[PATCH v4 13/28] cxl/mem: Expose DCD partition capabilities in sysfs

ira.weiny
2024-10-07T23:17:13Z

From: Navneet Singh <navneet.singh@intel.com>

To properly configure CXL regions on Dynamic Capacity Devices (DCD),
user space will need to know the details of the DC partitions available.

Expose dynamic capacity capabilities through sysfs.

Signed-off-by: Navneet Singh <navneet.singh@intel.com>
Co-developed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes:
[iweiny: Change .../memX/dc/* to .../memX/dcY/*]
[iweiny: add read only and shareable attributes from DSMAS]
[djiang: Split sysfs docs]
[iweiny: Adjust sysfs doc dates]
[iweiny: Add qos details]
---
Documentation/ABI/testing/sysfs-bus-cxl | 45 ++++++++++++
drivers/cxl/core/memdev.c | 126 ++++++++++++++++++++++++++++++++
2 files changed, 171 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 3f5627a1210a..b865eefdb74c 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -54,6 +54,51 @@ Description:
identically named field in the Identify Memory Device Output
Payload in the CXL-2.0 specification.

+What: /sys/bus/cxl/devices/memX/dcY/size
+Date: December, 2024
+KernelVersion: v6.13
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) Dynamic Capacity (DC) region information. Devices only
+ export dcY if DCD partition Y is supported.
+ dcY/size is the size of each of those partitions.
+
+What: /sys/bus/cxl/devices/memX/dcY/read_only
+Date: December, 2024
+KernelVersion: v6.13
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) Dynamic Capacity (DC) region information. Devices only
+ export dcY if DCD partition Y is supported.
+ dcY/read_only indicates true if the region is exported
+ read_only from the device.
+
+What: /sys/bus/cxl/devices/memX/dcY/shareable
+Date: December, 2024
+KernelVersion: v6.13
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) Dynamic Capacity (DC) region information. Devices only
+ export dcY if DCD partition Y is supported.
+ dcY/shareable indicates true if the region is exported
+ shareable from the device.
+
+What: /sys/bus/cxl/devices/memX/dcY/qos_class
+Date: December, 2024
+KernelVersion: v6.13
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) Dynamic Capacity (DC) region information. Devices only
+ export dcY if DCD partition Y is supported. For CXL host
+ platforms that support "QoS Telemmetry" this attribute conveys
+ a comma delimited list of platform specific cookies that
+ identifies a QoS performance class for the persistent partition
+ of the CXL mem device. These class-ids can be compared against
+ a similar "qos_class" published for a root decoder. While it is
+ not required that the endpoints map their local memory-class to
+ a matching platform class, mismatches are not recommended and
+ there are platform specific performance related side-effects
+ that may result. First class-id is displayed.

What: /sys/bus/cxl/devices/memX/pmem/qos_class
Date: May, 2023
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 84fefb76dafa..2565b10a769c 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -2,6 +2,7 @@
/* Copyright(c) 2020 Intel Corporation. */

#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/string_choices.h>
#include <linux/firmware.h>
#include <linux/device.h>
#include <linux/slab.h>
@@ -449,6 +450,123 @@ static struct attribute *cxl_memdev_security_attributes[] = {
NULL,
};

