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Message-ID: <Z8peDpw-9P00Peer@debian>
Date: Thu, 6 Mar 2025 18:46:38 -0800
From: Fan Ni <nifan.cxl@...il.com>
To: shiju.jose@...wei.com
Cc: linux-cxl@...r.kernel.org, dan.j.williams@...el.com, dave@...olabs.net,
jonathan.cameron@...wei.com, dave.jiang@...el.com,
alison.schofield@...el.com, vishal.l.verma@...el.com,
ira.weiny@...el.com, david@...hat.com, Vilas.Sridharan@....com,
linux-edac@...r.kernel.org, linux-acpi@...r.kernel.org,
linux-mm@...ck.org, linux-kernel@...r.kernel.org, bp@...en8.de,
tony.luck@...el.com, rafael@...nel.org, lenb@...nel.org,
mchehab@...nel.org, leo.duran@....com, Yazen.Ghannam@....com,
rientjes@...gle.com, jiaqiyan@...gle.com, Jon.Grimm@....com,
dave.hansen@...ux.intel.com, naoya.horiguchi@....com,
james.morse@....com, jthoughton@...gle.com, somasundaram.a@....com,
erdemaktas@...gle.com, pgonda@...gle.com, duenwen@...gle.com,
gthelen@...gle.com, wschwartz@...erecomputing.com,
dferguson@...erecomputing.com, wbs@...amperecomputing.com,
nifan.cxl@...il.com, tanxiaofei@...wei.com,
prime.zeng@...ilicon.com, roberto.sassu@...wei.com,
kangkang.shen@...urewei.com, wanghuiqiang@...wei.com,
linuxarm@...wei.com
Subject: Re: [PATCH 3/8] cxl/memfeature: Add CXL memory device ECS control
feature
On Thu, Feb 27, 2025 at 10:38:10PM +0000, shiju.jose@...wei.com wrote:
> From: Shiju Jose <shiju.jose@...wei.com>
>
> CXL spec 3.2 section 8.2.10.9.11.2 describes the DDR5 ECS (Error Check
> Scrub) control feature.
> The Error Check Scrub (ECS) is a feature defined in JEDEC DDR5 SDRAM
> Specification (JESD79-5) and allows the DRAM to internally read, correct
> single-bit errors, and write back corrected data bits to the DRAM array
> while providing transparency to error counts.
>
> The ECS control allows the requester to change the log entry type, the ECS
> threshold count (provided the request falls within the limits specified in
> DDR5 mode registers), switch between codeword mode and row count mode, and
> reset the ECS counter.
>
> Register with EDAC device driver, which retrieves the ECS attribute
> descriptors from the EDAC ECS and exposes the ECS control attributes to
> userspace via sysfs. For example, the ECS control for the memory media FRU0
> in CXL mem0 device is located at /sys/bus/edac/devices/cxl_mem0/ecs_fru0/
>
Reviewed-by: Fan Ni <fan.ni@...sung.com>
> Signed-off-by: Shiju Jose <shiju.jose@...wei.com>
> ---
> drivers/cxl/Kconfig | 1 +
> drivers/cxl/core/memfeatures.c | 355 ++++++++++++++++++++++++++++++++-
> 2 files changed, 355 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
> index b83bdb30b702..94321f5bed77 100644
> --- a/drivers/cxl/Kconfig
> +++ b/drivers/cxl/Kconfig
> @@ -119,6 +119,7 @@ config CXL_RAS_FEATURES
> depends on CXL_FEATURES
> depends on EDAC=y || (CXL_BUS=m && EDAC=m)
> depends on EDAC_SCRUB
> + depends on EDAC_ECS
> help
> The CXL memory RAS feature control is optional and allows host to
> control the RAS features configurations of CXL Type 3 devices.
> diff --git a/drivers/cxl/core/memfeatures.c b/drivers/cxl/core/memfeatures.c
> index 7a5c0645a07e..253930051e87 100644
> --- a/drivers/cxl/core/memfeatures.c
> +++ b/drivers/cxl/core/memfeatures.c
> @@ -19,7 +19,7 @@
> #include <cxlmem.h>
> #include "core.h"
>
> -#define CXL_DEV_NUM_RAS_FEATURES 1
> +#define CXL_DEV_NUM_RAS_FEATURES 2
> #define CXL_DEV_HOUR_IN_SECS 3600
>
> #define CXL_DEV_NAME_LEN 128
> @@ -428,6 +428,352 @@ static int cxl_region_scrub_init(struct cxl_region *cxlr,
> return 0;
> }
>
> +/*
> + * CXL DDR5 ECS control definitions.
