RE: [PATCH v2 04/10] cxl/memscrub: Add CXL device patrol scrub control feature

[Shiju Jose <shiju.jose@huawei.com>]

Hi Davidlohr,

Thanks for reviewing and comments.

>-----Original Message-----
>From: Davidlohr Bueso <dave@stgolabs.net>
>Sent: 22 November 2023 00:22
>To: Shiju Jose <shiju.jose@huawei.com>
>Cc: linux-cxl@vger.kernel.org; linux-mm@kvack.org; Jonathan Cameron
><jonathan.cameron@huawei.com>; dave.jiang@intel.com;
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>a.manzanares@samsung.com
>Subject: Re: [PATCH v2 04/10] cxl/memscrub: Add CXL device patrol scrub
>control feature
>
>On Tue, 21 Nov 2023, shiju.jose@huawei.com wrote:
>
>>From: Shiju Jose <shiju.jose@huawei.com>
>>
>>CXL spec 3.1 section 8.2.9.9.11.1 describes the device patrol scrub
>>control feature. The device patrol scrub proactively locates and makes
>>corrections to errors in regular cycle. The patrol scrub control allows
>>the request to configure patrol scrub input configurations.
>>
>>The patrol scrub control allows the requester to specify the number of
>>hours for which the patrol scrub cycles must be completed, provided
>>that the requested number is not less than the minimum number of hours
>>for the patrol scrub cycle that the device is capable of. In addition,
>>the patrol scrub controls allow the host to disable and enable the
>>feature in case disabling of the feature is needed for other purposes
>>such as performance-aware operations which require the background
>>operations to be turned off.
>>
>>Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
>>---
>> drivers/cxl/Kconfig         |  17 +++
>> drivers/cxl/core/Makefile   |   1 +
>> drivers/cxl/core/memscrub.c | 272
>++++++++++++++++++++++++++++++++++++
>> drivers/cxl/cxlmem.h        |   8 ++
>> drivers/cxl/pci.c           |   6 +
>> 5 files changed, 304 insertions(+)
>> create mode 100644 drivers/cxl/core/memscrub.c
>>
>>diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig index
>>8ea1d340e438..e91f5acc94f2 100644
>>--- a/drivers/cxl/Kconfig
>>+++ b/drivers/cxl/Kconfig
>>@@ -154,4 +154,21 @@ config CXL_PMU
>> 	  monitoring units and provide standard perf based interfaces.
>>
>> 	  If unsure say 'm'.
>>+
>>+config CXL_SCRUB
>>+	tristate "CXL: Memory scrub feature"
>>+	depends on CXL_PCI
>>+	depends on CXL_MEM
>>+	help
>>+	  The CXL memory scrub control is an optional feature allows host to
>>+	  control the scrub configurations of CXL Type 3 devices, which
>>+	  support patrol scrub and/or DDR5 ECS(Error Check Scrub).
>>+
>>+	  Say 'y/m' to enable the CXL memory scrub driver that will attach to
>>+	  CXL.mem devices for memory scrub control feature. See sections
>>+	  8.2.9.9.11.1 and 8.2.9.9.11.2 in the CXL 3.1 specification for a
>>+	  detailed description of CXL memory scrub control features.
>>+
>>+	  If unsure say 'm'.
>
>Does this really warrant yet another kconfig option?
I missed to change   'm' -> 'n' and tristate->bool.
  
