RAS: Introduce a FRU memory poison manager

Memory errors are an expected occurrence on systems with high memory
density. Generally, errors within a small number of unique physical
locations are acceptable, based on manufacturer and/or admin policy.
During run time, memory with errors may be retired so it is no longer
used by the system. This is done in mm through page poisoning, and the
effect will remain until the system is restarted.

If a memory location is consistently faulty, then the same run time
error handling may occur in the next reboot cycle, leading to
terminating jobs due to that already known bad memory. This could be
prevented if information from the previous boot was not lost.

Some add-in cards with driver-managed memory have on-board persistent
storage. Their driver saves memory error information to the persistent
storage during run time. The information is then restored after reset,
and known bad memory will be retired before the hardware is used.
A running log of bad memory locations is kept across multiple resets.

A similar solution is desirable for CPUs. However, this solution should
leverage industry-standard components as much as possible, rather than
a bespoke platform driver.

Two components are needed: a record format and a persistent storage
interface.

Implement a new module to manage the record formats on persistent
storage. Use the requirements for an AMD MI300-based system to start.
Vendor- and platform-specific details can be abstracted later as needed.

  [ bp: Massage commit message and code, squash 30-ish more fixes from
    Yazen and me. ]

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Co-developed-by: <naveenkrishna.chatradhi@amd.com>
Signed-off-by: <naveenkrishna.chatradhi@amd.com>
Co-developed-by: <muralidhara.mk@amd.com>
Signed-off-by: <muralidhara.mk@amd.com>
Tested-by: <sathyapriya.k@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240214033516.1344948-3-yazen.ghannam@amd.com

MAINTAINERS

@@ -18363,6 +18363,12 @@ F:	drivers/ras/
 F:	include/linux/ras.h
 F:	include/ras/ras_event.h
 
+RAS FRU MEMORY POISON MANAGER (FMPM)
+M:	Yazen Ghannam <Yazen.Ghannam@amd.com>
+L:	linux-edac@vger.kernel.org
+S:	Maintained
+F:	drivers/ras/amd/fmpm.c
+
 RC-CORE / LIRC FRAMEWORK
 M:	Sean Young <sean@mess.org>
 L:	linux-media@vger.kernel.org

drivers/ras/Kconfig

@@ -34,4 +34,16 @@ if RAS
 source "arch/x86/ras/Kconfig"
 source "drivers/ras/amd/atl/Kconfig"
 
+config RAS_FMPM
+	tristate "FRU Memory Poison Manager"
+	default m
+	depends on AMD_ATL && ACPI_APEI
+	help
+	  Support saving and restoring memory error information across reboot
+	  using ACPI ERST as persistent storage. Error information is saved with
+	  the UEFI CPER "FRU Memory Poison" section format.
+
+	  Memory will be retired during boot time and run time depending on
+	  platform-specific policies.
+
 endif

drivers/ras/Makefile

@@ -3,4 +3,5 @@ obj-$(CONFIG_RAS)	+= ras.o
 obj-$(CONFIG_DEBUG_FS)	+= debugfs.o
 obj-$(CONFIG_RAS_CEC)	+= cec.o
 