> + */
> +struct cxl_ecs_context {
> + u16 num_media_frus;
> + u16 get_feat_size;
> + u16 set_feat_size;
> + u8 get_version;
> + u8 set_version;
> + u16 effects;
> + struct cxl_memdev *cxlmd;
> +};
> +
> +enum {
> + CXL_ECS_PARAM_LOG_ENTRY_TYPE,
> + CXL_ECS_PARAM_THRESHOLD,
> + CXL_ECS_PARAM_MODE,
> + CXL_ECS_PARAM_RESET_COUNTER,
> +};
> +
> +#define CXL_ECS_LOG_ENTRY_TYPE_MASK GENMASK(1, 0)
> +#define CXL_ECS_REALTIME_REPORT_CAP_MASK BIT(0)
> +#define CXL_ECS_THRESHOLD_COUNT_MASK GENMASK(2, 0)
> +#define CXL_ECS_COUNT_MODE_MASK BIT(3)
> +#define CXL_ECS_RESET_COUNTER_MASK BIT(4)
> +#define CXL_ECS_RESET_COUNTER 1
> +
> +enum {
> + ECS_THRESHOLD_256 = 256,
> + ECS_THRESHOLD_1024 = 1024,
> + ECS_THRESHOLD_4096 = 4096,
> +};
> +
> +enum {
> + ECS_THRESHOLD_IDX_256 = 3,
> + ECS_THRESHOLD_IDX_1024 = 4,
> + ECS_THRESHOLD_IDX_4096 = 5,
> +};
> +
> +static const u16 ecs_supp_threshold[] = {
> + [ECS_THRESHOLD_IDX_256] = 256,
> + [ECS_THRESHOLD_IDX_1024] = 1024,
> + [ECS_THRESHOLD_IDX_4096] = 4096,
> +};
> +
> +enum {
> + ECS_LOG_ENTRY_TYPE_DRAM = 0x0,
> + ECS_LOG_ENTRY_TYPE_MEM_MEDIA_FRU = 0x1,
> +};
> +
> +enum cxl_ecs_count_mode {
> + ECS_MODE_COUNTS_ROWS = 0,
> + ECS_MODE_COUNTS_CODEWORDS = 1,
> +};
> +
> +/**
> + * struct cxl_ecs_params - CXL memory DDR5 ECS parameter data structure.
> + * @threshold: ECS threshold count per GB of memory cells.
> + * @log_entry_type: ECS log entry type, per DRAM or per memory media FRU.
> + * @reset_counter: [IN] reset ECC counter to default value.
> + * @count_mode: codeword/row count mode
> + * 0 : ECS counts rows with errors
> + * 1 : ECS counts codeword with errors
> + */
> +struct cxl_ecs_params {
> + u16 threshold;
> + u8 log_entry_type;
> + u8 reset_counter;
> + enum cxl_ecs_count_mode count_mode;
> +};
> +
> +/*
> + * See CXL spec rev 3.2 @8.2.10.9.11.2 Table 8-225 DDR5 ECS Control Feature
> + * Readable Attributes.
> + */
> +struct cxl_ecs_fru_rd_attrs {
> + u8 ecs_cap;
> + __le16 ecs_config;
> + u8 ecs_flags;
> +} __packed;
> +
> +struct cxl_ecs_rd_attrs {
> + u8 ecs_log_cap;
> + struct cxl_ecs_fru_rd_attrs fru_attrs[];
> +} __packed;
> +
> +/*
> + * See CXL spec rev 3.2 @8.2.10.9.11.2 Table 8-226 DDR5 ECS Control Feature
> + * Writable Attributes.
> + */
> +struct cxl_ecs_fru_wr_attrs {
> + __le16 ecs_config;
> +} __packed;
> +
> +struct cxl_ecs_wr_attrs {
> + u8 ecs_log_cap;
> + struct cxl_ecs_fru_wr_attrs fru_attrs[];
> +} __packed;
> +
> +/*
> + * CXL DDR5 ECS control functions.
