linux-kernel - Re: [PATCH v8 04/16] cxl/aer: AER service driver forwards CXL error to CXL driver

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Message-ID: <20250327171335.GA1436609@bhelgaas>
Date: Thu, 27 Mar 2025 12:13:35 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Terry Bowman <terry.bowman@....com>
Cc: linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, nifan.cxl@...il.com, dave@...olabs.net,
	jonathan.cameron@...wei.com, dave.jiang@...el.com,
	alison.schofield@...el.com, vishal.l.verma@...el.com,
	dan.j.williams@...el.com, bhelgaas@...gle.com, mahesh@...ux.ibm.com,
	ira.weiny@...el.com, oohall@...il.com, Benjamin.Cheatham@....com,
	rrichter@....com, nathan.fontenot@....com,
	Smita.KoralahalliChannabasappa@....com, lukas@...ner.de,
	ming.li@...omail.com, PradeepVineshReddy.Kodamati@....com
Subject: Re: [PATCH v8 04/16] cxl/aer: AER service driver forwards CXL error
 to CXL driver

On Wed, Mar 26, 2025 at 08:47:05PM -0500, Terry Bowman wrote:
> The AER service driver includes a CXL-specific kfifo, intended to forward
> CXL errors to the CXL driver. However, the forwarding functionality is
> currently unimplemented. Update the AER driver to enable error forwarding
> to the CXL driver.
> 
> Modify the AER service driver's handle_error_source(), which is called from
> process_aer_err_devices(), to distinguish between PCIe and CXL errors.
> 
> Rename and update is_internal_error() to is_cxl_error(). Ensuring it
> checks both the 'struct aer_info::is_cxl' flag and the AER internal error
> masks.
> 
> If the error is a standard PCIe error then continue calling pcie_aer_handle_error()
> as done in the current AER driver.
> 
> If the error is a CXL-related error then forward it to the CXL driver for
> handling using the kfifo mechanism.
> 
> Introduce a new function forward_cxl_error(), which constructs a CXL
> protocol error context using cxl_create_prot_err_info(). This context is
> then passed to the CXL driver via kfifo using a 'struct work_struct'.

This only touches drivers/pci, so I would make the subject prefix be
"PCI/AER".

> +static void forward_cxl_error(struct pci_dev *_pdev, struct aer_err_info *info)
> +{
> +	int severity = info->severity;
> +	struct cxl_prot_err_work_data wd;
> +	struct cxl_prot_error_info *err_info = &wd.err_info;
> +	struct pci_dev *pdev __free(pci_dev_put) = pci_dev_get(_pdev);
> +
> +	if (!cxl_create_prot_err_info) {
> +		pci_err(pdev, "Failed. CXL-AER interface not initialized.");
> +		return;
> +	}
> +
> +	if (cxl_create_prot_err_info(pdev, severity, err_info)) {
> +		pci_err(pdev, "Failed to create CXL protocol error information");
> +		return;
> +	}
> +
> +	struct device *cxl_dev __free(put_device) = get_device(err_info->dev);
> +
> +	if (!kfifo_put(&cxl_prot_err_fifo, wd)) {
> +		pr_err_ratelimited("CXL kfifo overflow\n");

Needs a dev identifier here to anchor the message to something.

> +		return;
> +	}
> +
> +	schedule_work(cxl_prot_err_work);
> +}