Re: [PATCH v15 7/9] cxl: Update Endpoint AER uncorrectable handler

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

On 2/3/2026 11:31 AM, Dave Jiang wrote:
> 
> 
> On 2/2/26 7:52 PM, Terry Bowman wrote:
>> CXL drivers now implement protocol RAS support. PCI protocol errors,
>> however, continue to be reported via the AER capability and must still be
>> handled by a PCI error recovery callback.
>>
>> Replace the existing cxl_error_detected() callback in cxl/pci.c with a
>> new cxl_pci_error_detected() implementation that handles only uncorrectable
>> PCI protocol errors reported through AER.
> 
> Do we need to explain why only uncorrectable is handled?
> 

Would it be Ok if I removed "only" with s/only// ? 

After mentioning an important detail I shoud elaborate. But, how about if 
remove it and not refer to the CE at all here? CE shouldnt be mentioned unless 
good reason in a primarily UCE patch.

- Terry

>>
>> Introduce helper named cxl_handler_aer() amd implement to handle and
>> log the CXL device's AER error.
>>
>> This cleanly separates CXL protocol error handling from PCI AER handling
>> and ensures that each subsystem processes only the errors it is
>> responsible.
>>
>> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
>>
>> ---
>>
>> Changes in v14->v15:
>> - Title update (Terry)
>> - Change cxl_pci_error-detected() to handle & log AER (Terry)
>> - Update commit message (Terry)
>> - Moved cxl_handle_ras()/cxl_handle_cor_ras() to earlier patch (Terry)
>>
>> Changes in v13->v14:
>> - Update commit headline (Bjorn)
>> - Rename pci_error_detected()/pci_cor_error_detected() ->
>>   cxl_pci_error_detected/cxl_pci_cor_error_detected() (Jonathan)
>> - Remove now-invalid comment in cxl_error_detected() (Jonathan)
>> - Split into separate patches for UCE and CE (Terry)
>>
>> Changes in v12->v13:
>> - Update commit messaqge (Terry)
>> - Updated all the implementation and commit message. (Terry)
>> - Refactored cxl_cor_error_detected()/cxl_error_detected() to remove
>>   pdev (Dave Jiang)
>>
>> Changes in v11->v12:
>> - None
>>
>> Changes in v10->v11:
>> - cxl_error_detected() - Change handlers' scoped_guard() to guard() (Jonathan)
>> - cxl_error_detected() - Remove extra line (Shiju)
>> - Changes moved to core/ras.c (Terry)
>> - cxl_error_detected(), remove 'ue' and return with function call. (Jonathan)
>> - Remove extra space in documentation for PCI_ERS_RESULT_PANIC definition
>> - Move #include "pci.h from cxl.h to core.h (Terry)
>> - Remove unnecessary includes of cxl.h and core.h in mem.c (Terry)
>> ---
>>  drivers/cxl/core/ras.c | 68 +++++++++++++++---------------------------
>>  drivers/cxl/cxlpci.h   |  9 +++---
>>  drivers/cxl/pci.c      |  6 ++--
>>  3 files changed, 31 insertions(+), 52 deletions(-)
>>
>> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
>> index 970ff3df442c..061e6aaec176 100644
>> --- a/drivers/cxl/core/ras.c
>> +++ b/drivers/cxl/core/ras.c
>> @@ -441,55 +441,35 @@ void cxl_cor_error_detected(struct pci_dev *pdev)
>>  }
>>  EXPORT_SYMBOL_NS_GPL(cxl_cor_error_detected, "CXL");
>>  
>> -pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
>> -				    pci_channel_state_t state)
>> +static bool cxl_handle_aer(struct pci_dev *pdev)
> 
> For a function that returns a bool, the function name doesn't sound quite right. Maybe cxl_uncor_aer_present()?
> 
> DJ
> 

I was trying to follow the pattern of detected() function calls the 
handle() function as done for cxl_handle_ras() and cxl_handle_cor_ras().

I will change to cxl_uncor_aer_present().

