Message-ID: <827fe047-a456-48b4-9db1-d28c184b9cb3@intel.com>
Date: Tue, 5 Nov 2024 13:32:26 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: shiju.jose@...wei.com, linux-edac@...r.kernel.org,
 linux-cxl@...r.kernel.org, linux-acpi@...r.kernel.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org
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Subject: Re: [PATCH v15 13/15] cxl/memfeature: Add CXL memory device sPPR
 control feature



On 11/1/24 2:17 AM, shiju.jose@...wei.com wrote:
> From: Shiju Jose <shiju.jose@...wei.com>
> 
> Post Package Repair (PPR) maintenance operations may be supported by CXL
> devices that implement CXL.mem protocol. A PPR maintenance operation
> requests the CXL device to perform a repair operation on its media.
> For example, a CXL device with DRAM components that support PPR features
> may implement PPR Maintenance operations. DRAM components may support two
> types of PPR: Hard PPR (hPPR), for a permanent row repair, and Soft PPR
> (sPPR), for a temporary row repair. sPPR is much faster than hPPR, but the
> repair is lost with a power cycle.
> 
> During the execution of a PPR Maintenance operation, a CXL memory device:
> - May or may not retain data
> - May or may not be able to process CXL.mem requests correctly, including
> the ones that target the DPA involved in the repair.
> These CXL Memory Device capabilities are specified by Restriction Flags
> in the sPPR Feature and hPPR Feature.
> 
> sPPR maintenance operation may be executed at runtime, if data is retained
> and CXL.mem requests are correctly processed. For CXL devices with DRAM
> components, hPPR maintenance operation may be executed only at boot because
> data would not be retained.
> When a CXL device identifies a failure on a memory component, the device
> may inform the host about the need for a PPR maintenance operation by using
> an Event Record, where the Maintenance Needed flag is set. The Event Record
> specifies the DPA that should be repaired. A CXL device may not keep track
> of the requests that have already been sent and the information on which
> DPA should be repaired may be lost upon power cycle.
> The userspace tool requests for maintenance operation if the number of
> corrected error reported on a CXL.mem media exceeds error threshold.
> 
> CXL spec 3.1 section 8.2.9.7.1.2 describes the device's sPPR (soft PPR)
> maintenance operation and section 8.2.9.7.1.3 describes the device's
> hPPR (hard PPR) maintenance operation feature.
> 
> CXL spec 3.1 section 8.2.9.7.2.1 describes the sPPR feature discovery and
> configuration.
> 
> CXL spec 3.1 section 8.2.9.7.2.2 describes the hPPR feature discovery and
> configuration.
> 
> Add support for controlling CXL memory device sPPR feature.
> Register with EDAC driver, which gets the memory repair attr descriptors
> from the EDAC memory repair driver and exposes sysfs repair control
> attributes for PRR to the userspace. For example CXL PPR control for the
> CXL mem0 device is exposed in /sys/bus/edac/devices/cxl_mem0/mem_repairX/
> 
> Tested with QEMU patch for CXL PPR feature.
> https://lore.kernel.org/all/20240730045722.71482-1-dave@stgolabs.net/
> 
> Signed-off-by: Shiju Jose <shiju.jose@...wei.com>

Just a nit below.

