Re: [RFC PATCH 8/9] PCI/AER: Export pci_aer_unmask_internal_errors()

Bjorn Helgaas
2024-07-10T21:47:47Z

On Mon, Jun 17, 2024 at 03:04:10PM -0500, Terry Bowman wrote:
> AER correctable internal errors (CIE) and AER uncorrectable internal
> errors (UIE) are disabled through the AER mask register by default.[1]

Nit: "Correctable Errors" and "Uncorrectable Errors" are generic PCIe
concepts that exist independent of AER, so I wouldn't prefix them with
AER. The AER mask registers control *reporting* of errors, but of
course they don't disable the errors themselves.

> CXL PCIe ports use the CIE/UIE to report RAS errors and as a result
> need CIE/UIE enabled.[2]
>
> Change pci_aer_unmask_internal_errors() function to be exported for
> the CXL driver and other drivers to use.
>
> [1] PCI6.0 - 7.8.4.3 Uncorrectable

s/PCI6.0 .../PCIe r6.0, sec 7.8.4.3/ since there is a conventional PCI
spec as well.

> [2] CXL3.1 - 12.2.2 CXL Root Ports, Downstream Switch Ports, and Upstream
> Switch Ports
>
> Signed-off-by: Terry Bowman <terry.bowman@amd.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> Cc: linux-pci@vger.kernel.org
> ---
> drivers/pci/pcie/aer.c | 3 ++-
> include/linux/aer.h | 6 ++++++
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index 4dc03cb9aff0..d7a1982f0c50 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -951,7 +951,7 @@ static bool find_source_device(struct pci_dev *parent,
> * 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;
> @@ -964,6 +964,7 @@ 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);
>
> static bool is_cxl_mem_dev(struct pci_dev *dev)
> {
> diff --git a/include/linux/aer.h b/include/linux/aer.h
> index 4b97f38f3fcf..a4fd25ea0280 100644
> --- a/include/linux/aer.h
> +++ b/include/linux/aer.h
> @@ -50,6 +50,12 @@ static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
> static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
> #endif
>
> +#ifdef CONFIG_PCIEAER_CXL
> +void pci_aer_unmask_internal_errors(struct pci_dev *dev);
> +#else
> +static inline void pci_aer_unmask_internal_errors(struct pci_dev *dev) { }
> +#endif

I don't like the idea of exporting a generic PCI interface that only
does something when CONFIG_PCIEAER_CXL is enabled. If there's ever a
non-CXL caller, it will be confused.

Bjorn