To properly configure CXL regions user space will need to know the
details of the dynamic ram partition.
Expose the first dynamic ram partition through sysfs.
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
---
Changes:
[iweiny: Complete rewrite of the old patch.]
---
Documentation/ABI/testing/sysfs-bus-cxl | 24 ++++++++++++++
drivers/cxl/core/memdev.c | 57 +++++++++++++++++++++++++++++++++
2 files changed, 81 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 99bb3faf7a0e..2b59041bb410 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -89,6 +89,30 @@ Description:
and there are platform specific performance related
side-effects that may result. First class-id is displayed.
+What: /sys/bus/cxl/devices/memX/dynamic_ram_a/size
+Date: May, 2025
+KernelVersion: v6.16
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) The first Dynamic RAM partition capacity as bytes.
+
+
+What: /sys/bus/cxl/devices/memX/dynamic_ram_a/qos_class
+Date: May, 2025
+KernelVersion: v6.16
+Contact: linux-cxl@vger.kernel.org
+Description:
+ (RO) 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/serial
Date: January, 2022
diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 9d6f8800e37a..063a14c1973a 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -101,6 +101,19 @@ static ssize_t pmem_size_show(struct device *dev, struct device_attribute *attr,
static struct device_attribute dev_attr_pmem_size =
__ATTR(size, 0444, pmem_size_show, NULL);
+static ssize_t dynamic_ram_a_size_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+ struct cxl_dev_state *cxlds = cxlmd->cxlds;
+ unsigned long long len = cxl_part_size(cxlds, CXL_PARTMODE_DYNAMIC_RAM_A);
+
+ return sysfs_emit(buf, "%#llx\n", len);
+}
+
+static struct device_attribute dev_attr_dynamic_ram_a_size =
+ __ATTR(size, 0444, dynamic_ram_a_size_show, NULL);
+
static ssize_t serial_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
@@ -426,6 +439,25 @@ static struct attribute *cxl_memdev_pmem_attributes[] = {
NULL,
};
+static ssize_t dynamic_ram_a_qos_class_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+ struct cxl_dev_state *cxlds = cxlmd->cxlds;
+
+ return sysfs_emit(buf, "%d\n",
+ part_perf(cxlds, CXL_PARTMODE_DYNAMIC_RAM_A)->qos_class);
+}
+
+static struct device_attribute dev_attr_dynamic_ram_a_qos_class =
+ __ATTR(qos_class, 0444, dynamic_ram_a_qos_class_show, NULL);
+
+static struct attribute *cxl_memdev_dynamic_ram_a_attributes[] = {
+ &dev_attr_dynamic_ram_a_size.attr,
+ &dev_attr_dynamic_ram_a_qos_class.attr,
+ NULL,
+};
+
static ssize_t ram_qos_class_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -502,6 +534,29 @@ static struct attribute_group cxl_memdev_pmem_attribute_group = {
.is_visible = cxl_pmem_visible,
};
+static umode_t cxl_dynamic_ram_a_visible(struct kobject *kobj, struct attribute *a, int n)
+{
+ struct device *dev = kobj_to_dev(kobj);
+ struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+ struct cxl_dpa_perf *perf = part_perf(cxlmd->cxlds, CXL_PARTMODE_DYNAMIC_RAM_A);
+
+ if (a == &dev_attr_dynamic_ram_a_qos_class.attr &&
+ (!perf || perf->qos_class == CXL_QOS_CLASS_INVALID))
+ return 0;
+
+ if (a == &dev_attr_dynamic_ram_a_size.attr &&
+ (!cxl_part_size(cxlmd->cxlds, CXL_PARTMODE_DYNAMIC_RAM_A)))
+ return 0;
+
+ return a->mode;
+}
+
+static struct attribute_group cxl_memdev_dynamic_ram_a_attribute_group = {
+ .name = "dynamic_ram_a",
+ .attrs = cxl_memdev_dynamic_ram_a_attributes,
+ .is_visible = cxl_dynamic_ram_a_visible,
+};
+
static umode_t cxl_memdev_security_visible(struct kobject *kobj,
struct attribute *a, int n)
{
@@ -530,6 +585,7 @@ static const struct attribute_group *cxl_memdev_attribute_groups[] = {
&cxl_memdev_attribute_group,
&cxl_memdev_ram_attribute_group,
&cxl_memdev_pmem_attribute_group,
+ &cxl_memdev_dynamic_ram_a_attribute_group,
&cxl_memdev_security_attribute_group,
NULL,
};
@@ -538,6 +594,7 @@ void cxl_memdev_update_perf(struct cxl_memdev *cxlmd)
{
sysfs_update_group(&cxlmd->dev.kobj, &cxl_memdev_ram_attribute_group);
sysfs_update_group(&cxlmd->dev.kobj, &cxl_memdev_pmem_attribute_group);
+ sysfs_update_group(&cxlmd->dev.kobj, &cxl_memdev_dynamic_ram_a_attribute_group);
}
EXPORT_SYMBOL_NS_GPL(cxl_memdev_update_perf, "CXL");
--
2.49.0