Reviewed-by: Dave Jiang <dave.jiang@...el.com>

> ---
>  drivers/cxl/core/memfeature.c | 369 +++++++++++++++++++++++++++++++++-
>  1 file changed, 368 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cxl/core/memfeature.c b/drivers/cxl/core/memfeature.c
> index e641396a32f5..9238ad10766e 100644
> --- a/drivers/cxl/core/memfeature.c
> +++ b/drivers/cxl/core/memfeature.c
> @@ -16,8 +16,9 @@
>  #include <linux/limits.h>
>  #include <cxl.h>
>  #include <cxlmem.h>
> +#include "core.h"
>  
> -#define CXL_DEV_NUM_RAS_FEATURES	2
> +#define CXL_DEV_NUM_RAS_FEATURES	3
>  #define CXL_DEV_HOUR_IN_SECS	3600
>  
>  #define CXL_SCRUB_NAME_LEN	128
> @@ -606,17 +607,350 @@ static const struct edac_ecs_ops cxl_ecs_ops = {
>  	.set_threshold = cxl_ecs_set_threshold,
>  };
>  
> +/* CXL memory soft PPR & hard PPR control definitions */
> +/* See CXL rev 3.1 @8.2.9.7.2 Table 8-110 Maintenance Operation */
> +static const uuid_t cxl_sppr_uuid =
> +	UUID_INIT(0x892ba475, 0xfad8, 0x474e, 0x9d, 0x3e, 0x69, 0x2c, 0x91, 0x75, 0x68, 0xbb);
> +
> +static const uuid_t cxl_hppr_uuid =
> +	UUID_INIT(0x80ea4521, 0x786f, 0x4127, 0xaf, 0xb1, 0xec, 0x74, 0x59, 0xfb, 0x0e, 0x24);
> +
> +struct cxl_ppr_context {
> +	uuid_t repair_uuid;
> +	u8 instance;
> +	u16 get_feat_size;
> +	u16 set_feat_size;
> +	u8 get_version;
> +	u8 set_version;
> +	u16 set_effects;
> +	struct cxl_memdev *cxlmd;
> +	enum edac_mem_repair_type repair_type;
> +	enum edac_mem_repair_persist_mode persist_mode;
> +	u64 dpa;
> +	u32 nibble_mask;
> +};
> +
> +/**
> + * struct cxl_memdev_ppr_params - CXL memory PPR parameter data structure.
> + * @op_class: PPR operation class.
> + * @op_subclass: PPR operation subclass.
> + * @dpa_support: device physical address for PPR support.
> + * @media_accessible: memory media is accessible or not during PPR operation.
> + * @data_retained: data is retained or not during PPR operation.
> + * @dpa: device physical address.
> + */
> +struct cxl_memdev_ppr_params {
> +	u8 op_class;
> +	u8 op_subclass;
> +	bool dpa_support;
> +	bool media_accessible;
> +	bool data_retained;
> +	u64 dpa;
> +};
> +
> +enum cxl_ppr_param {
> +	CXL_PPR_PARAM_DO_QUERY,
> +	CXL_PPR_PARAM_DO_PPR,
> +};
> +
> +/* See CXL rev 3.1 @8.2.9.7.2.1 Table 8-113 sPPR Feature Readable Attributes */
> +/* See CXL rev 3.1 @8.2.9.7.2.2 Table 8-116 hPPR Feature Readable Attributes */
> +#define	CXL_MEMDEV_PPR_QUERY_RESOURCE_FLAG BIT(0)

Are all the extra spaces after #define intended?

DJ

> +
> +#define CXL_MEMDEV_PPR_DEVICE_INITIATED_MASK BIT(0)
> +#define CXL_MEMDEV_PPR_FLAG_DPA_SUPPORT_MASK BIT(0)
> +#define CXL_MEMDEV_PPR_FLAG_NIBBLE_SUPPORT_MASK BIT(1)
> +#define CXL_MEMDEV_PPR_FLAG_MEM_SPARING_EV_REC_SUPPORT_MASK BIT(2)
> +
> +#define CXL_MEMDEV_PPR_RESTRICTION_FLAG_MEDIA_ACCESSIBLE_MASK BIT(0)
> +#define CXL_MEMDEV_PPR_RESTRICTION_FLAG_DATA_RETAINED_MASK BIT(2)
> +
> +#define CXL_MEMDEV_PPR_SPARING_EV_REC_EN_MASK BIT(0)
> +
> +struct cxl_memdev_repair_rd_attrs_hdr {
> +	u8 max_op_latency;
> +	__le16 op_cap;
> +	__le16 op_mode;
> +	u8 op_class;
> +	u8 op_subclass;
> +	u8 rsvd[9];
> +}  __packed;
> +
> +struct cxl_memdev_ppr_rd_attrs {
> +	struct cxl_memdev_repair_rd_attrs_hdr hdr;
