Re: [PATCH V6 10/18] cxl/mem: Refactor cxl pmem region auto-assembling

[Dave Jiang <dave.jiang@intel.com>]

On 1/23/26 4:31 AM, Neeraj Kumar wrote:
> In 84ec985944ef3, devm_cxl_add_nvdimm() sequence was changed and called
> before devm_cxl_add_endpoint(). It's because cxl pmem region auto-assembly
> used to get called at last in cxl_endpoint_port_probe(), which requires
> cxl_nvd presence.
> 
> For cxl region persistency, region creation happens during nvdimm_probe
> which need the completion of endpoint probe.
> 
> In order to accommodate both cxl pmem region auto-assembly and cxl region
> persistency, refactored following
> 
> 1. Re-Sequence devm_cxl_add_nvdimm() after devm_cxl_add_endpoint(). This
>    will be called only after successful completion of endpoint probe.
> 
> 2. Create cxl_region_discovery() which performs pmem region
>    auto-assembly and remove cxl pmem region auto-assembly from
>    cxl_endpoint_port_probe()
> 
> 3. Register cxl_region_discovery() with devm_cxl_add_memdev() which gets
>    called during cxl_pci_probe() in context of cxl_mem_probe()
> 
> 4. As cxlmd->attach->probe() calls registered cxl_region_discovery(), so
>    move devm_cxl_add_nvdimm() before cxlmd->attach->probe(). It guarantees
>    both the completion of endpoint probe and cxl_nvd presence before
>    calling cxlmd->attach->probe().
> 
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Signed-off-by: Neeraj Kumar <s.neeraj@samsung.com>

Hi Neeraj,
Just FYI this is the patch that breaks the auto-region assemble in cxl_test.

