they support.
+ */
+
+/* PDSM-header + payload expected with ND_CMD_CALL ioctl from libnvdimm */
+struct nd_pdsm_cmd_pkg {
+	struct nd_cmd_pkg hdr;	/* Package header containing sub-cmd */
+	__s32 cmd_status;	/* Out: Sub-cmd status returned back */
+	__u16 reserved[5];	/* Ignored and to be used in future */
+	__u16 payload_version;	/* In/Out: version of the payload */
+	__u8 payload[];		/* In/Out: Sub-cmd data buffer */
+} __packed;
+
+/*
+ * 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_MAX,
+};
+
+/* Convert a libnvdimm nd_cmd_pkg to pdsm specific pkg */
+static inline struct nd_pdsm_cmd_pkg *nd_to_pdsm_cmd_pkg(struct nd_cmd_pkg *cmd)
+{
+	return (struct nd_pdsm_cmd_pkg *) cmd;
+}
+
+/* Return the payload pointer for a given pcmd */
+static inline void *pdsm_cmd_to_payload(struct nd_pdsm_cmd_pkg *pcmd)
+{
+	if (pcmd->hdr.nd_size_in == 0 && pcmd->hdr.nd_size_out == 0)
+		return NULL;
+	else
+		return (void *)(pcmd->payload);
+}
+
+#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 149431594839..5e2237e7ec08 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -15,13 +15,15 @@
 #include <linux/seq_buf.h>
 
 #include <asm/plpar_wrappers.h>
+#include <asm/papr_pdsm.h>
 
 #define BIND_ANY_ADDR (~0ul)
 
 #define PAPR_SCM_DIMM_CMD_MASK \
 	((1ul << ND_CMD_GET_CONFIG_SIZE) | \
 	 (1ul << ND_CMD_GET_CONFIG_DATA) | \
-	 (1ul << ND_CMD_SET_CONFIG_DATA))
+	 (1ul << ND_CMD_SET_CONFIG_DATA) | \
+	 (1ul << ND_CMD_CALL))
 
 /* DIMM health bitmap bitmap indicators */
 /* SCM device is unable to persist memory contents */
@@ -350,16 +352,97 @@ static int papr_scm_meta_set(struct papr_scm_priv *p,
 	return 0;
 }
 
+/*
+ * Validate the inputs args to dimm-control function and return '0' if valid.
+ * This also does initial sanity validation to ND_CMD_CALL sub-command packages.
+ */
+static int is_cmd_valid(struct nvdimm *nvdimm, unsigned int cmd, void *buf,
+		       unsigned int buf_len)
+{
+	unsigned long cmd_mask = PAPR_SCM_DIMM_CMD_MASK;
+	struct nd_pdsm_cmd_pkg *pkg = nd_to_pdsm_cmd_pkg(buf);
+	struct papr_scm_priv *p;
+
+	/* Only dimm-specific calls are supported atm */
+	if (!nvdimm)
+		return -EINVAL;
+
+	/* get the provider date from struct nvdimm */
+	p = nvdimm_provider_data(nvdimm);
+
+	if (!test_bit(cmd, &cmd_mask)) {
+		dev_dbg(&p->pdev->dev, "Unsupported cmd=%u\n", cmd);
+		return -EINVAL;
+	} else if (cmd == ND_CMD_CALL) {
+
+		/* Verify the envelope package */
+		if (!buf || buf_len < sizeof(struct nd_pdsm_cmd_pkg)) {
+			dev_dbg(&p->pdev->dev, "Invalid pkg size=%u\n",
+				buf_len);
+			return -EINVAL;
+		}
+
+		/* Verify that the PDSM family is valid */
+		if (pkg->hdr.nd_family != NVDIMM_FAMILY_PAPR) {
+			dev_dbg(&p->pdev->dev, "Invalid pkg family=0x%llx\n",
+				pkg->hdr.nd_family);
+			return -EINVAL;
+
+		}
+
+		/* We except a payload with all PDSM commands */
+		if (pdsm_cmd_to_payload(pkg) == NULL) {
+			dev_dbg(&p->pdev->dev,
+				"Empty payload for sub-command=0x%llx\n",
+				pkg->hdr.nd_command);
+			return -EINVAL;
+		}
+	}
+
+	/* Command looks valid */
+	return 0;
+}
+
+static int papr_scm_service_pdsm(struct papr_scm_priv *p,
+				struct nd_pdsm_cmd_pkg *call_pkg)
+{
+	/* unknown subcommands return error in packages */
+	if (call_pkg->hdr.nd_command <= PAPR_PDSM_MIN ||
+	    call_pkg->hdr.nd_command >= PAPR_PDSM_MAX) {
+		dev_dbg(&p->pdev->dev, "Invalid PDSM request 0x%llx\n",
+			call_pkg->hdr.nd_command);
+		call_pkg->cmd_status = -EINVAL;
+		return 0;
+	}
+
+	/* Depending on the DSM command call appropriate service routine */
+	switch (call_pkg->hdr.nd_command) {
+	default:
+		dev_dbg(&p->pdev->dev, "Unsupported PDSM request 0x%llx\n",
+			call_pkg->hdr.nd_command);
+		call_pkg->cmd_status = -ENOENT;
+		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)
 {
 	struct nd_cmd_get_config_size *get_size_hdr;
 	struct papr_scm_priv *p;
+	struct nd_pdsm_cmd_pkg *call_pkg = NULL;
+	int rc;
 
