linux-kernel - Re: [PATCH v9 04/16] PCI/AER: Dequeue forwarded CXL error

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Message-ID: <aEexYj8uImRt0kr9@wunner.de>
Date: Tue, 10 Jun 2025 06:15:30 +0200
From: Lukas Wunner <lukas@...ner.de>
To: Terry Bowman <terry.bowman@....com>
Cc: PradeepVineshReddy.Kodamati@....com, dave@...olabs.net,
	jonathan.cameron@...wei.com, dave.jiang@...el.com,
	alison.schofield@...el.com, vishal.l.verma@...el.com,
	ira.weiny@...el.com, dan.j.williams@...el.com, bhelgaas@...gle.com,
	bp@...en8.de, ming.li@...omail.com, shiju.jose@...wei.com,
	dan.carpenter@...aro.org, Smita.KoralahalliChannabasappa@....com,
	kobayashi.da-06@...itsu.com, yanfei.xu@...el.com, rrichter@....com,
	peterz@...radead.org, colyli@...e.de, uaisheng.ye@...el.com,
	fabio.m.de.francesco@...ux.intel.com, ilpo.jarvinen@...ux.intel.com,
	yazen.ghannam@....com, linux-cxl@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v9 04/16] PCI/AER: Dequeue forwarded CXL error

On Tue, Jun 03, 2025 at 12:22:27PM -0500, Terry Bowman wrote:
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> +static int cxl_rch_handle_error_iter(struct pci_dev *pdev, void *data)
> +{
> +	struct cxl_prot_error_info *err_info = data;
> +	struct pci_dev *pdev_ref __free(pci_dev_put) = pci_dev_get(pdev);
> +	struct cxl_dev_state *cxlds;
> +
> +	/*
> +	 * The capability, status, and control fields in Device 0,
> +	 * Function 0 DVSEC control the CXL functionality of the
> +	 * entire device (CXL 3.0, 8.1.3).
> +	 */
> +	if (pdev->devfn != PCI_DEVFN(0, 0))
> +		return 0;
> +
> +	/*
> +	 * CXL Memory Devices must have the 502h class code set (CXL
> +	 * 3.0, 8.1.12.1).
> +	 */
> +	if ((pdev->class >> 8) != PCI_CLASS_MEMORY_CXL)
> +		return 0;
> +
> +	if (!is_cxl_memdev(&pdev->dev) || !pdev->dev.driver)
> +		return 0;

Is the point of the "!pdev->dev.driver" check to ascertain that
pdev is bound to cxl_pci_driver?

If so, you need to check "if (pdev->driver != &cxl_pci_driver)"
directly (like cxl_handle_cper_event() does).

That's because there are drivers which may bind to *any* PCI device,
e.g. vfio_pci_driver.

Thanks,

Lukas