[PATCH v2 01/21] cxl: Export QTG ids from CFMWS to sysfs

From: Dave Jiang <dave.jiang@intel.com>
To: linux-cxl@vger.kernel.org, linux-acpi@vger.kernel.org
Cc: dan.j.williams@intel.com, ira.weiny@intel.com,
	vishal.l.verma@intel.com, alison.schofield@intel.com,
	rafael@kernel.org, lukas@wunner.de
Subject: [PATCH v2 01/21] cxl: Export QTG ids from CFMWS to sysfs
Date: Mon, 27 Mar 2023 14:44:08 -0700	[thread overview]
Message-ID: <167995344806.2857312.16258432683708945736.stgit@djiang5-mobl3> (raw)
In-Reply-To: <167995336797.2857312.539473939839316778.stgit@djiang5-mobl3>

Export the QoS Throttling Group ID from the CXL Fixed Memory Window
Structure (CFMWS) under the root decoder sysfs attributes.
CXL rev3.0 9.17.1.3 CXL Fixed Memory Window Structure (CFMWS)

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

Signed-off-by: Dave Jiang <dave.jiang@intel.com>

---
v2:
- Add explanation commit header (Jonathan)
---
 Documentation/ABI/testing/sysfs-bus-cxl |    9 +++++++++
 drivers/cxl/acpi.c                      |    3 +++
 drivers/cxl/core/port.c                 |   14 ++++++++++++++
 drivers/cxl/cxl.h                       |    3 +++
 4 files changed, 29 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
index 3acf2f17a73f..471ac9a37078 100644
--- a/Documentation/ABI/testing/sysfs-bus-cxl
+++ b/Documentation/ABI/testing/sysfs-bus-cxl
@@ -309,6 +309,15 @@ Description:
 		(WO) Write a string in the form 'regionZ' to delete that region,
 		provided it is currently idle / not bound to a driver.
 
+What:		/sys/bus/cxl/devices/decoderX.Y/qtg_id
+Date:		Jan, 2023
+KernelVersion:	v6.4
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) Shows the QoS Throttling Group ID. The QTG ID for a root
+		decoder comes from the CFMWS structure of the CEDT. A value of
+		-1 indicates that no QTG ID was retrieved. The QTG ID is used as
+		guidance to match against the QTG ID of a hot-plugged device.
 
 What:		/sys/bus/cxl/devices/regionZ/uuid
 Date:		May, 2022
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 7e1765b09e04..abc24137c291 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,
 			}
 		}
 	}
+
+	cxld->qtg_id = 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 8ee6b6e2e2a4..5ec48dddb2f9 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -276,6 +276,16 @@ static ssize_t interleave_ways_show(struct device *dev,
 
 static DEVICE_ATTR_RO(interleave_ways);
 
+static ssize_t qtg_id_show(struct device *dev,
+			   struct device_attribute *attr, char *buf)
+{
+	struct cxl_decoder *cxld = to_cxl_decoder(dev);
+
+	return sysfs_emit(buf, "%d\n", cxld->qtg_id);
+}
+
+static DEVICE_ATTR_RO(qtg_id);
+
 static struct attribute *cxl_decoder_base_attrs[] = {
 	&dev_attr_start.attr,
 	&dev_attr_size.attr,
@@ -295,6 +305,7 @@ static struct attribute *cxl_decoder_root_attrs[] = {
 	&dev_attr_cap_type2.attr,
 	&dev_attr_cap_type3.attr,
 	&dev_attr_target_list.attr,
+	&dev_attr_qtg_id.attr,
 	SET_CXL_REGION_ATTR(create_pmem_region)
 	SET_CXL_REGION_ATTR(create_ram_region)
 	SET_CXL_REGION_ATTR(delete_region)
@@ -1649,6 +1660,7 @@ struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
 	}
 
 	atomic_set(&cxlrd->region_id, rc);
+	cxld->qtg_id = CXL_QTG_ID_INVALID;
 	return cxlrd;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_root_decoder_alloc, CXL);
@@ -1686,6 +1698,7 @@ struct cxl_switch_decoder *cxl_switch_decoder_alloc(struct cxl_port *port,
 
 	cxld = &cxlsd->cxld;
 	cxld->dev.type = &cxl_decoder_switch_type;
+	cxld->qtg_id = CXL_QTG_ID_INVALID;
 	return cxlsd;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_switch_decoder_alloc, CXL);
@@ -1718,6 +1731,7 @@ struct cxl_endpoint_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port)
 	}
 
 	cxld->dev.type = &cxl_decoder_endpoint_type;
+	cxld->qtg_id = CXL_QTG_ID_INVALID;
 	return cxled;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_endpoint_decoder_alloc, CXL);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f2b0962a552d..cc3309794b45 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_QTG_ID_INVALID	-1
 
 /**
  * struct cxl_decoder - Common CXL HDM Decoder Attributes
@@ -311,6 +312,7 @@ enum cxl_decoder_type {
  * @target_type: accelerator vs expander (type2 vs type3) selector
  * @region: currently assigned region for this decoder
  * @flags: memory type capabilities and locking
+ * @qtg_id: QoS Throttling Group ID
  * @commit: device/decoder-type specific callback to commit settings to hw
  * @reset: device/decoder-type specific callback to reset hw settings
 */
@@ -323,6 +325,7 @@ struct cxl_decoder {
 	enum cxl_decoder_type target_type;
 	struct cxl_region *region;
 	unsigned long flags;
+	int qtg_id;
 	int (*commit)(struct cxl_decoder *cxld);
 	int (*reset)(struct cxl_decoder *cxld);
 };