+static ssize_t show_size_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
+{
+ struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+
+ return sysfs_emit(buf, "%#llx\n", mds->dc_region[pos].decode_len);
+}
+
+static ssize_t show_read_only_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
+{
+ struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+
+ return sysfs_emit(buf, "%s\n",
+ str_false_true(mds->dc_region[pos].read_only));
+}
+
+static ssize_t show_shareable_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
+{
+ struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+
+ return sysfs_emit(buf, "%s\n",
+ str_false_true(mds->dc_region[pos].shareable));
+}
+
+static ssize_t show_qos_class_dcN(struct cxl_memdev *cxlmd, char *buf, int pos)
+{
+ struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
+
+ return sysfs_emit(buf, "%d\n", mds->dc_perf[pos].qos_class);
+}
+
+#define CXL_MEMDEV_DC_ATTR_GROUP(n) \
+static ssize_t dc##n##_size_show(struct device *dev, \
+ struct device_attribute *attr, \
+ char *buf) \
+{ \
+ return show_size_dcN(to_cxl_memdev(dev), buf, (n)); \
+} \
+struct device_attribute dc##n##_size = { \
+ .attr = { .name = "size", .mode = 0444 }, \
+ .show = dc##n##_size_show, \
+}; \
+static ssize_t dc##n##_read_only_show(struct device *dev, \
+ struct device_attribute *attr, \
+ char *buf) \
+{ \
+ return show_read_only_dcN(to_cxl_memdev(dev), buf, (n)); \
+} \
+struct device_attribute dc##n##_read_only = { \
+ .attr = { .name = "read_only", .mode = 0444 }, \
+ .show = dc##n##_read_only_show, \
+}; \
+static ssize_t dc##n##_shareable_show(struct device *dev, \
+ struct device_attribute *attr, \
+ char *buf) \
+{ \
+ return show_shareable_dcN(to_cxl_memdev(dev), buf, (n)); \
+} \
+struct device_attribute dc##n##_shareable = { \
+ .attr = { .name = "shareable", .mode = 0444 }, \
+ .show = dc##n##_shareable_show, \
+}; \
+static ssize_t dc##n##_qos_class_show(struct device *dev, \
+ struct device_attribute *attr, \
+ char *buf) \
+{ \
+ return show_qos_class_dcN(to_cxl_memdev(dev), buf, (n)); \
+} \
+struct device_attribute dc##n##_qos_class = { \
+ .attr = { .name = "qos_class", .mode = 0444 }, \
+ .show = dc##n##_qos_class_show, \
+}; \
+static struct attribute *cxl_memdev_dc##n##_attributes[] = { \
+ &dc##n##_size.attr, \
+ &dc##n##_read_only.attr, \
+ &dc##n##_shareable.attr, \
+ &dc##n##_qos_class.attr, \
+ NULL, \
+}; \
+static umode_t cxl_memdev_dc##n##_attr_visible(struct kobject *kobj, \
+ struct attribute *a, \
+ int pos) \
+{ \
+ struct device *dev = kobj_to_dev(kobj); \
+ struct cxl_memdev *cxlmd = to_cxl_memdev(dev); \
+ struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds); \
+ \
+ /* Not a memory device */ \
+ if (!mds) \
+ return 0; \
+ return a->mode; \
+} \
+static umode_t cxl_memdev_dc##n##_group_visible(struct kobject *kobj) \
+{ \
+ struct device *dev = kobj_to_dev(kobj); \
+ struct cxl_memdev *cxlmd = to_cxl_memdev(dev); \
+ struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds); \
+ \
+ /* Not a memory device or partition not supported */ \
+ if (!mds || n >= mds->nr_dc_region) \
+ return false; \
+ return true; \
+} \
+DEFINE_SYSFS_GROUP_VISIBLE(cxl_memdev_dc##n); \
+static struct attribute_group cxl_memdev_dc##n##_group = { \
+ .name = "dc"#n, \
+ .attrs = cxl_memdev_dc##n##_attributes, \
+ .is_visible = SYSFS_GROUP_VISIBLE(cxl_memdev_dc##n), \
+}
+CXL_MEMDEV_DC_ATTR_GROUP(0);
+CXL_MEMDEV_DC_ATTR_GROUP(1);
+CXL_MEMDEV_DC_ATTR_GROUP(2);
+CXL_MEMDEV_DC_ATTR_GROUP(3);
+CXL_MEMDEV_DC_ATTR_GROUP(4);
+CXL_MEMDEV_DC_ATTR_GROUP(5);
+CXL_MEMDEV_DC_ATTR_GROUP(6);
+CXL_MEMDEV_DC_ATTR_GROUP(7);
+
static umode_t cxl_memdev_visible(struct kobject *kobj, struct attribute *a,
int n)
{
@@ -525,6 +643,14 @@ static struct attribute_group cxl_memdev_security_attribute_group = {
};

static const struct attribute_group *cxl_memdev_attribute_groups[] = {
+ &cxl_memdev_dc0_group,
+ &cxl_memdev_dc1_group,
+ &cxl_memdev_dc2_group,
+ &cxl_memdev_dc3_group,
+ &cxl_memdev_dc4_group,
+ &cxl_memdev_dc5_group,
+ &cxl_memdev_dc6_group,
+ &cxl_memdev_dc7_group,
&cxl_memdev_attribute_group,
&cxl_memdev_ram_attribute_group,
&cxl_memdev_pmem_attribute_group,

--
2.46.0