[PATCH v9 00/10] cxl: Delay HB port and switch dport probing until endpoint dev probe

[PATCH v9 00/10] cxl: Delay HB port and switch dport probing until endpoint dev probe

[Dave Jiang]

v9:
- Reworked the port enumeration iteration loop. (Robert)
  All please re-review "cxl: Defer dport allocation for switch ports"
- Created helper functions for dealing with switch and endpoint decoder enumeration.
  Main goal is to reduce cxl_test interface burden. (Robert)
  - Dropped cxl_test changes for decoder functions
- Dropped the cxl_test for region replay. It's not 100% ready and can be submitted later. (Alison)
- See specific commits for more detailed changes.

v8:
- A bit of changes from Dan and Robert's comments. Main change is moving the port MMIO
  register probing to after the first dport shows up. This resulted with decoder allocation
  happens after the register probe.
- See specific commits for more detailed changes.

v7:
- Remove -EEXIST to simplify error flow. (Ming)
- Set dport to NULL during declare. (Jonathan)

v6:
- Return -EEXIST when a dport already exists. (Jonathan)
- Fix checking wrong port for NULL. (Ming)
- Check host_bridge and call devm_cxl_add_dport_by_uport() directly vs add_port_attach_ep(). (Ming)
- Set dport to NULL during declaration. (Jonathan)

v5:
- Return dport instead of errno with dport pointer as output param. (Jonathan)
- Consolidate common code in cxl_test. (Jonathan)
- Rename cxl_port_get_total_dports() to cxl_port_update_total_dports(). (Jonathan)

v4:
- Push dport allocation to when they are discovered. (Robert)
- Drop linux id for dport with above changes.

v3:
- Main changes revolve around improving naming of hostbridge uport and dport (Gregory)
- See specific patches for detailed change log

This series attempts to delay the allocation of dports until when the endpoint device
(memdev) are being probed. At this point, the CXL link is established and all the
devices along the CXL link path up to the Root Port (RP) should be active.

And hopefully this help a bit with Robert's issue raised in the "Inactive
downstream port handling" series [1]. Testing would be appreicated. Thank you!

[1]: https://lore.kernel.org/linux-cxl/67c8a0cc23ec_24b64294f6@dwillia2-xfh.jf.intel.com.notmuch/

Dave Jiang (10):
  cxl: Add helper to detect top of CXL device topology
  cxl: Add helper to reap dport
  cxl: Add a cached copy of target_map to cxl_decoder
  cxl: Move port register setup to first dport appear
  cxl/test: Refactor decoder setup to reduce cxl_test burden
  cxl: Defer dport allocation for switch ports
  cxl/test: Add mock version of devm_cxl_add_dport_by_dev()
  cxl/test: Adjust the mock version of
    devm_cxl_switch_port_decoders_setup()
  cxl/test: Setup target_map for cxl_test decoder initialization
  cxl: Change sslbis handler to only handle single dport

 drivers/cxl/acpi.c                   |   7 +-
 drivers/cxl/core/cdat.c              |  25 +--
 drivers/cxl/core/core.h              |   5 +
 drivers/cxl/core/hdm.c               | 105 ++++++---
 drivers/cxl/core/pci.c               |  89 ++++++++
 drivers/cxl/core/port.c              | 317 ++++++++++++++++++++-------
 drivers/cxl/core/region.c            |   4 +-
 drivers/cxl/cxl.h                    |  44 +++-
 drivers/cxl/cxlpci.h                 |   2 -
 drivers/cxl/port.c                   |  47 +---
 tools/testing/cxl/Kbuild             |   7 +-
 tools/testing/cxl/cxl_core_exports.c |  22 ++
 tools/testing/cxl/exports.h          |  13 ++
 tools/testing/cxl/test/cxl.c         | 115 ++++++++--
 tools/testing/cxl/test/mock.c        |  96 +++-----
 tools/testing/cxl/test/mock.h        |   9 +-
 16 files changed, 642 insertions(+), 265 deletions(-)
 create mode 100644 tools/testing/cxl/exports.h


base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
-- 
2.50.1

[PATCH v9 01/10] cxl: Add helper to detect top of CXL device topology

[Dave Jiang]

Add a helper to replace the open code detection of CXL device hierarchy
root, or the host bridge. The helper will be used for delayed downstream
port (dport) creation.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Robert Richter <rrichter@amd.com>
Tested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/port.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 29197376b18e..855623cebd7d 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -33,6 +33,15 @@
 static DEFINE_IDA(cxl_port_ida);
 static DEFINE_XARRAY(cxl_root_buses);
 
+/*
+ * The terminal device in PCI is NULL and @platform_bus
+ * for platform devices (for cxl_test)
+ */
+static bool is_cxl_host_bridge(struct device *dev)
+{
+	return (!dev || dev == &platform_bus);
+}
+
 int cxl_num_decoders_committed(struct cxl_port *port)
 {
 	lockdep_assert_held(&cxl_rwsem.region);
@@ -1541,7 +1550,7 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 	resource_size_t component_reg_phys;
 	int rc;
 
-	if (!dparent) {
+	if (is_cxl_host_bridge(dparent)) {
 		/*
 		 * The iteration reached the topology root without finding the
 		 * CXL-root 'cxl_port' on a previous iteration, fail for now to
@@ -1629,11 +1638,7 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 		struct device *uport_dev;
 		struct cxl_dport *dport;
 
-		/*
-		 * The terminal "grandparent" in PCI is NULL and @platform_bus
-		 * for platform devices
-		 */
-		if (!dport_dev || dport_dev == &platform_bus)
+		if (is_cxl_host_bridge(dport_dev))
 			return 0;
 
 		uport_dev = dport_dev->parent;
-- 
2.50.1

[PATCH v9 02/10] cxl: Add helper to reap dport

[Dave Jiang]

Refactor the code in reap_dports() out to provide a helper function that
reaps a single dport. This will be used later in the cleanup path for
allocating a dport. Renaming to del_port() and del_dports() to mirror
devm_cxl_add_dport().

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/port.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 855623cebd7d..88f19abf3327 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1432,7 +1432,7 @@ EXPORT_SYMBOL_NS_GPL(cxl_endpoint_autoremove, "CXL");
  * through ->remove(). This "bottom-up" removal selectively removes individual
  * child ports manually. This depends on devm_cxl_add_port() to not change is
  * devm action registration order, and for dports to have already been
- * destroyed by reap_dports().
+ * destroyed by del_dports().
  */
 static void delete_switch_port(struct cxl_port *port)
 {
@@ -1441,18 +1441,24 @@ static void delete_switch_port(struct cxl_port *port)
 	devm_release_action(port->dev.parent, unregister_port, port);
 }
 
-static void reap_dports(struct cxl_port *port)
+static void del_dport(struct cxl_dport *dport)
+{
+	struct cxl_port *port = dport->port;
+
+	devm_release_action(&port->dev, cxl_dport_unlink, dport);
+	devm_release_action(&port->dev, cxl_dport_remove, dport);
+	devm_kfree(&port->dev, dport);
+}
+
+static void del_dports(struct cxl_port *port)
 {
 	struct cxl_dport *dport;
 	unsigned long index;
 
 	device_lock_assert(&port->dev);
 
-	xa_for_each(&port->dports, index, dport) {
-		devm_release_action(&port->dev, cxl_dport_unlink, dport);
-		devm_release_action(&port->dev, cxl_dport_remove, dport);
-		devm_kfree(&port->dev, dport);
-	}
+	xa_for_each(&port->dports, index, dport)
+		del_dport(dport);
 }
 
 struct detach_ctx {
@@ -1510,7 +1516,7 @@ static void cxl_detach_ep(void *data)
 			 */
 			died = true;
 			port->dead = true;
-			reap_dports(port);
+			del_dports(port);
 		}
 		device_unlock(&port->dev);
 
-- 
2.50.1

Re: [PATCH v9 02/10] cxl: Add helper to reap dport

[Robert Richter]

On 29.08.25 11:09:20, Dave Jiang wrote:
> Refactor the code in reap_dports() out to provide a helper function that
> reaps a single dport. This will be used later in the cleanup path for
> allocating a dport. Renaming to del_port() and del_dports() to mirror
> devm_cxl_add_dport().

In case there is another version, reword the subject too.

-Robert

> 
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Reviewed-by: Li Ming <ming.li@zohomail.com>
> Reviewed-by: Alison Schofield <alison.schofield@intel.com>
> Reviewed-by: Dan Williams <dan.j.williams@intel.com>
> Tested-by: Robert Richter <rrichter@amd.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>  drivers/cxl/core/port.c | 22 ++++++++++++++--------
>  1 file changed, 14 insertions(+), 8 deletions(-)

[PATCH v9 03/10] cxl: Add a cached copy of target_map to cxl_decoder

[Dave Jiang]

Add a cached copy of the hardware port-id list that is available at init
before all @dport objects have been instantiated. Change is in preparation
of delayed dport instantiation.

Reviewed-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Tested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
v9:
- Add region target_map update for manual assemble
---
 drivers/cxl/acpi.c           |  7 +++----
 drivers/cxl/core/hdm.c       | 20 ++++++++------------
 drivers/cxl/core/port.c      | 22 +++++++---------------
 drivers/cxl/core/region.c    |  4 +++-
 drivers/cxl/cxl.h            |  8 ++++++--
 tools/testing/cxl/test/cxl.c |  8 ++++----
 6 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index 712624cba2b6..bb0871d92620 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -398,7 +398,6 @@ DEFINE_FREE(del_cxl_resource, struct resource *, if (_T) del_cxl_resource(_T))
 static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 			     struct cxl_cfmws_context *ctx)
 {
-	int target_map[CXL_DECODER_MAX_INTERLEAVE];
 	struct cxl_port *root_port = ctx->root_port;
 	struct cxl_cxims_context cxims_ctx;
 	struct device *dev = ctx->dev;
@@ -416,8 +415,6 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	rc = eig_to_granularity(cfmws->granularity, &ig);
 	if (rc)
 		return rc;
-	for (i = 0; i < ways; i++)
-		target_map[i] = cfmws->interleave_targets[i];
 
 	struct resource *res __free(del_cxl_resource) = alloc_cxl_resource(
 		cfmws->base_hpa, cfmws->window_size, ctx->id++);
@@ -443,6 +440,8 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 		.end = cfmws->base_hpa + cfmws->window_size - 1,
 	};
 	cxld->interleave_ways = ways;
+	for (i = 0; i < ways; i++)
+		cxld->target_map[i] = cfmws->interleave_targets[i];
 	/*
 	 * Minimize the x1 granularity to advertise support for any
 	 * valid region granularity
@@ -475,7 +474,7 @@ static int __cxl_parse_cfmws(struct acpi_cedt_cfmws *cfmws,
 	if (cfmws->interleave_arithmetic == ACPI_CEDT_CFMWS_ARITHMETIC_XOR)
 		cxlrd->hpa_to_spa = cxl_xor_hpa_to_spa;
 
-	rc = cxl_decoder_add(cxld, target_map);
+	rc = cxl_decoder_add(cxld);
 	if (rc)
 		return rc;
 
diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index e9e1d555cec6..cee68bbc7ff6 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -21,12 +21,11 @@ struct cxl_rwsem cxl_rwsem = {
 	.dpa = __RWSEM_INITIALIZER(cxl_rwsem.dpa),
 };
 
-static int add_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
-			   int *target_map)
+static int add_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld)
 {
 	int rc;
 
-	rc = cxl_decoder_add_locked(cxld, target_map);
+	rc = cxl_decoder_add_locked(cxld);
 	if (rc) {
 		put_device(&cxld->dev);
 		dev_err(&port->dev, "Failed to add decoder\n");
@@ -54,7 +53,6 @@ int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 {
 	struct cxl_switch_decoder *cxlsd;
 	struct cxl_dport *dport = NULL;
-	int single_port_map[1];
 	unsigned long index;
 	struct cxl_hdm *cxlhdm = dev_get_drvdata(&port->dev);
 
@@ -73,9 +71,9 @@ int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 
 	xa_for_each(&port->dports, index, dport)
 		break;
-	single_port_map[0] = dport->port_id;
+	cxlsd->cxld.target_map[0] = dport->port_id;
 
-	return add_hdm_decoder(port, &cxlsd->cxld, single_port_map);
+	return add_hdm_decoder(port, &cxlsd->cxld);
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_add_passthrough_decoder, "CXL");
 
@@ -984,7 +982,7 @@ static int cxl_setup_hdm_decoder_from_dvsec(
 }
 
 static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
-			    int *target_map, void __iomem *hdm, int which,
+			    void __iomem *hdm, int which,
 			    u64 *dpa_base, struct cxl_endpoint_dvsec_info *info)
 {
 	struct cxl_endpoint_decoder *cxled = NULL;
@@ -1103,7 +1101,7 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
 		hi = readl(hdm + CXL_HDM_DECODER0_TL_HIGH(which));
 		target_list.value = (hi << 32) + lo;
 		for (i = 0; i < cxld->interleave_ways; i++)
-			target_map[i] = target_list.target_id[i];
+			cxld->target_map[i] = target_list.target_id[i];
 
 		return 0;
 	}
@@ -1179,7 +1177,6 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 	cxl_settle_decoders(cxlhdm);
 
 	for (i = 0; i < cxlhdm->decoder_count; i++) {
-		int target_map[CXL_DECODER_MAX_INTERLEAVE] = { 0 };
 		int rc, target_count = cxlhdm->target_count;
 		struct cxl_decoder *cxld;
 
@@ -1207,8 +1204,7 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 			cxld = &cxlsd->cxld;
 		}
 
-		rc = init_hdm_decoder(port, cxld, target_map, hdm, i,
-				      &dpa_base, info);
+		rc = init_hdm_decoder(port, cxld, hdm, i, &dpa_base, info);
 		if (rc) {
 			dev_warn(&port->dev,
 				 "Failed to initialize decoder%d.%d\n",
@@ -1216,7 +1212,7 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 			put_device(&cxld->dev);
 			return rc;
 		}
-		rc = add_hdm_decoder(port, cxld, target_map);
+		rc = add_hdm_decoder(port, cxld);
 		if (rc) {
 			dev_warn(&port->dev,
 				 "Failed to add decoder%d.%d\n", port->id, i);
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 88f19abf3327..7344048f678e 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1715,13 +1715,11 @@ struct cxl_port *cxl_mem_find_port(struct cxl_memdev *cxlmd,
 EXPORT_SYMBOL_NS_GPL(cxl_mem_find_port, "CXL");
 
 static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
-				    struct cxl_port *port, int *target_map)
+				    struct cxl_port *port)
 {
+	struct cxl_decoder *cxld = &cxlsd->cxld;
 	int i;
 