+obj-$(CONFIG_RAS_FMPM)	+= amd/fmpm.o
 obj-y			+= amd/atl/

drivers/ras/amd/fmpm.c

@@ -0,0 +1,812 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * FRU (Field-Replaceable Unit) Memory Poison Manager
+ *
+ * Copyright (c) 2024, Advanced Micro Devices, Inc.
+ * All Rights Reserved.
+ *
+ * Authors:
+ *	Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
+ *	Muralidhara M K <muralidhara.mk@amd.com>
+ *	Yazen Ghannam <Yazen.Ghannam@amd.com>
+ *
+ * Implementation notes, assumptions, and limitations:
+ *
+ * - FRU memory poison section and memory poison descriptor definitions are not yet
+ *   included in the UEFI specification. So they are defined here. Afterwards, they
+ *   may be moved to linux/cper.h, if appropriate.
+ *
+ * - Platforms based on AMD MI300 systems will be the first to use these structures.
+ *   There are a number of assumptions made here that will need to be generalized
+ *   to support other platforms.
+ *
+ *   AMD MI300-based platform(s) assumptions:
+ *   - Memory errors are reported through x86 MCA.
+ *   - The entire DRAM row containing a memory error should be retired.
+ *   - There will be (1) FRU memory poison section per CPER.
+ *   - The FRU will be the CPU package (processor socket).
+ *   - The default number of memory poison descriptor entries should be (8).
+ *   - The platform will use ACPI ERST for persistent storage.
+ *   - All FRU records should be saved to persistent storage. Module init will
+ *     fail if any FRU record is not successfully written.
+ *
+ * - Boot time memory retirement may occur later than ideal due to dependencies
+ *   on other libraries and drivers. This leaves a gap where bad memory may be
+ *   accessed during early boot stages.
+ *
+ * - Enough memory should be pre-allocated for each FRU record to be able to hold
+ *   the expected number of descriptor entries. This, mostly empty, record is
+ *   written to storage during init time. Subsequent writes to the same record
+ *   should allow the Platform to update the stored record in-place. Otherwise,
+ *   if the record is extended, then the Platform may need to perform costly memory
+ *   management operations on the storage. For example, the Platform may spend time
+ *   in Firmware copying and invalidating memory on a relatively slow SPI ROM.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cper.h>
+#include <linux/ras.h>
+#include <linux/cpu.h>
+
+#include <acpi/apei.h>
+
+#include <asm/cpu_device_id.h>
+#include <asm/mce.h>
+
+#define INVALID_CPU			UINT_MAX
+
+/* Validation Bits */
+#define FMP_VALID_ARCH_TYPE		BIT_ULL(0)
+#define FMP_VALID_ARCH			BIT_ULL(1)
+#define FMP_VALID_ID_TYPE		BIT_ULL(2)
+#define FMP_VALID_ID			BIT_ULL(3)
+#define FMP_VALID_LIST_ENTRIES		BIT_ULL(4)
+#define FMP_VALID_LIST			BIT_ULL(5)
+
+/* FRU Architecture Types */
+#define FMP_ARCH_TYPE_X86_CPUID_1_EAX	0
+
+/* FRU ID Types */
+#define FMP_ID_TYPE_X86_PPIN		0
+
+/* FRU Memory Poison Section */
+struct cper_sec_fru_mem_poison {
+	u32 checksum;
+	u64 validation_bits;
+	u32 fru_arch_type;
+	u64 fru_arch;
+	u32 fru_id_type;
+	u64 fru_id;
+	u32 nr_entries;
