ghes.c

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/*
 * APEI Generic Hardware Error Source support
 *
 * Generic Hardware Error Source provides a way to report platform
 * hardware errors (such as that from chipset). It works in so called
 * "Firmware First" mode, that is, hardware errors are reported to
 * firmware firstly, then reported to Linux by firmware. This way,
 * some non-standard hardware error registers or non-standard hardware
 * link can be checked by firmware to produce more hardware error
 * information for Linux.
 *
 * For more information about Generic Hardware Error Source, please
 * refer to ACPI Specification version 4.0, section 17.3.2.6
 *
 * Copyright 2010,2011 Intel Corp.
 *   Author: Huang Ying <[email protected]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation;
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/acpi_io.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/timer.h>
#include <linux/cper.h>
#include <linux/kdebug.h>
#include <linux/platform_device.h>
#include <linux/mutex.h>
#include <linux/ratelimit.h>
#include <linux/vmalloc.h>
#include <linux/irq_work.h>
#include <linux/llist.h>
#include <linux/genalloc.h>
#include <linux/pci.h>
#include <linux/aer.h>
#include <acpi/apei.h>
#include <acpi/hed.h>
#include <asm/mce.h>
#include <asm/tlbflush.h>
#include <asm/nmi.h>

#include "apei-internal.h"

#define GHES_PFX    "GHES: "

#define GHES_ESTATUS_MAX_SIZE       65536
#define GHES_ESOURCE_PREALLOC_MAX_SIZE  65536

#define GHES_ESTATUS_POOL_MIN_ALLOC_ORDER 3

/* This is just an estimation for memory pool allocation */
#define GHES_ESTATUS_CACHE_AVG_SIZE 512

#define GHES_ESTATUS_CACHES_SIZE    4

#define GHES_ESTATUS_IN_CACHE_MAX_NSEC  10000000000ULL
/* Prevent too many caches are allocated because of RCU */
#define GHES_ESTATUS_CACHE_ALLOCED_MAX  (GHES_ESTATUS_CACHES_SIZE * 3 / 2)

#define GHES_ESTATUS_CACHE_LEN(estatus_len)         \
    (sizeof(struct ghes_estatus_cache) + (estatus_len))
#define GHES_ESTATUS_FROM_CACHE(estatus_cache)          \
    ((struct acpi_hest_generic_status *)            \
     ((struct ghes_estatus_cache *)(estatus_cache) + 1))

#define GHES_ESTATUS_NODE_LEN(estatus_len)          \
    (sizeof(struct ghes_estatus_node) + (estatus_len))
#define GHES_ESTATUS_FROM_NODE(estatus_node)                \
    ((struct acpi_hest_generic_status *)                \
     ((struct ghes_estatus_node *)(estatus_node) + 1))

/*
 * One struct ghes is created for each generic hardware error source.
 * It provides the context for APEI hardware error timer/IRQ/SCI/NMI
 * handler.
 *
 * estatus: memory buffer for error status block, allocated during
 * HEST parsing.
 */
#define GHES_TO_CLEAR       0x0001
#define GHES_EXITING        0x0002

struct ghes {
    struct acpi_hest_generic *generic;
    struct acpi_hest_generic_status *estatus;
    u64 buffer_paddr;
    unsigned long flags;
    union {
        struct list_head list;
        struct timer_list timer;
        unsigned int irq;
    };
};

struct ghes_estatus_node {
    struct llist_node llnode;
    struct acpi_hest_generic *generic;
};

struct ghes_estatus_cache {
    u32 estatus_len;
    atomic_t count;
    struct acpi_hest_generic *generic;
    unsigned long long time_in;
    struct rcu_head rcu;
};

bool ghes_disable;
module_param_named(disable, ghes_disable, bool, 0);

static int ghes_panic_timeout   __read_mostly = 30;

/*
 * All error sources notified with SCI shares one notifier function,
 * so they need to be linked and checked one by one.  This is applied
 * to NMI too.
 *
 * RCU is used for these lists, so ghes_list_mutex is only used for
 * list changing, not for traversing.
 */
static LIST_HEAD(ghes_sci);
static LIST_HEAD(ghes_nmi);
static DEFINE_MUTEX(ghes_list_mutex);

/*
 * NMI may be triggered on any CPU, so ghes_nmi_lock is used for
 * mutual exclusion.
 */
static DEFINE_RAW_SPINLOCK(ghes_nmi_lock);

/*
 * Because the memory area used to transfer hardware error information
 * from BIOS to Linux can be determined only in NMI, IRQ or timer
 * handler, but general ioremap can not be used in atomic context, so
 * a special version of atomic ioremap is implemented for that.
 */