-	/* Only dimm-specific calls are supported atm */
-	if (!nvdimm)
-		return -EINVAL;
+	/* Use a local variable in case cmd_rc pointer is NULL */
+	if (cmd_rc == NULL)
+		cmd_rc = &rc;
+
+	*cmd_rc = is_cmd_valid(nvdimm, cmd, buf, buf_len);
+	if (*cmd_rc) {
+		pr_debug("Invalid cmd=0x%x. Err=%d\n", cmd, *cmd_rc);
+		return *cmd_rc;
+	}
 
 	p = nvdimm_provider_data(nvdimm);
 
@@ -381,13 +464,19 @@ static int papr_scm_ndctl(struct nvdimm_bus_descriptor *nd_desc,
 		*cmd_rc = papr_scm_meta_set(p, buf);
 		break;
 
+	case ND_CMD_CALL:
+		call_pkg = nd_to_pdsm_cmd_pkg(buf);
+		*cmd_rc = papr_scm_service_pdsm(p, call_pkg);
+		break;
+
 	default:
-		return -EINVAL;
+		dev_dbg(&p->pdev->dev, "Unknown command = %d\n", cmd);
+		*cmd_rc = -EINVAL;
 	}
 
 	dev_dbg(&p->pdev->dev, "returned with cmd_rc = %d\n", *cmd_rc);
 
-	return 0;
+	return *cmd_rc;
 }
 
 static ssize_t flags_show(struct device *dev,
diff --git a/include/uapi/linux/ndctl.h b/include/uapi/linux/ndctl.h
index de5d90212409..0e09dc5cec19 100644
--- a/include/uapi/linux/ndctl.h
+++ b/include/uapi/linux/ndctl.h
@@ -244,6 +244,7 @@ struct nd_cmd_pkg {
 #define NVDIMM_FAMILY_HPE2 2
 #define NVDIMM_FAMILY_MSFT 3
 #define NVDIMM_FAMILY_HYPERV 4
+#define NVDIMM_FAMILY_PAPR 5
 
 #define ND_IOCTL_CALL			_IOWR(ND_IOCTL, ND_CMD_CALL,\
 					struct nd_cmd_pkg)
-- 
2.26.2
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[PATCH v9 5/5] 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'.

The patch also introduces a new member 'struct papr_scm_priv.health'
thats an instance of 'struct nd_papr_pdsm_health' to cache the health
information of a nvdimm. As a result functions drc_pmem_query_health()
and flags_show() are updated to populate and use this new struct
instead of a u64 integer that was earlier used.

Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
---
Changelog:

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 |  39 +++++++
 arch/powerpc/platforms/pseries/papr_scm.c | 125 +++++++++++++++++++---
 2 files changed, 147 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/include/uapi/asm/papr_pdsm.h b/arch/powerpc/include/uapi/asm/papr_pdsm.h
index 6407fefcc007..411725a91591 100644
--- a/arch/powerpc/include/uapi/asm/papr_pdsm.h
+++ b/arch/powerpc/include/uapi/asm/papr_pdsm.h
@@ -115,6 +115,7 @@ struct nd_pdsm_cmd_pkg {
  */
 enum papr_pdsm {
 	PAPR_PDSM_MIN = 0x0,
+	PAPR_PDSM_HEALTH,
 	PAPR_PDSM_MAX,
 };
 
@@ -133,4 +134,42 @@ 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_v1 {
+	__u8 dimm_unarmed;
+	__u8 dimm_bad_shutdown;
+	__u8 dimm_bad_restore;
+	__u8 dimm_scrubbed;
+	__u8 dimm_locked;
+	__u8 dimm_encrypted;
+	__u16 dimm_health;
+} __packed;
+
+/*
+ * Typedef the current struct for dimm_health so that any application
+ * or kernel recompiled after introducing a new version automatically
+ * supports the new version.
+ */
+#define nd_papr_pdsm_health nd_papr_pdsm_health_v1
+
+/* Current version number for the dimm health struct */
+#define ND_PAPR_PDSM_HEALTH_VERSION 1
+
 #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 5e2237e7ec08..c0606c0c659c 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -88,7 +88,7 @@ struct papr_scm_priv {
 	unsigned long lasthealth_jiffies;
 
 	/* Health information for the dimm */
-	u64 health_bitmap;
+	struct nd_papr_pdsm_health health;
 };
 
 static int drc_pmem_bind(struct papr_scm_priv *p)
@@ -201,6 +201,7 @@ static int drc_pmem_query_n_bind(struct papr_scm_priv *p)
 static int __drc_pmem_query_health(struct papr_scm_priv *p)
 {
 	unsigned long ret[PLPAR_HCALL_BUFSIZE];
+	u64 health;
 	long rc;
 
 	/* issue the hcall */
@@ -208,18 +209,46 @@ static int __drc_pmem_query_health(struct papr_scm_priv *p)
 	if (rc != H_SUCCESS) {
 		dev_err(&p->pdev->dev,
 			 "Failed to query health information, Err:%ld\n", rc);
-		rc = -ENXIO;
-		goto out;
+		return -ENXIO;
 	}
 
 	p->lasthealth_jiffies = jiffies;
-	p->health_bitmap = ret[0] & ret[1];
+	health = ret[0] & ret[1];
 
 	dev_dbg(&p->pdev->dev,
 		"Queried dimm health info. Bitmap:0x%016lx Mask:0x%016lx\n",
 		ret[0], ret[1]);
-out:
-	return rc;
+
+	memset(&p->health, 0, sizeof(p->health));
+
+	/* Check for various masks in bitmap and set the buffer */
+	if (health & PAPR_PMEM_UNARMED_MASK)
+		p->health.dimm_unarmed = 1;
+
+	if (health & PAPR_PMEM_BAD_SHUTDOWN_MASK)
+		p->health.dimm_bad_shutdown = 1;
+
+	if (health & PAPR_PMEM_BAD_RESTORE_MASK)
+		p->health.dimm_bad_restore = 1;
+
+	if (health & PAPR_PMEM_ENCRYPTED)
+		p->health.dimm_encrypted = 1;
+
+	if (health & PAPR_PMEM_SCRUBBED_AND_LOCKED) {
+		p->health.dimm_locked = 1;
+		p->health.dimm_scrubbed = 1;
+	}
+
+	if (health & PAPR_PMEM_HEALTH_UNHEALTHY)
+		p->health.dimm_health = PAPR_PDSM_DIMM_UNHEALTHY;
+
+	if (health & PAPR_PMEM_HEALTH_CRITICAL)
+		p->health.dimm_health = PAPR_PDSM_DIMM_CRITICAL;
+
+	if (health & PAPR_PMEM_HEALTH_FATAL)
+		p->health.dimm_health = PAPR_PDSM_DIMM_FATAL;
+
+	return 0;
 }
 
