Re: [PATCH v9 12/16] cxl/pci: Introduce CXL Endpoint protocol error handlers

[Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>]

On 6/3/25 10:22 AM, Terry Bowman wrote:
> CXL Endpoint protocol errors are currently handled using PCI error
> handlers. The CXL Endpoint requires CXL specific handling in the case of
> uncorrectable error handling not provided by the PCI handlers.
>
> Add CXL specific handlers for CXL Endpoints. Rename the existing
> cxl_error_handlers to be pci_error_handlers to more correctly indicate
> the error type and follow naming consistency.
>
> Keep the existing PCI Endpoint handlers. PCI handlers can be called if the
> CXL device is not trained for alternate protocol (CXL). Update the CXL
> Endpoint PCI handlers to call the CXL handler. If the CXL uncorrectable
> handler returns PCI_ERS_RESULT_PANIC then the PCI handler invokes panic().
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> ---

Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>

>   drivers/cxl/core/pci.c | 80 ++++++++++++++++++++++--------------------
>   drivers/cxl/core/ras.c | 10 +++---
>   drivers/cxl/cxl.h      |  4 +++
>   drivers/cxl/cxlpci.h   |  6 ++--
>   drivers/cxl/pci.c      |  8 ++---
>   5 files changed, 58 insertions(+), 50 deletions(-)
>
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index f5f87c2c3fd5..e094ef518e0a 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -710,8 +710,8 @@ static void header_log_copy(void __iomem *ras_base, u32 *log)
>    * Log the state of the RAS status registers and prepare them to log the
>    * next error status. Return 1 if reset needed.
>    */
> -static bool __cxl_handle_ras(struct device *dev, u64 serial,
> -			     void __iomem *ras_base)
> +static pci_ers_result_t __cxl_handle_ras(struct device *dev, u64 serial,
> +					 void __iomem *ras_base)
>   {
>   	u32 hl[CXL_HEADERLOG_SIZE_U32];
>   	void __iomem *addr;
> @@ -720,13 +720,13 @@ static bool __cxl_handle_ras(struct device *dev, u64 serial,
>   
>   	if (!ras_base) {
>   		dev_warn_once(dev, "CXL RAS register block is not mapped");
> -		return false;
> +		return PCI_ERS_RESULT_NONE;
>   	}
>   
>   	addr = ras_base + CXL_RAS_UNCORRECTABLE_STATUS_OFFSET;
>   	status = readl(addr);
>   	if (!(status & CXL_RAS_UNCORRECTABLE_STATUS_MASK))
> -		return false;
> +		return PCI_ERS_RESULT_NONE;
>   
>   	/* If multiple errors, log header points to first error from ctrl reg */
>   	if (hweight32(status) > 1) {
> @@ -743,12 +743,11 @@ static bool __cxl_handle_ras(struct device *dev, u64 serial,
>   	trace_cxl_aer_uncorrectable_error(dev, serial, status, fe, hl);
>   	writel(status & CXL_RAS_UNCORRECTABLE_STATUS_MASK, addr);
>   
> -	return true;
> +	return PCI_ERS_RESULT_PANIC;
>   }
>   
>   static bool cxl_handle_endpoint_ras(struct cxl_dev_state *cxlds)
>   {
> -
>   	return __cxl_handle_ras(&cxlds->cxlmd->dev, cxlds->serial, cxlds->regs.ras);
>   }
>   
> @@ -844,14 +843,15 @@ static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds)
>   static void cxl_handle_rdport_errors(struct cxl_dev_state *cxlds) { }
>   #endif
>   
> -void cxl_cor_error_detected(struct pci_dev *pdev)
> +void cxl_cor_error_detected(struct device *dev)
>   {
> +	struct pci_dev *pdev = to_pci_dev(dev);
>   	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> -	struct device *dev = &cxlds->cxlmd->dev;
> +	struct device *cxlmd_dev = &cxlds->cxlmd->dev;
>   
> -	scoped_guard(device, dev) {
> -		if (!dev->driver) {
> -			dev_warn(&pdev->dev,
> +	scoped_guard(device, cxlmd_dev) {
> +		if (!cxlmd_dev->driver) {
> +			dev_warn(dev,
>   				 "%s: memdev disabled, abort error handling\n",
>   				 dev_name(dev));
>   			return;
> @@ -865,20 +865,28 @@ 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)
> +void pci_cor_error_detected(struct pci_dev *pdev)
>   {
>   	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> -	struct cxl_memdev *cxlmd = cxlds->cxlmd;
> -	struct device *dev = &cxlmd->dev;
> -	bool ue;
> +	struct device *cxlmd_dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
>   
> -	scoped_guard(device, dev) {
> +	cxl_cor_error_detected(&pdev->dev);
> +}
> +EXPORT_SYMBOL_NS_GPL(pci_cor_error_detected, "CXL");
> +
> +pci_ers_result_t cxl_error_detected(struct device *dev)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> +	struct device *cxlmd_dev = &cxlds->cxlmd->dev;
> +	pci_ers_result_t ue;
> +
> +	scoped_guard(device, cxlmd_dev) {
>   		if (!dev->driver) {
>   			dev_warn(&pdev->dev,
>   				 "%s: memdev disabled, abort error handling\n",
>   				 dev_name(dev));
> -			return PCI_ERS_RESULT_DISCONNECT;
> +			return PCI_ERS_RESULT_PANIC;