/*
 * Two virtual pages are used, one for NMI context, the other for
 * IRQ/PROCESS context
 */
#define GHES_IOREMAP_PAGES      2
#define GHES_IOREMAP_NMI_PAGE(base) (base)
#define GHES_IOREMAP_IRQ_PAGE(base) ((base) + PAGE_SIZE)

/* virtual memory area for atomic ioremap */
static struct vm_struct *ghes_ioremap_area;
/*
 * These 2 spinlock is used to prevent atomic ioremap virtual memory
 * area from being mapped simultaneously.
 */
static DEFINE_RAW_SPINLOCK(ghes_ioremap_lock_nmi);
static DEFINE_SPINLOCK(ghes_ioremap_lock_irq);

/*
 * printk is not safe in NMI context.  So in NMI handler, we allocate
 * required memory from lock-less memory allocator
 * (ghes_estatus_pool), save estatus into it, put them into lock-less
 * list (ghes_estatus_llist), then delay printk into IRQ context via
 * irq_work (ghes_proc_irq_work).  ghes_estatus_size_request record
 * required pool size by all NMI error source.
 */
static struct gen_pool *ghes_estatus_pool;
static unsigned long ghes_estatus_pool_size_request;
static struct llist_head ghes_estatus_llist;
static struct irq_work ghes_proc_irq_work;

struct ghes_estatus_cache *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE];
static atomic_t ghes_estatus_cache_alloced;

static int ghes_ioremap_init(void)
{
    ghes_ioremap_area = __get_vm_area(PAGE_SIZE * GHES_IOREMAP_PAGES,
        VM_IOREMAP, VMALLOC_START, VMALLOC_END);
    if (!ghes_ioremap_area) {
        pr_err(GHES_PFX "Failed to allocate virtual memory area for atomic ioremap.\n");
        return -ENOMEM;
    }

    return 0;
}

static void ghes_ioremap_exit(void)
{
    free_vm_area(ghes_ioremap_area);
}

static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn)
{
    unsigned long vaddr;

    vaddr = (unsigned long)GHES_IOREMAP_NMI_PAGE(ghes_ioremap_area->addr);
    ioremap_page_range(vaddr, vaddr + PAGE_SIZE,
               pfn << PAGE_SHIFT, PAGE_KERNEL);

    return (void __iomem *)vaddr;
}

static void __iomem *ghes_ioremap_pfn_irq(u64 pfn)
{
    unsigned long vaddr;

    vaddr = (unsigned long)GHES_IOREMAP_IRQ_PAGE(ghes_ioremap_area->addr);
    ioremap_page_range(vaddr, vaddr + PAGE_SIZE,
               pfn << PAGE_SHIFT, PAGE_KERNEL);

    return (void __iomem *)vaddr;
}

static void ghes_iounmap_nmi(void __iomem *vaddr_ptr)
{
    unsigned long vaddr = (unsigned long __force)vaddr_ptr;
    void *base = ghes_ioremap_area->addr;

    BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_NMI_PAGE(base));
    unmap_kernel_range_noflush(vaddr, PAGE_SIZE);
    __flush_tlb_one(vaddr);
}

static void ghes_iounmap_irq(void __iomem *vaddr_ptr)
{
    unsigned long vaddr = (unsigned long __force)vaddr_ptr;
    void *base = ghes_ioremap_area->addr;

    BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_IRQ_PAGE(base));
    unmap_kernel_range_noflush(vaddr, PAGE_SIZE);
    __flush_tlb_one(vaddr);
}

static int ghes_estatus_pool_init(void)
{
    ghes_estatus_pool = gen_pool_create(GHES_ESTATUS_POOL_MIN_ALLOC_ORDER, -1);
    if (!ghes_estatus_pool)
        return -ENOMEM;
    return 0;
}

static void ghes_estatus_pool_free_chunk_page(struct gen_pool *pool,
                          struct gen_pool_chunk *chunk,
                          void *data)
{
    free_page(chunk->start_addr);
}

static void ghes_estatus_pool_exit(void)
{
    gen_pool_for_each_chunk(ghes_estatus_pool,
                ghes_estatus_pool_free_chunk_page, NULL);
    gen_pool_destroy(ghes_estatus_pool);
}

static int ghes_estatus_pool_expand(unsigned long len)
{
    unsigned long i, pages, size, addr;
    int ret;

    ghes_estatus_pool_size_request += PAGE_ALIGN(len);
    size = gen_pool_size(ghes_estatus_pool);
    if (size >= ghes_estatus_pool_size_request)
        return 0;
    pages = (ghes_estatus_pool_size_request - size) / PAGE_SIZE;
    for (i = 0; i < pages; i++) {
        addr = __get_free_page(GFP_KERNEL);
        if (!addr)
            return -ENOMEM;
        ret = gen_pool_add(ghes_estatus_pool, addr, PAGE_SIZE, -1);
        if (ret)
            return ret;
    }