> +	u8 ppr_flags;
> +	__le16 restriction_flags;
> +	u8 ppr_op_mode;
> +}  __packed;
> +
> +/* See CXL rev 3.1 @8.2.9.7.2.1 Table 8-114 sPPR Feature Writable Attributes */
> +/* See CXL rev 3.1 @8.2.9.7.2.2 Table 8-117 hPPR Feature Writable Attributes */
> +struct cxl_memdev_ppr_wr_attrs {
> +	__le16 op_mode;
> +	u8 ppr_op_mode;
> +}  __packed;
> +
> +/* See CXL rev 3.1 @8.2.9.7.1.2 Table 8-103 sPPR Maintenance Input Payload */
> +/* See CXL rev 3.1 @8.2.9.7.1.3 Table 8-104 hPPR Maintenance Input Payload */
> +struct cxl_memdev_ppr_maintenance_attrs {
> +	u8 flags;
> +	__le64 dpa;
> +	u8 nibble_mask[3];
> +}  __packed;
> +
> +static int cxl_mem_ppr_get_attrs(struct device *dev,
> +				 struct cxl_ppr_context *cxl_ppr_ctx,
> +				 struct cxl_memdev_ppr_params *params)
> +{
> +	struct cxl_memdev *cxlmd = cxl_ppr_ctx->cxlmd;
> +	struct cxl_dev_state *cxlds = cxlmd->cxlds;
> +	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
> +	size_t rd_data_size = sizeof(struct cxl_memdev_ppr_rd_attrs);
> +	size_t data_size;
> +	struct cxl_memdev_ppr_rd_attrs *rd_attrs __free(kfree) =
> +				kmalloc(rd_data_size, GFP_KERNEL);
> +	if (!rd_attrs)
> +		return -ENOMEM;
> +
> +	data_size = cxl_get_feature(mds, cxl_ppr_ctx->repair_uuid,
> +				    CXL_GET_FEAT_SEL_CURRENT_VALUE,
> +				    rd_attrs, rd_data_size);
> +	if (!data_size)
> +		return -EIO;
> +
> +	params->op_class = rd_attrs->hdr.op_class;
> +	params->op_subclass = rd_attrs->hdr.op_subclass;
> +	params->dpa_support = FIELD_GET(CXL_MEMDEV_PPR_FLAG_DPA_SUPPORT_MASK,
> +					rd_attrs->ppr_flags);
> +	params->media_accessible = FIELD_GET(CXL_MEMDEV_PPR_RESTRICTION_FLAG_MEDIA_ACCESSIBLE_MASK,
> +					     rd_attrs->restriction_flags) ^ 1;
> +	params->data_retained = FIELD_GET(CXL_MEMDEV_PPR_RESTRICTION_FLAG_DATA_RETAINED_MASK,
> +					  rd_attrs->restriction_flags) ^ 1;
> +
> +	return 0;
> +}
> +
> +static int cxl_mem_do_ppr_op(struct device *dev,
> +			     struct cxl_ppr_context *cxl_ppr_ctx,
> +			     struct cxl_memdev_ppr_params *rd_params,
> +			     enum cxl_ppr_param param_type)
> +{
> +	struct cxl_memdev_ppr_maintenance_attrs maintenance_attrs;
> +	struct cxl_memdev *cxlmd = cxl_ppr_ctx->cxlmd;
> +	struct cxl_dev_state *cxlds = cxlmd->cxlds;
> +	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
> +	int ret;
> +
> +	if (!rd_params->media_accessible || !rd_params->data_retained) {
> +		/* Check if DPA is mapped */
> +		if (cxl_dpa_to_region(cxlmd, cxl_ppr_ctx->dpa)) {
> +			dev_err(dev, "CXL can't do PPR as DPA is mapped\n");
> +			return -EBUSY;
> +		}
> +	}
> +	memset(&maintenance_attrs, 0, sizeof(maintenance_attrs));
> +	if (param_type == CXL_PPR_PARAM_DO_QUERY)
> +		maintenance_attrs.flags = CXL_MEMDEV_PPR_QUERY_RESOURCE_FLAG;
> +	else
> +		maintenance_attrs.flags = 0;
> +	maintenance_attrs.dpa = cxl_ppr_ctx->dpa;
> +	*((u32 *)&maintenance_attrs.nibble_mask[0]) = cxl_ppr_ctx->nibble_mask;
> +	ret = cxl_do_maintenance(mds, rd_params->op_class, rd_params->op_subclass,
> +				 &maintenance_attrs, sizeof(maintenance_attrs));
> +	if (ret) {
> +		dev_err(dev, "CXL do PPR failed ret=%d\n", ret);
> +		up_read(&cxl_region_rwsem);
> +		cxl_ppr_ctx->nibble_mask = 0;