+} __packed;
+
+/* FRU Descriptor ID Types */
+#define FPD_HW_ID_TYPE_MCA_IPID		0
+
+/* FRU Descriptor Address Types */
+#define FPD_ADDR_TYPE_MCA_ADDR		0
+
+/* Memory Poison Descriptor */
+struct cper_fru_poison_desc {
+	u64 timestamp;
+	u32 hw_id_type;
+	u64 hw_id;
+	u32 addr_type;
+	u64 addr;
+} __packed;
+
+/* Collection of headers and sections for easy pointer use. */
+struct fru_rec {
+	struct cper_record_header	hdr;
+	struct cper_section_descriptor	sec_desc;
+	struct cper_sec_fru_mem_poison	fmp;
+	struct cper_fru_poison_desc	entries[];
+} __packed;
+
+/*
+ * Pointers to the complete CPER record of each FRU.
+ *
+ * Memory allocation will include padded space for descriptor entries.
+ */
+static struct fru_rec **fru_records;
+
+#define CPER_CREATOR_FMP						\
+	GUID_INIT(0xcd5c2993, 0xf4b2, 0x41b2, 0xb5, 0xd4, 0xf9, 0xc3,	\
+		  0xa0, 0x33, 0x08, 0x75)
+
+#define CPER_SECTION_TYPE_FMP						\
+	GUID_INIT(0x5e4706c1, 0x5356, 0x48c6, 0x93, 0x0b, 0x52, 0xf2,	\
+		  0x12, 0x0a, 0x44, 0x58)
+
+/**
+ * DOC: fru_poison_entries (byte)
+ * Maximum number of descriptor entries possible for each FRU.
+ *
+ * Values between '1' and '255' are valid.
+ * No input or '0' will default to FMPM_DEFAULT_MAX_NR_ENTRIES.
+ */
+static u8 max_nr_entries;
+module_param(max_nr_entries, byte, 0644);
+MODULE_PARM_DESC(max_nr_entries,
+		 "Maximum number of memory poison descriptor entries per FRU");
+
+#define FMPM_DEFAULT_MAX_NR_ENTRIES	8
+
+/* Maximum number of FRUs in the system. */
+#define FMPM_MAX_NR_FRU			256
+static unsigned int max_nr_fru;
+
+/* Total length of record including headers and list of descriptor entries. */
+static size_t max_rec_len;
+
+/*
+ * Protect the local records cache in fru_records and prevent concurrent
+ * writes to storage. This is only needed after init once notifier block
+ * registration is done.
+ */
+static DEFINE_MUTEX(fmpm_update_mutex);
+
+#define for_each_fru(i, rec) \
+	for (i = 0; rec = fru_records[i], i < max_nr_fru; i++)
+
+static inline u32 get_fmp_len(struct fru_rec *rec)
+{
+	return rec->sec_desc.section_length - sizeof(struct cper_section_descriptor);
+}
+
+static struct fru_rec *get_fru_record(u64 fru_id)
+{
+	struct fru_rec *rec;
+	unsigned int i;
+
+	for_each_fru(i, rec) {
+		if (rec->fmp.fru_id == fru_id)
+			return rec;
+	}
+
+	pr_debug("Record not found for FRU 0x%016llx\n", fru_id);
+
+	return NULL;
+}
+
+/*
+ * Sum up all bytes within the FRU Memory Poison Section including the Memory
+ * Poison Descriptor entries.
+ *
+ * Don't include the old checksum here. It's a u32 value, so summing each of its
+ * bytes will give the wrong total.
+ */
+static u32 do_fmp_checksum(struct cper_sec_fru_mem_poison *fmp, u32 len)
+{
+	u32 checksum = 0;
+	u8 *buf, *end;
+
+	/* Skip old checksum. */
+	buf = (u8 *)fmp + sizeof(u32);
+	end = buf + len;
+
+	while (buf < end)
+		checksum += (u8)(*(buf++));
+
+	return checksum;
+}
+
+static int update_record_on_storage(struct fru_rec *rec)
+{
+	u32 len, checksum;
+	int ret;
+
+	/* Calculate a new checksum. */
+	len = get_fmp_len(rec);
+
+	/* Get the current total. */
