[PATCH v5 1/4] powerpc/papr_scm: Fetch nvdimm health information from PHYP

[Vaibhav Jain <vaibhav@linux.ibm.com>]

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 big-endian integers which are then stored in 'struct
papr_scm_priv' and subsequently partially exposed to user-space via
newly introduced dimm specific attribute 'papr_flags'. Also a new asm
header named 'papr-scm.h' is added that describes the interface
between PHYP and guest kernel.

Following flags are reported via 'papr_flags' sysfs attribute contents
of which are space separated string flags indicating various nvdimm
states:

 * "not_armed" 	: Indicating that nvdimm contents wont survive a power
		   cycle.
 * "save_fail" 	: Indicating that nvdimm contents couldn't be flushed
		   during last shutdown event.
 * "restore_fail": Indicating that nvdimm contents couldn't be restored
		   during dimm initialization.
 * "encrypted" 	: Dimm 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.

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

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

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.
---
 arch/powerpc/include/asm/papr_scm.h       |  48 ++++++++++
 arch/powerpc/platforms/pseries/papr_scm.c | 105 +++++++++++++++++++++-
 2 files changed, 151 insertions(+), 2 deletions(-)
 create mode 100644 arch/powerpc/include/asm/papr_scm.h

diff --git a/arch/powerpc/include/asm/papr_scm.h b/arch/powerpc/include/asm/papr_scm.h
new file mode 100644
index 000000000000..868d3360f56a
--- /dev/null
+++ b/arch/powerpc/include/asm/papr_scm.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Structures and defines needed to manage nvdimms for spapr guests.
+ */
+#ifndef _ASM_POWERPC_PAPR_SCM_H_
+#define _ASM_POWERPC_PAPR_SCM_H_
+
+#include <linux/types.h>
+#include <asm/bitsperlong.h>
+
+/* DIMM health bitmap bitmap indicators */
+/* SCM device is unable to persist memory contents */
+#define PAPR_SCM_DIMM_UNARMED			PPC_BIT(0)
+/* SCM device failed to persist memory contents */
+#define PAPR_SCM_DIMM_SHUTDOWN_DIRTY		PPC_BIT(1)
+/* SCM device contents are persisted from previous IPL */
+#define PAPR_SCM_DIMM_SHUTDOWN_CLEAN		PPC_BIT(2)
+/* SCM device contents are not persisted from previous IPL */
+#define PAPR_SCM_DIMM_EMPTY			PPC_BIT(3)
+/* SCM device memory life remaining is critically low */
+#define PAPR_SCM_DIMM_HEALTH_CRITICAL		PPC_BIT(4)
+/* SCM device will be garded off next IPL due to failure */
+#define PAPR_SCM_DIMM_HEALTH_FATAL		PPC_BIT(5)
+/* SCM contents cannot persist due to current platform health status */
+#define PAPR_SCM_DIMM_HEALTH_UNHEALTHY		PPC_BIT(6)
+/* SCM device is unable to persist memory contents in certain conditions */
+#define PAPR_SCM_DIMM_HEALTH_NON_CRITICAL	PPC_BIT(7)
+/* SCM device is encrypted */
+#define PAPR_SCM_DIMM_ENCRYPTED			PPC_BIT(8)
+/* SCM device has been scrubbed and locked */
+#define PAPR_SCM_DIMM_SCRUBBED_AND_LOCKED	PPC_BIT(9)
+
+/* Bits status indicators for health bitmap indicating unarmed dimm */
+#define PAPR_SCM_DIMM_UNARMED_MASK (PAPR_SCM_DIMM_UNARMED |	\
+					PAPR_SCM_DIMM_HEALTH_UNHEALTHY)
+
+/* Bits status indicators for health bitmap indicating unflushed dimm */
+#define PAPR_SCM_DIMM_BAD_SHUTDOWN_MASK (PAPR_SCM_DIMM_SHUTDOWN_DIRTY)
+
+/* Bits status indicators for health bitmap indicating unrestored dimm */
+#define PAPR_SCM_DIMM_BAD_RESTORE_MASK  (PAPR_SCM_DIMM_EMPTY)
+
+/* Bit status indicators for smart event notification */
+#define PAPR_SCM_DIMM_SMART_EVENT_MASK (PAPR_SCM_DIMM_HEALTH_CRITICAL | \
+					   PAPR_SCM_DIMM_HEALTH_FATAL | \
+					   PAPR_SCM_DIMM_HEALTH_UNHEALTHY)
+
+#endif
diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
index 0b4467e378e5..aaf2e4ab1f75 100644
--- a/arch/powerpc/platforms/pseries/papr_scm.c
+++ b/arch/powerpc/platforms/pseries/papr_scm.c
@@ -14,6 +14,7 @@
 #include <linux/delay.h>
 