>
>>+
>> endif
>>diff --git a/drivers/cxl/core/Makefile b/drivers/cxl/core/Makefile
>>index 1f66b5d4d935..99e3202f868f 100644
>>--- a/drivers/cxl/core/Makefile
>>+++ b/drivers/cxl/core/Makefile
>>@@ -15,3 +15,4 @@ cxl_core-y += hdm.o
>> cxl_core-y += pmu.o
>> cxl_core-$(CONFIG_TRACING) += trace.o
>> cxl_core-$(CONFIG_CXL_REGION) += region.o
>>+cxl_core-$(CONFIG_CXL_SCRUB) += memscrub.o
>>diff --git a/drivers/cxl/core/memscrub.c b/drivers/cxl/core/memscrub.c
>>new file mode 100644 index 000000000000..7d98a1593abe
>>--- /dev/null
>>+++ b/drivers/cxl/core/memscrub.c
>>@@ -0,0 +1,272 @@
>>+// SPDX-License-Identifier: GPL-2.0-or-later
>>+/*
>>+ * cxl_memscrub.c - CXL memory scrub driver
>>+ *
>>+ * Copyright (c) 2023 HiSilicon Limited.
>>+ *
>>+ *  - Provides functions to configure patrol scrub
>>+ *    feature of the CXL memory devices.
>>+ */
>>+
>>+#define pr_fmt(fmt)	"CXL_MEM_SCRUB: " fmt
>>+
>>+#include <cxlmem.h>
>>+
>>+/* CXL memory scrub feature common definitions */
>>+#define CXL_SCRUB_MAX_ATTRB_RANGE_LENGTH	128
>>+
>>+static int cxl_mem_get_supported_feature_entry(struct cxl_memdev *cxlmd,
>const uuid_t *feat_uuid,
>>+					       struct cxl_mbox_supp_feat_entry
>*feat_entry_out)
>
>It would be nicer if the feat_entry_out pointer was returned instead of passed by
>parameter.
The memory for the feats_out would be freed when exit cxl_mem_get_supported_feature_entry(),
thus feats_out->feat_entries is invalid outside. Hence copying the requested feat_entry  data to the 
feat_entry_out pointer passed.
 
>
>>+{
>>+	struct cxl_mbox_get_supp_feats_out *feats_out __free(kvfree) = NULL;
>>+	struct cxl_mbox_supp_feat_entry *feat_entry;
>>+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
>>+	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
>>+	struct cxl_mbox_get_supp_feats_in pi;
>>+	bool is_support_feature = false;
>>+	int feat_index, count;
>>+	int nentries;
>>+	int ret;
>>+
>>+	feat_index = 0;
>>+	pi.count = sizeof(struct cxl_mbox_get_supp_feats_out) +
>>+			  sizeof(struct cxl_mbox_supp_feat_entry);
>>+	feats_out = kvmalloc(pi.count, GFP_KERNEL);
>>+	if (!feats_out)
>>+		return -ENOMEM;
>>+
>>+	do {
>>+		pi.start_index = feat_index;
>>+		memset(feats_out, 0, pi.count);
>>+		ret = cxl_get_supported_features(mds, &pi, feats_out);
>>+		if (ret)
>>+			return ret;
>>+
>>+		nentries = feats_out->entries;
>>+		if (!nentries)
>>+			break;
>>+
>>+		/* Check CXL memdev supports the feature */
>>+		feat_entry = (void *)feats_out->feat_entries;
>>+		for (count = 0; count < nentries; count++, feat_entry++) {
>>+			if (uuid_equal(&feat_entry->uuid, feat_uuid)) {
>>+				is_support_feature = true;
>>+				memcpy(feat_entry_out, feat_entry,
>sizeof(*feat_entry_out));
>>+				break;
>
>Just return 0 in this case, and then you can do without the is_supported_feature
>flag.
Sure.

>
>>+			}
>>+		}
>>+		if (is_support_feature)
>>+			break;
>>+		feat_index += nentries;
>>+	} while (nentries);
>>+
>>+	if (!is_support_feature)
>>+		return -ENOTSUPP;
>>+
>>+	return 0;
>>+}
>>+
>>+/* CXL memory patrol scrub control definitions */
>>+#define CXL_MEMDEV_PS_GET_FEAT_VERSION	0x01
>>+#define CXL_MEMDEV_PS_SET_FEAT_VERSION	0x01
>>+
>>+static const uuid_t cxl_patrol_scrub_uuid =
>>+	UUID_INIT(0x96dad7d6, 0xfde8, 0x482b, 0xa7, 0x33, 0x75, 0x77, 0x4e,
>\
>>+		  0x06, 0xdb, 0x8a);
>>+
>>+/* CXL memory patrol scrub control functions */ struct
>>+cxl_patrol_scrub_context {
>>+	struct device *dev;
>>+	u16 get_feat_size;
>>+	u16 set_feat_size;
>>+	bool scrub_cycle_changable;
>
>s/changable/changeable
Ok.

