RE: [RFC PATCH v5 05/12] cxl/memscrub: Add CXL device ECS control feature

From: Shiju Jose
Date: Tue Feb 20 2024 - 06:06:10 EST

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In reply to: fan: "Re: [RFC PATCH v5 05/12] cxl/memscrub: Add CXL device ECS control feature"
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Hi Fan,

>-----Original Message-----
>From: fan <nifan.cxl@xxxxxxxxx>
>Sent: 16 February 2024 17:59
>To: Shiju Jose <shiju.jose@xxxxxxxxxx>
>Cc: linux-cxl@xxxxxxxxxxxxxxx; linux-acpi@xxxxxxxxxxxxxxx; linux-
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>Linuxarm <linuxarm@xxxxxxxxxx>
>Subject: Re: [RFC PATCH v5 05/12] cxl/memscrub: Add CXL device ECS control
>feature
>
>On Thu, Jan 11, 2024 at 09:17:34PM +0800, shiju.jose@xxxxxxxxxx wrote:
>> From: Shiju Jose <shiju.jose@xxxxxxxxxx>
>>
>> CXL spec 3.1 section 8.2.9.9.11.2 describes the DDR5 Error Check Scrub
>> (ECS) 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 feature allows the request to configure ECS input
>> configurations during system boot or at run-time.
>>
>> The ECS control allows the requester to change the log entry type, the
>> ECS threshold count provided that the request is within the definition
>> specified in DDR5 mode registers, change mode between codeword mode
>> and row count mode, and reset the ECS counter.
>>
>> Open Question:
>> Is cxl_mem_ecs_init() invoked in the right function in cxl/core/region.c?
>>
>> Signed-off-by: Shiju Jose <shiju.jose@xxxxxxxxxx>
>> ---
>> drivers/cxl/core/memscrub.c | 303
>+++++++++++++++++++++++++++++++++++-
>> drivers/cxl/core/region.c | 1 +
>> drivers/cxl/cxlmem.h | 3 +
>> 3 files changed, 306 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/cxl/core/memscrub.c b/drivers/cxl/core/memscrub.c
>> index e0d482b0bf3a..e7741e2fdbdb 100644
>> --- a/drivers/cxl/core/memscrub.c
>> +++ b/drivers/cxl/core/memscrub.c
>> @@ -5,7 +5,7 @@
>> * Copyright (c) 2023 HiSilicon Limited.
>> *
>> * - Provides functions to configure patrol scrub
>> - * feature of the CXL memory devices.
>> + * and DDR5 ECS features of the CXL memory devices.
>> */
>>
>> #define pr_fmt(fmt) "CXL_MEM_SCRUB: " fmt
>> @@ -264,3 +264,304 @@ int cxl_mem_patrol_scrub_init(struct cxl_memdev
>*cxlmd)
>> return 0;
>> }
>> EXPORT_SYMBOL_NS_GPL(cxl_mem_patrol_scrub_init, CXL);
>> +
>> +/* CXL DDR5 ECS control definitions */
>> +#define CXL_MEMDEV_ECS_GET_FEAT_VERSION 0x01
>> +#define CXL_MEMDEV_ECS_SET_FEAT_VERSION 0x01
>> +
>> +static const uuid_t cxl_ecs_uuid =
>> + UUID_INIT(0xe5b13f22, 0x2328, 0x4a14, 0xb8, 0xba, 0xb9, 0x69, 0x1e,
>\
>> + 0x89, 0x33, 0x86);
>> +
>> +struct cxl_ecs_context {
>> + struct device *dev;
>> + u16 nregions;
>> + int region_id;
>> + u16 get_feat_size;
>> + u16 set_feat_size;
>> +};
>> +
>> +/**
>> + * struct cxl_memdev_ecs_params - CXL memory DDR5 ECS parameter data
>structure.
>> + * @log_entry_type: ECS log entry type, per DRAM or per memory media
>FRU.
>> + * @threshold: ECS threshold count per GB of memory cells.
>> + * @mode: codeword/row count mode
>> + * 0 : ECS counts rows with errors
>> + * 1 : ECS counts codeword with errors
>> + * @reset_counter: [IN] reset ECC counter to default value.