 #include <asm/plpar_wrappers.h>
+#include <asm/papr_scm.h>
 
 #define BIND_ANY_ADDR (~0ul)
 
@@ -39,6 +40,13 @@ struct papr_scm_priv {
 	struct resource res;
 	struct nd_region *region;
 	struct nd_interleave_set nd_set;
+
+	/* Protect dimm data from concurrent access */
+	struct mutex dimm_mutex;
+
+	/* Health information for the dimm */
+	__be64 health_bitmap;
+	__be64 health_bitmap_valid;
 };
 
 static int drc_pmem_bind(struct papr_scm_priv *p)
@@ -144,6 +152,35 @@ static int drc_pmem_query_n_bind(struct papr_scm_priv *p)
 	return drc_pmem_bind(p);
 }
 
+static int drc_pmem_query_health(struct papr_scm_priv *p)
+{
+	unsigned long ret[PLPAR_HCALL_BUFSIZE];
+	int64_t rc;
+
+	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:%lld\n", rc);
+		return -ENXIO;
+	}
+
+	/* Protect modifications to papr_scm_priv with the mutex */
+	rc = mutex_lock_interruptible(&p->dimm_mutex);
+	if (rc)
+		return rc;
+
+	/* Store the retrieved health information in dimm platform data */
+	p->health_bitmap = ret[0];
+	p->health_bitmap_valid = ret[1];
+
+	dev_dbg(&p->pdev->dev,
+		"Queried dimm health info. Bitmap:0x%016llx Mask:0x%016llx\n",
+		be64_to_cpu(p->health_bitmap),
+		be64_to_cpu(p->health_bitmap_valid));
+
+	mutex_unlock(&p->dimm_mutex);
+	return 0;
+}
 
 static int papr_scm_meta_get(struct papr_scm_priv *p,
 			     struct nd_cmd_get_config_data_hdr *hdr)
@@ -304,6 +341,67 @@ static inline int papr_scm_node(int node)
 	return min_node;
 }
 
+static ssize_t papr_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);
+	__be64 health;
+	int rc;
+
+	rc = drc_pmem_query_health(p);
+	if (rc)
+		return rc;
+
+	/* Protect against modifications to papr_scm_priv with the mutex */
+	rc = mutex_lock_interruptible(&p->dimm_mutex);
+	if (rc)
+		return rc;
+
+	health = p->health_bitmap & p->health_bitmap_valid;
+
+	/* Check for various masks in bitmap and set the buffer */
+	if (health & PAPR_SCM_DIMM_UNARMED_MASK)
+		rc += sprintf(buf, "not_armed ");
+
+	if (health & PAPR_SCM_DIMM_BAD_SHUTDOWN_MASK)
+		rc += sprintf(buf + rc, "save_fail ");
+
+	if (health & PAPR_SCM_DIMM_BAD_RESTORE_MASK)
+		rc += sprintf(buf + rc, "restore_fail ");
+
+	if (health & PAPR_SCM_DIMM_ENCRYPTED)
+		rc += sprintf(buf + rc, "encrypted ");
+
+	if (health & PAPR_SCM_DIMM_SMART_EVENT_MASK)
+		rc += sprintf(buf + rc, "smart_notify ");
+
+	if (health & PAPR_SCM_DIMM_SCRUBBED_AND_LOCKED)
+		rc += sprintf(buf + rc, "scrubbed locked ");
+
+	if (rc > 0)
+		rc += sprintf(buf + rc, "\n");
+
+	mutex_unlock(&p->dimm_mutex);
+	return rc;
+}
+DEVICE_ATTR_RO(papr_flags);
+
+/* papr_scm specific dimm attributes */
+static struct attribute *papr_scm_nd_attributes[] = {
+	&dev_attr_papr_flags.attr,
+	NULL,
+};
+
+static struct attribute_group papr_scm_nd_attribute_group = {
+	.attrs = papr_scm_nd_attributes,
+};
+
+static const struct attribute_group *papr_scm_dimm_attr_groups[] = {
+	&papr_scm_nd_attribute_group,
+	NULL,
+};
+
 static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 {
 	struct device *dev = &p->pdev->dev;
@@ -330,8 +428,8 @@ static int papr_scm_nvdimm_init(struct papr_scm_priv *p)
 	dimm_flags = 0;
 	set_bit(NDD_ALIASING, &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_scm_dimm_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;
@@ -415,6 +513,9 @@ static int papr_scm_probe(struct platform_device *pdev)
 	if (!p)
 		return -ENOMEM;
 
+	/* Initialize the dimm mutex */
+	mutex_init(&p->dimm_mutex);
+
 	/* optional DT properties */
 	of_property_read_u32(dn, "ibm,metadata-size", &metadata_size);
 
-- 
2.25.1
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