>
>>+};
>>+
>>+/**
>>+ * struct cxl_memdev_ps_params - CXL memory patrol scrub parameter data
>structure.
>>+ * @enable:     [IN] enable(1)/disable(0) patrol scrub.
>>+ * @scrub_cycle_changable: [OUT] scrub cycle attribute of patrol scrub is
>changeable.
>>+ * @speed:      [IN] Requested patrol scrub cycle in hours.
>>+ *              [OUT] Current patrol scrub cycle in hours.
>>+ * @min_speed:[OUT] minimum patrol scrub cycle, in hours, supported.
>>+ * @speed_avail:[OUT] Supported patrol scrub cycle in hours.
>>+ */
>>+struct cxl_memdev_ps_params {
>>+	bool enable;
>>+	bool scrub_cycle_changable;
>>+	u16 speed;
>>+	u16 min_speed;
>>+	char speed_avail[CXL_SCRUB_MAX_ATTRB_RANGE_LENGTH];
>>+};
>>+
>>+enum {
>>+	CXL_MEMDEV_PS_PARAM_ENABLE = 0,
>>+	CXL_MEMDEV_PS_PARAM_SPEED,
>>+};
>>+
>>+#define	CXL_MEMDEV_PS_SCRUB_CYCLE_CHANGE_CAP_MASK	BIT(0)
>>+#define
>	CXL_MEMDEV_PS_SCRUB_CYCLE_REALTIME_REPORT_CAP_MASK
>	BIT(1)
>>+#define	CXL_MEMDEV_PS_CUR_SCRUB_CYCLE_MASK	GENMASK(7, 0)
>>+#define	CXL_MEMDEV_PS_MIN_SCRUB_CYCLE_MASK	GENMASK(15,
>8)
>>+#define	CXL_MEMDEV_PS_FLAG_ENABLED_MASK	BIT(0)
>>+
>>+struct cxl_memdev_ps_feat_read_attrbs {
>>+	u8 scrub_cycle_cap;
>>+	__le16 scrub_cycle;
>>+	u8 scrub_flags;
>>+}  __packed;
>>+
>>+struct cxl_memdev_ps_set_feat_pi {
>>+	struct cxl_mbox_set_feat_in pi;
>>+	u8 scrub_cycle_hr;
>>+	u8 scrub_flags;
>>+}  __packed;
>>+
>>+static int cxl_mem_ps_get_attrbs(struct device *dev,
>>+				 struct cxl_memdev_ps_params *params) {
>>+	struct cxl_memdev_ps_feat_read_attrbs *rd_attrbs __free(kvfree) =
>NULL;
>>+	struct cxl_mbox_get_feat_in pi = {
>>+		.uuid = cxl_patrol_scrub_uuid,
>>+		.offset = 0,
>>+		.count = sizeof(struct cxl_memdev_ps_feat_read_attrbs),
>>+		.selection = CXL_GET_FEAT_SEL_CURRENT_VALUE,
>>+	};
>>+	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
>>+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
>>+	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
>>+	int ret;
>>+
>>+	if (!mds)
>>+		return -EFAULT;
>>+
>>+	rd_attrbs = kvmalloc(pi.count, GFP_KERNEL);
>>+	if (!rd_attrbs)
>>+		return -ENOMEM;
>>+
>>+	ret = cxl_get_feature(mds, &pi, rd_attrbs);
>>+	if (ret) {
>>+		params->enable = 0;
>>+		params->speed = 0;
>>+		snprintf(params->speed_avail,
>CXL_SCRUB_MAX_ATTRB_RANGE_LENGTH,
>>+			"Unavailable");
>>+		return ret;
>>+	}
>>+	params->scrub_cycle_changable =
>FIELD_GET(CXL_MEMDEV_PS_SCRUB_CYCLE_CHANGE_CAP_MASK,
>>+						  rd_attrbs->scrub_cycle_cap);
>>+	params->enable =