+	checksum = do_fmp_checksum(&rec->fmp, len);
+
+	/* Use the complement value. */
+	rec->fmp.checksum = -checksum;
+
+	pr_debug("Writing to storage\n");
+
+	ret = erst_write(&rec->hdr);
+	if (ret) {
+		pr_warn("Storage update failed for FRU 0x%016llx\n", rec->fmp.fru_id);
+
+		if (ret == -ENOSPC)
+			pr_warn("Not enough space on storage\n");
+	}
+
+	return ret;
+}
+
+static bool rec_has_valid_entries(struct fru_rec *rec)
+{
+	if (!(rec->fmp.validation_bits & FMP_VALID_LIST_ENTRIES))
+		return false;
+
+	if (!(rec->fmp.validation_bits & FMP_VALID_LIST))
+		return false;
+
+	return true;
+}
+
+static bool fpds_equal(struct cper_fru_poison_desc *old, struct cper_fru_poison_desc *new)
+{
+	/*
+	 * Ignore timestamp field.
+	 * The same physical error may be reported multiple times due to stuck bits, etc.
+	 *
+	 * Also, order the checks from most->least likely to fail to shortcut the code.
+	 */
+	if (old->addr != new->addr)
+		return false;
+
+	if (old->hw_id != new->hw_id)
+		return false;
+
+	if (old->addr_type != new->addr_type)
+		return false;
+
+	if (old->hw_id_type != new->hw_id_type)
+		return false;
+
+	return true;
+}
+
+static bool rec_has_fpd(struct fru_rec *rec, struct cper_fru_poison_desc *fpd)
+{
+	unsigned int i;
+
+	for (i = 0; i < rec->fmp.nr_entries; i++) {
+		struct cper_fru_poison_desc *fpd_i = &rec->entries[i];
+
+		if (fpds_equal(fpd_i, fpd)) {
+			pr_debug("Found duplicate record\n");
+			return true;
+		}
+	}
+
+	return false;
+}
+
+static void update_fru_record(struct fru_rec *rec, struct mce *m)
+{
+	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
+	struct cper_fru_poison_desc fpd, *fpd_dest;
+	u32 entry = 0;
+
+	mutex_lock(&fmpm_update_mutex);
+
+	memset(&fpd, 0, sizeof(struct cper_fru_poison_desc));
+
+	fpd.timestamp	= m->time;
+	fpd.hw_id_type = FPD_HW_ID_TYPE_MCA_IPID;
+	fpd.hw_id	= m->ipid;
+	fpd.addr_type	= FPD_ADDR_TYPE_MCA_ADDR;
+	fpd.addr	= m->addr;
+
+	/* This is the first entry, so just save it. */
+	if (!rec_has_valid_entries(rec))
+		goto save_fpd;
+
+	/* Ignore already recorded errors. */
+	if (rec_has_fpd(rec, &fpd))
+		goto out_unlock;
+
+	if (rec->fmp.nr_entries >= max_nr_entries) {
+		pr_warn("Exceeded number of entries for FRU 0x%016llx\n", rec->fmp.fru_id);
+		goto out_unlock;
+	}
+
+	entry  = fmp->nr_entries;
+
+save_fpd:
+	fpd_dest  = &rec->entries[entry];
+	memcpy(fpd_dest, &fpd, sizeof(struct cper_fru_poison_desc));
+
+	fmp->nr_entries		 = entry + 1;
+	fmp->validation_bits	|= FMP_VALID_LIST_ENTRIES;
+	fmp->validation_bits	|= FMP_VALID_LIST;
+
+	pr_debug("Updated FRU 0x%016llx entry #%u\n", fmp->fru_id, entry);
+
+	update_record_on_storage(rec);
+
+out_unlock:
+	mutex_unlock(&fmpm_update_mutex);
+}
+
+static void retire_dram_row(u64 addr, u64 id, u32 cpu)
+{
+	struct atl_err a_err;
+
+	memset(&a_err, 0, sizeof(struct atl_err));
+
+	a_err.addr = addr;
+	a_err.ipid = id;
+	a_err.cpu  = cpu;
+
+	amd_retire_dram_row(&a_err);
+}
+
+static int fru_handle_mem_poison(struct notifier_block *nb, unsigned long val, void *data)
+{
+	struct mce *m = (struct mce *)data;
+	struct fru_rec *rec;
+
+	if (!mce_is_memory_error(m))
