Re: [PATCH v12 21/25] CXL/PCI: Introduce CXL Port protocol error handlers

["Cheatham, Benjamin" <benjamin.cheatham@amd.com>]

On 9/25/2025 5:34 PM, Terry Bowman wrote:
> Introduce CXL error handlers for CXL Port devices.
> 
> Add functions cxl_port_cor_error_detected() and cxl_port_error_detected().
> These will serve as the handlers for all CXL Port devices. Introduce
> cxl_get_ras_base() to provide the RAS base address needed by the handlers.
> 
> Update cxl_handle_proto_error() to call the CXL Port or CXL Endpoint
> handler depending on which CXL device reports the error.
> 
> Implement cxl_get_ras_base() to return the cached RAS register address of a
> CXL Root Port, CXL Downstream Port, or CXL Upstream Port.
> 
> Introduce get_pci_cxl_host_dev() to return the host responsible for
> releasing the RAS mapped resources. CXL endpoints do not use a host to
> manage its resources, allow for NULL in the case of an EP. Use reference
> count increment on the host to prevent resource release. Make the caller
> responsible for the reference decrement.
> 
> Update the AER driver's is_cxl_error() PCI type check because CXL Port
> devices are now supported.
> 
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> 
> ---
> 
> Changes in v11->v12:
> - Add call to cxl_pci_drv_bound() in cxl_handle_proto_error() and
>   pci_to_cxl_dev()
> - Change cxl_error_detected() -> cxl_cor_error_detected()
> - Remove NULL variable assignments
> - Replace bus_find_device() with find_cxl_port_by_uport() for upstream
>   port searches.
> 
> Changes in v10->v11:
> - None
> ---
>  drivers/cxl/core/core.h       |  10 +++
>  drivers/cxl/core/port.c       |   7 +-
>  drivers/cxl/core/ras.c        | 159 ++++++++++++++++++++++++++++++++--
>  drivers/pci/pcie/aer_cxl_vh.c |   5 +-
>  4 files changed, 170 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h
> index 9ceff8acf844..3197a71bf7b8 100644
> --- a/drivers/cxl/core/core.h
> +++ b/drivers/cxl/core/core.h
> @@ -156,6 +156,8 @@ pci_ers_result_t pci_error_detected(struct pci_dev *pdev,
>  void pci_cor_error_detected(struct pci_dev *pdev);
>  void cxl_cor_error_detected(struct device *dev);
>  pci_ers_result_t cxl_error_detected(struct device *dev);
> +void cxl_port_cor_error_detected(struct device *dev);
> +pci_ers_result_t cxl_port_error_detected(struct device *dev);
>  #else
>  static inline int cxl_ras_init(void)
>  {
> @@ -180,9 +182,17 @@ static inline pci_ers_result_t cxl_error_detected(struct device *dev)
>  {
>  	return PCI_ERS_RESULT_NONE;
>  }
> +static inline void cxl_port_cor_error_detected(struct device *dev) { }
> +static inline pci_ers_result_t cxl_port_error_detected(struct device *dev)
> +{
> +	return PCI_ERS_RESULT_NONE;

Same question as endpoint error handler on if this should be a PCI_ERS_RESULT_PANIC instead.

> +}
>  #endif // CONFIG_CXL_RAS

Wrong comment style.