> + */
> +static int cxl_mem_ecs_get_attrs(struct device *dev,
> + struct cxl_ecs_context *cxl_ecs_ctx,
> + int fru_id, struct cxl_ecs_params *params)
> +{
> + struct cxl_memdev *cxlmd = cxl_ecs_ctx->cxlmd;
> + struct cxl_mailbox *cxl_mbox = &cxlmd->cxlds->cxl_mbox;
> + struct cxl_ecs_fru_rd_attrs *fru_rd_attrs;
> + size_t rd_data_size;
> + u8 threshold_index;
> + size_t data_size;
> + u16 ecs_config;
> +
> + rd_data_size = cxl_ecs_ctx->get_feat_size;
> +
> + struct cxl_ecs_rd_attrs *rd_attrs __free(kvfree) =
> + kvzalloc(rd_data_size, GFP_KERNEL);
> + if (!rd_attrs)
> + return -ENOMEM;
> +
> + params->log_entry_type = 0;
> + params->threshold = 0;
> + params->count_mode = 0;
> + data_size = cxl_get_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
> + CXL_GET_FEAT_SEL_CURRENT_VALUE,
> + rd_attrs, rd_data_size, 0, NULL);
> + if (!data_size)
> + return -EIO;
> +
> + fru_rd_attrs = rd_attrs->fru_attrs;
> + params->log_entry_type = FIELD_GET(CXL_ECS_LOG_ENTRY_TYPE_MASK,
> + rd_attrs->ecs_log_cap);
> + ecs_config = le16_to_cpu(fru_rd_attrs[fru_id].ecs_config);
> + threshold_index = FIELD_GET(CXL_ECS_THRESHOLD_COUNT_MASK,
> + ecs_config);
> + params->threshold = ecs_supp_threshold[threshold_index];
> + params->count_mode = FIELD_GET(CXL_ECS_COUNT_MODE_MASK,
> + ecs_config);
> + return 0;
> +}
> +
> +static int cxl_mem_ecs_set_attrs(struct device *dev,
> + struct cxl_ecs_context *cxl_ecs_ctx,
> + int fru_id, struct cxl_ecs_params *params,
> + u8 param_type)
> +{
> + struct cxl_memdev *cxlmd = cxl_ecs_ctx->cxlmd;
> + struct cxl_mailbox *cxl_mbox = &cxlmd->cxlds->cxl_mbox;
> + struct cxl_ecs_fru_rd_attrs *fru_rd_attrs;
> + struct cxl_ecs_fru_wr_attrs *fru_wr_attrs;
> + size_t rd_data_size, wr_data_size;
> + u16 num_media_frus, count;
> + size_t data_size;
> + u16 ecs_config;
> +
> + num_media_frus = cxl_ecs_ctx->num_media_frus;
> + rd_data_size = cxl_ecs_ctx->get_feat_size;
> + wr_data_size = cxl_ecs_ctx->set_feat_size;
> + struct cxl_ecs_rd_attrs *rd_attrs __free(kvfree) =
> + kvzalloc(rd_data_size, GFP_KERNEL);
> + if (!rd_attrs)
> + return -ENOMEM;
> +
> + data_size = cxl_get_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
> + CXL_GET_FEAT_SEL_CURRENT_VALUE,
> + rd_attrs, rd_data_size, 0, NULL);
> + if (!data_size)
> + return -EIO;
> +
> + struct cxl_ecs_wr_attrs *wr_attrs __free(kvfree) =
> + kvzalloc(wr_data_size, GFP_KERNEL);
> + if (!wr_attrs)
> + return -ENOMEM;
> +
> + /*
> + * Fill writable attributes from the current attributes read
> + * for all the media FRUs.