-	if (!target_map)
-		return 0;
-
 	device_lock_assert(&port->dev);
 
 	if (xa_empty(&port->dports))
@@ -1729,7 +1727,7 @@ static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
 
 	guard(rwsem_write)(&cxl_rwsem.region);
 	for (i = 0; i < cxlsd->cxld.interleave_ways; i++) {
-		struct cxl_dport *dport = find_dport(port, target_map[i]);
+		struct cxl_dport *dport = find_dport(port, cxld->target_map[i]);
 
 		if (!dport)
 			return -ENXIO;
@@ -1921,9 +1919,6 @@ EXPORT_SYMBOL_NS_GPL(cxl_endpoint_decoder_alloc, "CXL");
 /**
  * cxl_decoder_add_locked - Add a decoder with targets
  * @cxld: The cxl decoder allocated by cxl_<type>_decoder_alloc()
- * @target_map: A list of downstream ports that this decoder can direct memory
- *              traffic to. These numbers should correspond with the port number
- *              in the PCIe Link Capabilities structure.
  *
  * Certain types of decoders may not have any targets. The main example of this
  * is an endpoint device. A more awkward example is a hostbridge whose root
@@ -1937,7 +1932,7 @@ EXPORT_SYMBOL_NS_GPL(cxl_endpoint_decoder_alloc, "CXL");
  * Return: Negative error code if the decoder wasn't properly configured; else
  *	   returns 0.
  */
-int cxl_decoder_add_locked(struct cxl_decoder *cxld, int *target_map)
+int cxl_decoder_add_locked(struct cxl_decoder *cxld)
 {
 	struct cxl_port *port;
 	struct device *dev;
@@ -1958,7 +1953,7 @@ int cxl_decoder_add_locked(struct cxl_decoder *cxld, int *target_map)
 	if (!is_endpoint_decoder(dev)) {
 		struct cxl_switch_decoder *cxlsd = to_cxl_switch_decoder(dev);
 
-		rc = decoder_populate_targets(cxlsd, port, target_map);
+		rc = decoder_populate_targets(cxlsd, port);
 		if (rc && (cxld->flags & CXL_DECODER_F_ENABLE)) {
 			dev_err(&port->dev,
 				"Failed to populate active decoder targets\n");
@@ -1977,9 +1972,6 @@ EXPORT_SYMBOL_NS_GPL(cxl_decoder_add_locked, "CXL");
 /**
  * cxl_decoder_add - Add a decoder with targets
  * @cxld: The cxl decoder allocated by cxl_<type>_decoder_alloc()
- * @target_map: A list of downstream ports that this decoder can direct memory
- *              traffic to. These numbers should correspond with the port number
- *              in the PCIe Link Capabilities structure.
  *
  * This is the unlocked variant of cxl_decoder_add_locked().
  * See cxl_decoder_add_locked().
@@ -1987,7 +1979,7 @@ EXPORT_SYMBOL_NS_GPL(cxl_decoder_add_locked, "CXL");
  * Context: Process context. Takes and releases the device lock of the port that
  *	    owns the @cxld.
  */
-int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map)
+int cxl_decoder_add(struct cxl_decoder *cxld)
 {
 	struct cxl_port *port;
 
@@ -2000,7 +1992,7 @@ int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map)
 	port = to_cxl_port(cxld->dev.parent);
 
 	guard(device)(&port->dev);
-	return cxl_decoder_add_locked(cxld, target_map);
+	return cxl_decoder_add_locked(cxld);
 }
 EXPORT_SYMBOL_NS_GPL(cxl_decoder_add, "CXL");
 
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 71cc42d05248..bba62867df90 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -1510,8 +1510,10 @@ static int cxl_port_setup_targets(struct cxl_port *port,
 				cxl_rr->nr_targets_set);
 			return -ENXIO;
 		}
-	} else
+	} else {
 		cxlsd->target[cxl_rr->nr_targets_set] = ep->dport;
+		cxlsd->cxld.target_map[cxl_rr->nr_targets_set] = ep->dport->port_id;
+	}
 	inc = 1;
 out_target_set:
 	cxl_rr->nr_targets_set += inc;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 847e37be42c4..4b858f3d44c6 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -357,6 +357,9 @@ 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
+ * @target_map: cached copy of hardware port-id list, available at init
+ *              before all @dport objects have been instantiated. While
+ *              dport id is 8bit, CFMWS interleave targets are 32bits.
  * @commit: device/decoder-type specific callback to commit settings to hw
  * @reset: device/decoder-type specific callback to reset hw settings
 */
@@ -369,6 +372,7 @@ struct cxl_decoder {
 	enum cxl_decoder_type target_type;
 	struct cxl_region *region;
 	unsigned long flags;
+	u32 target_map[CXL_DECODER_MAX_INTERLEAVE];
 	int (*commit)(struct cxl_decoder *cxld);
 	void (*reset)(struct cxl_decoder *cxld);
 };
@@ -781,9 +785,9 @@ struct cxl_root_decoder *cxl_root_decoder_alloc(struct cxl_port *port,
 						unsigned int nr_targets);
 struct cxl_switch_decoder *cxl_switch_decoder_alloc(struct cxl_port *port,
 						    unsigned int nr_targets);
-int cxl_decoder_add(struct cxl_decoder *cxld, int *target_map);
+int cxl_decoder_add(struct cxl_decoder *cxld);
 struct cxl_endpoint_decoder *cxl_endpoint_decoder_alloc(struct cxl_port *port);
-int cxl_decoder_add_locked(struct cxl_decoder *cxld, int *target_map);
+int cxl_decoder_add_locked(struct cxl_decoder *cxld);
 int cxl_decoder_autoremove(struct device *host, struct cxl_decoder *cxld);
 static inline int cxl_root_decoder_autoremove(struct device *host,
 					      struct cxl_root_decoder *cxlrd)
diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
index 6a25cca5636f..8faf4143d04e 100644
--- a/tools/testing/cxl/test/cxl.c
+++ b/tools/testing/cxl/test/cxl.c
@@ -651,7 +651,7 @@ static int mock_cxl_add_passthrough_decoder(struct cxl_port *port)
 
 
 struct target_map_ctx {
-	int *target_map;
+	u32 *target_map;
 	int index;
 	int target_count;
 };
@@ -863,9 +863,7 @@ static int mock_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 		target_count = NR_CXL_SWITCH_PORTS;
 
 	for (i = 0; i < NR_CXL_PORT_DECODERS; i++) {
-		int target_map[CXL_DECODER_MAX_INTERLEAVE] = { 0 };
 		struct target_map_ctx ctx = {
-			.target_map = target_map,
 			.target_count = target_count,
 		};
 		struct cxl_decoder *cxld;
@@ -894,6 +892,8 @@ static int mock_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 			cxld = &cxled->cxld;
 		}
 
+		ctx.target_map = cxld->target_map;
+
 		mock_init_hdm_decoder(cxld);
 
 		if (target_count) {
@@ -905,7 +905,7 @@ static int mock_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 			}
 		}
 
-		rc = cxl_decoder_add_locked(cxld, target_map);
+		rc = cxl_decoder_add_locked(cxld);
 		if (rc) {
 			put_device(&cxld->dev);
 			dev_err(&port->dev, "Failed to add decoder\n");
-- 
2.50.1

Re: [PATCH v9 03/10] cxl: Add a cached copy of target_map to cxl_decoder

[Alison Schofield]

On Fri, Aug 29, 2025 at 11:09:21AM -0700, Dave Jiang wrote:
> Add a cached copy of the hardware port-id list that is available at init
> before all @dport objects have been instantiated. Change is in preparation
> of delayed dport instantiation.

Reviewed-by: Alison Schofield <alison.schofield@intel.com>

Re: [PATCH v9 03/10] cxl: Add a cached copy of target_map to cxl_decoder

[Robert Richter]

On 29.08.25 11:09:21, Dave Jiang wrote:
> Add a cached copy of the hardware port-id list that is available at init
> before all @dport objects have been instantiated. Change is in preparation
> of delayed dport instantiation.
> 
> Reviewed-by: Robert Richter <rrichter@amd.com>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Tested-by: Robert Richter <rrichter@amd.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
> v9:
> - Add region target_map update for manual assemble
> ---
>  drivers/cxl/acpi.c           |  7 +++----
>  drivers/cxl/core/hdm.c       | 20 ++++++++------------
>  drivers/cxl/core/port.c      | 22 +++++++---------------
>  drivers/cxl/core/region.c    |  4 +++-
>  drivers/cxl/cxl.h            |  8 ++++++--
>  tools/testing/cxl/test/cxl.c |  8 ++++----
>  6 files changed, 31 insertions(+), 38 deletions(-)

> @@ -984,7 +982,7 @@ static int cxl_setup_hdm_decoder_from_dvsec(
>  }
>  
>  static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
> -			    int *target_map, void __iomem *hdm, int which,
> +			    void __iomem *hdm, int which,
>  			    u64 *dpa_base, struct cxl_endpoint_dvsec_info *info)

Stumbled over that again in v9: Use 80 char limit here.

Anyway, not a show-stopper.

-Robert

[PATCH v9 04/10] cxl: Move port register setup to first dport appear

[Dave Jiang]

This patch moves the port register setup to when the first dport appears
via the memdev probe path. At this point, the CXL link should be
established and the register access is expected to succeed. This change
addresses an error message observed when PCIe hotplug is enabled on
an Intel platform. The error messages "cxl portN: Couldn't locate the
CXL.cache and CXL.mem capability array header" is observed for the
hostbridge during cxl_acpi driver probe. If the cxl_acpi module
probe is running before the CXL link between the endpoint device and the
RP is established, then the platform may not have exposed DVSEC ID 3
and/or DVSEC ID 7 blocks which will trigger the error message. This
behavior is defined by the spec and not a hardware quirk.

This change also needs the dport enumeration to be moved to the memdev
probe path in order to address the issue. This change is just part of
the code refactoring and is not a wholly contained fix itself.

Suggested-by: Dan Williamsn <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Tested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/port.c | 16 +++++++++++++---
 drivers/cxl/cxl.h       |  2 ++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index 7344048f678e..f379e4c5121d 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -867,9 +867,7 @@ static int cxl_port_add(struct cxl_port *port,
 		if (rc)
 			return rc;
 
-		rc = cxl_port_setup_regs(port, component_reg_phys);
-		if (rc)
-			return rc;
+		port->component_reg_phys = component_reg_phys;
 	} else {
 		rc = dev_set_name(dev, "root%d", port->id);
 		if (rc)
@@ -1200,6 +1198,18 @@ __devm_cxl_add_dport(struct cxl_port *port, struct device *dport_dev,
 
 	cxl_debugfs_create_dport_dir(dport);
 
+	/*
+	 * Setup port register if this is the first dport showed up. Having
+	 * a dport also means that there is at least 1 active link.
+	 */
+	if (port->nr_dports == 1 &&
+	    port->component_reg_phys != CXL_RESOURCE_NONE) {
+		rc = cxl_port_setup_regs(port, port->component_reg_phys);
+		if (rc)
+			return ERR_PTR(rc);
+		port->component_reg_phys = CXL_RESOURCE_NONE;
+	}
+
 	return dport;
 }
 
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 4b858f3d44c6..87a905db5ffb 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -599,6 +599,7 @@ struct cxl_dax_region {
  * @cdat: Cached CDAT data
  * @cdat_available: Should a CDAT attribute be available in sysfs
  * @pci_latency: Upstream latency in picoseconds
+ * @component_reg_phys: Physical address of component register
  */
 struct cxl_port {
 	struct device dev;
@@ -622,6 +623,7 @@ struct cxl_port {
 	} cdat;
 	bool cdat_available;
 	long pci_latency;
+	resource_size_t component_reg_phys;
 };
 
 /**
-- 
2.50.1

Re: [PATCH v9 04/10] cxl: Move port register setup to first dport appear

[Alison Schofield]

On Fri, Aug 29, 2025 at 11:09:22AM -0700, Dave Jiang wrote:
> This patch moves the port register setup to when the first dport appears
> via the memdev probe path. At this point, the CXL link should be
> established and the register access is expected to succeed. This change
> addresses an error message observed when PCIe hotplug is enabled on
> an Intel platform. The error messages "cxl portN: Couldn't locate the
> CXL.cache and CXL.mem capability array header" is observed for the
> hostbridge during cxl_acpi driver probe. If the cxl_acpi module
> probe is running before the CXL link between the endpoint device and the
> RP is established, then the platform may not have exposed DVSEC ID 3
> and/or DVSEC ID 7 blocks which will trigger the error message. This
> behavior is defined by the spec and not a hardware quirk.
> 
> This change also needs the dport enumeration to be moved to the memdev
> probe path in order to address the issue. This change is just part of
> the code refactoring and is not a wholly contained fix itself.

Reviewed-by: Alison Schofield <alison.schofield@intel.com>

[PATCH v9 05/10] cxl/test: Refactor decoder setup to reduce cxl_test burden

[Dave Jiang]

Group the decoder setup code in switch and endpoint port probe into a
single function for each to reduce the number of functions to be mocked
in cxl_test. Introduce devm_cxl_switch_port_decoders_setup() and
devm_cxl_endpoint_decoders_setup(). These two functions will be mocked
instead with some functions optimized out since the mock version does
not do anything. Remove devm_cxl_setup_hdm(),
devm_cxl_add_passthrough_decoder(), and devm_cxl_enumerate_decoders() in
cxl_test mock code. In turn, mock_cxl_add_passthrough_decoder() can be
removed since cxl_test does not setup passthrough decoders.
__wrap_cxl_hdm_decode_init() and __wrap_cxl_dvsec_rr_decode() can be
removed as well since they only return 0 when called.

