Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1260 insertions, 0 deletions

diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
new file mode 100644
index 000000000..be6d233fd
--- /dev/null
+++ b/drivers/acpi/apei/ghes.c
@@ -0,0 +1,1260 @@
+/*
+ * 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 <ying.huang@intel.com>
+ *
+ * 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/moduleparam.h>
+#include <linux/init.h>
+#include <linux/acpi.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/timer.h>
+#include <linux/cper.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 <linux/nmi.h>
+#include <linux/sched/clock.h>
+#include <linux/uuid.h>
+#include <linux/ras.h>
+
+#include <acpi/actbl1.h>
+#include <acpi/ghes.h>
+#include <acpi/apei.h>
+#include <asm/fixmap.h>
+#include <asm/tlbflush.h>
+#include <ras/ras_event.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))
+
+static inline bool is_hest_type_generic_v2(struct ghes *ghes)
+{
+	return ghes->generic->header.type == ACPI_HEST_TYPE_GENERIC_ERROR_V2;
+}
+
+/*
+ * This driver isn't really modular, however for the time being,
+ * continuing to use module_param is the easiest way to remain
+ * compatible with existing boot arg use cases.
+ */
+bool ghes_disable;
+module_param_named(disable, ghes_disable, bool, 0);
+
+/*
+ * All error sources notified with HED (Hardware Error Device) share a
+ * single notifier callback, so they need to be linked and checked one
+ * by one. This holds true for 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_hed);
+static DEFINE_MUTEX(ghes_list_mutex);
+
+/*
+ * 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
+ * the fixmap is used instead.
+ *
+ * These 2 spinlocks are used to prevent the fixmap entries from being used
+ * simultaneously.
+ */
+static DEFINE_RAW_SPINLOCK(ghes_ioremap_lock_nmi);
+static DEFINE_SPINLOCK(ghes_ioremap_lock_irq);
+
+static struct gen_pool *ghes_estatus_pool;
+static unsigned long ghes_estatus_pool_size_request;
+
+static struct ghes_estatus_cache *ghes_estatus_caches[GHES_ESTATUS_CACHES_SIZE];
+static atomic_t ghes_estatus_cache_alloced;
+
+static int ghes_panic_timeout __read_mostly = 30;
+
+static void __iomem *ghes_ioremap_pfn_nmi(u64 pfn)
+{
+	phys_addr_t paddr;
+	pgprot_t prot;
+
+	paddr = pfn << PAGE_SHIFT;
+	prot = arch_apei_get_mem_attribute(paddr);
+	__set_fixmap(FIX_APEI_GHES_NMI, paddr, prot);
+
+	return (void __iomem *) fix_to_virt(FIX_APEI_GHES_NMI);
+}
+
+static void __iomem *ghes_ioremap_pfn_irq(u64 pfn)
+{
+	phys_addr_t paddr;
+	pgprot_t prot;
+
+	paddr = pfn << PAGE_SHIFT;
+	prot = arch_apei_get_mem_attribute(paddr);
+	__set_fixmap(FIX_APEI_GHES_IRQ, paddr, prot);
+
+	return (void __iomem *) fix_to_virt(FIX_APEI_GHES_IRQ);
+}
+
+static void ghes_iounmap_nmi(void)
+{
+	clear_fixmap(FIX_APEI_GHES_NMI);
+}
+
+static void ghes_iounmap_irq(void)
+{
+	clear_fixmap(FIX_APEI_GHES_IRQ);
+}
+
+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(struct gen_pool *pool,
+					      struct gen_pool_chunk *chunk,
+					      void *data)
+{
+	vfree((void *)chunk->start_addr);
+}
+
+static void ghes_estatus_pool_exit(void)
+{
+	gen_pool_for_each_chunk(ghes_estatus_pool,
+				ghes_estatus_pool_free_chunk, NULL);
+	gen_pool_destroy(ghes_estatus_pool);
+}
+
+static int ghes_estatus_pool_expand(unsigned long len)
+{
+	unsigned long size, addr;
+
+	ghes_estatus_pool_size_request += PAGE_ALIGN(len);
+	size = gen_pool_size(ghes_estatus_pool);
+	if (size >= ghes_estatus_pool_size_request)
+		return 0;
+
+	addr = (unsigned long)vmalloc(PAGE_ALIGN(len));
+	if (!addr)
+		return -ENOMEM;
+
+	/*
+	 * New allocation must be visible in all pgd before it can be found by
+	 * an NMI allocating from the pool.
