linux-kernel - Re: [PATCH v13 08/25] CXL/AER: Move AER drivers RCH error handling into pcie/aer_cxl

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Message-ID: <20251208180624.GA3300935@bhelgaas>
Date: Mon, 8 Dec 2025 12:06:24 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: Terry Bowman <terry.bowman@....com>
Cc: dave@...olabs.net, jonathan.cameron@...wei.com, dave.jiang@...el.com,
	alison.schofield@...el.com, dan.j.williams@...el.com,
	bhelgaas@...gle.com, shiju.jose@...wei.com, ming.li@...omail.com,
	Smita.KoralahalliChannabasappa@....com, rrichter@....com,
	dan.carpenter@...aro.org, PradeepVineshReddy.Kodamati@....com,
	lukas@...ner.de, Benjamin.Cheatham@....com,
	sathyanarayanan.kuppuswamy@...ux.intel.com,
	linux-cxl@...r.kernel.org, alucerop@....com, ira.weiny@...el.com,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v13 08/25] CXL/AER: Move AER drivers RCH error handling
 into pcie/aer_cxl_rch.c

I vote for a subject like:

  PCI/AER: Move CXL RCH error handling to aer_cxl_rch.c

I think stuff in drivers/pci should have a PCI/... prefix.  "CXL" is
really its own major subsystem, not a feature of PCI.

On Mon, Nov 03, 2025 at 06:09:44PM -0600, Terry Bowman wrote:
> The restricted CXL Host (RCH) AER error handling logic currently resides
> in the AER driver file, drivers/pci/pcie/aer.c. CXL specific changes are
> conditionally compiled using #ifdefs.

s|the AER driver file, drivers/pci/pcie/aer.c|aer.c|

> Improve the AER driver maintainability by separating the RCH specific logic
> from the AER driver's core functionality and removing the ifdefs. Introduce
> drivers/pci/pcie/aer_cxl_rch.c for moving the RCH AER logic into.
> Conditionally compile the file using the CONFIG_CXL_RCH_RAS Kconfig.
> 
> Move the CXL logic into the new file but leave helper functions in aer.c
> for now as they will be moved in future patch for CXL virtual hierarchy
> handling. Export the handler functions as needed. Export
> pci_aer_unmask_internal_errors() allowing for all subsystems to use.
> Avoid multiple declaration moves and export cxl_error_is_native() now to
> allow access from cxl_core.
> 
> Inorder to maintain compilation after the move other changes are required.
> Change cxl_rch_handle_error() & cxl_rch_enable_rcec() to be non-static
> inorder for accessing from the AER driver in aer.c.

s/Inorder to/In order to/  (or just "To maintain ...")
/inorder for accessing from the AER driver in/so they can be used by/

> Update the new file with the SPDX and 2023 AMD copyright notations because
> the RCH bits were initally contributed in 2023 by AMD.

Maybe cite the commit that did this so it's easy to check.

> +++ b/drivers/pci/pci.h

> +#ifdef CONFIG_CXL_RAS
> +bool is_internal_error(struct aer_err_info *info);
> +#else
> +static inline bool is_internal_error(struct aer_err_info *info) { return false; }

This used to be static and internal.  "is_internal_error()" seems a
little too generic now that it's not static; probably should include
"aer".  Maybe rename it in a preliminary patch so the move is more of
a pure move.

> +++ b/drivers/pci/pcie/aer.c
> @@ -1130,7 +1130,7 @@ 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;
> @@ -1143,116 +1143,25 @@ 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);

Not sure why these EXPORTs are needed.  Is there a caller that can be
a module?  The callers I see look like they would be builtin.  If you
add callers later that need this, the export can be done then.

> +++ b/include/linux/aer.h
> @@ -56,12 +56,20 @@ struct aer_capability_regs {
>  #if defined(CONFIG_PCIEAER)
>  int pci_aer_clear_nonfatal_status(struct pci_dev *dev);
>  int pcie_aer_is_native(struct pci_dev *dev);
> +void pci_aer_unmask_internal_errors(struct pci_dev *dev);
>  #else
>  static inline int pci_aer_clear_nonfatal_status(struct pci_dev *dev)
>  {
>  	return -EINVAL;
>  }
>  static inline int pcie_aer_is_native(struct pci_dev *dev) { return 0; }
> +static inline void pci_aer_unmask_internal_errors(struct pci_dev *dev) { }
> +#endif
> +
> +#ifdef CONFIG_CXL_RAS
> +bool cxl_error_is_native(struct pci_dev *dev);
> +#else
> +static inline bool cxl_error_is_native(struct pci_dev *dev) { return false; }

These include/linux/aer.h changes look like a separate patch.  Moving
code from aer.c to aer_cxl_rch.c doesn't add any callers outside
drivers/pci, so these shouldn't need to be in include/linux/.