+		return NOTIFY_DONE;
+
+	retire_dram_row(m->addr, m->ipid, m->extcpu);
+
+	/*
+	 * An invalid FRU ID should not happen on real errors. But it
+	 * could happen from software error injection, etc.
+	 */
+	rec = get_fru_record(m->ppin);
+	if (!rec)
+		return NOTIFY_DONE;
+
+	update_fru_record(rec, m);
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block fru_mem_poison_nb = {
+	.notifier_call  = fru_handle_mem_poison,
+	.priority	= MCE_PRIO_LOWEST,
+};
+
+static void retire_mem_fmp(struct fru_rec *rec)
+{
+	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
+	unsigned int i, cpu;
+
+	for (i = 0; i < fmp->nr_entries; i++) {
+		struct cper_fru_poison_desc *fpd = &rec->entries[i];
+		unsigned int err_cpu = INVALID_CPU;
+
+		if (fpd->hw_id_type != FPD_HW_ID_TYPE_MCA_IPID)
+			continue;
+
+		if (fpd->addr_type != FPD_ADDR_TYPE_MCA_ADDR)
+			continue;
+
+		cpus_read_lock();
+		for_each_online_cpu(cpu) {
+			if (topology_ppin(cpu) == fmp->fru_id) {
+				err_cpu = cpu;
+				break;
+			}
+		}
+		cpus_read_unlock();
+
+		if (err_cpu == INVALID_CPU)
+			continue;
+
+		retire_dram_row(fpd->addr, fpd->hw_id, err_cpu);
+	}
+}
+
+static void retire_mem_records(void)
+{
+	struct fru_rec *rec;
+	unsigned int i;
+
+	for_each_fru(i, rec) {
+		if (!rec_has_valid_entries(rec))
+			continue;
+
+		retire_mem_fmp(rec);
+	}
+}
+
+/* Set the CPER Record Header and CPER Section Descriptor fields. */
+static void set_rec_fields(struct fru_rec *rec)
+{
+	struct cper_section_descriptor	*sec_desc = &rec->sec_desc;
+	struct cper_record_header	*hdr	  = &rec->hdr;
+
+	memcpy(hdr->signature, CPER_SIG_RECORD, CPER_SIG_SIZE);
+	hdr->revision			= CPER_RECORD_REV;
+	hdr->signature_end		= CPER_SIG_END;
+
+	/*
+	 * Currently, it is assumed that there is one FRU Memory Poison
+	 * section per CPER. But this may change for other implementations.
+	 */
+	hdr->section_count		= 1;
+
+	/* The logged errors are recoverable. Otherwise, they'd never make it here. */
+	hdr->error_severity		= CPER_SEV_RECOVERABLE;
+
+	hdr->validation_bits		= 0;
+	hdr->record_length		= max_rec_len;
+	hdr->creator_id			= CPER_CREATOR_FMP;
+	hdr->notification_type		= CPER_NOTIFY_MCE;
+	hdr->record_id			= cper_next_record_id();
+	hdr->flags			= CPER_HW_ERROR_FLAGS_PREVERR;
+
+	sec_desc->section_offset	= sizeof(struct cper_record_header);
+	sec_desc->section_length	= max_rec_len - sizeof(struct cper_record_header);
+	sec_desc->revision		= CPER_SEC_REV;
+	sec_desc->validation_bits	= 0;
+	sec_desc->flags			= CPER_SEC_PRIMARY;
+	sec_desc->section_type		= CPER_SECTION_TYPE_FMP;
+	sec_desc->section_severity	= CPER_SEV_RECOVERABLE;
+}
+
+static int save_new_records(void)
+{
+	DECLARE_BITMAP(new_records, FMPM_MAX_NR_FRU);
+	struct fru_rec *rec;
+	unsigned int i;
+	int ret = 0;
+
+	for_each_fru(i, rec) {
+		if (rec->hdr.record_length)
+			continue;
+
+		set_rec_fields(rec);
+
+		ret = update_record_on_storage(rec);
+		if (ret)
+			goto out_clear;
+
+		set_bit(i, new_records);
+	}
+
+	return ret;
+
+out_clear:
+	for_each_fru(i, rec) {
+		if (!test_bit(i, new_records))
+			continue;
+
+		erst_clear(rec->hdr.record_id);
+	}
+