+	 */
+	vmalloc_sync_mappings();
+
+	return gen_pool_add(ghes_estatus_pool, addr, PAGE_ALIGN(len), -1);
+}
+
+static int map_gen_v2(struct ghes *ghes)
+{
+	return apei_map_generic_address(&ghes->generic_v2->read_ack_register);
+}
+
+static void unmap_gen_v2(struct ghes *ghes)
+{
+	apei_unmap_generic_address(&ghes->generic_v2->read_ack_register);
+}
+
+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;
+	if (is_hest_type_generic_v2(ghes)) {
+		rc = map_gen_v2(ghes);
+		if (rc)
+			goto err_free;
+	}
+
+	rc = apei_map_generic_address(&generic->error_status_address);
+	if (rc)
+		goto err_unmap_read_ack_addr;
+	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_status_addr;
+	}
+
+	return ghes;
+
+err_unmap_status_addr:
+	apei_unmap_generic_address(&generic->error_status_address);
+err_unmap_read_ack_addr:
+	if (is_hest_type_generic_v2(ghes))
+		unmap_gen_v2(ghes);
+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);
+	if (is_hest_type_generic_v2(ghes))
+		unmap_gen_v2(ghes);
+}
+
+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();
+			raw_spin_unlock(&ghes_ioremap_lock_nmi);
+		} else {
+			ghes_iounmap_irq();
+			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 = cper_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 (cper_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 (cper_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_handle_memory_failure(struct acpi_hest_generic_data *gdata, int sev)
+{
+#ifdef CONFIG_ACPI_APEI_MEMORY_FAILURE
+	unsigned long pfn;
+	int flags = -1;
+	int sec_sev = ghes_severity(gdata->error_severity);
+	struct cper_sec_mem_err *mem_err = acpi_hest_get_payload(gdata);
+
+	if (!(mem_err->validation_bits & CPER_MEM_VALID_PA))
+		return;
+
+	pfn = mem_err->physical_addr >> PAGE_SHIFT;
+	if (!pfn_valid(pfn)) {
+		pr_warn_ratelimited(FW_WARN GHES_PFX
+		"Invalid address in generic error data: %#llx\n",
+		mem_err->physical_addr);
+		return;
+	}
+
+	/* iff following two events can be handled properly by now */
+	if (sec_sev == GHES_SEV_CORRECTED &&
+	    (gdata->flags & CPER_SEC_ERROR_THRESHOLD_EXCEEDED))
+		flags = MF_SOFT_OFFLINE;
+	if (sev == GHES_SEV_RECOVERABLE && sec_sev == GHES_SEV_RECOVERABLE)
+		flags = 0;
+
+	if (flags != -1)
+		memory_failure_queue(pfn, flags);
+#endif
+}
+
+/*
+ * PCIe AER errors need to be sent to the AER driver for reporting and
+ * recovery. The GHES severities map to the following AER severities and
+ * require the following handling:
+ *
+ * GHES_SEV_CORRECTABLE -> AER_CORRECTABLE
+ *     These need to be reported by the AER driver but no recovery is
+ *     necessary.
+ * GHES_SEV_RECOVERABLE -> AER_NONFATAL
+ * GHES_SEV_RECOVERABLE && CPER_SEC_RESET -> AER_FATAL
+ *     These both need to be reported and recovered from by the AER driver.
+ * GHES_SEV_PANIC does not make it to this handling since the kernel must
+ *     panic.
+ */
+static void ghes_handle_aer(struct acpi_hest_generic_data *gdata)
+{
+#ifdef CONFIG_ACPI_APEI_PCIEAER
+	struct cper_sec_pcie *pcie_err = acpi_hest_get_payload(gdata);
+
+	if (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(gdata->error_severity);
+
+		/*
+		 * If firmware reset the component to contain
+		 * the error, we must reinitialize it before
+		 * use, so treat it as a fatal AER error.
