linux-kernel - Re: [PATCH v11 18/23] PCI/AER: Dequeue forwarded CXL error

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Message-ID: <20250910142906.000079d6@huawei.com>
Date: Wed, 10 Sep 2025 14:29:06 +0100
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Terry Bowman <terry.bowman@....com>
CC: <dave@...olabs.net>, <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 v11 18/23] PCI/AER: Dequeue forwarded CXL error

On Tue, 26 Aug 2025 20:35:33 -0500
Terry Bowman <terry.bowman@....com> wrote:

> The AER driver is now designed to forward CXL protocol errors to the CXL
> driver. Update the CXL driver with functionality to dequeue the forwarded
> CXL error from the kfifo. Also, update the CXL driver to begin the protocol
> error handling processing using the work received from the FIFO.
> 
> Update function cxl_proto_err_work_fn() to dequeue work forwarded by the
> AER service driver. This will begin the CXL protocol error processing with
> a call to cxl_handle_proto_error().
> 
> Introduce logic to take the SBDF values from 'struct cxl_proto_error_info'
> and use in discovering the erring PCI device. The call to pci_get_domain_bus_and_slot()
> will return a reference counted 'struct pci_dev *'. This will serve as
> reference count to prevent releasing the CXL Endpoint's mapped RAS while
> handling the error. Use scope base __free() to put the reference count.
> This will change when adding support for CXL port devices in the future.
> 
> Implement cxl_handle_proto_error() to differentiate between Restricted CXL
> Host (RCH) protocol errors and CXL virtual host (VH) protocol errors.
> Maintain the existing RCH handling. Export the AER driver's pcie_walk_rcec()
> allowing the CXL driver to walk the RCEC's secondary bus.
> 
> VH correctable error (CE) processing will call the CXL CE handler. VH
> uncorrectable errors (UCE) will call cxl_do_recovery(), implemented as a
> stub for now and to be updated in future patch. Export pci_aer_clean_fatal_status()
> and pci_clean_device_status() used to clean up AER status after handling.
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>

One additional comment.

> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index d775ed37a79b..2c9827690cb3 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2328,6 +2328,7 @@ void pcie_clear_device_status(struct pci_dev *dev)
>  	pcie_capability_read_word(dev, PCI_EXP_DEVSTA, &sta);
>  	pcie_capability_write_word(dev, PCI_EXP_DEVSTA, sta);
>  }
> +EXPORT_SYMBOL_NS_GPL(pcie_clear_device_status, "CXL");

Not seeing this as CXL specific. I don't think the namespace is appropriate.

>  #endif