 /* Min interval in seconds for assuming stable dimm health */
@@ -403,6 +432,58 @@ 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;
+	size_t copysize = sizeof(p->health);
+
+	/* 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)
+		goto out_unlock;
+	/*
+	 * If the requested payload version is greater than one we know
+	 * about, return the payload version we know about and let
+	 * caller/userspace handle.
+	 */
+	if (pkg->payload_version > ND_PAPR_PDSM_HEALTH_VERSION)
+		pkg->payload_version = ND_PAPR_PDSM_HEALTH_VERSION;
+
+	if (pkg->hdr.nd_size_out < copysize) {
+		dev_dbg(&p->pdev->dev, "Truncated payload (%u). Expected (%lu)",
+			pkg->hdr.nd_size_out, copysize);
+		rc = -ENOSPC;
+		goto out_unlock;
+	}
+
+	dev_dbg(&p->pdev->dev, "Copying payload size=%lu version=0x%x\n",
+		copysize, pkg->payload_version);
+
+	/* Copy the health struct to the payload */
+	memcpy(pdsm_cmd_to_payload(pkg), &p->health, copysize);
+	pkg->hdr.nd_fw_size = copysize;
+
+out_unlock:
+	mutex_unlock(&p->health_mutex);
+
+out:
+	/*
+	 * Put the error in out package and return success from function
+	 * so that errors if any are propogated back to userspace.
+	 */
+	pkg->cmd_status = rc;
+	dev_dbg(&p->pdev->dev, "completion code = %d\n", rc);
+
+	return 0;
+}
+
 static int papr_scm_service_pdsm(struct papr_scm_priv *p,
 				struct nd_pdsm_cmd_pkg *call_pkg)
 {
@@ -417,6 +498,9 @@ static int papr_scm_service_pdsm(struct papr_scm_priv *p,
 
 	/* Depending on the DSM command call appropriate service routine */
 	switch (call_pkg->hdr.nd_command) {
+	case PAPR_PDSM_HEALTH:
+		return papr_pdsm_health(p, call_pkg);
+
 	default:
 		dev_dbg(&p->pdev->dev, "Unsupported PDSM request 0x%llx\n",
 			call_pkg->hdr.nd_command);
@@ -485,34 +569,41 @@ static ssize_t flags_show(struct device *dev,
 	struct nvdimm *dimm = to_nvdimm(dev);
 	struct papr_scm_priv *p = nvdimm_provider_data(dimm);
 	struct seq_buf s;
-	u64 health;
 	int rc;
 
 	rc = drc_pmem_query_health(p);
 	if (rc)
 		return rc;
 
-	/* Copy health_bitmap locally, check masks & update out buffer */
-	health = READ_ONCE(p->health_bitmap);
-
 	seq_buf_init(&s, buf, PAGE_SIZE);
-	if (health & PAPR_PMEM_UNARMED_MASK)
+
+	/* Protect concurrent modifications to papr_scm_priv */
+	rc = mutex_lock_interruptible(&p->health_mutex);
+	if (rc)
+		return rc;
+
+	if (p->health.dimm_unarmed)
 		seq_buf_printf(&s, "not_armed ");
 
-	if (health & PAPR_PMEM_BAD_SHUTDOWN_MASK)
+	if (p->health.dimm_bad_shutdown)
 		seq_buf_printf(&s, "flush_fail ");
 
-	if (health & PAPR_PMEM_BAD_RESTORE_MASK)
+	if (p->health.dimm_bad_restore)
 		seq_buf_printf(&s, "restore_fail ");
 
-	if (health & PAPR_PMEM_ENCRYPTED)
+	if (p->health.dimm_encrypted)
 		seq_buf_printf(&s, "encrypted ");
 
-	if (health & PAPR_PMEM_SMART_EVENT_MASK)
+	if (p->health.dimm_health)
 		seq_buf_printf(&s, "smart_notify ");
 
-	if (health & PAPR_PMEM_SCRUBBED_AND_LOCKED)
-		seq_buf_printf(&s, "scrubbed locked ");
+	if (p->health.dimm_scrubbed)
+		seq_buf_printf(&s, "scrubbed ");
+
+	if (p->health.dimm_locked)
+		seq_buf_printf(&s, "locked ");
+
+	mutex_unlock(&p->health_mutex);
 
 	if (seq_buf_used(&s))
 		seq_buf_printf(&s, "\n");
-- 
2.26.2
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