+		 */
+		if (gdata->flags & CPER_SEC_RESET)
+			aer_severity = AER_FATAL;
+
+		aer_recover_queue(pcie_err->device_id.segment,
+				  pcie_err->device_id.bus,
+				  devfn, aer_severity,
+				  (struct aer_capability_regs *)
+				  pcie_err->aer_info);
+	}
+#endif
+}
+
+static void ghes_do_proc(struct ghes *ghes,
+			 const struct acpi_hest_generic_status *estatus)
+{
+	int sev, sec_sev;
+	struct acpi_hest_generic_data *gdata;
+	guid_t *sec_type;
+	guid_t *fru_id = &NULL_UUID_LE;
+	char *fru_text = "";
+
+	sev = ghes_severity(estatus->error_severity);
+	apei_estatus_for_each_section(estatus, gdata) {
+		sec_type = (guid_t *)gdata->section_type;
+		sec_sev = ghes_severity(gdata->error_severity);
+		if (gdata->validation_bits & CPER_SEC_VALID_FRU_ID)
+			fru_id = (guid_t *)gdata->fru_id;
+
+		if (gdata->validation_bits & CPER_SEC_VALID_FRU_TEXT)
+			fru_text = gdata->fru_text;
+
+		if (guid_equal(sec_type, &CPER_SEC_PLATFORM_MEM)) {
+			struct cper_sec_mem_err *mem_err = acpi_hest_get_payload(gdata);
+
+			ghes_edac_report_mem_error(sev, mem_err);
+
+			arch_apei_report_mem_error(sev, mem_err);
+			ghes_handle_memory_failure(gdata, sev);
+		}
+		else if (guid_equal(sec_type, &CPER_SEC_PCIE)) {
+			ghes_handle_aer(gdata);
+		}
+		else if (guid_equal(sec_type, &CPER_SEC_PROC_ARM)) {
+			struct cper_sec_proc_arm *err = acpi_hest_get_payload(gdata);
+
+			log_arm_hw_error(err);
+		} else {
+			void *err = acpi_hest_get_payload(gdata);
+
+			log_non_standard_event(sec_type, fru_id, fru_text,
+					       sec_sev, err,
+					       gdata->error_data_length);
+		}
+	}
+}
+
+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);
+	cper_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 = cper_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 = cper_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 = cper_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_ack_error(struct acpi_hest_generic_v2 *gv2)
+{
+	int rc;
+	u64 val = 0;
+
+	rc = apei_read(&val, &gv2->read_ack_register);
+	if (rc)
+		return rc;
+
+	val &= gv2->read_ack_preserve << gv2->read_ack_register.bit_offset;
+	val |= gv2->read_ack_write    << gv2->read_ack_register.bit_offset;
+
+	return apei_write(val, &gv2->read_ack_register);
+}
+
+static void __ghes_panic(struct ghes *ghes)
+{
+	__ghes_print_estatus(KERN_EMERG, ghes->generic, ghes->estatus);
+
+	ghes_clear_estatus(ghes);
+
+	/* reboot to log the error! */
+	if (!panic_timeout)
+		panic_timeout = ghes_panic_timeout;
+	panic("Fatal hardware error!");
+}
+
+static int ghes_proc(struct ghes *ghes)
+{
+	int rc;
+
+	rc = ghes_read_estatus(ghes, 0);
+	if (rc)
+		goto out;
+
+	if (ghes_severity(ghes->estatus->error_severity) >= GHES_SEV_PANIC) {
+		__ghes_panic(ghes);
+	}
+
+	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, ghes->estatus);
+
+out:
+	ghes_clear_estatus(ghes);
+
+	if (rc == -ENOENT)
+		return rc;
+
+	/*
+	 * GHESv2 type HEST entries introduce support for error acknowledgment,
+	 * so only acknowledge the error if this support is present.
+	 */
+	if (is_hest_type_generic_v2(ghes))
+		return ghes_ack_error(ghes->generic_v2);
+
+	return rc;
+}
+
+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(struct timer_list *t)
+{
+	struct ghes *ghes = from_timer(ghes, t, timer);
+
+	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_hed(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_hed, list) {
+		if (!ghes_proc(ghes))
+			ret = NOTIFY_OK;
+	}
+	rcu_read_unlock();
+
+	return ret;
+}
+
+static struct notifier_block ghes_notifier_hed = {
+	.notifier_call = ghes_notify_hed,
+};
+
+#ifdef CONFIG_ACPI_APEI_SEA
+static LIST_HEAD(ghes_sea);
+
+/*
+ * Return 0 only if one of the SEA error sources successfully reported an error
+ * record sent from the firmware.