Suggested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/core.h       |  5 +++
 drivers/cxl/core/hdm.c        | 81 +++++++++++++++++++++++++++++++----
 drivers/cxl/core/pci.c        | 42 ++++++++++++++++++
 drivers/cxl/cxl.h             | 10 ++---
 drivers/cxl/cxlpci.h          |  2 -
 drivers/cxl/port.c            | 38 +---------------
 tools/testing/cxl/Kbuild      |  7 +--
 tools/testing/cxl/test/cxl.c  | 42 +++++++++++++-----
 tools/testing/cxl/test/mock.c | 69 ++++-------------------------
 tools/testing/cxl/test/mock.h |  7 +--
 10 files changed, 170 insertions(+), 133 deletions(-)

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index 2669f251d677..b07490aa93c7 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -147,6 +147,11 @@ int cxl_ras_init(void);
 void cxl_ras_exit(void);
 int cxl_gpf_port_setup(struct cxl_dport *dport);
 
+struct cxl_hdm;
+int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
+			struct cxl_endpoint_dvsec_info *info);
+int cxl_port_get_possible_dports(struct cxl_port *port);
+
 #ifdef CONFIG_CXL_FEATURES
 struct cxl_feat_entry *
 cxl_feature_info(struct cxl_features_state *cxlfs, const uuid_t *uuid);
diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index cee68bbc7ff6..78bfe4f55b96 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -49,7 +49,7 @@ static int add_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld)
  * are claimed and passed to the single dport. Disable the range until the first
  * CXL region is enumerated / activated.
  */
-int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
+static int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 {
 	struct cxl_switch_decoder *cxlsd;
 	struct cxl_dport *dport = NULL;
@@ -75,7 +75,6 @@ int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 
 	return add_hdm_decoder(port, &cxlsd->cxld);
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_add_passthrough_decoder, "CXL");
 
 static void parse_hdm_decoder_caps(struct cxl_hdm *cxlhdm)
 {
@@ -145,8 +144,8 @@ static bool should_emulate_decoders(struct cxl_endpoint_dvsec_info *info)
  * @port: cxl_port to map
  * @info: cached DVSEC range register info
  */
-struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
-				   struct cxl_endpoint_dvsec_info *info)
+static struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
+					  struct cxl_endpoint_dvsec_info *info)
 {
 	struct cxl_register_map *reg_map = &port->reg_map;
 	struct device *dev = &port->dev;
@@ -201,7 +200,6 @@ struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
 
 	return cxlhdm;
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_setup_hdm, "CXL");
 
 static void __cxl_dpa_debug(struct seq_file *file, struct resource *r, int depth)
 {
@@ -1166,8 +1164,8 @@ static void cxl_settle_decoders(struct cxl_hdm *cxlhdm)
  * @cxlhdm: Structure to populate with HDM capabilities
  * @info: cached DVSEC range register info
  */
-int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
-				struct cxl_endpoint_dvsec_info *info)
+static int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
+				       struct cxl_endpoint_dvsec_info *info)
 {
 	void __iomem *hdm = cxlhdm->regs.hdm_decoder;
 	struct cxl_port *port = cxlhdm->port;
@@ -1222,4 +1220,71 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 
 	return 0;
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_enumerate_decoders, "CXL");
+
+/**
+ * devm_cxl_switch_port_decoders_setup - allocate and setup switch decoders
+ * @port: CXL port context
+ *
+ * Return 0 or -errno on error
+ */
+int devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
+{
+	struct cxl_hdm *cxlhdm;
+
+	if (is_cxl_root(port) || is_cxl_endpoint(port))
+		return -EOPNOTSUPP;
+
+	cxlhdm = devm_cxl_setup_hdm(port, NULL);
+	if (!IS_ERR(cxlhdm))
+		return devm_cxl_enumerate_decoders(cxlhdm, NULL);
+
+	if (PTR_ERR(cxlhdm) != -ENODEV) {
+		dev_err(&port->dev, "Failed to map HDM decoder capability\n");
+		return PTR_ERR(cxlhdm);
+	}
+
+	if (cxl_port_get_possible_dports(port) == 1) {
+		dev_dbg(&port->dev, "Fallback to passthrough decoder\n");
+		return devm_cxl_add_passthrough_decoder(port);
+	}
+
+	dev_err(&port->dev, "HDM decoder capability not found\n");
+	return -ENXIO;
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_switch_port_decoders_setup, "CXL");
+
+/**
+ * devm_cxl_endpoint_decoders_setup - allocate and setup endpoint decoders
+ * @port: CXL port context
+ *
+ * Return 0 or -errno on error
+ */
+int devm_cxl_endpoint_decoders_setup(struct cxl_port *port)
+{
+	struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
+	struct cxl_endpoint_dvsec_info info = { .port = port };
+	struct cxl_dev_state *cxlds = cxlmd->cxlds;
+	struct cxl_hdm *cxlhdm;
+	int rc;
+
+	if (!is_cxl_endpoint(port))
+		return -EOPNOTSUPP;
+
+	rc = cxl_dvsec_rr_decode(cxlds, &info);
+	if (rc < 0)
+		return rc;
+
+	cxlhdm = devm_cxl_setup_hdm(port, &info);
+	if (IS_ERR(cxlhdm)) {
+		if (PTR_ERR(cxlhdm) == -ENODEV)
+			dev_err(&port->dev, "HDM decoder registers not found\n");
+		return PTR_ERR(cxlhdm);
+	}
+
+	rc = cxl_hdm_decode_init(cxlds, cxlhdm, &info);
+	if (rc)
+		return rc;
+
+	return devm_cxl_enumerate_decoders(cxlhdm, &info);
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_endpoint_decoders_setup, "CXL");
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index b50551601c2e..fa02366d35f2 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -1169,3 +1169,45 @@ int cxl_gpf_port_setup(struct cxl_dport *dport)
 
 	return 0;
 }
+
+static int count_dports(struct pci_dev *pdev, void *data)
+{
+	struct cxl_walk_context *ctx = data;
+	int type = pci_pcie_type(pdev);
+
+	if (pdev->bus != ctx->bus)
+		return 0;
+	if (!pci_is_pcie(pdev))
+		return 0;
+	if (type != ctx->type)
+		return 0;
+
+	ctx->count++;
+	return 0;
+}
+
+int cxl_port_get_possible_dports(struct cxl_port *port)
+{
+	struct pci_bus *bus = cxl_port_to_pci_bus(port);
+	struct cxl_walk_context ctx;
+	int type;
+
+	if (!bus) {
+		dev_err(&port->dev, "No PCI bus found for port %s\n",
+			dev_name(&port->dev));
+		return -ENXIO;
+	}
+
+	if (pci_is_root_bus(bus))
+		type = PCI_EXP_TYPE_ROOT_PORT;
+	else
+		type = PCI_EXP_TYPE_DOWNSTREAM;
+
+	ctx = (struct cxl_walk_context) {
+		.bus = bus,
+		.type = type,
+	};
+	pci_walk_bus(bus, count_dports, &ctx);
+
+	return ctx.count;
+}
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 87a905db5ffb..2139b0935500 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -812,12 +812,10 @@ struct cxl_endpoint_dvsec_info {
 	struct range dvsec_range[2];
 };
 
-struct cxl_hdm;
-struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
-				   struct cxl_endpoint_dvsec_info *info);
-int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
-				struct cxl_endpoint_dvsec_info *info);
-int devm_cxl_add_passthrough_decoder(struct cxl_port *port);
+struct cxl_port;
+int devm_cxl_switch_port_decoders_setup(struct cxl_port *port);
+int devm_cxl_endpoint_decoders_setup(struct cxl_port *port);
+
 struct cxl_dev_state;
 int cxl_dvsec_rr_decode(struct cxl_dev_state *cxlds,
 			struct cxl_endpoint_dvsec_info *info);
diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
index 54e219b0049e..7ae621e618e7 100644
--- a/drivers/cxl/cxlpci.h
+++ b/drivers/cxl/cxlpci.h
@@ -129,8 +129,6 @@ static inline bool cxl_pci_flit_256(struct pci_dev *pdev)
 
 int devm_cxl_port_enumerate_dports(struct cxl_port *port);
 struct cxl_dev_state;
-int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
-			struct cxl_endpoint_dvsec_info *info);
 void read_cdat_data(struct cxl_port *port);
 void cxl_cor_error_detected(struct pci_dev *pdev);
 pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
index cf32dc50b7a6..d8cae2b5bac6 100644
--- a/drivers/cxl/port.c
+++ b/drivers/cxl/port.c
@@ -59,7 +59,6 @@ static int discover_region(struct device *dev, void *unused)
 
 static int cxl_switch_port_probe(struct cxl_port *port)
 {
-	struct cxl_hdm *cxlhdm;
 	int rc;
 
 	/* Cache the data early to ensure is_visible() works */
@@ -71,43 +70,14 @@ static int cxl_switch_port_probe(struct cxl_port *port)
 
 	cxl_switch_parse_cdat(port);
 
-	cxlhdm = devm_cxl_setup_hdm(port, NULL);
-	if (!IS_ERR(cxlhdm))
-		return devm_cxl_enumerate_decoders(cxlhdm, NULL);
-
-	if (PTR_ERR(cxlhdm) != -ENODEV) {
-		dev_err(&port->dev, "Failed to map HDM decoder capability\n");
-		return PTR_ERR(cxlhdm);
-	}
-
-	if (rc == 1) {
-		dev_dbg(&port->dev, "Fallback to passthrough decoder\n");
-		return devm_cxl_add_passthrough_decoder(port);
-	}
-
-	dev_err(&port->dev, "HDM decoder capability not found\n");
-	return -ENXIO;
+	return devm_cxl_switch_port_decoders_setup(port);
 }
 
 static int cxl_endpoint_port_probe(struct cxl_port *port)
 {
-	struct cxl_endpoint_dvsec_info info = { .port = port };
 	struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
-	struct cxl_dev_state *cxlds = cxlmd->cxlds;
-	struct cxl_hdm *cxlhdm;
 	int rc;
 
-	rc = cxl_dvsec_rr_decode(cxlds, &info);
-	if (rc < 0)
-		return rc;
-
-	cxlhdm = devm_cxl_setup_hdm(port, &info);
-	if (IS_ERR(cxlhdm)) {
-		if (PTR_ERR(cxlhdm) == -ENODEV)
-			dev_err(&port->dev, "HDM decoder registers not found\n");
-		return PTR_ERR(cxlhdm);
-	}
-
 	/* Cache the data early to ensure is_visible() works */
 	read_cdat_data(port);
 	cxl_endpoint_parse_cdat(port);
@@ -117,11 +87,7 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
 	if (rc)
 		return rc;
 
-	rc = cxl_hdm_decode_init(cxlds, cxlhdm, &info);
-	if (rc)
-		return rc;
-
-	rc = devm_cxl_enumerate_decoders(cxlhdm, &info);
+	rc = devm_cxl_endpoint_decoders_setup(port);
 	if (rc)
 		return rc;
 
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index d07f14cb7aa4..51b8ab289eae 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -5,16 +5,13 @@ ldflags-y += --wrap=acpi_evaluate_integer
 ldflags-y += --wrap=acpi_pci_find_root
 ldflags-y += --wrap=nvdimm_bus_register
 ldflags-y += --wrap=devm_cxl_port_enumerate_dports
-ldflags-y += --wrap=devm_cxl_setup_hdm
-ldflags-y += --wrap=devm_cxl_add_passthrough_decoder
-ldflags-y += --wrap=devm_cxl_enumerate_decoders
 ldflags-y += --wrap=cxl_await_media_ready
-ldflags-y += --wrap=cxl_hdm_decode_init
-ldflags-y += --wrap=cxl_dvsec_rr_decode
 ldflags-y += --wrap=devm_cxl_add_rch_dport
 ldflags-y += --wrap=cxl_rcd_component_reg_phys
 ldflags-y += --wrap=cxl_endpoint_parse_cdat
 ldflags-y += --wrap=cxl_dport_init_ras_reporting
+ldflags-y += --wrap=devm_cxl_switch_port_decoders_setup
+ldflags-y += --wrap=devm_cxl_endpoint_decoders_setup
 
 DRIVERS := ../../../drivers
 CXL_SRC := $(DRIVERS)/cxl
diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
index 8faf4143d04e..8b5c559a4a8c 100644
--- a/tools/testing/cxl/test/cxl.c
+++ b/tools/testing/cxl/test/cxl.c
@@ -643,13 +643,6 @@ static struct cxl_hdm *mock_cxl_setup_hdm(struct cxl_port *port,
 	return cxlhdm;
 }
 
-static int mock_cxl_add_passthrough_decoder(struct cxl_port *port)
-{
-	dev_err(&port->dev, "unexpected passthrough decoder for cxl_test\n");
-	return -EOPNOTSUPP;
-}
-
-
 struct target_map_ctx {
 	u32 *target_map;
 	int index;
@@ -921,6 +914,36 @@ static int mock_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 	return 0;
 }
 
+static int __mock_cxl_decoders_setup(struct cxl_port *port)
+{
+	struct cxl_hdm *cxlhdm;
+
+	cxlhdm = mock_cxl_setup_hdm(port, NULL);
+	if (IS_ERR(cxlhdm)) {
+		if (PTR_ERR(cxlhdm) != -ENODEV)
+			dev_err(&port->dev, "Failed to map HDM decoder capability\n");
+		return PTR_ERR(cxlhdm);
+	}
+
+	return mock_cxl_enumerate_decoders(cxlhdm, NULL);
+}
+
+static int mock_cxl_switch_port_decoders_setup(struct cxl_port *port)
+{
+	if (is_cxl_root(port) || is_cxl_endpoint(port))
+		return -EOPNOTSUPP;
+
+	return __mock_cxl_decoders_setup(port);
+}
+
+static int mock_cxl_endpoint_decoders_setup(struct cxl_port *port)
+{
+	if (!is_cxl_endpoint(port))
+		return -EOPNOTSUPP;
+
+	return __mock_cxl_decoders_setup(port);
+}
+
 static int mock_cxl_port_enumerate_dports(struct cxl_port *port)
 {
 	struct platform_device **array;
@@ -1035,10 +1058,9 @@ static struct cxl_mock_ops cxl_mock_ops = {
 	.acpi_table_parse_cedt = mock_acpi_table_parse_cedt,
 	.acpi_evaluate_integer = mock_acpi_evaluate_integer,
 	.acpi_pci_find_root = mock_acpi_pci_find_root,
+	.devm_cxl_switch_port_decoders_setup = mock_cxl_switch_port_decoders_setup,
+	.devm_cxl_endpoint_decoders_setup = mock_cxl_endpoint_decoders_setup,
 	.devm_cxl_port_enumerate_dports = mock_cxl_port_enumerate_dports,
-	.devm_cxl_setup_hdm = mock_cxl_setup_hdm,
-	.devm_cxl_add_passthrough_decoder = mock_cxl_add_passthrough_decoder,
-	.devm_cxl_enumerate_decoders = mock_cxl_enumerate_decoders,
 	.cxl_endpoint_parse_cdat = mock_cxl_endpoint_parse_cdat,
 	.list = LIST_HEAD_INIT(cxl_mock_ops.list),
 };
diff --git a/tools/testing/cxl/test/mock.c b/tools/testing/cxl/test/mock.c
index 1989ae020df3..f335889b7756 100644
--- a/tools/testing/cxl/test/mock.c
+++ b/tools/testing/cxl/test/mock.c
@@ -131,55 +131,35 @@ __wrap_nvdimm_bus_register(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(__wrap_nvdimm_bus_register);
 