> +		cxl_ppr_ctx->dpa = 0;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int cxl_mem_ppr_set_attrs(struct device *dev,
> +				 struct cxl_ppr_context *cxl_ppr_ctx,
> +				 enum cxl_ppr_param param_type)
> +{
> +	struct cxl_memdev_ppr_params rd_params;
> +	int ret;
> +
> +	ret = cxl_mem_ppr_get_attrs(dev, cxl_ppr_ctx, &rd_params);
> +	if (ret) {
> +		dev_err(dev, "Get cxlmemdev PPR params failed ret=%d\n",
> +			ret);
> +		return ret;
> +	}
> +
> +	switch (param_type) {
> +	case CXL_PPR_PARAM_DO_QUERY:
> +	case CXL_PPR_PARAM_DO_PPR:
> +		ret = down_read_interruptible(&cxl_region_rwsem);
> +		if (ret)
> +			return ret;
> +		ret = down_read_interruptible(&cxl_dpa_rwsem);
> +		if (ret) {
> +			up_read(&cxl_region_rwsem);
> +			return ret;
> +		}
> +		ret = cxl_mem_do_ppr_op(dev, cxl_ppr_ctx, &rd_params, param_type);
> +		up_read(&cxl_dpa_rwsem);
> +		up_read(&cxl_region_rwsem);
> +		return ret;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int cxl_ppr_get_repair_type(struct device *dev, void *drv_data,
> +				   u32 *repair_type)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +
> +	*repair_type = cxl_ppr_ctx->repair_type;
> +
> +	return 0;
> +}
> +
> +static int cxl_ppr_get_persist_mode_avail(struct device *dev, void *drv_data,
> +					  char *buf)
> +{
> +	return sysfs_emit(buf, "%u\n", EDAC_MEM_REPAIR_SOFT);
> +}
> +
> +static int cxl_ppr_get_persist_mode(struct device *dev, void *drv_data,
> +				    u32 *persist_mode)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +
> +	*persist_mode = cxl_ppr_ctx->persist_mode;
> +
> +	return 0;
> +}
> +
> +static int cxl_ppr_get_dpa_support(struct device *dev, void *drv_data,
> +				   u32 *dpa_support)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +	struct cxl_memdev_ppr_params params;
> +	int ret;
> +
> +	ret = cxl_mem_ppr_get_attrs(dev, cxl_ppr_ctx, &params);
> +	if (ret)
> +		return ret;
> +
> +	*dpa_support = params.dpa_support;
> +
> +	return 0;
> +}
> +
> +static int cxl_get_ppr_safe_when_in_use(struct device *dev, void *drv_data,
> +					u32 *safe)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +	struct cxl_memdev_ppr_params params;
> +	int ret;
> +
> +	ret = cxl_mem_ppr_get_attrs(dev, cxl_ppr_ctx, &params);
> +	if (ret)
> +		return ret;
> +
> +	*safe = params.media_accessible & params.data_retained;
> +
> +	return 0;
> +}
> +
> +static int cxl_get_ppr_dpa(struct device *dev, void *drv_data,
> +			   u64 *dpa)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +
> +	*dpa = cxl_ppr_ctx->dpa;
> +
> +	return 0;
> +}
> +
> +static int cxl_set_ppr_dpa(struct device *dev, void *drv_data, u64 dpa)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +
> +	if (!dpa)
> +		return -EINVAL;
> +
> +	cxl_ppr_ctx->dpa = dpa;
> +
> +	return 0;
> +}
> +
> +static int cxl_get_ppr_nibble_mask(struct device *dev, void *drv_data,
> +				   u64 *nibble_mask)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +
> +	*nibble_mask = cxl_ppr_ctx->nibble_mask;
> +
> +	return 0;
> +}
> +
> +static int cxl_set_ppr_nibble_mask(struct device *dev, void *drv_data, u64 nibble_mask)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +
> +	cxl_ppr_ctx->nibble_mask = nibble_mask;
> +
> +	return 0;
> +}
> +
> +static int cxl_do_query_ppr(struct device *dev, void *drv_data)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +
> +	if (!cxl_ppr_ctx->dpa)
> +		return -EINVAL;
> +
> +	return cxl_mem_ppr_set_attrs(dev, cxl_ppr_ctx, CXL_PPR_PARAM_DO_QUERY);
> +}
> +
> +static int cxl_do_ppr(struct device *dev, void *drv_data)
> +{
> +	struct cxl_ppr_context *cxl_ppr_ctx = drv_data;
> +	int ret;
> +
> +	if (!cxl_ppr_ctx->dpa)
> +		return -EINVAL;
> +
> +	ret = cxl_mem_ppr_set_attrs(dev, cxl_ppr_ctx, CXL_PPR_PARAM_DO_PPR);
> +
> +	return ret;
> +}
> +
> +static const struct edac_mem_repair_ops cxl_sppr_ops = {
> +	.get_repair_type = cxl_ppr_get_repair_type,
> +	.get_persist_mode_avail = cxl_ppr_get_persist_mode_avail,
> +	.get_persist_mode = cxl_ppr_get_persist_mode,
> +	.get_dpa_support = cxl_ppr_get_dpa_support,
> +	.get_repair_safe_when_in_use = cxl_get_ppr_safe_when_in_use,
> +	.get_dpa = cxl_get_ppr_dpa,
> +	.set_dpa = cxl_set_ppr_dpa,
> +	.get_nibble_mask = cxl_get_ppr_nibble_mask,
> +	.set_nibble_mask = cxl_set_ppr_nibble_mask,
> +	.do_query = cxl_do_query_ppr,
> +	.do_repair = cxl_do_ppr,
> +};
> +
>  int cxl_mem_ras_features_init(struct cxl_memdev *cxlmd, struct cxl_region *cxlr)
>  {
>  	struct edac_dev_feature ras_features[CXL_DEV_NUM_RAS_FEATURES];
>  	struct cxl_patrol_scrub_context *cxl_ps_ctx;
>  	char cxl_dev_name[CXL_SCRUB_NAME_LEN];
> +	struct cxl_ppr_context *cxl_sppr_ctx;
>  	struct cxl_ecs_context *cxl_ecs_ctx;
>  	struct cxl_feat_entry feat_entry;
>  	struct cxl_memdev_state *mds;
>  	struct cxl_dev_state *cxlds;
>  	int num_ras_features = 0;
>  	int num_media_frus;
> +	u8 repair_inst = 0;
>  	u8 scrub_inst = 0;
>  	int rc, i;
>  
> @@ -714,6 +1048,39 @@ int cxl_mem_ras_features_init(struct cxl_memdev *cxlmd, struct cxl_region *cxlr)
>  	}
>  
>  feat_ecs_done:
> +	/* CXL sPPR */
> +	rc = cxl_get_supported_feature_entry(mds, &cxl_sppr_uuid,
> +					     &feat_entry);
> +	if (rc < 0)
> +		goto feat_sppr_done;
> +
> +	if (!(feat_entry.attr_flags & CXL_FEAT_ENTRY_FLAG_CHANGABLE))
> +		goto feat_sppr_done;
> +
> +	cxl_sppr_ctx = devm_kzalloc(&cxlmd->dev, sizeof(*cxl_sppr_ctx),
> +				    GFP_KERNEL);
> +	if (!cxl_sppr_ctx)
> +		goto feat_sppr_done;
> +	*cxl_sppr_ctx = (struct cxl_ppr_context) {
> +		.repair_uuid = cxl_sppr_uuid,
> +		.get_feat_size = feat_entry.get_feat_size,
> +		.set_feat_size = feat_entry.set_feat_size,
> +		.get_version = feat_entry.get_feat_ver,
> +		.set_version = feat_entry.set_feat_ver,
> +		.set_effects = feat_entry.set_effects,
> +		.cxlmd = cxlmd,
> +		.repair_type = EDAC_TYPE_SPPR,
> +		.persist_mode = EDAC_MEM_REPAIR_SOFT,
> +		.instance = repair_inst++,
> +	};
> +
> +	ras_features[num_ras_features].ft_type = RAS_FEAT_MEM_REPAIR;
> +	ras_features[num_ras_features].instance = cxl_sppr_ctx->instance;
> +	ras_features[num_ras_features].mem_repair_ops = &cxl_sppr_ops;
> +	ras_features[num_ras_features].ctx = cxl_sppr_ctx;
> +	num_ras_features++;
> +
> +feat_sppr_done:
>  	return edac_dev_register(&cxlmd->dev, cxl_dev_name, NULL,
>  				 num_ras_features, ras_features);
>  }

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