+	return ret;
+}
+
+/* Check that the record matches expected types for the current system.*/
+static bool fmp_is_usable(struct fru_rec *rec)
+{
+	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
+	u64 cpuid;
+
+	pr_debug("Validation bits: 0x%016llx\n", fmp->validation_bits);
+
+	if (!(fmp->validation_bits & FMP_VALID_ARCH_TYPE)) {
+		pr_debug("Arch type unknown\n");
+		return false;
+	}
+
+	if (fmp->fru_arch_type != FMP_ARCH_TYPE_X86_CPUID_1_EAX) {
+		pr_debug("Arch type not 'x86 Family/Model/Stepping'\n");
+		return false;
+	}
+
+	if (!(fmp->validation_bits & FMP_VALID_ARCH)) {
+		pr_debug("Arch value unknown\n");
+		return false;
+	}
+
+	cpuid = cpuid_eax(1);
+	if (fmp->fru_arch != cpuid) {
+		pr_debug("Arch value mismatch: record = 0x%016llx, system = 0x%016llx\n",
+			 fmp->fru_arch, cpuid);
+		return false;
+	}
+
+	if (!(fmp->validation_bits & FMP_VALID_ID_TYPE)) {
+		pr_debug("FRU ID type unknown\n");
+		return false;
+	}
+
+	if (fmp->fru_id_type != FMP_ID_TYPE_X86_PPIN) {
+		pr_debug("FRU ID type is not 'x86 PPIN'\n");
+		return false;
+	}
+
+	if (!(fmp->validation_bits & FMP_VALID_ID)) {
+		pr_debug("FRU ID value unknown\n");
+		return false;
+	}
+
+	return true;
+}
+
+static bool fmp_is_valid(struct fru_rec *rec)
+{
+	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
+	u32 checksum, len;
+
+	len = get_fmp_len(rec);
+	if (len < sizeof(struct cper_sec_fru_mem_poison)) {
+		pr_debug("fmp length is too small\n");
+		return false;
+	}
+
+	/* Checksum must sum to zero for the entire section. */
+	checksum = do_fmp_checksum(fmp, len) + fmp->checksum;
+	if (checksum) {
+		pr_debug("fmp checksum failed: sum = 0x%x\n", checksum);
+		print_hex_dump_debug("fmp record: ", DUMP_PREFIX_NONE, 16, 1, fmp, len, false);
+		return false;
+	}
+
+	if (!fmp_is_usable(rec))
+		return false;
+
+	return true;
+}
+
+static struct fru_rec *get_valid_record(struct fru_rec *old)
+{
+	struct fru_rec *new;
+
+	if (!fmp_is_valid(old)) {
+		pr_debug("Ignoring invalid record\n");
+		return NULL;
+	}
+
+	new = get_fru_record(old->fmp.fru_id);
+	if (!new)
+		pr_debug("Ignoring record for absent FRU\n");
+
+	return new;
+}
+
+/*
+ * Fetch saved records from persistent storage.
+ *
+ * For each found record:
+ * - If it was not created by this module, then ignore it.
+ * - If it is valid, then copy its data to the local cache.
+ * - If it is not valid, then erase it.
+ */
+static int get_saved_records(void)
+{
+	struct fru_rec *old, *new;
+	u64 record_id;
+	int ret, pos;
+	ssize_t len;
+
+	/*
+	 * Assume saved records match current max size.
+	 *
+	 * However, this may not be true depending on module parameters.
+	 */
+	old = kmalloc(max_rec_len, GFP_KERNEL);
+	if (!old) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = erst_get_record_id_begin(&pos);
+	if (ret < 0)
+		goto out_end;
+
+	while (!erst_get_record_id_next(&pos, &record_id)) {
+		if (record_id == APEI_ERST_INVALID_RECORD_ID)
+			goto out_end;
+		/*
+		 * Make sure to clear temporary buffer between reads to avoid
+		 * leftover data from records of various sizes.
+		 */
+		memset(old, 0, max_rec_len);
+