    return 0;
}

static void ghes_estatus_pool_shrink(unsigned long len)
{
    ghes_estatus_pool_size_request -= PAGE_ALIGN(len);
}

static struct ghes *ghes_new(struct acpi_hest_generic *generic)
{
    struct ghes *ghes;
    unsigned int error_block_length;
    int rc;

    ghes = kzalloc(sizeof(*ghes), GFP_KERNEL);
    if (!ghes)
        return ERR_PTR(-ENOMEM);
    ghes->generic = generic;
    rc = apei_map_generic_address(&generic->error_status_address);
    if (rc)
        goto err_free;
    error_block_length = generic->error_block_length;
    if (error_block_length > GHES_ESTATUS_MAX_SIZE) {
        pr_warning(FW_WARN GHES_PFX
               "Error status block length is too long: %u for "
               "generic hardware error source: %d.\n",
               error_block_length, generic->header.source_id);
        error_block_length = GHES_ESTATUS_MAX_SIZE;
    }
    ghes->estatus = kmalloc(error_block_length, GFP_KERNEL);
    if (!ghes->estatus) {
        rc = -ENOMEM;
        goto err_unmap;
    }

    return ghes;

err_unmap:
    apei_unmap_generic_address(&generic->error_status_address);
err_free:
    kfree(ghes);
    return ERR_PTR(rc);
}

static void ghes_fini(struct ghes *ghes)
{
    kfree(ghes->estatus);
    apei_unmap_generic_address(&ghes->generic->error_status_address);
}

enum {
    GHES_SEV_NO = 0x0,
    GHES_SEV_CORRECTED = 0x1,
    GHES_SEV_RECOVERABLE = 0x2,
    GHES_SEV_PANIC = 0x3,
};

static inline int ghes_severity(int severity)
{
    switch (severity) {
    case CPER_SEV_INFORMATIONAL:
        return GHES_SEV_NO;
    case CPER_SEV_CORRECTED:
        return GHES_SEV_CORRECTED;
    case CPER_SEV_RECOVERABLE:
        return GHES_SEV_RECOVERABLE;
    case CPER_SEV_FATAL:
        return GHES_SEV_PANIC;
    default:
        /* Unknown, go panic */
        return GHES_SEV_PANIC;
    }
}

static void ghes_copy_tofrom_phys(void *buffer, u64 paddr, u32 len,
                  int from_phys)
{
    void __iomem *vaddr;
    unsigned long flags = 0;
    int in_nmi = in_nmi();
    u64 offset;
    u32 trunk;

    while (len > 0) {
        offset = paddr - (paddr & PAGE_MASK);
        if (in_nmi) {
            raw_spin_lock(&ghes_ioremap_lock_nmi);
            vaddr = ghes_ioremap_pfn_nmi(paddr >> PAGE_SHIFT);
        } else {
            spin_lock_irqsave(&ghes_ioremap_lock_irq, flags);
            vaddr = ghes_ioremap_pfn_irq(paddr >> PAGE_SHIFT);
        }
        trunk = PAGE_SIZE - offset;
        trunk = min(trunk, len);
        if (from_phys)
            memcpy_fromio(buffer, vaddr + offset, trunk);
        else
            memcpy_toio(vaddr + offset, buffer, trunk);
        len -= trunk;
        paddr += trunk;
        buffer += trunk;
        if (in_nmi) {
            ghes_iounmap_nmi(vaddr);
            raw_spin_unlock(&ghes_ioremap_lock_nmi);
        } else {
            ghes_iounmap_irq(vaddr);
            spin_unlock_irqrestore(&ghes_ioremap_lock_irq, flags);
        }
    }
}

static int ghes_read_estatus(struct ghes *ghes, int silent)
{
    struct acpi_hest_generic *g = ghes->generic;
    u64 buf_paddr;
    u32 len;
    int rc;

    rc = apei_read(&buf_paddr, &g->error_status_address);
    if (rc) {
        if (!silent && printk_ratelimit())
            pr_warning(FW_WARN GHES_PFX
"Failed to read error status block address for hardware error source: %d.\n",
                   g->header.source_id);
        return -EIO;
    }
    if (!buf_paddr)
        return -ENOENT;

    ghes_copy_tofrom_phys(ghes->estatus, buf_paddr,
                  sizeof(*ghes->estatus), 1);
    if (!ghes->estatus->block_status)
        return -ENOENT;

    ghes->buffer_paddr = buf_paddr;
    ghes->flags |= GHES_TO_CLEAR;