-Terry

>>  {
>> -	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
>> -	struct cxl_memdev *cxlmd = cxlds->cxlmd;
>> -	struct device *dev = &cxlmd->dev;
>> -	bool ue;
>> -
>> -	scoped_guard(device, dev) {
>> -		if (!dev->driver) {
>> -			dev_warn(&pdev->dev,
>> -				 "%s: memdev disabled, abort error handling\n",
>> -				 dev_name(dev));
>> -			return PCI_ERS_RESULT_DISCONNECT;
>> -		}
>> +	struct aer_capability_regs aer;
>> +	u32 aer_cap = pdev->aer_cap;
>>  
>> -		if (cxlds->rcd)
>> -			cxl_handle_rdport_errors(cxlds);
>> -		/*
>> -		 * A frozen channel indicates an impending reset which is fatal to
>> -		 * CXL.mem operation, and will likely crash the system. On the off
>> -		 * chance the situation is recoverable dump the status of the RAS
>> -		 * capability registers and bounce the active state of the memdev.
>> -		 */
>> -		ue = cxl_handle_ras(&cxlds->cxlmd->dev, cxlds->serial,
>> -				    cxlmd->endpoint->regs.ras);
>> +	if (!aer_cap) {
>> +		pr_warn_ratelimited("%s: AER capability isn't present\n",
>> +				    pci_name(pdev));
>> +		return false;
>>  	}
>>  
>> -	switch (state) {
>> -	case pci_channel_io_normal:
>> -		if (ue) {
>> -			device_release_driver(dev);
>> -			return PCI_ERS_RESULT_NEED_RESET;
>> -		}
>> -		return PCI_ERS_RESULT_CAN_RECOVER;
>> -	case pci_channel_io_frozen:
>> -		dev_warn(&pdev->dev,
>> -			 "%s: frozen state error detected, disable CXL.mem\n",
>> -			 dev_name(dev));
>> -		device_release_driver(dev);
>> -		return PCI_ERS_RESULT_NEED_RESET;
>> -	case pci_channel_io_perm_failure:
>> -		dev_warn(&pdev->dev,
>> -			 "failure state error detected, request disconnect\n");
>> -		return PCI_ERS_RESULT_DISCONNECT;
>> -	}
>> -	return PCI_ERS_RESULT_NEED_RESET;
>> +	pci_read_config_dword(pdev, aer_cap + PCI_ERR_UNCOR_STATUS, &aer.uncor_status);
>> +	pci_read_config_dword(pdev, aer_cap + PCI_ERR_UNCOR_MASK, &aer.uncor_mask);
>> +
>> +	/* The AER driver logged the error */
>> +	pci_aer_clear_nonfatal_status(pdev);
>> +	pci_aer_clear_fatal_status(pdev);
>> +
>> +	return (aer.uncor_status & aer.uncor_mask);
>> +}
>> +
>> +pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
>> +					pci_channel_state_t error)
>> +{
>> +	u32 rc = cxl_handle_aer(pdev);
>> +
>> +	return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_CAN_RECOVER;
>>  }
>> -EXPORT_SYMBOL_NS_GPL(cxl_error_detected, "CXL");
>> +EXPORT_SYMBOL_NS_GPL(cxl_pci_error_detected, "CXL");
>>  
>>  static void cxl_handle_proto_error(struct cxl_proto_err_work_data *err_info)
>>  {
>> diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
>> index 970add0256e9..5534422b496c 100644
>> --- a/drivers/cxl/cxlpci.h
>> +++ b/drivers/cxl/cxlpci.h
>> @@ -79,15 +79,14 @@ void read_cdat_data(struct cxl_port *port);
>>  
>>  #ifdef CONFIG_CXL_RAS
>>  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 devm_cxl_dport_rch_ras_setup(struct cxl_dport *dport);
>> +pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
>> +					pci_channel_state_t error);
>>  void devm_cxl_port_ras_setup(struct cxl_port *port);
>>  #else
>>  static inline void cxl_cor_error_detected(struct pci_dev *pdev) { }
>> -
>> -static inline pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
>> -						  pci_channel_state_t state)
>> +static inline pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
>> +						      pci_channel_state_t state)
>>  {
>>  	return PCI_ERS_RESULT_NONE;
>>  }
>> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
>> index acb0eb2a13c3..ff741adc7c7f 100644
>> --- a/drivers/cxl/pci.c
>> +++ b/drivers/cxl/pci.c
>> @@ -1051,8 +1051,8 @@ static void cxl_reset_done(struct pci_dev *pdev)
>>  	}
>>  }
>>  
>> -static const struct pci_error_handlers cxl_error_handlers = {
>> -	.error_detected	= cxl_error_detected,
>> +static const struct pci_error_handlers pci_error_handlers = {
>> +	.error_detected	= cxl_pci_error_detected,
>>  	.slot_reset	= cxl_slot_reset,
>>  	.resume		= cxl_error_resume,
>>  	.cor_error_detected	= cxl_cor_error_detected,
>> @@ -1063,7 +1063,7 @@ static struct pci_driver cxl_pci_driver = {
>>  	.name			= KBUILD_MODNAME,
>>  	.id_table		= cxl_mem_pci_tbl,
>>  	.probe			= cxl_pci_probe,
>> -	.err_handler		= &cxl_error_handlers,
>> +	.err_handler		= &pci_error_handlers,
>>  	.dev_groups		= cxl_rcd_groups,
>>  	.driver	= {
>>  		.probe_type	= PROBE_PREFER_ASYNCHRONOUS,
>