-struct cxl_hdm *__wrap_devm_cxl_setup_hdm(struct cxl_port *port,
-					  struct cxl_endpoint_dvsec_info *info)
-
-{
-	int index;
-	struct cxl_hdm *cxlhdm;
-	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
-
-	if (ops && ops->is_mock_port(port->uport_dev))
-		cxlhdm = ops->devm_cxl_setup_hdm(port, info);
-	else
-		cxlhdm = devm_cxl_setup_hdm(port, info);
-	put_cxl_mock_ops(index);
-
-	return cxlhdm;
-}
-EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_setup_hdm, "CXL");
-
-int __wrap_devm_cxl_add_passthrough_decoder(struct cxl_port *port)
+int __wrap_devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
 {
 	int rc, index;
 	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
 
 	if (ops && ops->is_mock_port(port->uport_dev))
-		rc = ops->devm_cxl_add_passthrough_decoder(port);
+		rc = ops->devm_cxl_switch_port_decoders_setup(port);
 	else
-		rc = devm_cxl_add_passthrough_decoder(port);
+		rc = devm_cxl_switch_port_decoders_setup(port);
 	put_cxl_mock_ops(index);
 
 	return rc;
 }
-EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_add_passthrough_decoder, "CXL");
+EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_switch_port_decoders_setup, "CXL");
 
-int __wrap_devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
-				       struct cxl_endpoint_dvsec_info *info)
+int __wrap_devm_cxl_endpoint_decoders_setup(struct cxl_port *port)
 {
 	int rc, index;
-	struct cxl_port *port = cxlhdm->port;
 	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
 
 	if (ops && ops->is_mock_port(port->uport_dev))
-		rc = ops->devm_cxl_enumerate_decoders(cxlhdm, info);
+		rc = ops->devm_cxl_endpoint_decoders_setup(port);
 	else
-		rc = devm_cxl_enumerate_decoders(cxlhdm, info);
+		rc = devm_cxl_endpoint_decoders_setup(port);
 	put_cxl_mock_ops(index);
 
 	return rc;
 }
-EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_enumerate_decoders, "CXL");
+EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_endpoint_decoders_setup, "CXL");
 
 int __wrap_devm_cxl_port_enumerate_dports(struct cxl_port *port)
 {
@@ -211,39 +191,6 @@ int __wrap_cxl_await_media_ready(struct cxl_dev_state *cxlds)
 }
 EXPORT_SYMBOL_NS_GPL(__wrap_cxl_await_media_ready, "CXL");
 
-int __wrap_cxl_hdm_decode_init(struct cxl_dev_state *cxlds,
-			       struct cxl_hdm *cxlhdm,
-			       struct cxl_endpoint_dvsec_info *info)
-{
-	int rc = 0, index;
-	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
-
-	if (ops && ops->is_mock_dev(cxlds->dev))
-		rc = 0;
-	else
-		rc = cxl_hdm_decode_init(cxlds, cxlhdm, info);
-	put_cxl_mock_ops(index);
-
-	return rc;
-}
-EXPORT_SYMBOL_NS_GPL(__wrap_cxl_hdm_decode_init, "CXL");
-
-int __wrap_cxl_dvsec_rr_decode(struct cxl_dev_state *cxlds,
-			       struct cxl_endpoint_dvsec_info *info)
-{
-	int rc = 0, index;
-	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
-
-	if (ops && ops->is_mock_dev(cxlds->dev))
-		rc = 0;
-	else
-		rc = cxl_dvsec_rr_decode(cxlds, info);
-	put_cxl_mock_ops(index);
-
-	return rc;
-}
-EXPORT_SYMBOL_NS_GPL(__wrap_cxl_dvsec_rr_decode, "CXL");
-
 struct cxl_dport *__wrap_devm_cxl_add_rch_dport(struct cxl_port *port,
 						struct device *dport_dev,
 						int port_id,
diff --git a/tools/testing/cxl/test/mock.h b/tools/testing/cxl/test/mock.h
index d1b0271d2822..9d5ad3fd55ec 100644
--- a/tools/testing/cxl/test/mock.h
+++ b/tools/testing/cxl/test/mock.h
@@ -20,11 +20,8 @@ struct cxl_mock_ops {
 	bool (*is_mock_port)(struct device *dev);
 	bool (*is_mock_dev)(struct device *dev);
 	int (*devm_cxl_port_enumerate_dports)(struct cxl_port *port);
-	struct cxl_hdm *(*devm_cxl_setup_hdm)(
-		struct cxl_port *port, struct cxl_endpoint_dvsec_info *info);
-	int (*devm_cxl_add_passthrough_decoder)(struct cxl_port *port);
-	int (*devm_cxl_enumerate_decoders)(
-		struct cxl_hdm *hdm, struct cxl_endpoint_dvsec_info *info);
+	int (*devm_cxl_switch_port_decoders_setup)(struct cxl_port *port);
+	int (*devm_cxl_endpoint_decoders_setup)(struct cxl_port *port);
 	void (*cxl_endpoint_parse_cdat)(struct cxl_port *port);
 };
 
-- 
2.50.1

Re: [PATCH v9 05/10] cxl/test: Refactor decoder setup to reduce cxl_test burden

[Jonathan Cameron]

On Fri, 29 Aug 2025 11:09:23 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> Group the decoder setup code in switch and endpoint port probe into a
> single function for each to reduce the number of functions to be mocked
> in cxl_test. Introduce devm_cxl_switch_port_decoders_setup() and
> devm_cxl_endpoint_decoders_setup(). These two functions will be mocked
> instead with some functions optimized out since the mock version does
> not do anything. Remove devm_cxl_setup_hdm(),
> devm_cxl_add_passthrough_decoder(), and devm_cxl_enumerate_decoders() in
> cxl_test mock code. In turn, mock_cxl_add_passthrough_decoder() can be
> removed since cxl_test does not setup passthrough decoders.
> __wrap_cxl_hdm_decode_init() and __wrap_cxl_dvsec_rr_decode() can be
> removed as well since they only return 0 when called.
> 
> Suggested-by: Robert Richter <rrichter@amd.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

There was a bit of code reordering in here that made it a little hard
to check but I can't see an easy way to make that more obvious.
A precursor patch shuffling the code would perhaps allow it to be
discussed in the patch description, but perhaps that's overkill

Anyhow, I'm fairly sure it is fine.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

> diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
> index cf32dc50b7a6..d8cae2b5bac6 100644
> --- a/drivers/cxl/port.c
> +++ b/drivers/cxl/port.c

>  
>  static int cxl_endpoint_port_probe(struct cxl_port *port)
>  {
> -	struct cxl_endpoint_dvsec_info info = { .port = port };
>  	struct cxl_memdev *cxlmd = to_cxl_memdev(port->uport_dev);
> -	struct cxl_dev_state *cxlds = cxlmd->cxlds;
> -	struct cxl_hdm *cxlhdm;
>  	int rc;
>  
> -	rc = cxl_dvsec_rr_decode(cxlds, &info);
> -	if (rc < 0)
> -		return rc;
> -
> -	cxlhdm = devm_cxl_setup_hdm(port, &info);
> -	if (IS_ERR(cxlhdm)) {
> -		if (PTR_ERR(cxlhdm) == -ENODEV)
> -			dev_err(&port->dev, "HDM decoder registers not found\n");
> -		return PTR_ERR(cxlhdm);
> -	}
> -
>  	/* Cache the data early to ensure is_visible() works */
>  	read_cdat_data(port);
>  	cxl_endpoint_parse_cdat(port);
> @@ -117,11 +87,7 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
>  	if (rc)
>  		return rc;

Hmm. The reordering makes me a little nervous but I 'think' it's ok as the
code in between is all related to the cxlmd which none of the
code above is directly related to.
 
>  
> -	rc = cxl_hdm_decode_init(cxlds, cxlhdm, &info);
> -	if (rc)
> -		return rc;
> -
> -	rc = devm_cxl_enumerate_decoders(cxlhdm, &info);
> +	rc = devm_cxl_endpoint_decoders_setup(port);
>  	if (rc)
>  		return rc;

Re: [PATCH v9 05/10] cxl/test: Refactor decoder setup to reduce cxl_test burden

[Alison Schofield]

On Fri, Aug 29, 2025 at 11:09:23AM -0700, Dave Jiang wrote:
> Group the decoder setup code in switch and endpoint port probe into a
> single function for each to reduce the number of functions to be mocked
> in cxl_test. Introduce devm_cxl_switch_port_decoders_setup() and
> devm_cxl_endpoint_decoders_setup(). These two functions will be mocked
> instead with some functions optimized out since the mock version does
> not do anything. Remove devm_cxl_setup_hdm(),
> devm_cxl_add_passthrough_decoder(), and devm_cxl_enumerate_decoders() in
> cxl_test mock code. In turn, mock_cxl_add_passthrough_decoder() can be
> removed since cxl_test does not setup passthrough decoders.
> __wrap_cxl_hdm_decode_init() and __wrap_cxl_dvsec_rr_decode() can be
> removed as well since they only return 0 when called.

Nice refactor!

Reviewed-by: Alison Schofield <alison.schofield@intel.com>

Re: [PATCH v9 05/10] cxl/test: Refactor decoder setup to reduce cxl_test burden

[Robert Richter]

On 29.08.25 11:09:23, Dave Jiang wrote:
> Group the decoder setup code in switch and endpoint port probe into a
> single function for each to reduce the number of functions to be mocked
> in cxl_test. Introduce devm_cxl_switch_port_decoders_setup() and
> devm_cxl_endpoint_decoders_setup(). These two functions will be mocked
> instead with some functions optimized out since the mock version does
> not do anything. Remove devm_cxl_setup_hdm(),
> devm_cxl_add_passthrough_decoder(), and devm_cxl_enumerate_decoders() in
> cxl_test mock code. In turn, mock_cxl_add_passthrough_decoder() can be
> removed since cxl_test does not setup passthrough decoders.
> __wrap_cxl_hdm_decode_init() and __wrap_cxl_dvsec_rr_decode() can be
> removed as well since they only return 0 when called.
> 
> Suggested-by: Robert Richter <rrichter@amd.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Great rework. I saw you applied it already, but in case you rebase
again:

Reviewed-by: Robert Richter <rrichter@amd.com>

One small comment:

> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 87a905db5ffb..2139b0935500 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -812,12 +812,10 @@ struct cxl_endpoint_dvsec_info {
>  	struct range dvsec_range[2];
>  };
>  
> -struct cxl_hdm;
> -struct cxl_hdm *devm_cxl_setup_hdm(struct cxl_port *port,
> -				   struct cxl_endpoint_dvsec_info *info);
> -int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
> -				struct cxl_endpoint_dvsec_info *info);
> -int devm_cxl_add_passthrough_decoder(struct cxl_port *port);
> +struct cxl_port;

cxl_port is already defined here. It can be dropped.

Feel free to fold the change in. On top patch fine with me too.

Thanks,

-Robert

> +int devm_cxl_switch_port_decoders_setup(struct cxl_port *port);
> +int devm_cxl_endpoint_decoders_setup(struct cxl_port *port);
> +
>  struct cxl_dev_state;
>  int cxl_dvsec_rr_decode(struct cxl_dev_state *cxlds,
>  			struct cxl_endpoint_dvsec_info *info);

[PATCH v9 06/10] cxl: Defer dport allocation for switch ports

[Dave Jiang]

The current implementation enumerates the dports during the cxl_port
driver probe. Without an endpoint connected, the dport may not be
active during port probe. This scheme may prevent a valid hardware
dport id to be retrieved and MMIO registers to be read when an endpoint
is hot-plugged. Move the dport allocation and setup to behind memdev
probe so the endpoint is guaranteed to be connected.

In the original enumeration behavior, there are 3 phases (or 2 if no CXL
switches) for port creation. cxl_acpi() creates a Root Port (RP) from the
ACPI0017.N device. Through that it enumerates downstream ports composed
of ACPI0016.N devices through add_host_bridge_dport(). Once done, it
uses add_host_bridge_uport() to create the ports that enumerate the PCI
RPs as the dports of these ports. Every time a port is created, the port
driver is attached, cxl_switch_porbe_probe() is called and
devm_cxl_port_enumerate_dports() is invoked to enumerate and probe
the dports.

The second phase is if there are any CXL switches. When the pci endpoint
device driver (cxl_pci) calls probe, it will add a mem device and triggers
the cxl_mem_probe(). cxl_mem_probe() calls devm_cxl_enumerate_ports()
and attempts to discovery and create all the ports represent CXL switches.
During this phase, a port is created per switch and the attached dports
are also enumerated and probed.

The last phase is creating endpoint port which happens for all endpoint
devices.

The new sequence is instead of creating all possible dports at initial
port creation, defer port instantiation until a memdev beneath that
dport arrives. Introduce devm_cxl_create_or_extend_port() to centralize
the creation and extension of ports with new dports as memory devices
arrive. As part of this rework, switch decoder target list is amended
at runtime as dports show up.