    rc = -EIO;
    len = apei_estatus_len(ghes->estatus);
    if (len < sizeof(*ghes->estatus))
        goto err_read_block;
    if (len > ghes->generic->error_block_length)
        goto err_read_block;
    if (apei_estatus_check_header(ghes->estatus))
        goto err_read_block;
    ghes_copy_tofrom_phys(ghes->estatus + 1,
                  buf_paddr + sizeof(*ghes->estatus),
                  len - sizeof(*ghes->estatus), 1);
    if (apei_estatus_check(ghes->estatus))
        goto err_read_block;
    rc = 0;

err_read_block:
    if (rc && !silent && printk_ratelimit())
        pr_warning(FW_WARN GHES_PFX
               "Failed to read error status block!\n");
    return rc;
}

static void ghes_clear_estatus(struct ghes *ghes)
{
    ghes->estatus->block_status = 0;
    if (!(ghes->flags & GHES_TO_CLEAR))
        return;
    ghes_copy_tofrom_phys(ghes->estatus, ghes->buffer_paddr,
                  sizeof(ghes->estatus->block_status), 0);
    ghes->flags &= ~GHES_TO_CLEAR;
}

static void ghes_do_proc(const struct acpi_hest_generic_status *estatus)
{
    int sev, sec_sev;
    struct acpi_hest_generic_data *gdata;

    sev = ghes_severity(estatus->error_severity);
    apei_estatus_for_each_section(estatus, gdata) {
        sec_sev = ghes_severity(gdata->error_severity);
        if (!uuid_le_cmp(*(uuid_le *)gdata->section_type,
                 CPER_SEC_PLATFORM_MEM)) {
            struct cper_sec_mem_err *mem_err;
            mem_err = (struct cper_sec_mem_err *)(gdata+1);
#ifdef CONFIG_X86_MCE
            apei_mce_report_mem_error(sev == GHES_SEV_CORRECTED,
                          mem_err);
#endif
#ifdef CONFIG_ACPI_APEI_MEMORY_FAILURE
            if (sev == GHES_SEV_RECOVERABLE &&
                sec_sev == GHES_SEV_RECOVERABLE &&
                mem_err->validation_bits & CPER_MEM_VALID_PHYSICAL_ADDRESS) {
                unsigned long pfn;
                pfn = mem_err->physical_addr >> PAGE_SHIFT;
                memory_failure_queue(pfn, 0, 0);
            }
#endif
        }
#ifdef CONFIG_ACPI_APEI_PCIEAER
        else if (!uuid_le_cmp(*(uuid_le *)gdata->section_type,
                      CPER_SEC_PCIE)) {
            struct cper_sec_pcie *pcie_err;
            pcie_err = (struct cper_sec_pcie *)(gdata+1);
            if (sev == GHES_SEV_RECOVERABLE &&
                sec_sev == GHES_SEV_RECOVERABLE &&
                pcie_err->validation_bits & CPER_PCIE_VALID_DEVICE_ID &&
                pcie_err->validation_bits & CPER_PCIE_VALID_AER_INFO) {
                unsigned int devfn;
                int aer_severity;
                devfn = PCI_DEVFN(pcie_err->device_id.device,
                          pcie_err->device_id.function);
                aer_severity = cper_severity_to_aer(sev);
                aer_recover_queue(pcie_err->device_id.segment,
                          pcie_err->device_id.bus,
                          devfn, aer_severity);
            }

        }
#endif
    }
}

static void __ghes_print_estatus(const char *pfx,
                 const struct acpi_hest_generic *generic,
                 const struct acpi_hest_generic_status *estatus)
{
    static atomic_t seqno;
    unsigned int curr_seqno;
    char pfx_seq[64];

    if (pfx == NULL) {
        if (ghes_severity(estatus->error_severity) <=
            GHES_SEV_CORRECTED)
            pfx = KERN_WARNING;
        else
            pfx = KERN_ERR;
    }
    curr_seqno = atomic_inc_return(&seqno);
    snprintf(pfx_seq, sizeof(pfx_seq), "%s{%u}" HW_ERR, pfx, curr_seqno);
    printk("%s""Hardware error from APEI Generic Hardware Error Source: %d\n",
           pfx_seq, generic->header.source_id);
    apei_estatus_print(pfx_seq, estatus);
}

static int ghes_print_estatus(const char *pfx,
                  const struct acpi_hest_generic *generic,
                  const struct acpi_hest_generic_status *estatus)
{
    /* Not more than 2 messages every 5 seconds */
    static DEFINE_RATELIMIT_STATE(ratelimit_corrected, 5*HZ, 2);
    static DEFINE_RATELIMIT_STATE(ratelimit_uncorrected, 5*HZ, 2);
    struct ratelimit_state *ratelimit;

    if (ghes_severity(estatus->error_severity) <= GHES_SEV_CORRECTED)
        ratelimit = &ratelimit_corrected;
    else
        ratelimit = &ratelimit_uncorrected;
    if (__ratelimit(ratelimit)) {
        __ghes_print_estatus(pfx, generic, estatus);
        return 1;
    }
    return 0;
}