+ */
+int ghes_notify_sea(void)
+{
+	struct ghes *ghes;
+	int ret = -ENOENT;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(ghes, &ghes_sea, list) {
+		if (!ghes_proc(ghes))
+			ret = 0;
+	}
+	rcu_read_unlock();
+	return ret;
+}
+
+static void ghes_sea_add(struct ghes *ghes)
+{
+	mutex_lock(&ghes_list_mutex);
+	list_add_rcu(&ghes->list, &ghes_sea);
+	mutex_unlock(&ghes_list_mutex);
+}
+
+static void ghes_sea_remove(struct ghes *ghes)
+{
+	mutex_lock(&ghes_list_mutex);
+	list_del_rcu(&ghes->list);
+	mutex_unlock(&ghes_list_mutex);
+	synchronize_rcu();
+}
+#else /* CONFIG_ACPI_APEI_SEA */
+static inline void ghes_sea_add(struct ghes *ghes) { }
+static inline void ghes_sea_remove(struct ghes *ghes) { }
+#endif /* CONFIG_ACPI_APEI_SEA */
+
+#ifdef CONFIG_HAVE_ACPI_APEI_NMI
+/*
+ * 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 llist_head ghes_estatus_llist;
+static struct irq_work ghes_proc_irq_work;
+
+/*
+ * NMI may be triggered on any CPU, so ghes_in_nmi is used for
+ * having only one concurrent reader.
+ */
+static atomic_t ghes_in_nmi = ATOMIC_INIT(0);
+
+static LIST_HEAD(ghes_nmi);
+
+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_reverse_order(llnode);
+	while (llnode) {
+		next = llnode->next;
+		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
+					   llnode);
+		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
+		len = cper_estatus_len(estatus);
+		node_len = GHES_ESTATUS_NODE_LEN(len);
+		ghes_do_proc(estatus_node->ghes, 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;
+
+	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_reverse_order(llnode);
+	while (llnode) {
+		estatus_node = llist_entry(llnode, struct ghes_estatus_node,
+					   llnode);
+		estatus = GHES_ESTATUS_FROM_NODE(estatus_node);
+		generic = estatus_node->generic;
+		ghes_print_estatus(NULL, generic, estatus);
+		llnode = llnode->next;
+	}
+}
+
+/* Save estatus for further processing in IRQ context */
+static void __process_error(struct ghes *ghes)
+{
+#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+	u32 len, node_len;
+	struct ghes_estatus_node *estatus_node;
+	struct acpi_hest_generic_status *estatus;
+
+	if (ghes_estatus_cached(ghes->estatus))
+		return;
+
+	len = cper_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)
+		return;
+
+	estatus_node->ghes = ghes;
+	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);
+#endif
+}
+
+static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
+{
+	struct ghes *ghes;
+	int sev, ret = NMI_DONE;
+
+	if (!atomic_add_unless(&ghes_in_nmi, 1, 1))
+		return ret;
+
+	list_for_each_entry_rcu(ghes, &ghes_nmi, list) {
+		if (ghes_read_estatus(ghes, 1)) {
+			ghes_clear_estatus(ghes);
+			continue;
+		} else {
+			ret = NMI_HANDLED;
+		}
+
+		sev = ghes_severity(ghes->estatus->error_severity);
+		if (sev >= GHES_SEV_PANIC) {
+			ghes_print_queued_estatus();
+			__ghes_panic(ghes);
+		}
+
+		if (!(ghes->flags & GHES_TO_CLEAR))
+			continue;
+
+		__process_error(ghes);
+		ghes_clear_estatus(ghes);
+	}
+
+#ifdef CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG
+	if (ret == NMI_HANDLED)
+		irq_work_queue(&ghes_proc_irq_work);
+#endif
+	atomic_dec(&ghes_in_nmi);
+	return ret;
+}
+
+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 void ghes_estatus_pool_shrink(unsigned long len)
+{
+	ghes_estatus_pool_size_request -= PAGE_ALIGN(len);
+}
+
+static void ghes_nmi_add(struct ghes *ghes)
+{
+	unsigned long len;
+
+	len = ghes_esource_prealloc_size(ghes->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);
+}
+
+static void ghes_nmi_remove(struct ghes *ghes)
+{
+	unsigned long len;
+
+	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(ghes->generic);
+	ghes_estatus_pool_shrink(len);
+}
+
+static void ghes_nmi_init_cxt(void)