DJ

> ---
>  drivers/cxl/core/region.c | 37 +++++++++++++++++++++++++++++++++++++
>  drivers/cxl/cxl.h         |  5 +++++
>  drivers/cxl/mem.c         | 18 +++++++++---------
>  drivers/cxl/pci.c         |  4 +++-
>  drivers/cxl/port.c        | 39 +--------------------------------------
>  5 files changed, 55 insertions(+), 48 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index ae899f68551f..26238fb5e8cf 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3727,6 +3727,43 @@ int cxl_add_to_region(struct cxl_endpoint_decoder *cxled)
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_add_to_region, "CXL");
>  
> +static int discover_region(struct device *dev, void *unused)
> +{
> +	struct cxl_endpoint_decoder *cxled;
> +	int rc;
> +
> +	if (!is_endpoint_decoder(dev))
> +		return 0;
> +
> +	cxled = to_cxl_endpoint_decoder(dev);
> +	if ((cxled->cxld.flags & CXL_DECODER_F_ENABLE) == 0)
> +		return 0;
> +
> +	if (cxled->state != CXL_DECODER_STATE_AUTO)
> +		return 0;
> +
> +	/*
> +	 * Region enumeration is opportunistic, if this add-event fails,
> +	 * continue to the next endpoint decoder.
> +	 */
> +	rc = cxl_add_to_region(cxled);
> +	if (rc)
> +		dev_dbg(dev, "failed to add to region: %#llx-%#llx\n",
> +			cxled->cxld.hpa_range.start, cxled->cxld.hpa_range.end);
> +
> +	return 0;
> +}
> +
> +int cxl_region_discovery(struct cxl_memdev *cxlmd)
> +{
> +	struct cxl_port *port = cxlmd->endpoint;
> +
> +	device_for_each_child(&port->dev, NULL, discover_region);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_NS_GPL(cxl_region_discovery, "CXL");
> +
>  u64 cxl_port_get_spa_cache_alias(struct cxl_port *endpoint, u64 spa)
>  {
>  	struct cxl_region_ref *iter;
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index c796c3db36e0..86efcc4fb963 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -906,6 +906,7 @@ struct cxl_pmem_region *to_cxl_pmem_region(struct device *dev);
>  int cxl_add_to_region(struct cxl_endpoint_decoder *cxled);
>  struct cxl_dax_region *to_cxl_dax_region(struct device *dev);
>  u64 cxl_port_get_spa_cache_alias(struct cxl_port *endpoint, u64 spa);
> +int cxl_region_discovery(struct cxl_memdev *cxlmd);
>  #else
>  static inline bool is_cxl_pmem_region(struct device *dev)
>  {
> @@ -928,6 +929,10 @@ static inline u64 cxl_port_get_spa_cache_alias(struct cxl_port *endpoint,
>  {
>  	return 0;
>  }
> +static inline int cxl_region_discovery(struct cxl_memdev *cxlmd)
> +{
> +	return 0;
> +}
>  #endif
>  
>  void cxl_endpoint_parse_cdat(struct cxl_port *port);
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index 333c366b69e7..7d19528d9b55 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -114,15 +114,6 @@ static int cxl_mem_probe(struct device *dev)
>  		return -ENXIO;
>  	}
>  
> -	if (cxl_pmem_size(cxlds) && IS_ENABLED(CONFIG_CXL_PMEM)) {
> -		rc = devm_cxl_add_nvdimm(parent_port, cxlmd);
> -		if (rc) {
> -			if (rc == -ENODEV)
> -				dev_info(dev, "PMEM disabled by platform\n");
> -			return rc;
> -		}
> -	}
> -
>  	if (dport->rch)
>  		endpoint_parent = parent_port->uport_dev;
>  	else
> @@ -142,6 +133,15 @@ static int cxl_mem_probe(struct device *dev)
>  			return rc;
>  	}
>  
> +	if (cxl_pmem_size(cxlds) && IS_ENABLED(CONFIG_CXL_PMEM)) {
> +		rc = devm_cxl_add_nvdimm(parent_port, cxlmd);
> +		if (rc) {
> +			if (rc == -ENODEV)
> +				dev_info(dev, "PMEM disabled by platform\n");
> +			return rc;
> +		}
> +	}
> +
>  	if (cxlmd->attach) {
>  		rc = cxlmd->attach->probe(cxlmd);
>  		if (rc)
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 549368a9c868..70b40a10be7a 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -903,6 +903,7 @@ __ATTRIBUTE_GROUPS(cxl_rcd);
>  static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  {
>  	struct pci_host_bridge *host_bridge = pci_find_host_bridge(pdev->bus);
> +	struct cxl_memdev_attach memdev_attach = { 0 };
>  	struct cxl_dpa_info range_info = { 0 };
>  	struct cxl_memdev_state *mds;
>  	struct cxl_dev_state *cxlds;
> @@ -1006,7 +1007,8 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	if (rc)
>  		dev_dbg(&pdev->dev, "No CXL Features discovered\n");
>  
> -	cxlmd = devm_cxl_add_memdev(cxlds, NULL);
> +	memdev_attach.probe = cxl_region_discovery;
> +	cxlmd = devm_cxl_add_memdev(cxlds, &memdev_attach);
>  	if (IS_ERR(cxlmd))
>  		return PTR_ERR(cxlmd);
>  
> diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
> index 7937e7e53797..fbeff1978bfb 100644
> --- a/drivers/cxl/port.c
> +++ b/drivers/cxl/port.c
> @@ -30,33 +30,6 @@ static void schedule_detach(void *cxlmd)
>  	schedule_cxl_memdev_detach(cxlmd);
>  }
>  
> -static int discover_region(struct device *dev, void *unused)
> -{
> -	struct cxl_endpoint_decoder *cxled;
> -	int rc;
> -
> -	if (!is_endpoint_decoder(dev))
> -		return 0;
> -
> -	cxled = to_cxl_endpoint_decoder(dev);
> -	if ((cxled->cxld.flags & CXL_DECODER_F_ENABLE) == 0)
> -		return 0;
> -
> -	if (cxled->state != CXL_DECODER_STATE_AUTO)
> -		return 0;
> -
> -	/*
> -	 * Region enumeration is opportunistic, if this add-event fails,
> -	 * continue to the next endpoint decoder.
> -	 */
> -	rc = cxl_add_to_region(cxled);
> -	if (rc)
> -		dev_dbg(dev, "failed to add to region: %#llx-%#llx\n",
> -			cxled->cxld.hpa_range.start, cxled->cxld.hpa_range.end);
> -
> -	return 0;
> -}
> -
>  static int cxl_switch_port_probe(struct cxl_port *port)
>  {
>  	/* Reset nr_dports for rebind of driver */
> @@ -82,17 +55,7 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
>  	if (rc)
>  		return rc;
>  
> -	rc = devm_cxl_endpoint_decoders_setup(port);
> -	if (rc)
> -		return rc;
> -
> -	/*
> -	 * Now that all endpoint decoders are successfully enumerated, try to
> -	 * assemble regions from committed decoders
> -	 */
> -	device_for_each_child(&port->dev, NULL, discover_region);
> -
> -	return 0;
> +	return devm_cxl_endpoint_decoders_setup(port);
>  }
>  
>  static int cxl_port_probe(struct device *dev)