/*
 * GHES error status reporting throttle, to report more kinds of
 * errors, instead of just most frequently occurred errors.
 */
static int ghes_estatus_cached(struct acpi_hest_generic_status *estatus)
{
    u32 len;
    int i, cached = 0;
    unsigned long long now;
    struct ghes_estatus_cache *cache;
    struct acpi_hest_generic_status *cache_estatus;

    len = apei_estatus_len(estatus);
    rcu_read_lock();
    for (i = 0; i < GHES_ESTATUS_CACHES_SIZE; i++) {
        cache = rcu_dereference(ghes_estatus_caches[i]);
        if (cache == NULL)
            continue;
        if (len != cache->estatus_len)
            continue;
        cache_estatus = GHES_ESTATUS_FROM_CACHE(cache);
        if (memcmp(estatus, cache_estatus, len))
            continue;
        atomic_inc(&cache->count);
        now = sched_clock();
        if (now - cache->time_in < GHES_ESTATUS_IN_CACHE_MAX_NSEC)
            cached = 1;
        break;
    }
    rcu_read_unlock();
    return cached;
}

static struct ghes_estatus_cache *ghes_estatus_cache_alloc(
    struct acpi_hest_generic *generic,
    struct acpi_hest_generic_status *estatus)
{
    int alloced;
    u32 len, cache_len;
    struct ghes_estatus_cache *cache;
    struct acpi_hest_generic_status *cache_estatus;

    alloced = atomic_add_return(1, &ghes_estatus_cache_alloced);
    if (alloced > GHES_ESTATUS_CACHE_ALLOCED_MAX) {
        atomic_dec(&ghes_estatus_cache_alloced);
        return NULL;
    }
    len = apei_estatus_len(estatus);
    cache_len = GHES_ESTATUS_CACHE_LEN(len);
    cache = (void *)gen_pool_alloc(ghes_estatus_pool, cache_len);
    if (!cache) {
        atomic_dec(&ghes_estatus_cache_alloced);
        return NULL;
    }
    cache_estatus = GHES_ESTATUS_FROM_CACHE(cache);
    memcpy(cache_estatus, estatus, len);
    cache->estatus_len = len;
    atomic_set(&cache->count, 0);
    cache->generic = generic;
    cache->time_in = sched_clock();
    return cache;
}

static void ghes_estatus_cache_free(struct ghes_estatus_cache *cache)
{
    u32 len;

    len = apei_estatus_len(GHES_ESTATUS_FROM_CACHE(cache));
    len = GHES_ESTATUS_CACHE_LEN(len);
    gen_pool_free(ghes_estatus_pool, (unsigned long)cache, len);
    atomic_dec(&ghes_estatus_cache_alloced);
}

static void ghes_estatus_cache_rcu_free(struct rcu_head *head)
{
    struct ghes_estatus_cache *cache;

    cache = container_of(head, struct ghes_estatus_cache, rcu);
    ghes_estatus_cache_free(cache);
}

static void ghes_estatus_cache_add(
    struct acpi_hest_generic *generic,
    struct acpi_hest_generic_status *estatus)
{
    int i, slot = -1, count;
    unsigned long long now, duration, period, max_period = 0;
    struct ghes_estatus_cache *cache, *slot_cache = NULL, *new_cache;

    new_cache = ghes_estatus_cache_alloc(generic, estatus);
    if (new_cache == NULL)
        return;
    rcu_read_lock();
    now = sched_clock();
    for (i = 0; i < GHES_ESTATUS_CACHES_SIZE; i++) {
        cache = rcu_dereference(ghes_estatus_caches[i]);
        if (cache == NULL) {
            slot = i;
            slot_cache = NULL;
            break;
        }
        duration = now - cache->time_in;
        if (duration >= GHES_ESTATUS_IN_CACHE_MAX_NSEC) {
            slot = i;
            slot_cache = cache;
            break;
        }
        count = atomic_read(&cache->count);
        period = duration;
        do_div(period, (count + 1));
        if (period > max_period) {
            max_period = period;
            slot = i;
            slot_cache = cache;
        }
    }
    /* new_cache must be put into array after its contents are written */
    smp_wmb();
    if (slot != -1 && cmpxchg(ghes_estatus_caches + slot,
                  slot_cache, new_cache) == slot_cache) {
        if (slot_cache)
            call_rcu(&slot_cache->rcu, ghes_estatus_cache_rcu_free);
    } else
        ghes_estatus_cache_free(new_cache);
    rcu_read_unlock();
}

static int ghes_proc(struct ghes *ghes)
{
    int rc;

