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

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

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?

> 
> 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

>  {
> -	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,