>> + */
>> +struct cxl_memdev_ecs_params {
>> + u8 log_entry_type;
>> + u16 threshold;
>
>Why need to be u16? It has only 3 bits.
Here u16 threshold stores the ECS threshold count 256/1024/4096 from the user and converted to the corresponding 3 bit value in cxl_mem_ecs_set_attrbs() below.
Please see spec r3.1, Table 8-210. DDR5 ECS Control Feature Readable Attributes
Bits[2:0]: ECS Threshold Count per Gb of Memory Cells:
- 011b = 256 (default)
- 100b = 1024
- 101b = 4096

>
>> + u8 mode;
>> + bool reset_counter;
>> +};
>> +
>> +enum {
>> + CXL_MEMDEV_ECS_PARAM_LOG_ENTRY_TYPE = 0,
>> + CXL_MEMDEV_ECS_PARAM_THRESHOLD,
>> + CXL_MEMDEV_ECS_PARAM_MODE,
>> + CXL_MEMDEV_ECS_PARAM_RESET_COUNTER,
>> +};
>> +
>> +#define CXL_MEMDEV_ECS_LOG_ENTRY_TYPE_MASK GENMASK(1, 0)
>> +#define CXL_MEMDEV_ECS_REALTIME_REPORT_CAP_MASK BIT(0)
>> +#define CXL_MEMDEV_ECS_THRESHOLD_COUNT_MASK
> GENMASK(2, 0)
>> +#define CXL_MEMDEV_ECS_MODE_MASK BIT(3)
>> +#define CXL_MEMDEV_ECS_RESET_COUNTER_MASK BIT(4)
>> +
>> +static const u16 ecs_supp_threshold[] = { 0, 0, 0, 256, 1024, 4096 };
>> +
>> +enum {
>> + ECS_LOG_ENTRY_TYPE_DRAM = 0x0,
>> + ECS_LOG_ENTRY_TYPE_MEM_MEDIA_FRU = 0x1, };
>> +
>> +enum {
>> + ECS_THRESHOLD_256 = 3,
>> + ECS_THRESHOLD_1024 = 4,
>> + ECS_THRESHOLD_4096 = 5,
>> +};
>> +
>> +enum {
>> + ECS_MODE_COUNTS_ROWS = 0,
>> + ECS_MODE_COUNTS_CODEWORDS = 1,
>> +};
>> +
>> +struct cxl_memdev_ecs_feat_read_attrbs {
>> + u8 ecs_log_cap;
>> + u8 ecs_cap;
>> + __le16 ecs_config;
>> + u8 ecs_flags;
>> +} __packed;
>> +
>> +struct cxl_memdev_ecs_set_feat_pi {
>> + struct cxl_mbox_set_feat_in pi;
>> + struct cxl_memdev_ecs_feat_wr_attrbs {
>> + u8 ecs_log_cap;
>> + __le16 ecs_config;
>> + } __packed wr_attrbs[];
>> +} __packed;
>> +
>> +/* CXL DDR5 ECS control functions */
>> +static int cxl_mem_ecs_get_attrbs(struct device *dev, int fru_id,
>> + struct cxl_memdev_ecs_params *params) {
>> + struct cxl_memdev_ecs_feat_read_attrbs *rd_attrbs __free(kvfree) =
>NULL;
>> + struct cxl_memdev *cxlmd = to_cxl_memdev(dev->parent);
>> + struct cxl_dev_state *cxlds = cxlmd->cxlds;
>> + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
>> + struct cxl_mbox_get_feat_in pi = {
>> + .uuid = cxl_ecs_uuid,
>> + .offset = 0,
>> + .selection = CXL_GET_FEAT_SEL_CURRENT_VALUE,
>> + };
>> + struct cxl_ecs_context *cxl_ecs_ctx;
>> + u8 threshold_index;
>> + int ret;
>> +
>> + if (!mds)
>> + return -EFAULT;
>> + cxl_ecs_ctx = dev_get_drvdata(dev);
>> +
>> + pi.count = cxl_ecs_ctx->get_feat_size;
>> + rd_attrbs = kvmalloc(pi.count, GFP_KERNEL);
>> + if (!rd_attrbs)
>> + return -ENOMEM;
>> +
>> + ret = cxl_get_feature(mds, &pi, rd_attrbs);
>> + if (ret) {
>> + params->log_entry_type = 0;
>> + params->threshold = 0;