>FIELD_GET(CXL_MEMDEV_PS_FLAG_ENABLED_MASK,
>>+				   rd_attrbs->scrub_flags);
>>+	params->speed =
>FIELD_GET(CXL_MEMDEV_PS_CUR_SCRUB_CYCLE_MASK,
>>+				  rd_attrbs->scrub_cycle);
>>+	params->min_speed  =
>FIELD_GET(CXL_MEMDEV_PS_MIN_SCRUB_CYCLE_MASK,
>>+				       rd_attrbs->scrub_cycle);
>>+	snprintf(params->speed_avail,
>CXL_SCRUB_MAX_ATTRB_RANGE_LENGTH,
>>+		 "Minimum scrub cycle = %d hour", params->min_speed);
>>+
>>+	return 0;
>>+}
>>+
>>+static int cxl_mem_ps_set_attrbs(struct device *dev,
>>+				 struct cxl_memdev_ps_params *params, u8
>param_type) {
>>+	struct cxl_memdev_ps_set_feat_pi set_pi = {
>>+		.pi.uuid = cxl_patrol_scrub_uuid,
>>+		.pi.flags =
>CXL_SET_FEAT_FLAG_MOD_VALUE_SAVED_ACROSS_RESET |
>>+			    CXL_SET_FEAT_FLAG_FULL_DATA_TRANSFER,
>>+		.pi.offset = 0,
>>+		.pi.version = CXL_MEMDEV_PS_SET_FEAT_VERSION,
>>+	};
>>+	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
>>+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
>>+	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
>>+	struct cxl_memdev_ps_params rd_params;
>>+	int ret;
>>+
>>+	if (!mds)
>>+		return -EFAULT;
>>+
>>+	ret = cxl_mem_ps_get_attrbs(dev, &rd_params);
>>+	if (ret) {
>>+		dev_err(dev, "Get cxlmemdev patrol scrub params fail
>ret=%d\n",
>>+			ret);
>>+		return ret;
>>+	}
>>+
>>+	switch (param_type) {
>>+	case CXL_MEMDEV_PS_PARAM_ENABLE:
>>+		set_pi.scrub_flags =
>FIELD_PREP(CXL_MEMDEV_PS_FLAG_ENABLED_MASK,
>>+						   params->enable);
>>+		set_pi.scrub_cycle_hr =
>FIELD_PREP(CXL_MEMDEV_PS_CUR_SCRUB_CYCLE_MASK,
>>+						      rd_params.speed);
>>+		break;
>>+	case CXL_MEMDEV_PS_PARAM_SPEED:
>>+		if (params->speed < rd_params.min_speed) {
>>+			dev_err(dev, "Invalid CXL patrol scrub cycle(%d) to
>set\n",
>>+				params->speed);
>>+			dev_err(dev, "Minimum supported CXL patrol scrub
>cycle in hour %d\n",
>>+			       params->min_speed);
>>+			return -EINVAL;
>>+		}
>>+		set_pi.scrub_cycle_hr =
>FIELD_PREP(CXL_MEMDEV_PS_CUR_SCRUB_CYCLE_MASK,
>>+						      params->speed);
>>+		set_pi.scrub_flags =
>FIELD_PREP(CXL_MEMDEV_PS_FLAG_ENABLED_MASK,
>>+						   rd_params.enable);
>>+		break;
>>+	default:
>>+		dev_err(dev, "Invalid CXL patrol scrub parameter to set\n");
>>+		return -EINVAL;
>>+	}
>>+
>>+	ret = cxl_set_feature(mds, &set_pi, sizeof(set_pi));
>>+	if (ret) {
>>+		dev_err(dev, "CXL patrol scrub set feature fail ret=%d\n",
>>+			ret);
>>+		return ret;
>>+	}
>>+
>>+	/* Verify attribute set successfully */
>>+	if (param_type == CXL_MEMDEV_PS_PARAM_SPEED) {