    rc = ghes_read_estatus(ghes, 0);
    if (rc)
        goto out;
    if (!ghes_estatus_cached(ghes->estatus)) {
        if (ghes_print_estatus(NULL, ghes->generic, ghes->estatus))
            ghes_estatus_cache_add(ghes->generic, ghes->estatus);
    }
    ghes_do_proc(ghes->estatus);
out:
    ghes_clear_estatus(ghes);
    return 0;
}

static void ghes_add_timer(struct ghes *ghes)
{
    struct acpi_hest_generic *g = ghes->generic;
    unsigned long expire;

    if (!g->notify.poll_interval) {
        pr_warning(FW_WARN GHES_PFX "Poll interval is 0 for generic hardware error source: %d, disabled.\n",
               g->header.source_id);
        return;
    }
    expire = jiffies + msecs_to_jiffies(g->notify.poll_interval);
    ghes->timer.expires = round_jiffies_relative(expire);
    add_timer(&ghes->timer);
}

static void ghes_poll_func(unsigned long data)
{
    struct ghes *ghes = (void *)data;

    ghes_proc(ghes);
    if (!(ghes->flags & GHES_EXITING))
        ghes_add_timer(ghes);
}

static irqreturn_t ghes_irq_func(int irq, void *data)
{
    struct ghes *ghes = data;
    int rc;

    rc = ghes_proc(ghes);
    if (rc)
        return IRQ_NONE;

    return IRQ_HANDLED;
}

static int ghes_notify_sci(struct notifier_block *this,
                  unsigned long event, void *data)
{
    struct ghes *ghes;
    int ret = NOTIFY_DONE;

    rcu_read_lock();
    list_for_each_entry_rcu(ghes, &ghes_sci, list) {
        if (!ghes_proc(ghes))
            ret = NOTIFY_OK;
    }
    rcu_read_unlock();

    return ret;
}

static struct llist_node *llist_nodes_reverse(struct llist_node *llnode)
{
    struct llist_node *next, *tail = NULL;

    while (llnode) {
        next = llnode->next;
        llnode->next = tail;
        tail = llnode;
        llnode = next;
    }

    return tail;
}

static void ghes_proc_in_irq(struct irq_work *irq_work)
{
    struct llist_node *llnode, *next;
    struct ghes_estatus_node *estatus_node;
    struct acpi_hest_generic *generic;
    struct acpi_hest_generic_status *estatus;
    u32 len, node_len;

    llnode = llist_del_all(&ghes_estatus_llist);
    /*
     * Because the time order of estatus in list is reversed,
     * revert it back to proper order.
     */
    llnode = llist_nodes_reverse(llnode);
    while (llnode) {
        next = llnode->next;
        estatus_node = llist_entry(llnode, struct ghes_estatus_node,
                       llnode);
        estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
        len = apei_estatus_len(estatus);
        node_len = GHES_ESTATUS_NODE_LEN(len);
        ghes_do_proc(estatus);
        if (!ghes_estatus_cached(estatus)) {
            generic = estatus_node->generic;
            if (ghes_print_estatus(NULL, generic, estatus))
                ghes_estatus_cache_add(generic, estatus);
        }
        gen_pool_free(ghes_estatus_pool, (unsigned long)estatus_node,
                  node_len);
        llnode = next;
    }
}

static void ghes_print_queued_estatus(void)
{
    struct llist_node *llnode;
    struct ghes_estatus_node *estatus_node;
    struct acpi_hest_generic *generic;
    struct acpi_hest_generic_status *estatus;
    u32 len, node_len;

    llnode = llist_del_all(&ghes_estatus_llist);
    /*
     * Because the time order of estatus in list is reversed,
     * revert it back to proper order.
     */
    llnode = llist_nodes_reverse(llnode);
    while (llnode) {
        estatus_node = llist_entry(llnode, struct ghes_estatus_node,
                       llnode);
        estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
        len = apei_estatus_len(estatus);
        node_len = GHES_ESTATUS_NODE_LEN(len);
        generic = estatus_node->generic;
        ghes_print_estatus(NULL, generic, estatus);
        llnode = llnode->next;
    }
}

static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
{
    struct ghes *ghes, *ghes_global = NULL;
    int sev, sev_global = -1;
    int ret = NMI_DONE;

    raw_spin_lock(&ghes_nmi_lock);
    list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
        if (ghes_read_estatus(ghes, 1)) {
            ghes_clear_estatus(ghes);
            continue;
        }
        sev = ghes_severity(ghes->estatus->error_severity);
        if (sev > sev_global) {
            sev_global = sev;
            ghes_global = ghes;
        }
        ret = NMI_HANDLED;
    }

    if (ret == NMI_DONE)
        goto out;