>> + params->mode = 0;
>> + return ret;
>> + }
>> + params->log_entry_type =
>FIELD_GET(CXL_MEMDEV_ECS_LOG_ENTRY_TYPE_MASK,
>> + rd_attrbs[fru_id].ecs_log_cap);
>> + threshold_index =
>FIELD_GET(CXL_MEMDEV_ECS_THRESHOLD_COUNT_MASK,
>> + rd_attrbs[fru_id].ecs_config);
>> + params->threshold = ecs_supp_threshold[threshold_index];
>> + params->mode = FIELD_GET(CXL_MEMDEV_ECS_MODE_MASK,
>> + rd_attrbs[fru_id].ecs_config);
>> +
>> + return 0;
>> +}
>> +
>> +static int __maybe_unused
>> +cxl_mem_ecs_set_attrbs(struct device *dev, int fru_id,
>> + struct cxl_memdev_ecs_params *params, u8 param_type) {
>> + struct cxl_memdev_ecs_feat_read_attrbs *rd_attrbs __free(kvfree) =
>NULL;
>> + struct cxl_memdev_ecs_set_feat_pi *set_pi __free(kvfree) = NULL;
>> + struct cxl_memdev *cxlmd = to_cxl_memdev(dev->parent);
>> + struct cxl_dev_state *cxlds = cxlmd->cxlds;
>> + struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
>> + struct cxl_mbox_get_feat_in pi = {
>> + .uuid = cxl_ecs_uuid,
>> + .offset = 0,
>> + .selection = CXL_GET_FEAT_SEL_CURRENT_VALUE,
>> + };
>> + struct cxl_memdev_ecs_feat_wr_attrbs *wr_attrbs;
>> + struct cxl_memdev_ecs_params rd_params;
>> + struct cxl_ecs_context *cxl_ecs_ctx;
>> + u16 nmedia_frus, count;
>> + u32 set_pi_size;
>> + int ret;
>> +
>> + if (!mds)
>> + return -EFAULT;
>> +
>> + cxl_ecs_ctx = dev_get_drvdata(dev);
>> + nmedia_frus = cxl_ecs_ctx->nregions;
>> +
>> + rd_attrbs = kvmalloc(cxl_ecs_ctx->get_feat_size, GFP_KERNEL);
>> + if (!rd_attrbs)
>> + return -ENOMEM;
>> +
>> + pi.count = cxl_ecs_ctx->get_feat_size;
>> + ret = cxl_get_feature(mds, &pi, rd_attrbs);
>> + if (ret)
>> + return ret;
>> + set_pi_size = sizeof(struct cxl_mbox_set_feat_in) +
>> + cxl_ecs_ctx->set_feat_size;
>> + set_pi = kvmalloc(set_pi_size, GFP_KERNEL);
>> + if (!set_pi)
>> + return -ENOMEM;
>> +
>> + set_pi->pi.uuid = cxl_ecs_uuid;
>> + set_pi->pi.flags =
>CXL_SET_FEAT_FLAG_MOD_VALUE_SAVED_ACROSS_RESET |
>> + CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER;
>> + set_pi->pi.offset = 0;
>> + set_pi->pi.version = CXL_MEMDEV_ECS_SET_FEAT_VERSION;
>> + /* Fill writable attributes from the current attributes read for all the
>media FRUs */
>> + wr_attrbs = set_pi->wr_attrbs;
>> + for (count = 0; count < nmedia_frus; count++) {
>> + wr_attrbs[count].ecs_log_cap = rd_attrbs[count].ecs_log_cap;
>> + wr_attrbs[count].ecs_config = rd_attrbs[count].ecs_config;
>> + }
>> +
>> + /* Fill attribute to be set for the media FRU */
>> + switch (param_type) {
>> + case CXL_MEMDEV_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) {
>> + dev_err(dev->parent,
>> + "Invalid CXL ECS scrub log entry type(%d) to
>set\n",
>> + params->log_entry_type);