While the decoders are allocated during the port driver probe,
The decoders must also be updated since previously it's all done when all
the dports are setup and now every time a dport is setup per endpoint, the
switch target listing need to be updated with new dport. A
guard(rwsem_write) is used to update decoder targets. This is similar to
when decoder_populate_target() is called and the decoder programming
must be protected.

Also the port registers are probed the first time when the first dport
shows up. This ensures that the CXL link is established when the port
registers are probed.

Link: https://lore.kernel.org/linux-cxl/20250305100123.3077031-1-rrichter@amd.com/
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

---
v9:
- Dropped tested-by tag by Robert since significant code changes.
  Also dropped review tags.
- Rework iteration loop. (Robert)
- Dropped possible_ports in 'struct cxl_port' (Robert)
- Stop the update_decoder_targets() iteration when found. (Robert)
- Use number of decoders to gate decoder allocation.
- cxl_port_get_or_add_dport() ->cxl_port_add_dport(). (Robert)
- Unfold cxl_decoders_dport_update() (Robert)
- Remove devm_cxl_add_dport_by_uport() (Robert)
---
 drivers/cxl/core/cdat.c |   2 +-
 drivers/cxl/core/core.h |   2 +
 drivers/cxl/core/hdm.c  |   6 -
 drivers/cxl/core/pci.c  |  46 ++++++++
 drivers/cxl/core/port.c | 240 ++++++++++++++++++++++++++++++++--------
 drivers/cxl/port.c      |  11 +-
 6 files changed, 247 insertions(+), 60 deletions(-)

diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
index c0af645425f4..b156b81a9b20 100644
--- a/drivers/cxl/core/cdat.c
+++ b/drivers/cxl/core/cdat.c
@@ -338,7 +338,7 @@ static int match_cxlrd_hb(struct device *dev, void *data)
 
 	guard(rwsem_read)(&cxl_rwsem.region);
 	for (int i = 0; i < cxlsd->nr_targets; i++) {
-		if (host_bridge == cxlsd->target[i]->dport_dev)
+		if (cxlsd->target[i] && host_bridge == cxlsd->target[i]->dport_dev)
 			return 1;
 	}
 
diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index b07490aa93c7..e18425f119bd 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -146,6 +146,8 @@ int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
 int cxl_ras_init(void);
 void cxl_ras_exit(void);
 int cxl_gpf_port_setup(struct cxl_dport *dport);
+struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					    struct device *dport_dev);
 
 struct cxl_hdm;
 int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 78bfe4f55b96..72594f84d2a1 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -52,8 +52,6 @@ static int add_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld)
 static int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 {
 	struct cxl_switch_decoder *cxlsd;
-	struct cxl_dport *dport = NULL;
-	unsigned long index;
 	struct cxl_hdm *cxlhdm = dev_get_drvdata(&port->dev);
 
 	/*
@@ -69,10 +67,6 @@ static int devm_cxl_add_passthrough_decoder(struct cxl_port *port)
 
 	device_lock_assert(&port->dev);
 
-	xa_for_each(&port->dports, index, dport)
-		break;
-	cxlsd->cxld.target_map[0] = dport->port_id;
-
 	return add_hdm_decoder(port, &cxlsd->cxld);
 }
 
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index fa02366d35f2..9ec288ed39ae 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -24,6 +24,52 @@ static unsigned short media_ready_timeout = 60;
 module_param(media_ready_timeout, ushort, 0644);
 MODULE_PARM_DESC(media_ready_timeout, "seconds to wait for media ready");
 
+static int pci_get_port_num(struct pci_dev *pdev)
+{
+	u32 lnkcap;
+	int type;
+
+	type = pci_pcie_type(pdev);
+	if (type != PCI_EXP_TYPE_DOWNSTREAM && type != PCI_EXP_TYPE_ROOT_PORT)
+		return -EINVAL;
+
+	if (pci_read_config_dword(pdev, pci_pcie_cap(pdev) + PCI_EXP_LNKCAP,
+				  &lnkcap))
+		return -ENXIO;
+
+	return FIELD_GET(PCI_EXP_LNKCAP_PN, lnkcap);
+}
+
+/**
+ * devm_cxl_add_dport_by_dev - allocate a dport by the dport device
+ * @port: cxl_port that hosts the dport
+ * @dport_dev: 'struct device' of the dport
+ *
+ * Returns the allocated dport on success or ERR_PTR() of -errno on error
+ */
+struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					    struct device *dport_dev)
+{
+	struct cxl_register_map map;
+	struct pci_dev *pdev;
+	int port_num, rc;
+
+	if (!dev_is_pci(dport_dev))
+		return ERR_PTR(-EINVAL);
+
+	pdev = to_pci_dev(dport_dev);
+	port_num = pci_get_port_num(pdev);
+	if (port_num < 0)
+		return ERR_PTR(port_num);
+
+	rc = cxl_find_regblock(pdev, CXL_REGLOC_RBI_COMPONENT, &map);
+	if (rc)
+		return ERR_PTR(rc);
+
+	device_lock_assert(&port->dev);
+	return devm_cxl_add_dport(port, dport_dev, port_num, map.resource);
+}
+
 struct cxl_walk_context {
 	struct pci_bus *bus;
 	struct cxl_port *port;
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index f379e4c5121d..fa7ed5d50064 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1367,21 +1367,6 @@ static struct cxl_port *find_cxl_port(struct device *dport_dev,
 	return port;
 }
 
-static struct cxl_port *find_cxl_port_at(struct cxl_port *parent_port,
-					 struct device *dport_dev,
-					 struct cxl_dport **dport)
-{
-	struct cxl_find_port_ctx ctx = {
-		.dport_dev = dport_dev,
-		.parent_port = parent_port,
-		.dport = dport,
-	};
-	struct cxl_port *port;
-
-	port = __find_cxl_port(&ctx);
-	return port;
-}
-
 /*
  * All users of grandparent() are using it to walk PCIe-like switch port
  * hierarchy. A PCIe switch is comprised of a bridge device representing the
@@ -1557,13 +1542,154 @@ static resource_size_t find_component_registers(struct device *dev)
 	return map.resource;
 }
 
+static int match_port_by_uport(struct device *dev, const void *data)
+{
+	const struct device *uport_dev = data;
+	struct cxl_port *port;
+
+	if (!is_cxl_port(dev))
+		return 0;
+
+	port = to_cxl_port(dev);
+	return uport_dev == port->uport_dev;
+}
+
+/*
+ * Function takes a device reference on the port device. Caller should do a
+ * put_device() when done.
+ */
+static struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev)
+{
+	struct device *dev;
+
+	dev = bus_find_device(&cxl_bus_type, NULL, uport_dev, match_port_by_uport);
+	if (dev)
+		return to_cxl_port(dev);
+	return NULL;
+}
+
+static int update_decoder_targets(struct device *dev, void *data)
+{
+	struct cxl_dport *dport = data;
+	struct cxl_switch_decoder *cxlsd;
+	struct cxl_decoder *cxld;
+	int i;
+
+	if (!is_switch_decoder(dev))
+		return 0;
+
+	cxlsd = to_cxl_switch_decoder(dev);
+	cxld = &cxlsd->cxld;
+	guard(rwsem_write)(&cxl_rwsem.region);
+
+	for (i = 0; i < cxld->interleave_ways; i++) {
+		if (cxld->target_map[i] == dport->port_id) {
+			cxlsd->target[i] = dport;
+			dev_dbg(dev, "dport%d found in target list, index %d\n",
+				dport->port_id, i);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+DEFINE_FREE(del_cxl_dport, struct cxl_dport *, if (!IS_ERR_OR_NULL(_T)) del_dport(_T))
+static struct cxl_dport *cxl_port_add_dport(struct cxl_port *port,
+					    struct device *dport_dev)
+{
+	struct cxl_dport *dport;
+	int rc;
+
+	device_lock_assert(&port->dev);
+	if (!port->dev.driver)
+		return ERR_PTR(-ENXIO);
+
+	dport = cxl_find_dport_by_dev(port, dport_dev);
+	if (dport) {
+		dev_dbg(&port->dev, "dport%d:%s already exists\n",
+			dport->port_id, dev_name(dport_dev));
+		return ERR_PTR(-EBUSY);
+	}
+
+	struct cxl_dport *new_dport __free(del_cxl_dport) =
+		devm_cxl_add_dport_by_dev(port, dport_dev);
+	if (IS_ERR(new_dport))
+		return new_dport;
+
+	cxl_switch_parse_cdat(port);
+
+	if (ida_is_empty(&port->decoder_ida)) {
+		rc = devm_cxl_switch_port_decoders_setup(port);
+		if (rc)
+			return ERR_PTR(rc);
+		dev_dbg(&port->dev, "first dport%d:%s added with decoders\n",
+			new_dport->port_id, dev_name(dport_dev));
+		return no_free_ptr(new_dport);
+	}
+
+	/* New dport added, update the decoder targets */
+	device_for_each_child(&port->dev, new_dport, update_decoder_targets);
+
+	dev_dbg(&port->dev, "dport%d:%s added\n", new_dport->port_id,
+		dev_name(dport_dev));
+
+	return no_free_ptr(new_dport);
+}
+
+static struct cxl_dport *devm_cxl_create_port(struct device *ep_dev,
+					      struct cxl_port *parent_port,
+					      struct cxl_dport *parent_dport,
+					      struct device *uport_dev,
+					      struct device *dport_dev)
+{
+	resource_size_t component_reg_phys;
+
+	device_lock_assert(&parent_port->dev);
+	if (!parent_port->dev.driver) {
+		dev_warn(ep_dev,
+			 "port %s:%s:%s disabled, failed to enumerate CXL.mem\n",
+			 dev_name(&parent_port->dev), dev_name(uport_dev),
+			 dev_name(dport_dev));
+	}
+
+	struct cxl_port *port __free(put_cxl_port) =
+		find_cxl_port_by_uport(uport_dev);
+	if (!port) {
+		component_reg_phys = find_component_registers(uport_dev);
+		port = devm_cxl_add_port(&parent_port->dev, uport_dev,
+					 component_reg_phys, parent_dport);
+		if (IS_ERR(port))
+			return (struct cxl_dport *)port;
+
+		/*
+		 * retry to make sure a port is found. a port device
+		 * reference is taken.
+		 */
+		port = find_cxl_port_by_uport(uport_dev);
+		if (!port)
+			return ERR_PTR(-ENODEV);
+
+		dev_dbg(ep_dev, "created port %s:%s\n",
+			dev_name(&port->dev), dev_name(port->uport_dev));
+	} else {
+		/*
+		 * Port was created before right before this function is
+		 * called. Signal the caller to deal with it.
+		 */
+		return ERR_PTR(-EAGAIN);
+	}
+
+	guard(device)(&port->dev);
+	return cxl_port_add_dport(port, dport_dev);
+}
+
 static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 			      struct device *uport_dev,
 			      struct device *dport_dev)
 {
 	struct device *dparent = grandparent(dport_dev);
 	struct cxl_dport *dport, *parent_dport;
-	resource_size_t component_reg_phys;
 	int rc;
 
 	if (is_cxl_host_bridge(dparent)) {
@@ -1578,42 +1704,31 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 	}
 
 	struct cxl_port *parent_port __free(put_cxl_port) =
-		find_cxl_port(dparent, &parent_dport);
+		find_cxl_port_by_uport(dparent->parent);
 	if (!parent_port) {
 		/* iterate to create this parent_port */
 		return -EAGAIN;
 	}
 
-	/*
-	 * Definition with __free() here to keep the sequence of
-	 * dereferencing the device of the port before the parent_port releasing.
-	 */
-	struct cxl_port *port __free(put_cxl_port) = NULL;
 	scoped_guard(device, &parent_port->dev) {
-		if (!parent_port->dev.driver) {
-			dev_warn(&cxlmd->dev,
-				 "port %s:%s disabled, failed to enumerate CXL.mem\n",
-				 dev_name(&parent_port->dev), dev_name(uport_dev));
-			return -ENXIO;
+		parent_dport = cxl_find_dport_by_dev(parent_port, dparent);
+		if (!parent_dport) {
+			parent_dport = cxl_port_add_dport(parent_port, dparent);
+			if (IS_ERR(parent_dport))
+				return PTR_ERR(parent_dport);
 		}
 
-		port = find_cxl_port_at(parent_port, dport_dev, &dport);
-		if (!port) {
-			component_reg_phys = find_component_registers(uport_dev);
-			port = devm_cxl_add_port(&parent_port->dev, uport_dev,
-						 component_reg_phys, parent_dport);
-			if (IS_ERR(port))
-				return PTR_ERR(port);
-
-			/* retry find to pick up the new dport information */
-			port = find_cxl_port_at(parent_port, dport_dev, &dport);
-			if (!port)
-				return -ENXIO;
+		dport = devm_cxl_create_port(&cxlmd->dev, parent_port,
+					     parent_dport, uport_dev,
+					     dport_dev);
+		if (IS_ERR(dport)) {
+			/* Port already exists, restart iteration */
+			if (PTR_ERR(dport) == -EAGAIN)
+				return 0;
+			return PTR_ERR(dport);
 		}
 	}
 
-	dev_dbg(&cxlmd->dev, "add to new port %s:%s\n",
-		dev_name(&port->dev), dev_name(port->uport_dev));
 	rc = cxl_add_ep(dport, &cxlmd->dev);
 	if (rc == -EBUSY) {
 		/*
@@ -1626,6 +1741,25 @@ static int add_port_attach_ep(struct cxl_memdev *cxlmd,
 	return rc;
 }
 
