drivers/pci/pcie/aer_cxl_rch.c

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2023 AMD Corporation. All rights reserved. */

#include <linux/pci.h>
#include <linux/aer.h>
#include <linux/bitfield.h>
#include "../pci.h"
#include "portdrv.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 bool cxl_error_is_native(struct pci_dev *dev)
{
	struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);

	return (pcie_ports_native || host->native_aer);
}

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;

	guard(device)(&dev->dev);

	err_handler = dev->driver ? dev->driver->err_handler : NULL;
	if (!err_handler)
		return 0;

	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);
	}
	return 0;
}

void cxl_rch_handle_error(struct pci_dev *dev, struct aer_err_info *info)
{
	/*
	 * Internal errors of an RCEC indicate an AER error in an
	 * RCH's downstream port. Check and handle them in the CXL.mem
	 * device driver.
	 */
	if (pci_pcie_type(dev) == PCI_EXP_TYPE_RC_EC &&
	    is_aer_internal_error(info))
		pcie_walk_rcec(dev, cxl_rch_handle_error_iter, info);
}

static int handles_cxl_error_iter(struct pci_dev *dev, void *data)
{
	bool *handles_cxl = data;

	if (!*handles_cxl)
		*handles_cxl = is_cxl_mem_dev(dev) && cxl_error_is_native(dev);

	/* Non-zero terminates iteration */
	return *handles_cxl;
}

static bool handles_cxl_errors(struct pci_dev *rcec)
{
	bool handles_cxl = false;

	if (pci_pcie_type(rcec) == PCI_EXP_TYPE_RC_EC &&
	    pcie_aer_is_native(rcec))
		pcie_walk_rcec(rcec, handles_cxl_error_iter, &handles_cxl);

	return handles_cxl;
}

void cxl_rch_enable_rcec(struct pci_dev *rcec)
{
	if (!handles_cxl_errors(rcec))
		return;

	pci_aer_unmask_internal_errors(rcec);
	pci_info(rcec, "CXL: Internal errors unmasked");
}