>>+		ret = cxl_mem_ps_get_attrbs(dev, &rd_params);
>>+		if (ret) {
>>+			dev_err(dev, "Get cxlmemdev patrol scrub params fail
>ret=%d\n", ret);
>>+			return ret;
>>+		}
>>+		if (rd_params.speed != params->speed)
>>+			return -EFAULT;
>>+	}
>>+
>>+	return 0;
>>+}
>>+
>>+int cxl_mem_patrol_scrub_init(struct cxl_memdev *cxlmd) {
>>+	struct cxl_patrol_scrub_context *cxl_ps_ctx;
>>+	struct cxl_mbox_supp_feat_entry feat_entry;
>>+	struct cxl_memdev_ps_params params;
>>+	int ret;
>>+
>>+	ret = cxl_mem_get_supported_feature_entry(cxlmd,
>&cxl_patrol_scrub_uuid,
>>+						  &feat_entry);
>>+	if (ret < 0)
>>+		return ret;
>>+
>>+	if (!(feat_entry.attrb_flags & CXL_FEAT_ENTRY_FLAG_CHANGABLE))
>>+		return -ENOTSUPP;
>>+
>>+	cxl_ps_ctx = devm_kzalloc(&cxlmd->dev, sizeof(*cxl_ps_ctx),
>GFP_KERNEL);
>>+	if (!cxl_ps_ctx)
>>+		return -ENOMEM;
>>+
>>+	cxl_ps_ctx->get_feat_size = feat_entry.get_feat_size;
>>+	cxl_ps_ctx->set_feat_size = feat_entry.set_feat_size;
>>+	ret = cxl_mem_ps_get_attrbs(&cxlmd->dev, &params);
>>+	if (ret) {
>>+		dev_err(&cxlmd->dev, "Get CXL patrol scrub params fail
>ret=%d\n",
>>+			ret);
>>+		return ret;
>>+	}
>>+	cxl_ps_ctx->scrub_cycle_changable =  params.scrub_cycle_changable;
>>+
>>+	return 0;
>>+}
>>+EXPORT_SYMBOL_NS_GPL(cxl_mem_patrol_scrub_init, CXL);
>>diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h index
>>46131dcd0900..25c46e72af16 100644
>>--- a/drivers/cxl/cxlmem.h
>>+++ b/drivers/cxl/cxlmem.h
>>@@ -983,6 +983,14 @@ int cxl_trigger_poison_list(struct cxl_memdev
>>*cxlmd);  int cxl_inject_poison(struct cxl_memdev *cxlmd, u64 dpa);
>>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); #else static
>>+inline int cxl_mem_patrol_scrub_init(struct cxl_memdev *cxlmd) {
>>+return -ENOTSUPP; } #endif
>>+
>> #ifdef CONFIG_CXL_SUSPEND
>> void cxl_mem_active_inc(void);
>> void cxl_mem_active_dec(void);
>>diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c index
>>0155fb66b580..86bba8794bb4 100644
>>--- a/drivers/cxl/pci.c
>>+++ b/drivers/cxl/pci.c
>>@@ -881,6 +881,12 @@ static int cxl_pci_probe(struct pci_dev *pdev, const
>struct pci_device_id *id)
>> 	if (rc)
>> 		return rc;
>>
>>+	/*
>>+	 * Initialize optional CXL scrub features
>>+	 */
>>+	if (cxl_mem_patrol_scrub_init(cxlmd))
>>+		dev_dbg(&pdev->dev, "cxl_mem_patrol_scrub_init failed\n");
>
>Unnecessary debug msg.
Will remove.

>
>>+
>> 	rc = devm_cxl_sanitize_setup_notifier(&pdev->dev, cxlmd);
>> 	if (rc)
>> 		return rc;
>>--
>>2.34.1
>>

Thanks,
Shiju