> + */
> + fru_rd_attrs = rd_attrs->fru_attrs;
> + fru_wr_attrs = wr_attrs->fru_attrs;
> + wr_attrs->ecs_log_cap = rd_attrs->ecs_log_cap;
> + for (count = 0; count < num_media_frus; count++)
> + fru_wr_attrs[count].ecs_config = fru_rd_attrs[count].ecs_config;
> +
> + /*
> + * Fill attribute to be set for the media FRU
> + */
> + ecs_config = le16_to_cpu(fru_rd_attrs[fru_id].ecs_config);
> + switch (param_type) {
> + case CXL_ECS_PARAM_LOG_ENTRY_TYPE:
> + if (params->log_entry_type != ECS_LOG_ENTRY_TYPE_DRAM &&
> + params->log_entry_type != ECS_LOG_ENTRY_TYPE_MEM_MEDIA_FRU)
> + return -EINVAL;
> +
> + wr_attrs->ecs_log_cap = FIELD_PREP(CXL_ECS_LOG_ENTRY_TYPE_MASK,
> + params->log_entry_type);
> + break;
> + case CXL_ECS_PARAM_THRESHOLD:
> + ecs_config &= ~CXL_ECS_THRESHOLD_COUNT_MASK;
> + switch (params->threshold) {
> + case ECS_THRESHOLD_256:
> + ecs_config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
> + ECS_THRESHOLD_IDX_256);
> + break;
> + case ECS_THRESHOLD_1024:
> + ecs_config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
> + ECS_THRESHOLD_IDX_1024);
> + break;
> + case ECS_THRESHOLD_4096:
> + ecs_config |= FIELD_PREP(CXL_ECS_THRESHOLD_COUNT_MASK,
> + ECS_THRESHOLD_IDX_4096);
> + break;
> + default:
> + dev_dbg(dev,
> + "Invalid CXL ECS scrub threshold count(%d) to set\n",
> + params->threshold);
> + dev_dbg(dev,
> + "Supported scrub threshold counts: %u, %u, %u\n",
> + ECS_THRESHOLD_256, ECS_THRESHOLD_1024, ECS_THRESHOLD_4096);
> + return -EINVAL;
> + }
> + break;
> + case CXL_ECS_PARAM_MODE:
> + if (params->count_mode != ECS_MODE_COUNTS_ROWS &&
> + params->count_mode != ECS_MODE_COUNTS_CODEWORDS) {
> + dev_dbg(dev,
> + "Invalid CXL ECS scrub mode(%d) to set\n",
> + params->count_mode);
> + dev_dbg(dev,
> + "Supported ECS Modes: 0: ECS counts rows with errors,"
> + " 1: ECS counts codewords with errors\n");
> + return -EINVAL;
> + }
> + ecs_config &= ~CXL_ECS_COUNT_MODE_MASK;
> + ecs_config |= FIELD_PREP(CXL_ECS_COUNT_MODE_MASK, params->count_mode);
> + break;
> + case CXL_ECS_PARAM_RESET_COUNTER:
> + if (params->reset_counter != CXL_ECS_RESET_COUNTER)
> + return -EINVAL;
> +
> + ecs_config &= ~CXL_ECS_RESET_COUNTER_MASK;
> + ecs_config |= FIELD_PREP(CXL_ECS_RESET_COUNTER_MASK, params->reset_counter);
> + break;
> + default:
> + return -EINVAL;
> + }
> + fru_wr_attrs[fru_id].ecs_config = cpu_to_le16(ecs_config);
> +
> + return cxl_set_feature(cxl_mbox, &CXL_FEAT_ECS_UUID,
> + cxl_ecs_ctx->set_version,
> + wr_attrs, wr_data_size,
> + CXL_SET_FEAT_FLAG_DATA_SAVED_ACROSS_RESET,
> + 0, NULL);
> +}
> +
> +#define CXL_ECS_GET_ATTR(attrib) \
> +static int cxl_ecs_get_##attrib(struct device *dev, void *drv_data, \
> + int fru_id, u32 *val) \
> +{ \
> + struct cxl_ecs_context *ctx = drv_data; \
> + struct cxl_ecs_params params; \
> + int ret; \
> + \
> + ret = cxl_mem_ecs_get_attrs(dev, ctx, fru_id, ¶ms); \
> + if (ret) \
> + return ret; \
> + \
> + *val = params.attrib; \
> + \
> + return 0; \
> +}
> +
> +CXL_ECS_GET_ATTR(log_entry_type)
