cxl/bus: Populate the target list at decoder create

As found by cxl_test, the implementation populated the target_list for
the single dport exceptional case, it missed populating the target_list
for the typical multi-dport case. Root decoders always know their target
list at the beginning of time, and even switch-level decoders should
have a target list of one or more zeros by default, depending on the
interleave-ways setting.

Walk the hosting port's dport list and populate based on the passed in
map.

Move devm_cxl_add_passthrough_decoder() out of line now that it does the
work of generating a target_map.

Before:
$ cat /sys/bus/cxl/devices/root2/decoder*/target_list
0

0

After:
$ cat /sys/bus/cxl/devices/root2/decoder*/target_list
0
0,1,2,3
0
0,1,2,3

Where root2 is a CXL topology root object generated by 'cxl_test'.

Acked-by: Ben Widawsky <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Link: https://lore.kernel.org/r/163116439000.2460985.11713777051267946018.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <[email protected]>

Author: djbw

drivers/cxl/acpi.c

@@ -52,6 +52,12 @@ static int cxl_acpi_cfmws_verify(struct device *dev,
 		return -EINVAL;
 	}
 
+	if (CFMWS_INTERLEAVE_WAYS(cfmws) > CXL_DECODER_MAX_INTERLEAVE) {
+		dev_err(dev, "CFMWS Interleave Ways (%d) too large\n",
+			CFMWS_INTERLEAVE_WAYS(cfmws));
+		return -EINVAL;
+	}
+
 	expected_len = struct_size((cfmws), interleave_targets,
 				   CFMWS_INTERLEAVE_WAYS(cfmws));
 
@@ -71,6 +77,7 @@ static int cxl_acpi_cfmws_verify(struct device *dev,
 static void cxl_add_cfmws_decoders(struct device *dev,
 				   struct cxl_port *root_port)
 {
+	int target_map[CXL_DECODER_MAX_INTERLEAVE];
 	struct acpi_cedt_cfmws *cfmws;
 	struct cxl_decoder *cxld;
 	acpi_size len, cur = 0;
@@ -83,6 +90,7 @@ static void cxl_add_cfmws_decoders(struct device *dev,
 
 	while (cur < len) {
 		struct acpi_cedt_header *c = cedt_subtable + cur;
+		int i;
 
 		if (c->type != ACPI_CEDT_TYPE_CFMWS) {
 			cur += c->length;
@@ -108,14 +116,17 @@ static void cxl_add_cfmws_decoders(struct device *dev,
 			continue;
 		}
 
+		for (i = 0; i < CFMWS_INTERLEAVE_WAYS(cfmws); i++)
+			target_map[i] = cfmws->interleave_targets[i];
+
 		flags = cfmws_to_decoder_flags(cfmws->restrictions);
 		cxld = devm_cxl_add_decoder(dev, root_port,
 					    CFMWS_INTERLEAVE_WAYS(cfmws),
 					    cfmws->base_hpa, cfmws->window_size,
 					    CFMWS_INTERLEAVE_WAYS(cfmws),
 					    CFMWS_INTERLEAVE_GRANULARITY(cfmws),
 					    CXL_DECODER_EXPANDER,
-					    flags);
+					    flags, target_map);
 
 		if (IS_ERR(cxld)) {
 			dev_err(dev, "Failed to add decoder for %#llx-%#llx\n",

drivers/cxl/core/bus.c

@@ -453,11 +453,38 @@ int cxl_add_dport(struct cxl_port *port, struct device *dport_dev, int port_id,
 }
 EXPORT_SYMBOL_GPL(cxl_add_dport);
 
+static int decoder_populate_targets(struct device *host,
+				    struct cxl_decoder *cxld,
+				    struct cxl_port *port, int *target_map,
+				    int nr_targets)
+{
+	int rc = 0, i;
+
+	if (!target_map)
+		return 0;
+
+	device_lock(&port->dev);
+	for (i = 0; i < nr_targets; i++) {
+		struct cxl_dport *dport = find_dport(port, target_map[i]);
+
+		if (!dport) {
+			rc = -ENXIO;
+			break;
+		}
+		dev_dbg(host, "%s: target: %d\n", dev_name(dport->dport), i);
+		cxld->target[i] = dport;
+	}
+	device_unlock(&port->dev);
+
+	return rc;
+}
+
 static struct cxl_decoder *
-cxl_decoder_alloc(struct cxl_port *port, int nr_targets, resource_size_t base,
-		  resource_size_t len, int interleave_ways,
-		  int interleave_granularity, enum cxl_decoder_type type,
-		  unsigned long flags)
+cxl_decoder_alloc(struct device *host, struct cxl_port *port, int nr_targets,
+		  resource_size_t base, resource_size_t len,
+		  int interleave_ways, int interleave_granularity,
+		  enum cxl_decoder_type type, unsigned long flags,
+		  int *target_map)
 {
 	struct cxl_decoder *cxld;
 	struct device *dev;
@@ -493,10 +520,10 @@ cxl_decoder_alloc(struct cxl_port *port, int nr_targets, resource_size_t base,
 		.target_type = type,
 	};
 
