Merge branch 'for-6.7/cxl-commited' into cxl/next

Add the committed decoder sysfs attribute for v6.7.

Author: djbw

Documentation/ABI/testing/sysfs-bus-cxl

@@ -178,6 +178,21 @@ Description:
 		hardware decoder target list.
 
 
+What:		/sys/bus/cxl/devices/portX/decoders_committed
+Date:		October, 2023
+KernelVersion:	v6.7
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) A memory device is considered active when any of its
+		decoders are in the "committed" state (See CXL 3.0 8.2.4.19.7
+		CXL HDM Decoder n Control Register). Hotplug and destructive
+		operations like "sanitize" are blocked while device is actively
+		decoding a Host Physical Address range. Note that this number
+		may be elevated without any regionX objects active or even
+		enumerated, as this may be due to decoders established by
+		platform firwmare or a previous kernel (kexec).
+
+
 What:		/sys/bus/cxl/devices/decoderX.Y
 Date:		June, 2021
 KernelVersion:	v5.14

drivers/cxl/core/hdm.c

@@ -633,10 +633,11 @@ static int cxl_decoder_commit(struct cxl_decoder *cxld)
 	if (cxld->flags & CXL_DECODER_F_ENABLE)
 		return 0;
 
-	if (port->commit_end + 1 != id) {
+	if (cxl_num_decoders_committed(port) != id) {
 		dev_dbg(&port->dev,
 			"%s: out of order commit, expected decoder%d.%d\n",
-			dev_name(&cxld->dev), port->id, port->commit_end + 1);
+			dev_name(&cxld->dev), port->id,
+			cxl_num_decoders_committed(port));
 		return -EBUSY;
 	}
 
@@ -853,7 +854,7 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
 			cxld->target_type = CXL_DECODER_HOSTONLYMEM;
 		else
 			cxld->target_type = CXL_DECODER_DEVMEM;
-		if (cxld->id != port->commit_end + 1) {
+		if (cxld->id != cxl_num_decoders_committed(port)) {
 			dev_warn(&port->dev,
 				 "decoder%d.%d: Committed out of order\n",
 				 port->id, cxld->id);

drivers/cxl/core/mbox.c

@@ -1200,7 +1200,7 @@ int cxl_mem_sanitize(struct cxl_memdev *cxlmd, u16 cmd)
 	 * Require an endpoint to be safe otherwise the driver can not
 	 * be sure that the device is unmapped.
 	 */
-	if (endpoint && endpoint->commit_end == -1)
+	if (endpoint && cxl_num_decoders_committed(endpoint) == 0)
 		rc = __cxl_mem_sanitize(mds, cmd);
 	else
 		rc = -EBUSY;

drivers/cxl/core/memdev.c

@@ -231,7 +231,7 @@ int cxl_trigger_poison_list(struct cxl_memdev *cxlmd)
 	if (rc)
 		return rc;
 
-	if (port->commit_end == -1) {
+	if (cxl_num_decoders_committed(port) == 0) {
 		/* No regions mapped to this memdev */
 		rc = cxl_get_poison_by_memdev(cxlmd);
 	} else {
@@ -282,7 +282,7 @@ static struct cxl_region *cxl_dpa_to_region(struct cxl_memdev *cxlmd, u64 dpa)
 		.dpa = dpa,
 	};
 	port = cxlmd->endpoint;
-	if (port && is_cxl_endpoint(port) && port->commit_end != -1)
+	if (port && is_cxl_endpoint(port) && cxl_num_decoders_committed(port))
 		device_for_each_child(&port->dev, &ctx, __cxl_dpa_to_region);
 
 	return ctx.cxlr;

drivers/cxl/core/port.c

@@ -37,6 +37,13 @@ DECLARE_RWSEM(cxl_region_rwsem);
 static DEFINE_IDA(cxl_port_ida);
 static DEFINE_XARRAY(cxl_root_buses);
 
+int cxl_num_decoders_committed(struct cxl_port *port)
+{
+	lockdep_assert_held(&cxl_region_rwsem);
+
+	return port->commit_end + 1;
+}
+
 static ssize_t devtype_show(struct device *dev, struct device_attribute *attr,
 			    char *buf)
 {
@@ -537,8 +544,33 @@ static void cxl_port_release(struct device *dev)
 	kfree(port);
 }
 
+static ssize_t decoders_committed_show(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct cxl_port *port = to_cxl_port(dev);
+	int rc;
+
+	down_read(&cxl_region_rwsem);
+	rc = sysfs_emit(buf, "%d\n", cxl_num_decoders_committed(port));
+	up_read(&cxl_region_rwsem);
+
+	return rc;
+}
+
+static DEVICE_ATTR_RO(decoders_committed);
+
+static struct attribute *cxl_port_attrs[] = {
+	&dev_attr_decoders_committed.attr,
+	NULL,
+};
+
+static struct attribute_group cxl_port_attribute_group = {
+	.attrs = cxl_port_attrs,
+};
+
 static const struct attribute_group *cxl_port_attribute_groups[] = {
 	&cxl_base_attribute_group,
+	&cxl_port_attribute_group,
 	NULL,
 };
 

drivers/cxl/cxl.h

@@ -689,6 +689,7 @@ static inline bool is_cxl_root(struct cxl_port *port)
 	return port->uport_dev == port->dev.parent;
 }
 
+int cxl_num_decoders_committed(struct cxl_port *port);
 bool is_cxl_port(const struct device *dev);
 struct cxl_port *to_cxl_port(const struct device *dev);
 struct pci_bus;