+static struct cxl_dport *find_or_add_dport(struct cxl_port *port,
+					   struct device *dport_dev)
+{
+	struct cxl_dport *dport;
+
+	device_lock_assert(&port->dev);
+	dport = cxl_find_dport_by_dev(port, dport_dev);
+	if (!dport) {
+		dport = cxl_port_add_dport(port, dport_dev);
+		if (IS_ERR(dport))
+			return dport;
+
+		/* New dport added, restart iteration */
+		return ERR_PTR(-EAGAIN);
+	}
+
+	return dport;
+}
+
 int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 {
 	struct device *dev = &cxlmd->dev;
@@ -1668,12 +1802,26 @@ int devm_cxl_enumerate_ports(struct cxl_memdev *cxlmd)
 			dev_name(iter), dev_name(dport_dev),
 			dev_name(uport_dev));
 		struct cxl_port *port __free(put_cxl_port) =
-			find_cxl_port(dport_dev, &dport);
+			find_cxl_port_by_uport(uport_dev);
 		if (port) {
 			dev_dbg(&cxlmd->dev,
 				"found already registered port %s:%s\n",
 				dev_name(&port->dev),
 				dev_name(port->uport_dev));
+
+			/*
+			 * RP port enumerated by cxl_acpi without dport will
+			 * have the dport added here.
+			 */
+			scoped_guard(device, &port->dev) {
+				dport = find_or_add_dport(port, dport_dev);
+				if (IS_ERR(dport)) {
+					if (PTR_ERR(dport) == -EAGAIN)
+						goto retry;
+					return PTR_ERR(dport);
+				}
+			}
+
 			rc = cxl_add_ep(dport, &cxlmd->dev);
 
 			/*
@@ -1733,14 +1881,16 @@ static int decoder_populate_targets(struct cxl_switch_decoder *cxlsd,
 	device_lock_assert(&port->dev);
 
 	if (xa_empty(&port->dports))
-		return -EINVAL;
+		return 0;
 
 	guard(rwsem_write)(&cxl_rwsem.region);
 	for (i = 0; i < cxlsd->cxld.interleave_ways; i++) {
 		struct cxl_dport *dport = find_dport(port, cxld->target_map[i]);
 
-		if (!dport)
-			return -ENXIO;
+		if (!dport) {
+			/* dport may be activated later */
+			continue;
+		}
 		cxlsd->target[i] = dport;
 	}
 
diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
index d8cae2b5bac6..51c8f2f84717 100644
--- a/drivers/cxl/port.c
+++ b/drivers/cxl/port.c
@@ -59,18 +59,13 @@ static int discover_region(struct device *dev, void *unused)
 
 static int cxl_switch_port_probe(struct cxl_port *port)
 {
-	int rc;
+	/* Reset nr_dports for rebind of driver */
+	port->nr_dports = 0;
 
 	/* Cache the data early to ensure is_visible() works */
 	read_cdat_data(port);
 
-	rc = devm_cxl_port_enumerate_dports(port);
-	if (rc < 0)
-		return rc;
-
-	cxl_switch_parse_cdat(port);
-
-	return devm_cxl_switch_port_decoders_setup(port);
+	return 0;
 }
 
 static int cxl_endpoint_port_probe(struct cxl_port *port)
-- 
2.50.1

Re: [PATCH v9 06/10] cxl: Defer dport allocation for switch ports

[Jonathan Cameron]

On Fri, 29 Aug 2025 11:09:24 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> The current implementation enumerates the dports during the cxl_port
> driver probe. Without an endpoint connected, the dport may not be
> active during port probe. This scheme may prevent a valid hardware
> dport id to be retrieved and MMIO registers to be read when an endpoint
> is hot-plugged. Move the dport allocation and setup to behind memdev
> probe so the endpoint is guaranteed to be connected.
> 
> In the original enumeration behavior, there are 3 phases (or 2 if no CXL
> switches) for port creation. cxl_acpi() creates a Root Port (RP) from the
> ACPI0017.N device. Through that it enumerates downstream ports composed
> of ACPI0016.N devices through add_host_bridge_dport(). Once done, it
> uses add_host_bridge_uport() to create the ports that enumerate the PCI
> RPs as the dports of these ports. Every time a port is created, the port
> driver is attached, cxl_switch_porbe_probe() is called and
> devm_cxl_port_enumerate_dports() is invoked to enumerate and probe
> the dports.
> 
> The second phase is if there are any CXL switches. When the pci endpoint
> device driver (cxl_pci) calls probe, it will add a mem device and triggers
> the cxl_mem_probe(). cxl_mem_probe() calls devm_cxl_enumerate_ports()
> and attempts to discovery and create all the ports represent CXL switches.
> During this phase, a port is created per switch and the attached dports
> are also enumerated and probed.
> 
> The last phase is creating endpoint port which happens for all endpoint
> devices.
> 
> The new sequence is instead of creating all possible dports at initial
> port creation, defer port instantiation until a memdev beneath that
> dport arrives. Introduce devm_cxl_create_or_extend_port() to centralize
> the creation and extension of ports with new dports as memory devices
> arrive. As part of this rework, switch decoder target list is amended
> at runtime as dports show up.
> 
> While the decoders are allocated during the port driver probe,
> The decoders must also be updated since previously it's all done when all

it was all done?

> the dports are setup and now every time a dport is setup per endpoint, the
> switch target listing need to be updated with new dport. A
> guard(rwsem_write) is used to update decoder targets. This is similar to
> when decoder_populate_target() is called and the decoder programming
> must be protected.
> 
> Also the port registers are probed the first time when the first dport
> shows up. This ensures that the CXL link is established when the port
> registers are probed.
> 
> Link: https://lore.kernel.org/linux-cxl/20250305100123.3077031-1-rrichter@amd.com/
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Hi Dave,

This isn't one of my more confident reviews but I think this looks ok.
Definitely could do with more eyes though. In the ideal world I'd emulate
a bunch of test cases to poke this with, but I'm snowed under for a while
so hopefully testing on the platforms that exhibit the problem will be enough.

One trivial comment inline.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

> 
> ---
> v9:
> - Dropped tested-by tag by Robert since significant code changes.
>   Also dropped review tags.
> - Rework iteration loop. (Robert)
> - Dropped possible_ports in 'struct cxl_port' (Robert)
> - Stop the update_decoder_targets() iteration when found. (Robert)
> - Use number of decoders to gate decoder allocation.
> - cxl_port_get_or_add_dport() ->cxl_port_add_dport(). (Robert)
> - Unfold cxl_decoders_dport_update() (Robert)
> - Remove devm_cxl_add_dport_by_uport() (Robert)


> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index fa02366d35f2..9ec288ed39ae 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c

>  struct cxl_walk_context {
>  	struct pci_bus *bus;
>  	struct cxl_port *port;
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index f379e4c5121d..fa7ed5d50064 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c

> +static struct cxl_dport *devm_cxl_create_port(struct device *ep_dev,
> +					      struct cxl_port *parent_port,
> +					      struct cxl_dport *parent_dport,
> +					      struct device *uport_dev,
> +					      struct device *dport_dev)
> +{
> +	resource_size_t component_reg_phys;
> +
> +	device_lock_assert(&parent_port->dev);
> +	if (!parent_port->dev.driver) {
> +		dev_warn(ep_dev,
> +			 "port %s:%s:%s disabled, failed to enumerate CXL.mem\n",
> +			 dev_name(&parent_port->dev), dev_name(uport_dev),
> +			 dev_name(dport_dev));
> +	}
> +
> +	struct cxl_port *port __free(put_cxl_port) =
> +		find_cxl_port_by_uport(uport_dev);
> +	if (!port) {
> +		component_reg_phys = find_component_registers(uport_dev);
> +		port = devm_cxl_add_port(&parent_port->dev, uport_dev,
> +					 component_reg_phys, parent_dport);
> +		if (IS_ERR(port))
> +			return (struct cxl_dport *)port;

			return ERR_CAST(port);
Just to make it even more obvious what is going on.

> +
> +		/*
> +		 * retry to make sure a port is found. a port device
> +		 * reference is taken.
> +		 */
> +		port = find_cxl_port_by_uport(uport_dev);
> +		if (!port)
> +			return ERR_PTR(-ENODEV);
> +
> +		dev_dbg(ep_dev, "created port %s:%s\n",
> +			dev_name(&port->dev), dev_name(port->uport_dev));
> +	} else {
> +		/*
> +		 * Port was created before right before this function is
> +		 * called. Signal the caller to deal with it.
> +		 */
> +		return ERR_PTR(-EAGAIN);
> +	}
> +
> +	guard(device)(&port->dev);
> +	return cxl_port_add_dport(port, dport_dev);
> +}

Re: [PATCH v9 06/10] cxl: Defer dport allocation for switch ports

[Alison Schofield]

On Fri, Aug 29, 2025 at 11:09:24AM -0700, Dave Jiang wrote:
> The current implementation enumerates the dports during the cxl_port
> driver probe. Without an endpoint connected, the dport may not be
> active during port probe. This scheme may prevent a valid hardware
> dport id to be retrieved and MMIO registers to be read when an endpoint
> is hot-plugged. Move the dport allocation and setup to behind memdev
> probe so the endpoint is guaranteed to be connected.
> 
> In the original enumeration behavior, there are 3 phases (or 2 if no CXL
> switches) for port creation. cxl_acpi() creates a Root Port (RP) from the
> ACPI0017.N device. Through that it enumerates downstream ports composed
> of ACPI0016.N devices through add_host_bridge_dport(). Once done, it
> uses add_host_bridge_uport() to create the ports that enumerate the PCI
> RPs as the dports of these ports. Every time a port is created, the port
> driver is attached, cxl_switch_porbe_probe() is called and
> devm_cxl_port_enumerate_dports() is invoked to enumerate and probe
> the dports.
> 
> The second phase is if there are any CXL switches. When the pci endpoint
> device driver (cxl_pci) calls probe, it will add a mem device and triggers
> the cxl_mem_probe(). cxl_mem_probe() calls devm_cxl_enumerate_ports()
> and attempts to discovery and create all the ports represent CXL switches.
> During this phase, a port is created per switch and the attached dports
> are also enumerated and probed.
> 
> The last phase is creating endpoint port which happens for all endpoint
> devices.
> 
> The new sequence is instead of creating all possible dports at initial
> port creation, defer port instantiation until a memdev beneath that
> dport arrives. Introduce devm_cxl_create_or_extend_port() to centralize
> the creation and extension of ports with new dports as memory devices
> arrive. As part of this rework, switch decoder target list is amended
> at runtime as dports show up.
> 
> While the decoders are allocated during the port driver probe,
> The decoders must also be updated since previously it's all done when all
> the dports are setup and now every time a dport is setup per endpoint, the
> switch target listing need to be updated with new dport. A
> guard(rwsem_write) is used to update decoder targets. This is similar to
> when decoder_populate_target() is called and the decoder programming
> must be protected.
> 
> Also the port registers are probed the first time when the first dport
> shows up. This ensures that the CXL link is established when the port
> registers are probed.
> 
> Link: https://lore.kernel.org/linux-cxl/20250305100123.3077031-1-rrichter@amd.com/
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Reviewed-by: Alison Schofield <alison.schofield@intel.com>

[PATCH v9 07/10] cxl/test: Add mock version of devm_cxl_add_dport_by_dev()

[Dave Jiang]

devm_cxl_add_dport_by_dev() outside of cxl_test is done through PCI
hierarchy. However with cxl_test, it needs to be done through the
platform device hierarchy. Add the mock function for
devm_cxl_add_dport_by_dev().

When cxl_core calls a cxl_core exported function and that function is
mocked by cxl_test, the call chain causes a circular dependency issue. Dan
provided a workaround to avoid this issue. Apply the method to changes from
the late dport allocation changes in order to enable cxl-test.

In cxl_core they are defined with "__" added in front of the function. A
macro is used to define the original function names for when non-test
version of the kernel is built. A bit of macros and typedefs are used to
allow mocking of those functions in cxl_test.

Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
Tested-by: Alison Schofield <alison.schofield@intel.com>
Tested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/core.h              |  2 --
 drivers/cxl/core/pci.c               |  7 ++--
 drivers/cxl/cxl.h                    | 20 +++++++++++
 tools/testing/cxl/Kbuild             |  1 +
 tools/testing/cxl/cxl_core_exports.c | 12 +++++++
 tools/testing/cxl/exports.h          | 10 ++++++
 tools/testing/cxl/test/cxl.c         | 53 ++++++++++++++++++++++++++--
 tools/testing/cxl/test/mock.c        | 23 ++++++++++++
 tools/testing/cxl/test/mock.h        |  2 ++
 9 files changed, 123 insertions(+), 7 deletions(-)
 create mode 100644 tools/testing/cxl/exports.h

diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
index e18425f119bd..b07490aa93c7 100644
--- a/drivers/cxl/core/core.h
+++ b/drivers/cxl/core/core.h
@@ -146,8 +146,6 @@ int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
 int cxl_ras_init(void);
 void cxl_ras_exit(void);
 int cxl_gpf_port_setup(struct cxl_dport *dport);
-struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
-					    struct device *dport_dev);
 
 struct cxl_hdm;
 int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 9ec288ed39ae..18825e1505d6 100644
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -41,14 +41,14 @@ static int pci_get_port_num(struct pci_dev *pdev)
 }
 
 /**
- * devm_cxl_add_dport_by_dev - allocate a dport by the dport device
+ * __devm_cxl_add_dport_by_dev - allocate a dport by dport device
  * @port: cxl_port that hosts the dport
  * @dport_dev: 'struct device' of the dport
  *
  * Returns the allocated dport on success or ERR_PTR() of -errno on error
  */
-struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
-					    struct device *dport_dev)
+struct cxl_dport *__devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					      struct device *dport_dev)
 {
 	struct cxl_register_map map;
 	struct pci_dev *pdev;
@@ -69,6 +69,7 @@ struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
 	device_lock_assert(&port->dev);
 	return devm_cxl_add_dport(port, dport_dev, port_num, map.resource);
 }
+EXPORT_SYMBOL_NS_GPL(__devm_cxl_add_dport_by_dev, "CXL");
 
 struct cxl_walk_context {
 	struct pci_bus *bus;
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 2139b0935500..aa916f0d186b 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -909,6 +909,10 @@ void cxl_coordinates_combine(struct access_coordinate *out,
 			     struct access_coordinate *c2);
 
 bool cxl_endpoint_decoder_reset_detected(struct cxl_port *port);
+struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					    struct device *dport_dev);
+struct cxl_dport *__devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					      struct device *dport_dev);
 
