Re: [PATCH v14 09/34] PCI/AER: Export pci_aer_unmask_internal_errors()

[dan.j.williams]

Terry Bowman wrote:
> Internal PCIe errors are not enabled by default during initialization. This
> creates a problem for CXL drivers, which rely on PCIe Correctable and
> Uncorrectable Internal Errors to receive CXL protocol error notifications.
> 
> Export pci_aer_unmask_internal_errors() so CXL and other drivers can
> enable internal PCIe errors.

I folded in the following to this patch because opening up internal
errors for PCIe drivers in general is not a goal.

1:  cb9a15481d8c ! 1:  7433e0204753 PCI/AER: Export pci_aer_unmask_internal_errors()
    @@ Metadata
      ## Commit message ##
         PCI/AER: Export pci_aer_unmask_internal_errors()
     
    -    Internal PCIe errors are not enabled by default during initialization. This
    -    creates a problem for CXL drivers, which rely on PCIe Correctable and
    -    Uncorrectable Internal Errors to receive CXL protocol error notifications.
    +    Internal PCIe errors are not enabled by default during initialization
    +    because their behavior is too device-specific and there is no standard way
    +    to reason about them. However, for CXL an internal error is the standard
    +    mechanism for conveying CXL protocol errors.
     
    -    Export pci_aer_unmask_internal_errors() so CXL and other drivers can
    -    enable internal PCIe errors.
    +    Export pci_aer_unmask_internal_errors() for CXL, but make it clear that
    +    they are only meant for CXL and the status quo for leaving them masked for
    +    PCIe in general remains.
     
         Signed-off-by: Terry Bowman <terry.bowman@xxxxxxx>
         Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
         Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
         Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>
         Link: https://patch.msgid.link/20260114182055.46029-10-terry.bowman@xxxxxxx
    +    Co-developed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
         Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
     
      ## include/linux/aer.h ##
    @@ drivers/pci/pcie/aer.c: static bool find_source_device(struct pci_dev *parent,
        int aer = dev->aer_cap;
        u32 mask;
     @@ drivers/pci/pcie/aer.c: 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_GPL(pci_aer_unmask_internal_errors);
      
    ++/*
    ++ * Internal errors are too device-specific to enable generally, however for CXL
    ++ * their behavior is standardized for conveying CXL protocol errors.
    ++ */
    ++EXPORT_SYMBOL_FOR_MODULES(pci_aer_unmask_internal_errors, "cxl_core");
    ++
     +#ifdef CONFIG_PCIEAER_CXL
      static bool is_cxl_mem_dev(struct pci_dev *dev)
      {