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

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

On 1/14/2025 5:45 PM, Ira Weiny wrote:
> Bowman, Terry wrote:
>>
>>
>> On 1/14/2025 5:26 PM, Ira Weiny wrote:
>>> 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
>> Bjorn (I believe in v1 or v2) directed me to remove
>> pci_aer_unmask_internal_errors() dependency on PCIEAER_CXL because it is
>> now exported. He wants the behavior for other users (and subsystems) to
>> be consistent with/without the PCIEAER_CXL setting.
>>
> I see...  If PCIEAER_CXL is not enabled why even set the cxl error
> handlers and enable these?
>
> I guess this is just adding some code which eventually calls
> handles_cxl_errors() which returns false in the !PCIEAER_CXL case?
>
> Ira

Re-sending because I somehow sent from Outlook earlier.

cxl_dport_init_ras_reporting() and cxl_uport_init_ras_reporting() assign the error 
handlers and are within #ifdef PCIEAER_CXL. The stubs are in cxl.h.

Correct. handles_cxl_errors() returns false in the !PCIEAER_CXL case.

Terry
>>>> 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@amd.com>
>>>> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.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
>>>>
>