>   		}
>   
>   		if (cxlds->rcd)
> @@ -892,29 +900,25 @@ pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
>   		ue = cxl_handle_endpoint_ras(cxlds);
>   	}
>   
> -
> -	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;
> +	return ue;
>   }
>   EXPORT_SYMBOL_NS_GPL(cxl_error_detected, "CXL");
>   
> +pci_ers_result_t pci_error_detected(struct pci_dev *pdev,
> +				    pci_channel_state_t error)
> +{
> +	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> +	struct device *cxlmd_dev __free(put_device) = &cxlds->cxlmd->dev;
> +	pci_ers_result_t rc;
> +
> +	rc = cxl_error_detected(&pdev->dev);
> +	if (rc == PCI_ERS_RESULT_PANIC)
> +		panic("CXL cachemem error.");
> +
> +	return rc;
> +}
> +EXPORT_SYMBOL_NS_GPL(pci_error_detected, "CXL");
> +
>   static int cxl_flit_size(struct pci_dev *pdev)
>   {
>   	if (cxl_pci_flit_256(pdev))
> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index 0ef8c2068c0c..664f532cc838 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> @@ -153,7 +153,7 @@ static int cxl_report_error_detected(struct pci_dev *pdev, void *data)
>   	struct device *dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
>   
>   	device_lock(&pdev->dev);
> -	vote = cxl_error_detected(pdev, pci_channel_io_frozen);
> +	vote = cxl_error_detected(&pdev->dev);
>   	*result = cxl_merge_result(*result, vote);
>   	device_unlock(&pdev->dev);
>   
> @@ -223,7 +223,7 @@ static int cxl_rch_handle_error_iter(struct pci_dev *pdev, void *data)
>   	struct device *dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
>   
>   	if (err_info->severity == AER_CORRECTABLE)
> -		cxl_cor_error_detected(pdev);
> +		cxl_cor_error_detected(dev);
>   	else
>   		cxl_do_recovery(pdev);
>   
> @@ -244,6 +244,8 @@ static struct pci_dev *sbdf_to_pci(struct cxl_prot_error_info *err_info)
>   static void cxl_handle_prot_error(struct cxl_prot_error_info *err_info)
>   {
>   	struct pci_dev *pdev __free(pci_dev_put) = pci_dev_get(sbdf_to_pci(err_info));
> +	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> +	struct device *cxlmd_dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
>   
>   	if (!pdev) {
>   		pr_err("Failed to find the CXL device\n");
> @@ -260,15 +262,13 @@ static void cxl_handle_prot_error(struct cxl_prot_error_info *err_info)
>   
>   	if (err_info->severity == AER_CORRECTABLE) {
>   		int aer = pdev->aer_cap;
> -		struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
> -		struct device *dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
>   
>   		if (aer)
>   			pci_clear_and_set_config_dword(pdev,
>   						       aer + PCI_ERR_COR_STATUS,
>   						       0, PCI_ERR_COR_INTERNAL);
>   
> -		cxl_cor_error_detected(pdev);
> +		cxl_cor_error_detected(&pdev->dev);
>   
>   		pcie_clear_device_status(pdev);
>   	} else {
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 73be66ef36a2..6fd9a42eb304 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -11,6 +11,7 @@
>   #include <linux/log2.h>
>   #include <linux/node.h>
>   #include <linux/io.h>
> +#include <linux/pci.h>
>   
>   extern const struct nvdimm_security_ops *cxl_security_ops;
>   
> @@ -797,6 +798,9 @@ static inline int cxl_root_decoder_autoremove(struct device *host,
>   }
>   int cxl_endpoint_autoremove(struct cxl_memdev *cxlmd, struct cxl_port *endpoint);
>   
> +void cxl_cor_error_detected(struct device *dev);
> +pci_ers_result_t cxl_error_detected(struct device *dev);
> +
>   /**
>    * struct cxl_endpoint_dvsec_info - Cached DVSEC info
>    * @mem_enabled: cached value of mem_enabled in the DVSEC at init time
> diff --git a/drivers/cxl/cxlpci.h b/drivers/cxl/cxlpci.h
> index 6f1396ef7b77..a572c57c6c63 100644
> --- a/drivers/cxl/cxlpci.h
> +++ b/drivers/cxl/cxlpci.h
> @@ -133,7 +133,7 @@ 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,
> -				    pci_channel_state_t state);
> +void pci_cor_error_detected(struct pci_dev *pdev);
> +pci_ers_result_t pci_error_detected(struct pci_dev *pdev,
> +				    pci_channel_state_t error);
>   #endif /* __CXL_PCI_H__ */
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 785aa2af5eaa..2b948e94bc97 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -1112,11 +1112,11 @@ 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 = pci_error_detected,
>   	.slot_reset	= cxl_slot_reset,
>   	.resume		= cxl_error_resume,
> -	.cor_error_detected	= cxl_cor_error_detected,
> +	.cor_error_detected	= pci_cor_error_detected,
>   	.reset_done	= cxl_reset_done,
>   };
>   
> @@ -1124,7 +1124,7 @@ 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,

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer