diff mbox series

[v2,1/4] cxl: Export QTG ids from CFMWS to sysfs as qos_class attribute

Message ID 168382792890.3510737.9466824452406784924.stgit@djiang5-mobl3
State New, archived
Headers show
Series cxl: Prep for QoS class support | expand

Commit Message

Dave Jiang May 11, 2023, 5:58 p.m. UTC 
Export the QoS Throttling Group ID from the CXL Fixed Memory Window
Structure (CFMWS) under the root decoder sysfs attributes as qos_class.

CXL rev3.0 9.17.1.3 CXL Fixed Memory Window Structure (CFMWS)

cxl cli will use this id to match with the _DSM retrieved id for a
hot-plugged CXL memory device DPA memory range to make sure that the
DPA range is under the right CFMWS window.

Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

---
v5:
- Documentation rewrite. (Dan)
- Rename attrib to qos_class
- Move qtg_id to root decoder
v4:
- Change kernel version for documentation to v6.5
v2:
- Add explanation commit header (Jonathan)
---
 Documentation/ABI/testing/sysfs-bus-cxl |   15 +++++++++++++++
 drivers/cxl/acpi.c                      |    3 +++
 drivers/cxl/core/port.c                 |   11 +++++++++++
 drivers/cxl/cxl.h                       |    3 +++
 4 files changed, 32 insertions(+)

Comments

Dan Williams May 11, 2023, 11:56 p.m. UTC | #1 
Dave Jiang wrote:
> Export the QoS Throttling Group ID from the CXL Fixed Memory Window
> Structure (CFMWS) under the root decoder sysfs attributes as qos_class.
> 
> CXL rev3.0 9.17.1.3 CXL Fixed Memory Window Structure (CFMWS)
> 
> cxl cli will use this id to match with the _DSM retrieved id for a
> hot-plugged CXL memory device DPA memory range to make sure that the
> DPA range is under the right CFMWS window.
> 
> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Looks good to me.

Will apply to a for-6.5/cxl-qos-class topic branch.
diff mbox series

Patch

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 3acf2f17a73f..2f24e42ef36d 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -310,6 +310,21 @@  Description:
 		provided it is currently idle / not bound to a driver.
 
 
+What:		/sys/bus/cxl/devices/decoderX.Y/qos_class
+Date:		May, 2023
+KernelVersion:	v6.5
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) For CXL host platforms that support "QoS Telemmetry" this
+		root-decoder-only attribute conveys a platform specific cookie
+		that identifies a QoS performance class for the CXL Window.
+		This class-id can be compared against a similar "qos_class"
+		published for each memory-type that an endpoint supports. While
+		it is not required that endpoints map their local memory-class
+		to a matching platform class, mismatches are not recommended and
+		there are platform specific side-effects that may result.
+
+
 What:		/sys/bus/cxl/devices/regionZ/uuid
 Date:		May, 2022
 KernelVersion:	v6.0
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 7e1765b09e04..e063df2bf876 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -289,6 +289,9 @@  static int cxl_parse_cfmws(union acpi_subtable_headers *header, void *arg,
 			}
 		}
 	}
+
+	cxlrd->qos_class = cfmws->qtg_id;
+
 	rc = cxl_decoder_add(cxld, target_map);
 err_xormap:
 	if (rc)
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 4d1f9c5b5029..a0130aeb8d42 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -276,6 +276,15 @@  static ssize_t interleave_ways_show(struct device *dev,
 
 static DEVICE_ATTR_RO(interleave_ways);
 
+static ssize_t qos_class_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(dev);
+
+	return sysfs_emit(buf, "%d\n", cxlrd->qos_class);
+}
+static DEVICE_ATTR_RO(qos_class);
+
 static struct attribute *cxl_decoder_base_attrs[] = {
 	&dev_attr_start.attr,
 	&dev_attr_size.attr,
@@ -295,6 +304,7 @@  static struct attribute *cxl_decoder_root_attrs[] = {
 	&dev_attr_cap_type2.attr,
 	&dev_attr_cap_type3.attr,
 	&dev_attr_target_list.attr,
+	&dev_attr_qos_class.attr,
 	SET_CXL_REGION_ATTR(create_pmem_region)
 	SET_CXL_REGION_ATTR(create_ram_region)
 	SET_CXL_REGION_ATTR(delete_region)
@@ -1625,6 +1635,7 @@  struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
 	}
 
 	atomic_set(&cxlrd->region_id, rc);
+	cxlrd->qos_class = CXL_QOS_CLASS_INVALID;
 	return cxlrd;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_root_decoder_alloc, CXL);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 044a92d9813e..4577d808ac6d 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -300,6 +300,7 @@  enum cxl_decoder_type {
  */
 #define CXL_DECODER_MAX_INTERLEAVE 16
 
+#define CXL_QOS_CLASS_INVALID -1
 
 /**
  * struct cxl_decoder - Common CXL HDM Decoder Attributes
@@ -411,6 +412,7 @@  typedef struct cxl_dport *(*cxl_calc_hb_fn)(struct cxl_root_decoder *cxlrd,
  * @calc_hb: which host bridge covers the n'th position by granularity
  * @platform_data: platform specific configuration data
  * @range_lock: sync region autodiscovery by address range
+ * @qos_class: QoS performance class cookie
  * @cxlsd: base cxl switch decoder
  */
 struct cxl_root_decoder {
@@ -419,6 +421,7 @@  struct cxl_root_decoder {
 	cxl_calc_hb_fn calc_hb;
 	void *platform_data;
 	struct mutex range_lock;
+	int qos_class;
 	struct cxl_switch_decoder cxlsd;
 };