linux-kernel - Re: [PATCH v12 06/25] CXL/AER: Introduce aer_cxl_rch.c into AER driver for handling CXL RCH errors

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Message-ID: <20251001164248.0000182a@huawei.com>
Date: Wed, 1 Oct 2025 16:42:48 +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 v12 06/25] CXL/AER: Introduce aer_cxl_rch.c into AER
 driver for handling CXL RCH errors

On Thu, 25 Sep 2025 17:34:21 -0500
Terry Bowman <terry.bowman@....com> 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.
> 
> 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 for cxl_core access.
> 
> 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.
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>
> 
> ---
> 
> Changes in v11->v12:
> - Rename drivers/pci/pcie/cxl_rch.c to drivers/pci/pcie/aer_cxl_rch.c (Lukas)
> - Removed forward declararation of 'struct aer_err_info' in pci/pci.h (Terry)

Unwise given the bot reply.

Fun is that it's only needed I think in the !CONFIG_CXL_RCH_RAS bit as that
can occur with !CONFIG_PCIE_AER.

Other than that, just a few trivial comments.

Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>

> diff --git a/drivers/pci/pcie/aer_cxl_rch.c b/drivers/pci/pcie/aer_cxl_rch.c
> new file mode 100644
> index 000000000000..bfe071eebf67
> --- /dev/null
> +++ b/drivers/pci/pcie/aer_cxl_rch.c
> @@ -0,0 +1,99 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/* Copyright(c) 2025 AMD Corporation. All rights reserved. */

For a code move, the date at least should I think be a bit older.

> +
> +#include <linux/pci.h>
> +#include <linux/aer.h>
> +#include <linux/bitfield.h>
> +#include "../pci.h"
> +
> +static bool is_cxl_mem_dev(struct pci_dev *dev)
> +{
> +	/*
> +	 * 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 (dev->devfn != PCI_DEVFN(0, 0))
> +		return false;
> +
> +	/*
> +	 * CXL Memory Devices must have the 502h class code set (CXL
> +	 * 3.0, 8.1.12.1).
> +	 */
> +	if ((dev->class >> 8) != PCI_CLASS_MEMORY_CXL)
> +		return false;
> +
> +	return true;
> +}
> +
> +static int cxl_rch_handle_error_iter(struct pci_dev *dev, void *data)
> +{
> +	struct aer_err_info *info = (struct aer_err_info *)data;
> +	const struct pci_error_handlers *err_handler;
> +
> +	if (!is_cxl_mem_dev(dev) || !cxl_error_is_native(dev))
> +		return 0;
> +
> +	/* Protect dev->driver */
> +	device_lock(&dev->dev);

Unrelated but guard() might be nice to use here.  Perhaps that's
in a later patch.

> +
> +	err_handler = dev->driver ? dev->driver->err_handler : NULL;
> +	if (!err_handler)
> +		goto out;
> +
> +	if (info->severity == AER_CORRECTABLE) {
> +		if (err_handler->cor_error_detected)
> +			err_handler->cor_error_detected(dev);
> +	} else if (err_handler->error_detected) {
> +		if (info->severity == AER_NONFATAL)
> +			err_handler->error_detected(dev, pci_channel_io_normal);
> +		else if (info->severity == AER_FATAL)
> +			err_handler->error_detected(dev, pci_channel_io_frozen);
> +	}
> +out:
> +	device_unlock(&dev->dev);
> +	return 0;
> +}