 /*
  * Unit test builds overrides this to __weak, find the 'strong' version
@@ -919,4 +923,20 @@ bool cxl_endpoint_decoder_reset_detected(struct cxl_port *port);
 #endif
 
 u16 cxl_gpf_get_dvsec(struct device *dev);
+
+/*
+ * Declaration for functions that are mocked by cxl_test that are called by
+ * cxl_core. The respective functions are defined as __foo() and called by
+ * cxl_core as foo(). The macros below ensures that those functions would
+ * exist as foo(). See tools/testing/cxl/cxl_core_exports.c and
+ * tools/testing/cxl/exports.h for setting up the mock functions. The dance
+ * is done to avoid a circular dependency where cxl_core calls a function that
+ * ends up being a mock function and goes to * cxl_test where it calls a
+ * cxl_core function.
+ */
+#ifndef CXL_TEST_ENABLE
+#define DECLARE_TESTABLE(x) __##x
+#define devm_cxl_add_dport_by_dev DECLARE_TESTABLE(devm_cxl_add_dport_by_dev)
+#endif
+
 #endif /* __CXL_H__ */
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index 51b8ab289eae..81e3795673c5 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -18,6 +18,7 @@ CXL_SRC := $(DRIVERS)/cxl
 CXL_CORE_SRC := $(DRIVERS)/cxl/core
 ccflags-y := -I$(srctree)/drivers/cxl/
 ccflags-y += -D__mock=__weak
+ccflags-y += -DCXL_TEST_ENABLE=1
 ccflags-y += -DTRACE_INCLUDE_PATH=$(CXL_CORE_SRC) -I$(srctree)/drivers/cxl/core/
 
 obj-m += cxl_acpi.o
diff --git a/tools/testing/cxl/cxl_core_exports.c b/tools/testing/cxl/cxl_core_exports.c
index f088792a8925..0d18abc1f5a3 100644
--- a/tools/testing/cxl/cxl_core_exports.c
+++ b/tools/testing/cxl/cxl_core_exports.c
@@ -2,6 +2,18 @@
 /* Copyright(c) 2022 Intel Corporation. All rights reserved. */
 
 #include "cxl.h"
+#include "exports.h"
 
 /* Exporting of cxl_core symbols that are only used by cxl_test */
 EXPORT_SYMBOL_NS_GPL(cxl_num_decoders_committed, "CXL");
+
+cxl_add_dport_by_dev_fn _devm_cxl_add_dport_by_dev =
+	__devm_cxl_add_dport_by_dev;
+EXPORT_SYMBOL_NS_GPL(_devm_cxl_add_dport_by_dev, "CXL");
+
+struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
+					    struct device *dport_dev)
+{
+	return _devm_cxl_add_dport_by_dev(port, dport_dev);
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_add_dport_by_dev, "CXL");
diff --git a/tools/testing/cxl/exports.h b/tools/testing/cxl/exports.h
new file mode 100644
index 000000000000..9261ce6f1197
--- /dev/null
+++ b/tools/testing/cxl/exports.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright(c) 2025 Intel Corporation */
+#ifndef __MOCK_CXL_EXPORTS_H_
+#define __MOCK_CXL_EXPORTS_H_
+
+typedef struct cxl_dport *(*cxl_add_dport_by_dev_fn)(struct cxl_port *port,
+							  struct device *dport_dev);
+extern cxl_add_dport_by_dev_fn _devm_cxl_add_dport_by_dev;
+
+#endif
diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
index 8b5c559a4a8c..e3b4dc265a3b 100644
--- a/tools/testing/cxl/test/cxl.c
+++ b/tools/testing/cxl/test/cxl.c
@@ -944,10 +944,12 @@ static int mock_cxl_endpoint_decoders_setup(struct cxl_port *port)
 	return __mock_cxl_decoders_setup(port);
 }
 
-static int mock_cxl_port_enumerate_dports(struct cxl_port *port)
+static int get_port_array(struct cxl_port *port,
+			  struct platform_device ***port_array,
+			  int *port_array_size)
 {
 	struct platform_device **array;
-	int i, array_size;
+	int array_size;
 
 	if (port->depth == 1) {
 		if (is_multi_bridge(port->uport_dev)) {
@@ -981,6 +983,22 @@ static int mock_cxl_port_enumerate_dports(struct cxl_port *port)
 		return -ENXIO;
 	}
 
+	*port_array = array;
+	*port_array_size = array_size;
+
+	return 0;
+}
+
+static int mock_cxl_port_enumerate_dports(struct cxl_port *port)
+{
+	struct platform_device **array;
+	int i, array_size;
+	int rc;
+
+	rc = get_port_array(port, &array, &array_size);
+	if (rc)
+		return rc;
+
 	for (i = 0; i < array_size; i++) {
 		struct platform_device *pdev = array[i];
 		struct cxl_dport *dport;
@@ -1002,6 +1020,36 @@ static int mock_cxl_port_enumerate_dports(struct cxl_port *port)
 	return 0;
 }
 
+static struct cxl_dport *mock_cxl_add_dport_by_dev(struct cxl_port *port,
+						   struct device *dport_dev)
+{
+	struct platform_device **array;
+	int rc, i, array_size;
+
+	rc = get_port_array(port, &array, &array_size);
+	if (rc)
+		return ERR_PTR(rc);
+
+	for (i = 0; i < array_size; i++) {
+		struct platform_device *pdev = array[i];
+
+		if (pdev->dev.parent != port->uport_dev) {
+			dev_dbg(&port->dev, "%s: mismatch parent %s\n",
+				dev_name(port->uport_dev),
+				dev_name(pdev->dev.parent));
+			continue;
+		}
+
+		if (&pdev->dev != dport_dev)
+			continue;
+
+		return devm_cxl_add_dport(port, &pdev->dev, pdev->id,
+					  CXL_RESOURCE_NONE);
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+
 /*
  * Faking the cxl_dpa_perf for the memdev when appropriate.
  */
@@ -1062,6 +1110,7 @@ static struct cxl_mock_ops cxl_mock_ops = {
 	.devm_cxl_endpoint_decoders_setup = mock_cxl_endpoint_decoders_setup,
 	.devm_cxl_port_enumerate_dports = mock_cxl_port_enumerate_dports,
 	.cxl_endpoint_parse_cdat = mock_cxl_endpoint_parse_cdat,
+	.devm_cxl_add_dport_by_dev = mock_cxl_add_dport_by_dev,
 	.list = LIST_HEAD_INIT(cxl_mock_ops.list),
 };
 
diff --git a/tools/testing/cxl/test/mock.c b/tools/testing/cxl/test/mock.c
index f335889b7756..e98101f083cd 100644
--- a/tools/testing/cxl/test/mock.c
+++ b/tools/testing/cxl/test/mock.c
@@ -10,12 +10,18 @@
 #include <cxlmem.h>
 #include <cxlpci.h>
 #include "mock.h"
+#include "../exports.h"
 
 static LIST_HEAD(mock);
 
+static struct cxl_dport *
+redirect_devm_cxl_add_dport_by_dev(struct cxl_port *port,
+				   struct device *dport_dev);
+
 void register_cxl_mock_ops(struct cxl_mock_ops *ops)
 {
 	list_add_rcu(&ops->list, &mock);
+	_devm_cxl_add_dport_by_dev = redirect_devm_cxl_add_dport_by_dev;
 }
 EXPORT_SYMBOL_GPL(register_cxl_mock_ops);
 
@@ -23,6 +29,7 @@ DEFINE_STATIC_SRCU(cxl_mock_srcu);
 
 void unregister_cxl_mock_ops(struct cxl_mock_ops *ops)
 {
+	_devm_cxl_add_dport_by_dev = __devm_cxl_add_dport_by_dev;
 	list_del_rcu(&ops->list);
 	synchronize_srcu(&cxl_mock_srcu);
 }
@@ -258,6 +265,22 @@ void __wrap_cxl_dport_init_ras_reporting(struct cxl_dport *dport, struct device
 }
 EXPORT_SYMBOL_NS_GPL(__wrap_cxl_dport_init_ras_reporting, "CXL");
 
+struct cxl_dport *redirect_devm_cxl_add_dport_by_dev(struct cxl_port *port,
+						     struct device *dport_dev)
+{
+	int index;
+	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
+	struct cxl_dport *dport;
+
+	if (ops && ops->is_mock_port(port->uport_dev))
+		dport = ops->devm_cxl_add_dport_by_dev(port, dport_dev);
+	else
+		dport = __devm_cxl_add_dport_by_dev(port, dport_dev);
+	put_cxl_mock_ops(index);
+
+	return dport;
+}
+
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("cxl_test: emulation module");
 MODULE_IMPORT_NS("ACPI");
diff --git a/tools/testing/cxl/test/mock.h b/tools/testing/cxl/test/mock.h
index 9d5ad3fd55ec..4ed932e76aae 100644
--- a/tools/testing/cxl/test/mock.h
+++ b/tools/testing/cxl/test/mock.h
@@ -23,6 +23,8 @@ struct cxl_mock_ops {
 	int (*devm_cxl_switch_port_decoders_setup)(struct cxl_port *port);
 	int (*devm_cxl_endpoint_decoders_setup)(struct cxl_port *port);
 	void (*cxl_endpoint_parse_cdat)(struct cxl_port *port);
+	struct cxl_dport *(*devm_cxl_add_dport_by_dev)(struct cxl_port *port,
+						       struct device *dport_dev);
 };
 
 void register_cxl_mock_ops(struct cxl_mock_ops *ops);
-- 
2.50.1

[PATCH v9 08/10] cxl/test: Adjust the mock version of devm_cxl_switch_port_decoders_setup()

[Dave Jiang]

With devm_cxl_switch_port_decoders_setup() being called within cxl_core
instead of by the port driver probe, adjustments are needed to deal with
circular symbol dependency when this function is being mock'd. Add the
appropriate changes to get around the circular dependency.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/hdm.c               |  6 +++---
 drivers/cxl/cxl.h                    |  2 ++
 tools/testing/cxl/Kbuild             |  1 -
 tools/testing/cxl/cxl_core_exports.c | 10 ++++++++++
 tools/testing/cxl/exports.h          |  3 +++
 tools/testing/cxl/test/mock.c        | 10 +++++++---
 6 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 72594f84d2a1..5fa7635c9b75 100644
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -1216,12 +1216,12 @@ static int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm,
 }
 
 /**
- * devm_cxl_switch_port_decoders_setup - allocate and setup switch decoders
+ * __devm_cxl_switch_port_decoders_setup - allocate and setup switch decoders
  * @port: CXL port context
  *
  * Return 0 or -errno on error
  */
-int devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
+int __devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
 {
 	struct cxl_hdm *cxlhdm;
 
@@ -1245,7 +1245,7 @@ int devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
 	dev_err(&port->dev, "HDM decoder capability not found\n");
 	return -ENXIO;
 }
-EXPORT_SYMBOL_NS_GPL(devm_cxl_switch_port_decoders_setup, "CXL");
+EXPORT_SYMBOL_NS_GPL(__devm_cxl_switch_port_decoders_setup, "CXL");
 
 /**
  * devm_cxl_endpoint_decoders_setup - allocate and setup endpoint decoders
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index aa916f0d186b..8bdc74121736 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -814,6 +814,7 @@ struct cxl_endpoint_dvsec_info {
 
 struct cxl_port;
 int devm_cxl_switch_port_decoders_setup(struct cxl_port *port);
+int __devm_cxl_switch_port_decoders_setup(struct cxl_port *port);
 int devm_cxl_endpoint_decoders_setup(struct cxl_port *port);
 
 struct cxl_dev_state;
@@ -937,6 +938,7 @@ u16 cxl_gpf_get_dvsec(struct device *dev);
 #ifndef CXL_TEST_ENABLE
 #define DECLARE_TESTABLE(x) __##x
 #define devm_cxl_add_dport_by_dev DECLARE_TESTABLE(devm_cxl_add_dport_by_dev)
+#define devm_cxl_switch_port_decoders_setup DECLARE_TESTABLE(devm_cxl_switch_port_decoders_setup)
 #endif
 
 #endif /* __CXL_H__ */
diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
index 81e3795673c5..0d5ce4b74b9f 100644
--- a/tools/testing/cxl/Kbuild
+++ b/tools/testing/cxl/Kbuild
@@ -10,7 +10,6 @@ ldflags-y += --wrap=devm_cxl_add_rch_dport
 ldflags-y += --wrap=cxl_rcd_component_reg_phys
 ldflags-y += --wrap=cxl_endpoint_parse_cdat
 ldflags-y += --wrap=cxl_dport_init_ras_reporting
-ldflags-y += --wrap=devm_cxl_switch_port_decoders_setup
 ldflags-y += --wrap=devm_cxl_endpoint_decoders_setup
 
 DRIVERS := ../../../drivers
diff --git a/tools/testing/cxl/cxl_core_exports.c b/tools/testing/cxl/cxl_core_exports.c
index 0d18abc1f5a3..6754de35598d 100644
--- a/tools/testing/cxl/cxl_core_exports.c
+++ b/tools/testing/cxl/cxl_core_exports.c
@@ -17,3 +17,13 @@ struct cxl_dport *devm_cxl_add_dport_by_dev(struct cxl_port *port,
 	return _devm_cxl_add_dport_by_dev(port, dport_dev);
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_add_dport_by_dev, "CXL");
+
+cxl_switch_decoders_setup_fn _devm_cxl_switch_port_decoders_setup =
+	__devm_cxl_switch_port_decoders_setup;
+EXPORT_SYMBOL_NS_GPL(_devm_cxl_switch_port_decoders_setup, "CXL");
+
+int devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
+{
+	return _devm_cxl_switch_port_decoders_setup(port);
+}
+EXPORT_SYMBOL_NS_GPL(devm_cxl_switch_port_decoders_setup, "CXL");
diff --git a/tools/testing/cxl/exports.h b/tools/testing/cxl/exports.h
index 9261ce6f1197..7ebee7c0bd67 100644
--- a/tools/testing/cxl/exports.h
+++ b/tools/testing/cxl/exports.h
@@ -7,4 +7,7 @@ typedef struct cxl_dport *(*cxl_add_dport_by_dev_fn)(struct cxl_port *port,
 							  struct device *dport_dev);
 extern cxl_add_dport_by_dev_fn _devm_cxl_add_dport_by_dev;
 