> +CXL_ECS_GET_ATTR(count_mode)
> +CXL_ECS_GET_ATTR(threshold)
> +
> +#define CXL_ECS_SET_ATTR(attrib, param_type) \
> +static int cxl_ecs_set_##attrib(struct device *dev, void *drv_data, \
> + int fru_id, u32 val) \
> +{ \
> + struct cxl_ecs_context *ctx = drv_data; \
> + struct cxl_ecs_params params = { \
> + .attrib = val, \
> + }; \
> + \
> + return cxl_mem_ecs_set_attrs(dev, ctx, fru_id, ¶ms, (param_type)); \
> +}
> +CXL_ECS_SET_ATTR(log_entry_type, CXL_ECS_PARAM_LOG_ENTRY_TYPE)
> +CXL_ECS_SET_ATTR(count_mode, CXL_ECS_PARAM_MODE)
> +CXL_ECS_SET_ATTR(reset_counter, CXL_ECS_PARAM_RESET_COUNTER)
> +CXL_ECS_SET_ATTR(threshold, CXL_ECS_PARAM_THRESHOLD)
> +
> +static const struct edac_ecs_ops cxl_ecs_ops = {
> + .get_log_entry_type = cxl_ecs_get_log_entry_type,
> + .set_log_entry_type = cxl_ecs_set_log_entry_type,
> + .get_mode = cxl_ecs_get_count_mode,
> + .set_mode = cxl_ecs_set_count_mode,
> + .reset = cxl_ecs_set_reset_counter,
> + .get_threshold = cxl_ecs_get_threshold,
> + .set_threshold = cxl_ecs_set_threshold,
> +};
> +
> +static int cxl_memdev_ecs_init(struct cxl_memdev *cxlmd,
> + struct edac_dev_feature *ras_feature)
> +{
> + struct cxl_ecs_context *cxl_ecs_ctx;
> + struct cxl_feat_entry *feat_entry;
> + int num_media_frus;
> +
> + feat_entry = cxl_get_feature_entry(cxlmd->cxlds, &CXL_FEAT_ECS_UUID);
> + if (IS_ERR(feat_entry))
> + return -EOPNOTSUPP;
> +
> + if (!(le32_to_cpu(feat_entry->flags) & CXL_FEATURE_F_CHANGEABLE))
> + return -EOPNOTSUPP;
> +
> + num_media_frus = (le16_to_cpu(feat_entry->get_feat_size) -
> + sizeof(struct cxl_ecs_rd_attrs)) /
> + sizeof(struct cxl_ecs_fru_rd_attrs);
> + if (!num_media_frus)
> + return -EOPNOTSUPP;
> +
> + cxl_ecs_ctx = devm_kzalloc(&cxlmd->dev, sizeof(*cxl_ecs_ctx),
> + GFP_KERNEL);
> + if (!cxl_ecs_ctx)
> + return -ENOMEM;
> +
> + *cxl_ecs_ctx = (struct cxl_ecs_context) {
> + .get_feat_size = le16_to_cpu(feat_entry->get_feat_size),
> + .set_feat_size = le16_to_cpu(feat_entry->set_feat_size),
> + .get_version = feat_entry->get_feat_ver,
> + .set_version = feat_entry->set_feat_ver,
> + .effects = le16_to_cpu(feat_entry->effects),
> + .num_media_frus = num_media_frus,
> + .cxlmd = cxlmd,
> + };
> +
> + ras_feature->ft_type = RAS_FEAT_ECS;
> + ras_feature->ecs_ops = &cxl_ecs_ops;
> + ras_feature->ctx = cxl_ecs_ctx;
> + ras_feature->ecs_info.num_media_frus = num_media_frus;
> +
> + return 0;
> +}
> +
> int devm_cxl_memdev_edac_register(struct cxl_memdev *cxlmd)
> {
> struct edac_dev_feature ras_features[CXL_DEV_NUM_RAS_FEATURES];
> @@ -444,6 +790,13 @@ int devm_cxl_memdev_edac_register(struct cxl_memdev *cxlmd)
> if (rc != -EOPNOTSUPP)
> num_ras_features++;
>
> + rc = cxl_memdev_ecs_init(cxlmd, &ras_features[num_ras_features]);
> + if (rc < 0 && rc != -EOPNOTSUPP)
> + return rc;
> +
> + if (rc != -EOPNOTSUPP)
> + num_ras_features++;
> +
> snprintf(cxl_dev_name, sizeof(cxl_dev_name), "%s_%s",
> "cxl", dev_name(&cxlmd->dev));
>
> --
> 2.43.0
>
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