// SPDX-License-Identifier: GPL-2.0-only
/*
 * APEI Hardware Error Source Table support
 *
 * HEST describes error sources in detail; communicates operational
 * parameters (i.e. severity levels, masking bits, and threshold
 * values) to Linux as necessary. It also allows the BIOS to report
 * non-standard error sources to Linux (for example, chipset-specific
 * error registers).
 *
 * For more information about HEST, please refer to ACPI Specification
 * version 4.0, section 17.3.2.
 *
 * Copyright 2009 Intel Corp.
 *   Author: Huang Ying <ying.huang@intel.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/kdebug.h>
#include <linux/highmem.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <acpi/apei.h>
#include <acpi/ghes.h>

#include "apei-internal.h"

#define HEST_PFX "HEST: "

int hest_disable;
EXPORT_SYMBOL_GPL(hest_disable);

/* HEST table parsing */

static struct acpi_table_hest *__read_mostly hest_tab;

/*
 * Since GHES_ASSIST is not supported, skip initialization of GHES_ASSIST
 * structures for MCA.
 * During HEST parsing, detected MCA error sources are cached from early
 * table entries so that the Flags and Source Id fields from these cached
 * values are then referred to in later table entries to determine if the
 * encountered GHES_ASSIST structure should be initialized.
 */
static struct {
        struct acpi_hest_ia_corrected *cmc;
        struct acpi_hest_ia_machine_check *mc;
        struct acpi_hest_ia_deferred_check *dmc;
} mces;

static const int hest_esrc_len_tab[ACPI_HEST_TYPE_RESERVED] = {
        [ACPI_HEST_TYPE_IA32_CHECK] = -1,       /* need further calculation */
        [ACPI_HEST_TYPE_IA32_CORRECTED_CHECK] = -1,
        [ACPI_HEST_TYPE_IA32_NMI] = sizeof(struct acpi_hest_ia_nmi),
        [ACPI_HEST_TYPE_AER_ROOT_PORT] = sizeof(struct acpi_hest_aer_root),
        [ACPI_HEST_TYPE_AER_ENDPOINT] = sizeof(struct acpi_hest_aer),
        [ACPI_HEST_TYPE_AER_BRIDGE] = sizeof(struct acpi_hest_aer_bridge),
        [ACPI_HEST_TYPE_GENERIC_ERROR] = sizeof(struct acpi_hest_generic),
        [ACPI_HEST_TYPE_GENERIC_ERROR_V2] = sizeof(struct acpi_hest_generic_v2),
        [ACPI_HEST_TYPE_IA32_DEFERRED_CHECK] = -1,
};

static inline bool is_generic_error(struct acpi_hest_header *hest_hdr)
{
        return hest_hdr->type == ACPI_HEST_TYPE_GENERIC_ERROR ||
               hest_hdr->type == ACPI_HEST_TYPE_GENERIC_ERROR_V2;
}

static int hest_esrc_len(struct acpi_hest_header *hest_hdr)
{
        u16 hest_type = hest_hdr->type;
        int len;

        if (hest_type >= ACPI_HEST_TYPE_RESERVED)
                return 0;

        len = hest_esrc_len_tab[hest_type];

        if (hest_type == ACPI_HEST_TYPE_IA32_CORRECTED_CHECK) {
                struct acpi_hest_ia_corrected *cmc;
                cmc = (struct acpi_hest_ia_corrected *)hest_hdr;
                len = sizeof(*cmc) + cmc->num_hardware_banks *
                        sizeof(struct acpi_hest_ia_error_bank);
                mces.cmc = cmc;
        } else if (hest_type == ACPI_HEST_TYPE_IA32_CHECK) {
                struct acpi_hest_ia_machine_check *mc;
                mc = (struct acpi_hest_ia_machine_check *)hest_hdr;
                len = sizeof(*mc) + mc->num_hardware_banks *
                        sizeof(struct acpi_hest_ia_error_bank);
                mces.mc = mc;
        } else if (hest_type == ACPI_HEST_TYPE_IA32_DEFERRED_CHECK) {
                struct acpi_hest_ia_deferred_check *mc;
                mc = (struct acpi_hest_ia_deferred_check *)hest_hdr;
                len = sizeof(*mc) + mc->num_hardware_banks *
                        sizeof(struct acpi_hest_ia_error_bank);
                mces.dmc = mc;
        }
        BUG_ON(len == -1);

        return len;
};

/*
 * GHES and GHESv2 structures share the same format, starting from
 * Source Id and ending in Error Status Block Length (inclusive).
 */
static bool is_ghes_assist_struct(struct acpi_hest_header *hest_hdr)
{
        struct acpi_hest_generic *ghes;
        u16 related_source_id;

        if (hest_hdr->type != ACPI_HEST_TYPE_GENERIC_ERROR &&
            hest_hdr->type != ACPI_HEST_TYPE_GENERIC_ERROR_V2)
                return false;

        ghes = (struct acpi_hest_generic *)hest_hdr;
        related_source_id = ghes->related_source_id;

        if (mces.cmc && mces.cmc->flags & ACPI_HEST_GHES_ASSIST &&
            related_source_id == mces.cmc->header.source_id)
                return true;
        if (mces.mc && mces.mc->flags & ACPI_HEST_GHES_ASSIST &&
            related_source_id == mces.mc->header.source_id)
                return true;
        if (mces.dmc && mces.dmc->flags & ACPI_HEST_GHES_ASSIST &&
            related_source_id == mces.dmc->header.source_id)
                return true;

        return false;
}

typedef int (*apei_hest_func_t)(struct acpi_hest_header *hest_hdr, void *data);