+{
+	init_irq_work(&ghes_proc_irq_work, ghes_proc_in_irq);
+}
+#else /* CONFIG_HAVE_ACPI_APEI_NMI */
+static inline void ghes_nmi_add(struct ghes *ghes) { }
+static inline void ghes_nmi_remove(struct ghes *ghes) { }
+static inline void ghes_nmi_init_cxt(void) { }
+#endif /* CONFIG_HAVE_ACPI_APEI_NMI */
+
+static int ghes_probe(struct platform_device *ghes_dev)
+{
+	struct acpi_hest_generic *generic;
+	struct ghes *ghes = NULL;
+
+	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_GSIV:
+	case ACPI_HEST_NOTIFY_GPIO:
+		break;
+
+	case ACPI_HEST_NOTIFY_SEA:
+		if (!IS_ENABLED(CONFIG_ACPI_APEI_SEA)) {
+			pr_warn(GHES_PFX "Generic hardware error source: %d notified via SEA is not supported\n",
+				generic->header.source_id);
+			rc = -ENOTSUPP;
+			goto err;
+		}
+		break;
+	case ACPI_HEST_NOTIFY_NMI:
+		if (!IS_ENABLED(CONFIG_HAVE_ACPI_APEI_NMI)) {
+			pr_warn(GHES_PFX "Generic hardware error source: %d notified via NMI interrupt is not supported!\n",
+				generic->header.source_id);
+			goto err;
+		}
+		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:
+		timer_setup(&ghes->timer, ghes_poll_func, TIMER_DEFERRABLE);
+		ghes_add_timer(ghes);
+		break;
+	case ACPI_HEST_NOTIFY_EXTERNAL:
+		/* External interrupt vector is GSI */
+		rc = acpi_gsi_to_irq(generic->notify.vector, &ghes->irq);
+		if (rc) {
+			pr_err(GHES_PFX "Failed to map GSI to IRQ for generic hardware error source: %d\n",
+			       generic->header.source_id);
+			goto err;
+		}
+		rc = request_irq(ghes->irq, ghes_irq_func, IRQF_SHARED,
+				 "GHES IRQ", ghes);
+		if (rc) {
+			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:
+	case ACPI_HEST_NOTIFY_GSIV:
+	case ACPI_HEST_NOTIFY_GPIO:
+		mutex_lock(&ghes_list_mutex);
+		if (list_empty(&ghes_hed))
+			register_acpi_hed_notifier(&ghes_notifier_hed);
+		list_add_rcu(&ghes->list, &ghes_hed);
+		mutex_unlock(&ghes_list_mutex);
+		break;
+
+	case ACPI_HEST_NOTIFY_SEA:
+		ghes_sea_add(ghes);
+		break;
+	case ACPI_HEST_NOTIFY_NMI:
+		ghes_nmi_add(ghes);
+		break;
+	default:
+		BUG();
+	}
+
+	platform_set_drvdata(ghes_dev, ghes);
+
+	ghes_edac_register(ghes, &ghes_dev->dev);
+
+	/* Handle any pending errors right away */
+	ghes_proc(ghes);
+
+	return 0;
+
+err:
+	if (ghes) {
+		ghes_fini(ghes);
+		kfree(ghes);
+	}
+	return rc;
+}
+
+static int ghes_remove(struct platform_device *ghes_dev)
+{
+	struct ghes *ghes;
+	struct acpi_hest_generic *generic;
+
+	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:
+	case ACPI_HEST_NOTIFY_GSIV:
+	case ACPI_HEST_NOTIFY_GPIO:
+		mutex_lock(&ghes_list_mutex);
+		list_del_rcu(&ghes->list);
+		if (list_empty(&ghes_hed))
+			unregister_acpi_hed_notifier(&ghes_notifier_hed);
+		mutex_unlock(&ghes_list_mutex);
+		synchronize_rcu();
+		break;
+
+	case ACPI_HEST_NOTIFY_SEA:
+		ghes_sea_remove(ghes);
+		break;
+	case ACPI_HEST_NOTIFY_NMI:
+		ghes_nmi_remove(ghes);
+		break;
+	default:
+		BUG();
+		break;
+	}
+
+	ghes_fini(ghes);
+
+	ghes_edac_unregister(ghes);
+
+	kfree(ghes);
+
+	platform_set_drvdata(ghes_dev, NULL);
+
+	return 0;
+}
+
+static struct platform_driver ghes_platform_driver = {
+	.driver		= {
+		.name	= "GHES",
+	},
+	.probe		= ghes_probe,
+	.remove		= ghes_remove,
+};
+
+static int __init ghes_init(void)
+{
+	int rc;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	switch (hest_disable) {
+	case HEST_NOT_FOUND:
+		return -ENODEV;
+	case HEST_DISABLED:
+		pr_info(GHES_PFX "HEST is not enabled!\n");
+		return -EINVAL;
+	default:
+		break;
+	}
+
+	if (ghes_disable) {
+		pr_info(GHES_PFX "GHES is not enabled!\n");
+		return -EINVAL;
+	}
+
+	ghes_nmi_init_cxt();
+
+	rc = ghes_estatus_pool_init();
+	if (rc)
+		goto err;
+
+	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:
+	return rc;
+}
+device_initcall(ghes_init);