linux-kernel - Re: [PATCH v5 16/16] PCI/AER: Enable internal errors for CXL Upstream and Downstream Switch Ports

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Message-ID: <6786f2a7b2b7f_186d9b294f7@iweiny-mobl.notmuch>
Date: Tue, 14 Jan 2025 17:26:31 -0600
From: Ira Weiny <ira.weiny@...el.com>
To: Terry Bowman <terry.bowman@....com>, <linux-cxl@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-pci@...r.kernel.org>,
	<nifan.cxl@...il.com>, <dave@...olabs.net>, <jonathan.cameron@...wei.com>,
	<dave.jiang@...el.com>, <alison.schofield@...el.com>,
	<vishal.l.verma@...el.com>, <dan.j.williams@...el.com>,
	<bhelgaas@...gle.com>, <mahesh@...ux.ibm.com>, <ira.weiny@...el.com>,
	<oohall@...il.com>, <Benjamin.Cheatham@....com>, <rrichter@....com>,
	<nathan.fontenot@....com>, <Smita.KoralahalliChannabasappa@....com>,
	<lukas@...ner.de>, <ming.li@...omail.com>,
	<PradeepVineshReddy.Kodamati@....com>, <alucerop@....com>
Subject: Re: [PATCH v5 16/16] PCI/AER: Enable internal errors for CXL
 Upstream and Downstream Switch Ports

Terry Bowman wrote:
> The AER service driver enables PCIe Uncorrectable Internal Errors (UIE) and
> Correctable Internal errors (CIE) for CXL Root Ports. The UIE and CIE are
> used in reporting CXL Protocol Errors. The same UIE/CIE enablement is
> needed for CXL Upstream Switch Ports and CXL Downstream Switch Ports
> inorder to notify the associated Root Port and OS.[1]
> 
> Export the AER service driver's pci_aer_unmask_internal_errors() function
> to CXL namespace.
> 
> Remove the function's dependency on the CONFIG_PCIEAER_CXL kernel config
> because it is now an exported function.

This seems wrong to me.  As of this patch CXL_PCI requires PCIEAER_CXL for
the AER code to handle the errors which were just enabled.

To keep PCIEAER_CXL optional pci_aer_unmask_internal_errors() should be
stubbed out in aer.h if !CONFIG_PCIEAER_CXL.

Ira

> 
> Call pci_aer_unmask_internal_errors() during RAS initialization in:
> cxl_uport_init_ras_reporting() and cxl_dport_init_ras_reporting().
> 
> [1] PCIe Base Spec r6.2-1.0, 6.2.3.2.2 Masking Individual Errors
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.com>
> ---
>  drivers/cxl/core/pci.c | 2 ++
>  drivers/pci/pcie/aer.c | 5 +++--
>  include/linux/aer.h    | 1 +
>  3 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
> index 9c162120f0fe..c62329cd9a87 100644
> --- a/drivers/cxl/core/pci.c
> +++ b/drivers/cxl/core/pci.c
> @@ -895,6 +895,7 @@ void cxl_uport_init_ras_reporting(struct cxl_port *port)
>  
>  	cxl_assign_port_error_handlers(pdev);
>  	devm_add_action_or_reset(&port->dev, cxl_clear_port_error_handlers, pdev);
> +	pci_aer_unmask_internal_errors(pdev);
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_uport_init_ras_reporting, "CXL");
>  
> @@ -935,6 +936,7 @@ void cxl_dport_init_ras_reporting(struct cxl_dport *dport)
>  	}
>  	cxl_assign_port_error_handlers(pdev);
>  	devm_add_action_or_reset(&port->dev, cxl_clear_port_error_handlers, pdev);
> +	pci_aer_unmask_internal_errors(pdev);
>  	put_device(&port->dev);
>  }
>  EXPORT_SYMBOL_NS_GPL(cxl_dport_init_ras_reporting, "CXL");
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 68e957459008..e6aaa3bd84f0 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -950,7 +950,6 @@ static bool is_internal_error(struct aer_err_info *info)
>  	return info->status & PCI_ERR_UNC_INTN;
>  }
>  
> -#ifdef CONFIG_PCIEAER_CXL
>  /**
>   * pci_aer_unmask_internal_errors - unmask internal errors
>   * @dev: pointer to the pcie_dev data structure
> @@ -961,7 +960,7 @@ static bool is_internal_error(struct aer_err_info *info)
>   * Note: AER must be enabled and supported by the device which must be
>   * checked in advance, e.g. with pcie_aer_is_native().
>   */
> -static void pci_aer_unmask_internal_errors(struct pci_dev *dev)
> +void pci_aer_unmask_internal_errors(struct pci_dev *dev)
>  {
>  	int aer = dev->aer_cap;
>  	u32 mask;
> @@ -974,7 +973,9 @@ static void pci_aer_unmask_internal_errors(struct pci_dev *dev)
>  	mask &= ~PCI_ERR_COR_INTERNAL;
>  	pci_write_config_dword(dev, aer + PCI_ERR_COR_MASK, mask);
>  }
> +EXPORT_SYMBOL_NS_GPL(pci_aer_unmask_internal_errors, "CXL");
>  
> +#ifdef CONFIG_PCIEAER_CXL
>  static bool is_cxl_mem_dev(struct pci_dev *dev)
>  {
>  	/*
> diff --git a/include/linux/aer.h b/include/linux/aer.h
> index 4b97f38f3fcf..093293f9f12b 100644
> --- a/include/linux/aer.h
> +++ b/include/linux/aer.h
> @@ -55,5 +55,6 @@ void pci_print_aer(struct pci_dev *dev, int aer_severity,
>  int cper_severity_to_aer(int cper_severity);
>  void aer_recover_queue(int domain, unsigned int bus, unsigned int devfn,
>  		       int severity, struct aer_capability_regs *aer_regs);
> +void pci_aer_unmask_internal_errors(struct pci_dev *dev);
>  #endif //_AER_H_
>  
> -- 
> 2.34.1
>