static int apei_hest_parse(apei_hest_func_t func, void *data)
{
        struct acpi_hest_header *hest_hdr;
        int i, rc, len;

        if (hest_disable || !hest_tab)
                return -EINVAL;

        hest_hdr = (struct acpi_hest_header *)(hest_tab + 1);
        for (i = 0; i < hest_tab->error_source_count; i++) {
                len = hest_esrc_len(hest_hdr);
                if (!len) {
                        pr_warn(FW_WARN HEST_PFX
                                "Unknown or unused hardware error source "
                                "type: %d for hardware error source: %d.\n",
                                hest_hdr->type, hest_hdr->source_id);
                        return -EINVAL;
                }
                if ((void *)hest_hdr + len >
                    (void *)hest_tab + hest_tab->header.length) {
                        pr_warn(FW_BUG HEST_PFX
                "Table contents overflow for hardware error source: %d.\n",
                                hest_hdr->source_id);
                        return -EINVAL;
                }

                if (is_ghes_assist_struct(hest_hdr)) {
                        hest_hdr = (void *)hest_hdr + len;
                        continue;
                }

                rc = func(hest_hdr, data);
                if (rc)
                        return rc;

                hest_hdr = (void *)hest_hdr + len;
        }

        return 0;
}

/*
 * Check if firmware advertises firmware first mode. We need FF bit to be set
 * along with a set of MC banks which work in FF mode.
 */
static int __init hest_parse_cmc(struct acpi_hest_header *hest_hdr, void *data)
{
        if (hest_hdr->type != ACPI_HEST_TYPE_IA32_CORRECTED_CHECK)
                return 0;

        if (!acpi_disable_cmcff)
                return !arch_apei_enable_cmcff(hest_hdr, data);

        return 0;
}

struct ghes_arr {
        struct platform_device **ghes_devs;
        unsigned int count;
};

static int __init hest_parse_ghes_count(struct acpi_hest_header *hest_hdr, void *data)
{
        int *count = data;

        if (is_generic_error(hest_hdr))
                (*count)++;
        return 0;
}

static int __init hest_parse_ghes(struct acpi_hest_header *hest_hdr, void *data)
{
        struct platform_device *ghes_dev;
        struct ghes_arr *ghes_arr = data;
        int rc, i;

        if (!is_generic_error(hest_hdr))
                return 0;

        if (!((struct acpi_hest_generic *)hest_hdr)->enabled)
                return 0;
        for (i = 0; i < ghes_arr->count; i++) {
                struct acpi_hest_header *hdr;
                ghes_dev = ghes_arr->ghes_devs[i];
                hdr = *(struct acpi_hest_header **)ghes_dev->dev.platform_data;
                if (hdr->source_id == hest_hdr->source_id) {
                        pr_warn(FW_WARN HEST_PFX "Duplicated hardware error source ID: %d.\n",
                                hdr->source_id);
                        return -EIO;
                }
        }
        ghes_dev = platform_device_alloc("GHES", hest_hdr->source_id);
        if (!ghes_dev)
                return -ENOMEM;

        rc = platform_device_add_data(ghes_dev, &hest_hdr, sizeof(void *));
        if (rc)
                goto err;

        rc = platform_device_add(ghes_dev);
        if (rc)
                goto err;
        ghes_arr->ghes_devs[ghes_arr->count++] = ghes_dev;

        return 0;
err:
        platform_device_put(ghes_dev);
        return rc;
}

static int __init hest_ghes_dev_register(unsigned int ghes_count)
{
        int rc, i;
        struct ghes_arr ghes_arr;

        ghes_arr.count = 0;
        ghes_arr.ghes_devs = kmalloc_array(ghes_count, sizeof(void *),
                                           GFP_KERNEL);
        if (!ghes_arr.ghes_devs)
                return -ENOMEM;

        rc = apei_hest_parse(hest_parse_ghes, &ghes_arr);
        if (rc)
                goto err;

        rc = ghes_estatus_pool_init(ghes_count);
        if (rc)
                goto err;

out:
        kfree(ghes_arr.ghes_devs);
        return rc;
err:
        for (i = 0; i < ghes_arr.count; i++)
                platform_device_unregister(ghes_arr.ghes_devs[i]);
        goto out;
}

static int __init setup_hest_disable(char *str)
{
        hest_disable = HEST_DISABLED;
        return 1;
}

__setup("hest_disable", setup_hest_disable);

void __init acpi_hest_init(void)
{
        acpi_status status;
        int rc;
        unsigned int ghes_count = 0;

        if (hest_disable) {
                pr_info(HEST_PFX "Table parsing disabled.\n");
                return;
        }

        status = acpi_get_table(ACPI_SIG_HEST, 0,
                                (struct acpi_table_header **)&hest_tab);
        if (status == AE_NOT_FOUND) {
                hest_disable = HEST_NOT_FOUND;
                return;
        } else if (ACPI_FAILURE(status)) {
                const char *msg = acpi_format_exception(status);
                pr_err(HEST_PFX "Failed to get table, %s\n", msg);
                hest_disable = HEST_DISABLED;
                return;
        }

        rc = apei_hest_parse(hest_parse_cmc, NULL);
        if (rc)
                goto err;

        if (!ghes_disable) {
                rc = apei_hest_parse(hest_parse_ghes_count, &ghes_count);
                if (rc)
                        goto err;

                if (ghes_count)
                        rc = hest_ghes_dev_register(ghes_count);
                if (rc)
                        goto err;
        }

        pr_info(HEST_PFX "Table parsing has been initialized.\n");
        return;
err:
        hest_disable = HEST_DISABLED;
        acpi_put_table((struct acpi_table_header *)hest_tab);
}