>> + dev_err(dev->parent,
>> + "Log Entry Type 0: per DRAM 1: per Memory
>Media FRU\n");
>> + return -EINVAL;
>> + }
>> + wr_attrbs[fru_id].ecs_log_cap =
>FIELD_PREP(CXL_MEMDEV_ECS_LOG_ENTRY_TYPE_MASK,
>> + params-
>>log_entry_type);
>> + break;
>> + case CXL_MEMDEV_ECS_PARAM_THRESHOLD:
>> + wr_attrbs[fru_id].ecs_config &=
>~CXL_MEMDEV_ECS_THRESHOLD_COUNT_MASK;
>> + switch (params->threshold) {
>> + case 256:
>> + wr_attrbs[fru_id].ecs_config |= FIELD_PREP(
>> +
> CXL_MEMDEV_ECS_THRESHOLD_COUNT_MASK,
>> + ECS_THRESHOLD_256);
>> + break;
>> + case 1024:
>> + wr_attrbs[fru_id].ecs_config |= FIELD_PREP(
>> +
> CXL_MEMDEV_ECS_THRESHOLD_COUNT_MASK,
>> + ECS_THRESHOLD_1024);
>> + break;
>> + case 4096:
>> + wr_attrbs[fru_id].ecs_config |= FIELD_PREP(
>> +
> CXL_MEMDEV_ECS_THRESHOLD_COUNT_MASK,
>> + ECS_THRESHOLD_4096);
>> + break;
>> + default:
>> + dev_err(dev->parent,
>> + "Invalid CXL ECS scrub threshold count(%d) to
>set\n",
>> + params->threshold);
>> + dev_err(dev->parent,
>> + "Supported scrub threshold count:
>256,1024,4096\n");
>> + return -EINVAL;
>> + }
>> + break;
>> + case CXL_MEMDEV_ECS_PARAM_MODE:
>> + if (params->mode != ECS_MODE_COUNTS_ROWS &&
>> + params->mode != ECS_MODE_COUNTS_CODEWORDS) {
>> + dev_err(dev->parent,
>> + "Invalid CXL ECS scrub mode(%d) to set\n",
>> + params->mode);
>> + dev_err(dev->parent,
>> + "Mode 0: ECS counts rows with errors"
>> + " 1: ECS counts codewords with errors\n");
>> + return -EINVAL;
>> + }
>> + wr_attrbs[fru_id].ecs_config &=
>~CXL_MEMDEV_ECS_MODE_MASK;
>> + wr_attrbs[fru_id].ecs_config |=
>FIELD_PREP(CXL_MEMDEV_ECS_MODE_MASK,
>> + params->mode);
>> + break;
>> + case CXL_MEMDEV_ECS_PARAM_RESET_COUNTER:
>> + wr_attrbs[fru_id].ecs_config &=
>~CXL_MEMDEV_ECS_RESET_COUNTER_MASK;
>> + wr_attrbs[fru_id].ecs_config |=
>FIELD_PREP(CXL_MEMDEV_ECS_RESET_COUNTER_MASK,
>> + params-
>>reset_counter);
>> + break;
>> + default:
>> + dev_err(dev->parent, "Invalid CXL ECS parameter to set\n");
>> + return -EINVAL;
>> + }
>> + ret = cxl_set_feature(mds, set_pi, set_pi_size);
>> + if (ret) {
>> + dev_err(dev->parent, "CXL ECS set feature fail ret=%d\n", ret);
>> + return ret;
>> + }
>> +
>> + /* Verify attribute is set successfully */
>> + ret = cxl_mem_ecs_get_attrbs(dev, fru_id, &rd_params);
>> + if (ret) {
>> + dev_err(dev->parent, "Get cxlmemdev ECS params fail
>ret=%d\n", ret);
>> + return ret;
>> + }
>> + switch (param_type) {
>> + case CXL_MEMDEV_ECS_PARAM_LOG_ENTRY_TYPE:
>> + if (rd_params.log_entry_type != params->log_entry_type)
>> + return -EFAULT;
>> + break;
>> + case CXL_MEMDEV_ECS_PARAM_THRESHOLD:
>> + if (rd_params.threshold != params->threshold)
>> + return -EFAULT;
>> + break;
>> + case CXL_MEMDEV_ECS_PARAM_MODE:
>> + if (rd_params.mode != params->mode)
>> + return -EFAULT;
>> + break;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +int cxl_mem_ecs_init(struct cxl_memdev *cxlmd, int region_id) {
>> + struct cxl_mbox_supp_feat_entry feat_entry;
>> + struct cxl_ecs_context *cxl_ecs_ctx;
>> + int nmedia_frus;
>> + int ret;
>> +
>> + ret = cxl_mem_get_supported_feature_entry(cxlmd, &cxl_ecs_uuid,
>&feat_entry);
>> + if (ret < 0)
>> + return ret;
>> +
>> + if (!(feat_entry.attrb_flags & CXL_FEAT_ENTRY_FLAG_CHANGABLE))
>> + return -ENOTSUPP;
>> + nmedia_frus = feat_entry.get_feat_size/
>> + sizeof(struct
>cxl_memdev_ecs_feat_read_attrbs);
>> + if (nmedia_frus) {
>> + cxl_ecs_ctx = devm_kzalloc(&cxlmd->dev, sizeof(*cxl_ecs_ctx),
>GFP_KERNEL);
>> + if (!cxl_ecs_ctx)
>> + return -ENOMEM;
>> +
>> + cxl_ecs_ctx->nregions = nmedia_frus;
>> + cxl_ecs_ctx->get_feat_size = feat_entry.get_feat_size;
>> + cxl_ecs_ctx->set_feat_size = feat_entry.set_feat_size;
>> + cxl_ecs_ctx->region_id = region_id;
>> + }
>> +
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_NS_GPL(cxl_mem_ecs_init, CXL);
>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
>> index 3e817a6f94c6..ca71ad403d62 100644
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>> @@ -2912,6 +2912,7 @@ int cxl_add_to_region(struct cxl_port *root, struct
>cxl_endpoint_decoder *cxled)
>> dev_err(&cxlr->dev, "failed to enable, range: %pr\n",
>> p->res);
>> }
>> + cxl_mem_ecs_init(cxlmd, atomic_read(&cxlrd->region_id));
>
>Check the return value and process accordingly.
Sure.

>
>Fan
>
>>
>> put_device(region_dev);
>> out:
>> diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h index
>> 25c46e72af16..c255063dd795 100644
>> --- a/drivers/cxl/cxlmem.h
>> +++ b/drivers/cxl/cxlmem.h
>> @@ -986,9 +986,12 @@ int cxl_clear_poison(struct cxl_memdev *cxlmd,
>> u64 dpa);
>> /* cxl memory scrub functions */
>> #ifdef CONFIG_CXL_SCRUB
>> int cxl_mem_patrol_scrub_init(struct cxl_memdev *cxlmd);
>> +int cxl_mem_ecs_init(struct cxl_memdev *cxlmd, int region_id);
>> #else
>> static inline int cxl_mem_patrol_scrub_init(struct cxl_memdev *cxlmd)
>> { return -ENOTSUPP; }
>> +static inline int cxl_mem_ecs_init(struct cxl_memdev *cxlmd, int
>> +region_id) { return -ENOTSUPP; }
>> #endif
>>
>> #ifdef CONFIG_CXL_SUSPEND
>> --
>> 2.34.1
>>

Thanks,
Shiju

Next message: Krzysztof Kozlowski: "Re: [PATCH 00/16] clk: samsung: Add CPU clocks for Exynos850"
Previous message: Oleksij Rempel: "Re: [PATCH net-next v4 14/17] dt-bindings: net: pse-pd: Add bindings for PD692x0 PSE controller"
In reply to: fan: "Re: [RFC PATCH v5 05/12] cxl/memscrub: Add CXL device ECS control feature"
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