Re: [PATCH v12 15/25] cxl/pci: Map CXL Endpoint Port and CXL Switch Port RAS registers

["Bowman, Terry" <terry.bowman@amd.com>]

On 10/24/2025 5:25 AM, Alejandro Lucero Palau wrote:
> On 9/26/25 22:10, Dave Jiang wrote:
>> On 9/25/25 3:34 PM, Terry Bowman wrote:
>>> CXL Endpoint (EP) Ports may include Root Ports (RP) or Downstream Switch
>>> Ports (DSP). CXL RPs and DSPs contain RAS registers that require memory
>>> mapping to enable RAS logging. This initialization is currently missing and
>>> must be added for CXL RPs and DSPs.
>>>
>>> Update cxl_dport_init_ras_reporting() to support RP and DSP RAS mapping.
>>> Add alongside the existing Restricted CXL Host Downstream Port RAS mapping.
>>>
>>> Update cxl_endpoint_port_probe() to invoke cxl_dport_init_ras_reporting().
>>> This will initiate the RAS mapping for CXL RPs and DSPs when each CXL EP is
>>> created and added to the EP port.
>>>
>>> Make a call to cxl_port_setup_regs() in cxl_port_add(). This will probe the
>>> Upstream Port's CXL capabilities' physical location to be used in mapping
>>> the RAS registers.
>>>
>>> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
>>>
>>> ---
>>>
>>> Changes in v11->v12:
>>> - Add check for dport_parent->rch before calling cxl_dport_init_ras_reporting().
>>> RCH dports are initialized from cxl_dport_init_ras_reporting cxl_mem_probe().
>>>
>>> Changes in v10->v11:
>>> - Use local pointer for readability in cxl_switch_port_init_ras() (Jonathan Cameron)
>>> - Rename port to be ep in cxl_endpoint_port_init_ras() (Dave Jiang)
>>> - Rename dport to be parent_dport in cxl_endpoint_port_init_ras()
>>>    and cxl_switch_port_init_ras() (Dave Jiang)
>>> - Port helper changes were in cxl/port.c, now in core/ras.c (Dave
>>> Jiang)
>>> ---
>>>   drivers/cxl/core/core.h |  7 ++++++
>>>   drivers/cxl/core/port.c |  1 +
>>>   drivers/cxl/core/ras.c  | 48 +++++++++++++++++++++++++++++++++++++++++
>>>   drivers/cxl/cxl.h       |  2 ++
>>>   drivers/cxl/cxlpci.h    |  4 ----
>>>   drivers/cxl/mem.c       |  4 +++-
>>>   drivers/cxl/port.c      |  5 +++++
>>>   7 files changed, 66 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
>>> index 9f4eb7e2feba..8c51a2631716 100644
>>> --- a/drivers/cxl/core/core.h
>>> +++ b/drivers/cxl/core/core.h
>>> @@ -147,6 +147,9 @@ int cxl_port_get_switch_dport_bandwidth(struct cxl_port *port,
>>>   #ifdef CONFIG_CXL_RAS
>>>   int cxl_ras_init(void);
>>>   void cxl_ras_exit(void);
>>> +void cxl_switch_port_init_ras(struct cxl_port *port);
>>> +void cxl_endpoint_port_init_ras(struct cxl_port *ep);
>>> +void cxl_dport_init_ras_reporting(struct cxl_dport *dport, struct device *host);
>>>   #else
>>>   static inline int cxl_ras_init(void)
>>>   {
>>> @@ -156,6 +159,10 @@ static inline int cxl_ras_init(void)
>>>   static inline void cxl_ras_exit(void)
>>>   {
>>>   }
>>> +static inline void cxl_switch_port_init_ras(struct cxl_port *port) { }
>>> +static inline void cxl_endpoint_port_init_ras(struct cxl_port *ep) { }
>>> +static inline void cxl_dport_init_ras_reporting(struct cxl_dport *dport,
>>> +						struct device *host) { }
>>>   #endif // CONFIG_CXL_RAS
>>>   
>>>   int cxl_gpf_port_setup(struct cxl_dport *dport);
>>> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
>>> index d5f71eb1ade8..bd4be046888a 100644
>>> --- a/drivers/cxl/core/port.c
>>> +++ b/drivers/cxl/core/port.c
>>> @@ -870,6 +870,7 @@ static int cxl_port_add(struct cxl_port *port,
>>>   			return rc;
>>>   
>>>   		port->component_reg_phys = component_reg_phys;
>>> +		cxl_port_setup_regs(port, port->component_reg_phys);
>> This was actually moved previously to delay the port register probe. It now happens when the first dport is discovered. See the end of __devm_cxl_add_dport().
>
> FWIW (other people not going through my discovery path :-) ) Dave is 
> pointing out to his patchset for delaying port probing and now applied 
> to next.
>
>
> Terry, any estimation of when your next version will be sent to the 
> list? My Type2 patchset is dependent on yours, so I'll be reviewing it 
> as soon as you do it.
>
>
> Thank you
>

