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

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

Vaibhav Jain <vaibhav@linux.ibm.com> writes:

> 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")
>

Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>

> 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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