@@ -28,6 +28,23 @@ Description:
Payload in the CXL-2.0 specification.
+What: /sys/bus/cxl/devices/memX/ram/qos_class
+Date: May, 2023
+KernelVersion: v6.7
+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 volatile 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/size
Date: December, 2020
KernelVersion: v5.12
@@ -38,6 +55,23 @@ Description:
Payload in the CXL-2.0 specification.
+What: /sys/bus/cxl/devices/memX/pmem/qos_class
+Date: May, 2023
+KernelVersion: v6.7
+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
KernelVersion: v5.18
@@ -88,6 +88,22 @@ static ssize_t ram_size_show(struct device *dev, struct device_attribute *attr,
static struct device_attribute dev_attr_ram_size =
__ATTR(size, 0444, ram_size_show, NULL);
+static ssize_t ram_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;
+ struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
+
+ if (!dev->driver)
+ return -ENOENT;
+
+ return sysfs_emit(buf, "%d\n", mds->ram_qos_class);
+}
+
+static struct device_attribute dev_attr_ram_qos_class =
+ __ATTR(qos_class, 0444, ram_qos_class_show, NULL);
+
static ssize_t pmem_size_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
@@ -101,6 +117,22 @@ 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 pmem_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;
+ struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlds);
+
+ if (!dev->driver)
+ return -ENOENT;
+
+ return sysfs_emit(buf, "%d\n", mds->pmem_qos_class);
+}
+
+static struct device_attribute dev_attr_pmem_qos_class =
+ __ATTR(qos_class, 0444, pmem_qos_class_show, NULL);
+
static ssize_t serial_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
@@ -439,11 +471,13 @@ static struct attribute *cxl_memdev_attributes[] = {
static struct attribute *cxl_memdev_pmem_attributes[] = {
&dev_attr_pmem_size.attr,
+ &dev_attr_pmem_qos_class.attr,
NULL,
};
static struct attribute *cxl_memdev_ram_attributes[] = {
&dev_attr_ram_size.attr,
+ &dev_attr_ram_qos_class.attr,
NULL,
};
Export qos_class sysfs attributes for the CXL memory device. The QoS clas should show up as /sys/bus/cxl/devices/memX/ram/qos_class for the volatile partition and /sys/bus/cxl/devices/memX/pmem/qos_class for the persistent partition. The QTG ID is retrieved via _DSM after supplying the calculated bandwidth and latency for the entire CXL path from device to the CPU. This ID is used to match up to the root decoder QoS class to determine which CFMWS the memory range of a hotplugged CXL mem device should be assigned under. While there may be multiple DSMAS exported by the device CDAT, the driver will only expose the first QTG ID per partition in sysfs for now. In the future when multiple QTG IDs are necessary, they can be exposed. [1] [1]: https://lore.kernel.org/linux-cxl/167571650007.587790.10040913293130712882.stgit@djiang5-mobl3.local/T/#md2a47b1ead3e1ba08f50eab29a4af1aed1d215ab Suggested-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Dave Jiang <dave.jiang@intel.com> --- v11: - Move qos_class0 to qos_class (Dan) v10: - Export only qos_class0, the first entry. Additional qos_class entries can be exported later as needed. (Dan) - Have the sysfs attrib return -ENOENT unless driver is attached. (Dan) - Removed Jonathan's review tag due to code changes. --- Documentation/ABI/testing/sysfs-bus-cxl | 34 +++++++++++++++++++++++++++++++ drivers/cxl/core/memdev.c | 34 +++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+)