    if (sev_global >= GHES_SEV_PANIC) {
        oops_begin();
        ghes_print_queued_estatus();
        __ghes_print_estatus(KERN_EMERG, ghes_global->generic,
                     ghes_global->estatus);
        /* reboot to log the error! */
        if (panic_timeout == 0)
            panic_timeout = ghes_panic_timeout;
        panic("Fatal hardware error!");
    }

    list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
        u32 len, node_len;
        struct ghes_estatus_node *estatus_node;
        struct acpi_hest_generic_status *estatus;
#endif
        if (!(ghes->flags & GHES_TO_CLEAR))
            continue;
#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
        if (ghes_estatus_cached(ghes->estatus))
            goto next;
        /* Save estatus for further processing in IRQ context */
        len = apei_estatus_len(ghes->estatus);
        node_len = GHES_ESTATUS_NODE_LEN(len);
        estatus_node = (void *)gen_pool_alloc(ghes_estatus_pool,
                              node_len);
        if (estatus_node) {
            estatus_node->generic = ghes->generic;
            estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
            memcpy(estatus, ghes->estatus, len);
            llist_add(&estatus_node->llnode, &ghes_estatus_llist);
        }
next:
#endif
        ghes_clear_estatus(ghes);
    }
#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
    irq_work_queue(&ghes_proc_irq_work);
#endif

out:
    raw_spin_unlock(&ghes_nmi_lock);
    return ret;
}

static struct notifier_block ghes_notifier_sci = {
    .notifier_call = ghes_notify_sci,
};

static unsigned long ghes_esource_prealloc_size(
    const struct acpi_hest_generic *generic)
{
    unsigned long block_length, prealloc_records, prealloc_size;

    block_length = min_t(unsigned long, generic->error_block_length,
                 GHES_ESTATUS_MAX_SIZE);
    prealloc_records = max_t(unsigned long,
                 generic->records_to_preallocate, 1);
    prealloc_size = min_t(unsigned long, block_length * prealloc_records,
                  GHES_ESOURCE_PREALLOC_MAX_SIZE);

    return prealloc_size;
}

static int __devinit ghes_probe(struct platform_device *ghes_dev)
{
    struct acpi_hest_generic *generic;
    struct ghes *ghes = NULL;
    unsigned long len;
    int rc = -EINVAL;

    generic = *(struct acpi_hest_generic **)ghes_dev->dev.platform_data;
    if (!generic->enabled)
        return -ENODEV;

    switch (generic->notify.type) {
    case ACPI_HEST_NOTIFY_POLLED:
    case ACPI_HEST_NOTIFY_EXTERNAL:
    case ACPI_HEST_NOTIFY_SCI:
    case ACPI_HEST_NOTIFY_NMI:
        break;
    case ACPI_HEST_NOTIFY_LOCAL:
        pr_warning(GHES_PFX "Generic hardware error source: %d notified via local interrupt is not supported!\n",
               generic->header.source_id);
        goto err;
    default:
        pr_warning(FW_WARN GHES_PFX "Unknown notification type: %u for generic hardware error source: %d\n",
               generic->notify.type, generic->header.source_id);
        goto err;
    }

    rc = -EIO;
    if (generic->error_block_length <
        sizeof(struct acpi_hest_generic_status)) {
        pr_warning(FW_BUG GHES_PFX "Invalid error block length: %u for generic hardware error source: %d\n",
               generic->error_block_length,
               generic->header.source_id);
        goto err;
    }
    ghes = ghes_new(generic);
    if (IS_ERR(ghes)) {
        rc = PTR_ERR(ghes);
        ghes = NULL;
        goto err;
    }
    switch (generic->notify.type) {
    case ACPI_HEST_NOTIFY_POLLED:
        ghes->timer.function = ghes_poll_func;
        ghes->timer.data = (unsigned long)ghes;
        init_timer_deferrable(&ghes->timer);
        ghes_add_timer(ghes);
        break;
    case ACPI_HEST_NOTIFY_EXTERNAL:
        /* External interrupt vector is GSI */
        if (acpi_gsi_to_irq(generic->notify.vector, &ghes->irq)) {
            pr_err(GHES_PFX "Failed to map GSI to IRQ for generic hardware error source: %d\n",
                   generic->header.source_id);
            goto err;
        }
        if (request_irq(ghes->irq, ghes_irq_func,
                0, "GHES IRQ", ghes)) {
            pr_err(GHES_PFX "Failed to register IRQ for generic hardware error source: %d\n",
                   generic->header.source_id);
            goto err;
        }
        break;
    case ACPI_HEST_NOTIFY_SCI:
        mutex_lock(&ghes_list_mutex);
        if (list_empty(&ghes_sci))
            register_acpi_hed_notifier(&ghes_notifier_sci);
        list_add_rcu(&ghes->list, &ghes_sci);
        mutex_unlock(&ghes_list_mutex);
        break;
    case ACPI_HEST_NOTIFY_NMI:
        len = ghes_esource_prealloc_size(generic);
        ghes_estatus_pool_expand(len);
        mutex_lock(&ghes_list_mutex);
        if (list_empty(&ghes_nmi))
            register_nmi_handler(NMI_LOCAL, ghes_notify_nmi, 0,
                        "ghes");
        list_add_rcu(&ghes->list, &ghes_nmi);
        mutex_unlock(&ghes_list_mutex);
        break;
    default:
        BUG();
    }
    platform_set_drvdata(ghes_dev, ghes);