+typedef int(*cxl_switch_decoders_setup_fn)(struct cxl_port *port);
+extern cxl_switch_decoders_setup_fn _devm_cxl_switch_port_decoders_setup;
+
 #endif
diff --git a/tools/testing/cxl/test/mock.c b/tools/testing/cxl/test/mock.c
index e98101f083cd..995269a75cbd 100644
--- a/tools/testing/cxl/test/mock.c
+++ b/tools/testing/cxl/test/mock.c
@@ -17,11 +17,14 @@ static LIST_HEAD(mock);
 static struct cxl_dport *
 redirect_devm_cxl_add_dport_by_dev(struct cxl_port *port,
 				   struct device *dport_dev);
+static int redirect_devm_cxl_switch_port_decoders_setup(struct cxl_port *port);
 
 void register_cxl_mock_ops(struct cxl_mock_ops *ops)
 {
 	list_add_rcu(&ops->list, &mock);
 	_devm_cxl_add_dport_by_dev = redirect_devm_cxl_add_dport_by_dev;
+	_devm_cxl_switch_port_decoders_setup =
+		redirect_devm_cxl_switch_port_decoders_setup;
 }
 EXPORT_SYMBOL_GPL(register_cxl_mock_ops);
 
@@ -29,6 +32,8 @@ DEFINE_STATIC_SRCU(cxl_mock_srcu);
 
 void unregister_cxl_mock_ops(struct cxl_mock_ops *ops)
 {
+	_devm_cxl_switch_port_decoders_setup =
+		__devm_cxl_switch_port_decoders_setup;
 	_devm_cxl_add_dport_by_dev = __devm_cxl_add_dport_by_dev;
 	list_del_rcu(&ops->list);
 	synchronize_srcu(&cxl_mock_srcu);
@@ -138,7 +143,7 @@ __wrap_nvdimm_bus_register(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(__wrap_nvdimm_bus_register);
 
-int __wrap_devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
+int redirect_devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
 {
 	int rc, index;
 	struct cxl_mock_ops *ops = get_cxl_mock_ops(&index);
@@ -146,12 +151,11 @@ int __wrap_devm_cxl_switch_port_decoders_setup(struct cxl_port *port)
 	if (ops && ops->is_mock_port(port->uport_dev))
 		rc = ops->devm_cxl_switch_port_decoders_setup(port);
 	else
-		rc = devm_cxl_switch_port_decoders_setup(port);
+		rc = __devm_cxl_switch_port_decoders_setup(port);
 	put_cxl_mock_ops(index);
 
 	return rc;
 }
-EXPORT_SYMBOL_NS_GPL(__wrap_devm_cxl_switch_port_decoders_setup, "CXL");
 
 int __wrap_devm_cxl_endpoint_decoders_setup(struct cxl_port *port)
 {
-- 
2.50.1

Re: [PATCH v9 08/10] cxl/test: Adjust the mock version of devm_cxl_switch_port_decoders_setup()

[Jonathan Cameron]

On Fri, 29 Aug 2025 11:09:26 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> With devm_cxl_switch_port_decoders_setup() being called within cxl_core
> instead of by the port driver probe, adjustments are needed to deal with
> circular symbol dependency when this function is being mock'd. Add the
> appropriate changes to get around the circular dependency.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Looks fairly standard.
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>

Re: [PATCH v9 08/10] cxl/test: Adjust the mock version of devm_cxl_switch_port_decoders_setup()

[Alison Schofield]

On Fri, Aug 29, 2025 at 11:09:26AM -0700, Dave Jiang wrote:
> With devm_cxl_switch_port_decoders_setup() being called within cxl_core
> instead of by the port driver probe, adjustments are needed to deal with
> circular symbol dependency when this function is being mock'd. Add the
> appropriate changes to get around the circular dependency.

Reviewed-by: Alison Schofield <alison.schofield@intel.com>

snip

[PATCH v9 09/10] cxl/test: Setup target_map for cxl_test decoder initialization

[Dave Jiang]

cxl_test uses mock functions for decoder enumaration. Add initialization
of the cxld->target_map[] for cxl_test based decoders in the mock
functions.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Tested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 tools/testing/cxl/test/cxl.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
index e3b4dc265a3b..5d0040b7d7db 100644
--- a/tools/testing/cxl/test/cxl.c
+++ b/tools/testing/cxl/test/cxl.c
@@ -811,15 +811,21 @@ static void mock_init_hdm_decoder(struct cxl_decoder *cxld)
 		 */
 		if (WARN_ON(!dev))
 			continue;
+
 		cxlsd = to_cxl_switch_decoder(dev);
 		if (i == 0) {
 			/* put cxl_mem.4 second in the decode order */
-			if (pdev->id == 4)
+			if (pdev->id == 4) {
 				cxlsd->target[1] = dport;
-			else
+				cxld->target_map[1] = dport->port_id;
+			} else {
 				cxlsd->target[0] = dport;
-		} else
+				cxld->target_map[0] = dport->port_id;
+			}
+		} else {
 			cxlsd->target[0] = dport;
+			cxld->target_map[0] = dport->port_id;
+		}
 		cxld = &cxlsd->cxld;
 		cxld->target_type = CXL_DECODER_HOSTONLYMEM;
 		cxld->flags = CXL_DECODER_F_ENABLE;
-- 
2.50.1

Re: [PATCH v9 09/10] cxl/test: Setup target_map for cxl_test decoder initialization

[Alison Schofield]

On Fri, Aug 29, 2025 at 11:09:27AM -0700, Dave Jiang wrote:
> cxl_test uses mock functions for decoder enumaration. Add initialization
> of the cxld->target_map[] for cxl_test based decoders in the mock
> functions.

Reviewed-by: Alison Schofield <alison.schofield@intel.com>

> 
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Tested-by: Robert Richter <rrichter@amd.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>

[PATCH v9 10/10] cxl: Change sslbis handler to only handle single dport

[Dave Jiang]

While cxl_switch_parse_cdat() is harmless to be run multiple times, it is
not efficient in the current scheme where one dport is being updated at
a time by the memdev probe path. Change the input parameter to the
specific dport being updated to pick up the SSLBIS information for just
that dport.

Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Li Ming <ming.li@zohomail.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
 drivers/cxl/core/cdat.c | 23 ++++++++++-------------
 drivers/cxl/core/port.c |  2 +-
 drivers/cxl/cxl.h       |  2 +-
 3 files changed, 12 insertions(+), 15 deletions(-)

diff --git a/drivers/cxl/core/cdat.c b/drivers/cxl/core/cdat.c
index b156b81a9b20..84c50e7e8d0a 100644
--- a/drivers/cxl/core/cdat.c
+++ b/drivers/cxl/core/cdat.c
@@ -440,8 +440,8 @@ static int cdat_sslbis_handler(union acpi_subtable_headers *header, void *arg,
 	} *tbl = (struct acpi_cdat_sslbis_table *)header;
 	int size = sizeof(header->cdat) + sizeof(tbl->sslbis_header);
 	struct acpi_cdat_sslbis *sslbis;
-	struct cxl_port *port = arg;
-	struct device *dev = &port->dev;
+	struct cxl_dport *dport = arg;
+	struct device *dev = &dport->port->dev;
 	int remain, entries, i;
 	u16 len;
 
@@ -467,8 +467,6 @@ static int cdat_sslbis_handler(union acpi_subtable_headers *header, void *arg,
 		u16 y = le16_to_cpu((__force __le16)tbl->entries[i].porty_id);
 		__le64 le_base;
 		__le16 le_val;
-		struct cxl_dport *dport;
-		unsigned long index;
 		u16 dsp_id;
 		u64 val;
 
@@ -499,28 +497,27 @@ static int cdat_sslbis_handler(union acpi_subtable_headers *header, void *arg,
 		val = cdat_normalize(le16_to_cpu(le_val), le64_to_cpu(le_base),
 				     sslbis->data_type);
 
-		xa_for_each(&port->dports, index, dport) {
-			if (dsp_id == ACPI_CDAT_SSLBIS_ANY_PORT ||
-			    dsp_id == dport->port_id) {
-				cxl_access_coordinate_set(dport->coord,
-							  sslbis->data_type,
-							  val);
-			}
+		if (dsp_id == ACPI_CDAT_SSLBIS_ANY_PORT ||
+		    dsp_id == dport->port_id) {
+			cxl_access_coordinate_set(dport->coord,
+						  sslbis->data_type, val);
+			return 0;
 		}
 	}
 
 	return 0;
 }
 
-void cxl_switch_parse_cdat(struct cxl_port *port)
+void cxl_switch_parse_cdat(struct cxl_dport *dport)
 {
+	struct cxl_port *port = dport->port;
 	int rc;
 
 	if (!port->cdat.table)
 		return;
 
 	rc = cdat_table_parse(ACPI_CDAT_TYPE_SSLBIS, cdat_sslbis_handler,
-			      port, port->cdat.table, port->cdat.length);
+			      dport, port->cdat.table, port->cdat.length);
 	rc = cdat_table_parse_output(rc);
 	if (rc)
 		dev_dbg(&port->dev, "Failed to parse SSLBIS: %d\n", rc);
diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
index fa7ed5d50064..416d45516d82 100644
--- a/drivers/cxl/core/port.c
+++ b/drivers/cxl/core/port.c
@@ -1617,7 +1617,7 @@ static struct cxl_dport *cxl_port_add_dport(struct cxl_port *port,
 	if (IS_ERR(new_dport))
 		return new_dport;
 
-	cxl_switch_parse_cdat(port);
+	cxl_switch_parse_cdat(new_dport);
 
 	if (ida_is_empty(&port->decoder_ida)) {
 		rc = devm_cxl_switch_port_decoders_setup(port);
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 8bdc74121736..bdc682a7d60b 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -895,7 +895,7 @@ static inline u64 cxl_port_get_spa_cache_alias(struct cxl_port *endpoint,
 #endif
 
 void cxl_endpoint_parse_cdat(struct cxl_port *port);
-void cxl_switch_parse_cdat(struct cxl_port *port);
+void cxl_switch_parse_cdat(struct cxl_dport *dport);
 
 int cxl_endpoint_get_perf_coordinates(struct cxl_port *port,
 				      struct access_coordinate *coord);
-- 
2.50.1

Re: [PATCH v9 00/10] cxl: Delay HB port and switch dport probing until endpoint dev probe

[Dave Jiang]

On 8/29/25 11:09 AM, Dave Jiang wrote:
> v9:
> - Reworked the port enumeration iteration loop. (Robert)
>   All please re-review "cxl: Defer dport allocation for switch ports"
> - Created helper functions for dealing with switch and endpoint decoder enumeration.
>   Main goal is to reduce cxl_test interface burden. (Robert)
>   - Dropped cxl_test changes for decoder functions
> - Dropped the cxl_test for region replay. It's not 100% ready and can be submitted later. (Alison)
> - See specific commits for more detailed changes.
> 
> v8:
> - A bit of changes from Dan and Robert's comments. Main change is moving the port MMIO
>   register probing to after the first dport shows up. This resulted with decoder allocation
>   happens after the register probe.
> - See specific commits for more detailed changes.
> 
> v7:
> - Remove -EEXIST to simplify error flow. (Ming)
> - Set dport to NULL during declare. (Jonathan)
> 
> v6:
> - Return -EEXIST when a dport already exists. (Jonathan)
> - Fix checking wrong port for NULL. (Ming)
> - Check host_bridge and call devm_cxl_add_dport_by_uport() directly vs add_port_attach_ep(). (Ming)
> - Set dport to NULL during declaration. (Jonathan)
> 
> v5:
> - Return dport instead of errno with dport pointer as output param. (Jonathan)
> - Consolidate common code in cxl_test. (Jonathan)
> - Rename cxl_port_get_total_dports() to cxl_port_update_total_dports(). (Jonathan)
> 
> v4:
> - Push dport allocation to when they are discovered. (Robert)
> - Drop linux id for dport with above changes.
> 
> v3:
> - Main changes revolve around improving naming of hostbridge uport and dport (Gregory)
> - See specific patches for detailed change log
> 
> This series attempts to delay the allocation of dports until when the endpoint device
> (memdev) are being probed. At this point, the CXL link is established and all the
> devices along the CXL link path up to the Root Port (RP) should be active.
> 
> And hopefully this help a bit with Robert's issue raised in the "Inactive
> downstream port handling" series [1]. Testing would be appreicated. Thank you!
> 
> [1]: https://lore.kernel.org/linux-cxl/67c8a0cc23ec_24b64294f6@dwillia2-xfh.jf.intel.com.notmuch/
> 
> Dave Jiang (10):
>   cxl: Add helper to detect top of CXL device topology
>   cxl: Add helper to reap dport
>   cxl: Add a cached copy of target_map to cxl_decoder
>   cxl: Move port register setup to first dport appear
>   cxl/test: Refactor decoder setup to reduce cxl_test burden
>   cxl: Defer dport allocation for switch ports
>   cxl/test: Add mock version of devm_cxl_add_dport_by_dev()
>   cxl/test: Adjust the mock version of
>     devm_cxl_switch_port_decoders_setup()
>   cxl/test: Setup target_map for cxl_test decoder initialization
>   cxl: Change sslbis handler to only handle single dport
> 
>  drivers/cxl/acpi.c                   |   7 +-
>  drivers/cxl/core/cdat.c              |  25 +--
>  drivers/cxl/core/core.h              |   5 +
>  drivers/cxl/core/hdm.c               | 105 ++++++---
>  drivers/cxl/core/pci.c               |  89 ++++++++
>  drivers/cxl/core/port.c              | 317 ++++++++++++++++++++-------
>  drivers/cxl/core/region.c            |   4 +-
>  drivers/cxl/cxl.h                    |  44 +++-
>  drivers/cxl/cxlpci.h                 |   2 -
>  drivers/cxl/port.c                   |  47 +---
>  tools/testing/cxl/Kbuild             |   7 +-
>  tools/testing/cxl/cxl_core_exports.c |  22 ++
>  tools/testing/cxl/exports.h          |  13 ++
>  tools/testing/cxl/test/cxl.c         | 115 ++++++++--
>  tools/testing/cxl/test/mock.c        |  96 +++-----
>  tools/testing/cxl/test/mock.h        |   9 +-
>  16 files changed, 642 insertions(+), 265 deletions(-)
>  create mode 100644 tools/testing/cxl/exports.h
> 
> 
> base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585

Applied to cxl/next with minor fixes from comments:
14868cf9e4b8cefac0fb9eea4993ac3f863a8c0d