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

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Message-ID: <db80cc07-b3e9-49b3-8415-7ab815b0dbd1@amd.com>
Date: Mon, 7 Apr 2025 09:00:50 -0500
From: "Bowman, Terry" <terry.bowman@....com>
To: Bjorn Helgaas <helgaas@...nel.org>
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 3/27/2025 12:13 PM, Bjorn Helgaas wrote:
> 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".
Got it. Thanks Bjorn.

>> +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.
Ok.

Regards,
Terry

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