    return 0;
err:
    if (ghes) {
        ghes_fini(ghes);
        kfree(ghes);
    }
    return rc;
}

static int __devexit ghes_remove(struct platform_device *ghes_dev)
{
    struct ghes *ghes;
    struct acpi_hest_generic *generic;
    unsigned long len;

    ghes = platform_get_drvdata(ghes_dev);
    generic = ghes->generic;

    ghes->flags |= GHES_EXITING;
    switch (generic->notify.type) {
    case ACPI_HEST_NOTIFY_POLLED:
        del_timer_sync(&ghes->timer);
        break;
    case ACPI_HEST_NOTIFY_EXTERNAL:
        free_irq(ghes->irq, ghes);
        break;
    case ACPI_HEST_NOTIFY_SCI:
        mutex_lock(&ghes_list_mutex);
        list_del_rcu(&ghes->list);
        if (list_empty(&ghes_sci))
            unregister_acpi_hed_notifier(&ghes_notifier_sci);
        mutex_unlock(&ghes_list_mutex);
        break;
    case ACPI_HEST_NOTIFY_NMI:
        mutex_lock(&ghes_list_mutex);
        list_del_rcu(&ghes->list);
        if (list_empty(&ghes_nmi))
            unregister_nmi_handler(NMI_LOCAL, "ghes");
        mutex_unlock(&ghes_list_mutex);
        /*
         * To synchronize with NMI handler, ghes can only be
         * freed after NMI handler finishes.
         */
        synchronize_rcu();
        len = ghes_esource_prealloc_size(generic);
        ghes_estatus_pool_shrink(len);
        break;
    default:
        BUG();
        break;
    }

    ghes_fini(ghes);
    kfree(ghes);

    platform_set_drvdata(ghes_dev, NULL);

    return 0;
}

static struct platform_driver ghes_platform_driver = {
    .driver     = {
        .name   = "GHES",
        .owner  = THIS_MODULE,
    },
    .probe      = ghes_probe,
    .remove     = ghes_remove,
};

static int __init ghes_init(void)
{
    int rc;

    if (acpi_disabled)
        return -ENODEV;

    if (hest_disable) {
        pr_info(GHES_PFX "HEST is not enabled!\n");
        return -EINVAL;
    }

    if (ghes_disable) {
        pr_info(GHES_PFX "GHES is not enabled!\n");
        return -EINVAL;
    }

    init_irq_work(&ghes_proc_irq_work, ghes_proc_in_irq);

    rc = ghes_ioremap_init();
    if (rc)
        goto err;

    rc = ghes_estatus_pool_init();
    if (rc)
        goto err_ioremap_exit;

    rc = ghes_estatus_pool_expand(GHES_ESTATUS_CACHE_AVG_SIZE *
                      GHES_ESTATUS_CACHE_ALLOCED_MAX);
    if (rc)
        goto err_pool_exit;

    rc = platform_driver_register(&ghes_platform_driver);
    if (rc)
        goto err_pool_exit;

    rc = apei_osc_setup();
    if (rc == 0 && osc_sb_apei_support_acked)
        pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit and WHEA _OSC.\n");
    else if (rc == 0 && !osc_sb_apei_support_acked)
        pr_info(GHES_PFX "APEI firmware first mode is enabled by WHEA _OSC.\n");
    else if (rc && osc_sb_apei_support_acked)
        pr_info(GHES_PFX "APEI firmware first mode is enabled by APEI bit.\n");
    else
        pr_info(GHES_PFX "Failed to enable APEI firmware first mode.\n");

    return 0;
err_pool_exit:
    ghes_estatus_pool_exit();
err_ioremap_exit:
    ghes_ioremap_exit();
err:
    return rc;
}

static void __exit ghes_exit(void)
{
    platform_driver_unregister(&ghes_platform_driver);
    ghes_estatus_pool_exit();
    ghes_ioremap_exit();
}

module_init(ghes_init);
module_exit(ghes_exit);

MODULE_AUTHOR("Huang Ying");
MODULE_DESCRIPTION("APEI Generic Hardware Error Source support");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:GHES");