-	/* handle implied target_list */
-	if (interleave_ways == 1)
-		cxld->target[0] =
-			list_first_entry(&port->dports, struct cxl_dport, list);
+	rc = decoder_populate_targets(host, cxld, port, target_map, nr_targets);
+	if (rc)
+		goto err;
+
 	dev = &cxld->dev;
 	device_initialize(dev);
 	device_set_pm_not_required(dev);
@@ -519,14 +546,19 @@ struct cxl_decoder *
 devm_cxl_add_decoder(struct device *host, struct cxl_port *port, int nr_targets,
 		     resource_size_t base, resource_size_t len,
 		     int interleave_ways, int interleave_granularity,
-		     enum cxl_decoder_type type, unsigned long flags)
+		     enum cxl_decoder_type type, unsigned long flags,
+		     int *target_map)
 {
 	struct cxl_decoder *cxld;
 	struct device *dev;
 	int rc;
 
-	cxld = cxl_decoder_alloc(port, nr_targets, base, len, interleave_ways,
-				 interleave_granularity, type, flags);
+	if (nr_targets > CXL_DECODER_MAX_INTERLEAVE)
+		return ERR_PTR(-EINVAL);
+
+	cxld = cxl_decoder_alloc(host, port, nr_targets, base, len,
+				 interleave_ways, interleave_granularity, type,
+				 flags, target_map);
 	if (IS_ERR(cxld))
 		return cxld;
 
@@ -550,6 +582,32 @@ devm_cxl_add_decoder(struct device *host, struct cxl_port *port, int nr_targets,
 }
 EXPORT_SYMBOL_GPL(devm_cxl_add_decoder);
 
+/*
+ * Per the CXL specification (8.2.5.12 CXL HDM Decoder Capability Structure)
+ * single ported host-bridges need not publish a decoder capability when a
+ * passthrough decode can be assumed, i.e. all transactions that the uport sees
+ * are claimed and passed to the single dport. Default the range a 0-base
+ * 0-length until the first CXL region is activated.
+ */
+struct cxl_decoder *devm_cxl_add_passthrough_decoder(struct device *host,
+						     struct cxl_port *port)
+{
+	struct cxl_dport *dport;
+	int target_map[1];
+
+	device_lock(&port->dev);
+	dport = list_first_entry_or_null(&port->dports, typeof(*dport), list);
+	device_unlock(&port->dev);
+
+	if (!dport)
+		return ERR_PTR(-ENXIO);
+
+	target_map[0] = dport->port_id;
+	return devm_cxl_add_decoder(host, port, 1, 0, 0, 1, PAGE_SIZE,
+				    CXL_DECODER_EXPANDER, 0, target_map);
+}
+EXPORT_SYMBOL_GPL(devm_cxl_add_passthrough_decoder);
+
 /**
  * __cxl_driver_register - register a driver for the cxl bus
  * @cxl_drv: cxl driver structure to attach

drivers/cxl/cxl.h

@@ -180,6 +180,12 @@ enum cxl_decoder_type {
        CXL_DECODER_EXPANDER = 3,
 };
 
+/*
+ * Current specification goes up to 8, double that seems a reasonable
+ * software max for the foreseeable future
+ */
+#define CXL_DECODER_MAX_INTERLEAVE 16
+
 /**
  * struct cxl_decoder - CXL address range decode configuration
  * @dev: this decoder's device
@@ -284,22 +290,11 @@ struct cxl_decoder *
 devm_cxl_add_decoder(struct device *host, struct cxl_port *port, int nr_targets,
 		     resource_size_t base, resource_size_t len,
 		     int interleave_ways, int interleave_granularity,
-		     enum cxl_decoder_type type, unsigned long flags);
-
-/*
- * Per the CXL specification (8.2.5.12 CXL HDM Decoder Capability Structure)
- * single ported host-bridges need not publish a decoder capability when a
- * passthrough decode can be assumed, i.e. all transactions that the uport sees
- * are claimed and passed to the single dport. Default the range a 0-base
- * 0-length until the first CXL region is activated.
- */
-static inline struct cxl_decoder *
-devm_cxl_add_passthrough_decoder(struct device *host, struct cxl_port *port)
-{
-	return devm_cxl_add_decoder(host, port, 1, 0, 0, 1, PAGE_SIZE,
-				    CXL_DECODER_EXPANDER, 0);
-}
+		     enum cxl_decoder_type type, unsigned long flags,
+		     int *target_map);
 
+struct cxl_decoder *devm_cxl_add_passthrough_decoder(struct device *host,
+						     struct cxl_port *port);
 extern struct bus_type cxl_bus_type;
 
 struct cxl_driver {