>  
>  int cxl_gpf_port_setup(struct cxl_dport *dport);
> +struct cxl_port *find_cxl_port(struct device *dport_dev,
> +			       struct cxl_dport **dport);
> +struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev);
>  
>  struct cxl_hdm;
>  int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm,
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index 56fa4ac33e8b..f34a44abb2c9 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -1357,8 +1357,8 @@ static struct cxl_port *__find_cxl_port(struct cxl_find_port_ctx *ctx)
>  	return NULL;
>  }
>  
> -static struct cxl_port *find_cxl_port(struct device *dport_dev,
> -				      struct cxl_dport **dport)
> +struct cxl_port *find_cxl_port(struct device *dport_dev,
> +			       struct cxl_dport **dport)
>  {
>  	struct cxl_find_port_ctx ctx = {
>  		.dport_dev = dport_dev,
> @@ -1561,7 +1561,7 @@ static int match_port_by_uport(struct device *dev, const void *data)
>   * Function takes a device reference on the port device. Caller should do a
>   * put_device() when done.
>   */
> -static struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev)
> +struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev)
>  {
>  	struct device *dev;
>  
> @@ -1570,6 +1570,7 @@ static struct cxl_port *find_cxl_port_by_uport(struct device *uport_dev)
>  		return to_cxl_port(dev);
>  	return NULL;
>  }
> +EXPORT_SYMBOL_NS_GPL(find_cxl_port_by_uport, "CXL");
>  
>  static int update_decoder_targets(struct device *dev, void *data)
>  {
> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index 9acfe24ba3bb..7e8d63c32d72 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> @@ -250,6 +250,129 @@ static void cxl_dport_map_ras(struct cxl_dport *dport)
>  		dev_dbg(dev, "Failed to map RAS capability.\n");
>  }
>  
> +static void __iomem *cxl_get_ras_base(struct device *dev)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +
> +	switch (pci_pcie_type(pdev)) {
> +	case PCI_EXP_TYPE_ROOT_PORT:
> +	case PCI_EXP_TYPE_DOWNSTREAM:
> +	{
> +		struct cxl_dport *dport;
> +		struct cxl_port *port __free(put_cxl_port) = find_cxl_port(&pdev->dev, &dport);
> +
> +		if (!dport || !dport->dport_dev) {
> +			pci_err(pdev, "Failed to find the CXL device");
> +			return NULL;
> +		}
> +
> +		return dport->regs.ras;
> +	}
> +	case PCI_EXP_TYPE_UPSTREAM:
> +	{
> +		struct cxl_port *port __free(put_cxl_port) = find_cxl_port_by_uport(&pdev->dev);
> +
> +		if (!port) {
> +			pci_err(pdev, "Failed to find the CXL device");
> +			return NULL;
> +		}
> +
> +		return port->uport_regs.ras;
> +	}
> +	}
> +
> +	dev_warn_once(dev, "Error: Unsupported device type (%X)", pci_pcie_type(pdev));
> +	return NULL;
> +}
> +
> +static struct device *pci_to_cxl_dev(struct pci_dev *pdev)
> +{
> +	switch (pci_pcie_type(pdev)) {
> +	case PCI_EXP_TYPE_ROOT_PORT:
> +	case PCI_EXP_TYPE_DOWNSTREAM:
> +	{
> +		struct cxl_dport *dport;
> +		struct cxl_port *port __free(put_cxl_port) = find_cxl_port(&pdev->dev, &dport);
> +
> +		if (!port) {
> +			pci_err(pdev, "Failed to find the CXL device");
> +			return NULL;
> +		}
> +
> +		return dport->dport_dev;
> +	}
> +	case PCI_EXP_TYPE_UPSTREAM:
> +	{
> +		struct cxl_port *port __free(put_cxl_port) = find_cxl_port_by_uport(&pdev->dev);
> +
> +		if (!port) {
> +			pci_err(pdev, "Failed to find the CXL device");
> +			return NULL;
> +		}
> +
> +		return port->uport_dev;
> +	}
> +	case PCI_EXP_TYPE_ENDPOINT:
> +	{
> +		struct cxl_dev_state *cxlds;
> +
> +		if (!cxl_pci_drv_bound(pdev))
> +			return NULL;
> +
> +		cxlds = pci_get_drvdata(pdev);
> +		return cxlds->dev;
> +	}
> +	}
> +
> +	pci_warn_once(pdev, "Error: Unsupported device type (%X)", pci_pcie_type(pdev));
> +	return NULL;
> +}
> +
> +/*
> + * Return 'struct device *' responsible for freeing pdev's CXL resources.
> + * Caller is responsible for reference count decrementing the return
> + * 'struct device *'.
> + *
> + * dev: Find the host of this dev
> + */
> +static struct device *get_cxl_host_dev(struct device *dev)
> +{
> +	struct pci_dev *pdev = to_pci_dev(dev);
> +
> +	switch (pci_pcie_type(pdev)) {
> +	case PCI_EXP_TYPE_ROOT_PORT:
> +	case PCI_EXP_TYPE_DOWNSTREAM:
> +	{
> +		struct cxl_dport *dport;
> +		struct cxl_port *port __free(put_cxl_port) = find_cxl_port(&pdev->dev, &dport);
> +
> +		if (!port) {
> +			pci_err(pdev, "Failed to find the CXL device");
> +			return NULL;
> +		}
> +
> +		return &port->dev;

I may just be tired, but won't the __free() action get called here unless you use no_free_ptr()?
You do the same thing with cxl_get_ras_base() and pci_to_cxl_dev() above, though I think it's the
intended behavior for the latter function.