Hi Alejandro,

It will be early next week.

Terry

>>>   	} else {
>>>   		rc = dev_set_name(dev, "root%d", port->id);
>>>   		if (rc)
>>> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
>>> index 97a5a5c3910f..14a434bd68f0 100644
>>> --- a/drivers/cxl/core/ras.c
>>> +++ b/drivers/cxl/core/ras.c
>>> @@ -283,6 +283,54 @@ void cxl_dport_init_ras_reporting(struct cxl_dport *dport, struct device *host)
>>>   }
>>>   EXPORT_SYMBOL_NS_GPL(cxl_dport_init_ras_reporting, "CXL");
>>>   
>>> +static void cxl_uport_init_ras_reporting(struct cxl_port *port,
>>> +					 struct device *host)
>>> +{
>>> +	struct cxl_register_map *map = &port->reg_map;
>>> +
>>> +	map->host = host;
>>> +	if (cxl_map_component_regs(map, &port->uport_regs,
>>> +				   BIT(CXL_CM_CAP_CAP_ID_RAS)))
>>> +		dev_dbg(&port->dev, "Failed to map RAS capability\n");
>>> +}
>>> +
>>> +void cxl_switch_port_init_ras(struct cxl_port *port)
>>> +{
>>> +	struct cxl_dport *parent_dport = port->parent_dport;
>>> +
>>> +	if (is_cxl_root(to_cxl_port(port->dev.parent)))
>>> +		return;
>>> +
>>> +	/* May have parent DSP or RP */
>>> +	if (parent_dport && dev_is_pci(parent_dport->dport_dev) &&
>>> +	    !parent_dport->rch) {
>>> +		struct pci_dev *pdev = to_pci_dev(parent_dport->dport_dev);
>>> +
>>> +		if ((pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT) ||
>>> +		    (pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM))
>>> +			cxl_dport_init_ras_reporting(parent_dport, &port->dev);
>>> +	}
>>> +
>>> +	cxl_uport_init_ras_reporting(port, &port->dev);
>>> +}
>>> +EXPORT_SYMBOL_NS_GPL(cxl_switch_port_init_ras, "CXL");
>>> +
>>> +void cxl_endpoint_port_init_ras(struct cxl_port *ep)
>>> +{
>>> +	struct cxl_dport *parent_dport;
>>> +	struct cxl_memdev *cxlmd = to_cxl_memdev(ep->uport_dev);
>>> +	struct cxl_port *parent_port __free(put_cxl_port) =
>>> +		cxl_mem_find_port(cxlmd, &parent_dport);
>>> +
>>> +	if (!parent_dport || !dev_is_pci(parent_dport->dport_dev) || parent_dport->rch) {
>>> +		dev_err(&ep->dev, "CXL port topology not found\n");
>>> +		return;
>>> +	}
>>> +
>>> +	cxl_dport_init_ras_reporting(parent_dport, cxlmd->cxlds->dev);
>>> +}
>>> +EXPORT_SYMBOL_NS_GPL(cxl_endpoint_port_init_ras, "CXL");
>>> +
>>>   static void cxl_handle_cor_ras(struct device *dev, u64 serial, void __iomem *ras_base)
>>>   {
>>>   	void __iomem *addr;
>>> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
>>> index 259ed4b676e1..b7654d40dc9e 100644
>>> --- a/drivers/cxl/cxl.h
>>> +++ b/drivers/cxl/cxl.h
>>> @@ -599,6 +599,7 @@ struct cxl_dax_region {
>>>    * @parent_dport: dport that points to this port in the parent
>>>    * @decoder_ida: allocator for decoder ids
>>>    * @reg_map: component and ras register mapping parameters
>>> + * @uport_regs: mapped component registers
>>>    * @nr_dports: number of entries in @dports
>>>    * @hdm_end: track last allocated HDM decoder instance for allocation ordering
>>>    * @commit_end: cursor to track highest committed decoder for commit ordering
>>> @@ -620,6 +621,7 @@ struct cxl_port {
>>>   	struct cxl_dport *parent_dport;
>>>   	struct ida decoder_ida;
>>>   	struct cxl_register_map reg_map;
>>> +	struct cxl_component_regs uport_regs;
>>>   	int nr_dports;
>>>   	int hdm_end;
>>>   	int commit_end;
>>> diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
>>> index 0c8b6ee7b6de..3882a089ae77 100644
>>> --- a/drivers/cxl/cxlpci.h
>>> +++ b/drivers/cxl/cxlpci.h
>>> @@ -82,7 +82,6 @@ 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,
>>>   				    pci_channel_state_t state);
>>> -void cxl_dport_init_ras_reporting(struct cxl_dport *dport, struct device *host);
>>>   #else
>>>   static inline void cxl_cor_error_detected(struct pci_dev *pdev) { }
>>>   
>>> @@ -91,9 +90,6 @@ static inline pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
>>>   {
>>>   	return PCI_ERS_RESULT_NONE;
>>>   }
>>> -
>>> -static inline void cxl_dport_init_ras_reporting(struct cxl_dport *dport,
>>> -						struct device *host) { }
>>>   #endif
>>>   
>>>   #endif /* __CXL_PCI_H__ */
>> I think this change broke cxl_test:
>>
>>    CC [M]  test/mem.o
>> test/mock.c: In function ‘__wrap_cxl_dport_init_ras_reporting’:
>> test/mock.c:266:17: error: implicit declaration of function ‘cxl_dport_init_ras_reporting’ [-Wimplicit-function-declaration]
>>    266 |                 cxl_dport_init_ras_reporting(dport, host);
>>        |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>>
>>> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
>>> index 6e6777b7bafb..f7dc0ba8905d 100644
>>> --- a/drivers/cxl/mem.c
>>> +++ b/drivers/cxl/mem.c
>>> @@ -7,6 +7,7 @@
>>>   
>>>   #include "cxlmem.h"
>>>   #include "cxlpci.h"
>>> +#include "core/core.h"
>>>   
>>>   /**
>>>    * DOC: cxl mem
>>> @@ -166,7 +167,8 @@ static int cxl_mem_probe(struct device *dev)
>>>   	else
>>>   		endpoint_parent = &parent_port->dev;
>>>   
>>> -	cxl_dport_init_ras_reporting(dport, dev);
>>> +	if (dport->rch)
>>> +		cxl_dport_init_ras_reporting(dport, dev);
>>>   
>>>   	scoped_guard(device, endpoint_parent) {
>>>   		if (!endpoint_parent->driver) {
>>> diff --git a/drivers/cxl/port.c b/drivers/cxl/port.c
>>> index 51c8f2f84717..2d12890b66fe 100644
>>> --- a/drivers/cxl/port.c
>>> +++ b/drivers/cxl/port.c
>>> @@ -6,6 +6,7 @@
>>>   
>>>   #include "cxlmem.h"
>>>   #include "cxlpci.h"
>>> +#include "core/core.h"
>>>   
>>>   /**
>>>    * DOC: cxl port
>>> @@ -65,6 +66,8 @@ static int cxl_switch_port_probe(struct cxl_port *port)
>>>   	/* Cache the data early to ensure is_visible() works */
>>>   	read_cdat_data(port);
>>>   
>>> +	cxl_switch_port_init_ras(port);
>> This is probably not the right place to do it because you have no dports yet with the new delayed dport setup. I would init the uport when the register gets probed in __devm_cxl_add_dport(), and init the dport on per dport basis as they are discovered. So maybe in cxl_port_add_dport(). This is where the old dport stuff in the switch probe got moved to.
>>
>>> +
>>>   	return 0;
>>>   }
>>>   
>>> @@ -86,6 +89,8 @@ static int cxl_endpoint_port_probe(struct cxl_port *port)
>>>   	if (rc)
>>>   		return rc;
>>>   
>>> +	cxl_endpoint_port_init_ras(port);
>>> +
>>>   	/*
>>>   	 * Now that all endpoint decoders are successfully enumerated, try to
>>>   	 * assemble regions from committed decoders