+		len = erst_read_record(record_id, &old->hdr, max_rec_len,
+				       sizeof(struct fru_rec), &CPER_CREATOR_FMP);
+		if (len < 0)
+			continue;
+
+		if (len > max_rec_len) {
+			pr_debug("Found record larger than max_rec_len\n");
+			continue;
+		}
+
+		new = get_valid_record(old);
+		if (!new)
+			erst_clear(record_id);
+
+		/* Restore the record */
+		memcpy(new, old, len);
+	}
+
+out_end:
+	erst_get_record_id_end();
+	kfree(old);
+out:
+	return ret;
+}
+
+static void set_fmp_fields(struct fru_rec *rec, unsigned int cpu)
+{
+	struct cper_sec_fru_mem_poison *fmp = &rec->fmp;
+
+	fmp->fru_arch_type    = FMP_ARCH_TYPE_X86_CPUID_1_EAX;
+	fmp->validation_bits |= FMP_VALID_ARCH_TYPE;
+
+	/* Assume all CPUs in the system have the same value for now. */
+	fmp->fru_arch	      = cpuid_eax(1);
+	fmp->validation_bits |= FMP_VALID_ARCH;
+
+	fmp->fru_id_type      = FMP_ID_TYPE_X86_PPIN;
+	fmp->validation_bits |= FMP_VALID_ID_TYPE;
+
+	fmp->fru_id	      = topology_ppin(cpu);
+	fmp->validation_bits |= FMP_VALID_ID;
+}
+
+static int init_fmps(void)
+{
+	struct fru_rec *rec;
+	unsigned int i, cpu;
+	int ret = 0;
+
+	for_each_fru(i, rec) {
+		unsigned int fru_cpu = INVALID_CPU;
+
+		cpus_read_lock();
+		for_each_online_cpu(cpu) {
+			if (topology_physical_package_id(cpu) == i) {
+				fru_cpu = cpu;
+				break;
+			}
+		}
+		cpus_read_unlock();
+
+		if (fru_cpu == INVALID_CPU) {
+			pr_debug("Failed to find matching CPU for FRU #%u\n", i);
+			ret = -ENODEV;
+			break;
+		}
+
+		set_fmp_fields(rec, fru_cpu);
+	}
+
+	return ret;
+}
+
+static int get_system_info(void)
+{
+	/* Only load on MI300A systems for now. */
+	if (!(boot_cpu_data.x86_model >= 0x90 &&
+	      boot_cpu_data.x86_model <= 0x9f))
+		return -ENODEV;
+
+	if (!cpu_feature_enabled(X86_FEATURE_AMD_PPIN)) {
+		pr_debug("PPIN feature not available\n");
+		return -ENODEV;
+	}
+
+	/* Use CPU socket as FRU for MI300 systems. */
+	max_nr_fru = topology_max_packages();
+	if (!max_nr_fru)
+		return -ENODEV;
+
+	if (max_nr_fru > FMPM_MAX_NR_FRU) {
+		pr_warn("Too many FRUs to manage: found: %u, max: %u\n",
+			max_nr_fru, FMPM_MAX_NR_FRU);
+		return -ENODEV;
+	}
+
+	if (!max_nr_entries)
+		max_nr_entries = FMPM_DEFAULT_MAX_NR_ENTRIES;
+
+	max_rec_len  = sizeof(struct fru_rec);
+	max_rec_len += sizeof(struct cper_fru_poison_desc) * max_nr_entries;
+
+	pr_info("max FRUs: %u, max entries: %u, max record length: %lu\n",
+		 max_nr_fru, max_nr_entries, max_rec_len);
+
+	return 0;
+}
+
+static void free_records(void)
+{
+	struct fru_rec *rec;
+	int i;
+
+	for_each_fru(i, rec)
+		kfree(rec);
+
+	kfree(fru_records);
+}
+
+static int allocate_records(void)
+{
+	int i, ret = 0;
+
+	fru_records = kcalloc(max_nr_fru, sizeof(struct fru_rec *), GFP_KERNEL);
+	if (!fru_records) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	for (i = 0; i < max_nr_fru; i++) {
+		fru_records[i] = kzalloc(max_rec_len, GFP_KERNEL);
+		if (!fru_records[i]) {
+			ret = -ENOMEM;
+			goto out_free;
+		}
+	}
+
+	return ret;
+
+out_free:
+	for (; i >= 0; i--)
+		kfree(fru_records[i]);
+
+	kfree(fru_records);
+out:
+	return ret;
+}
+
+static const struct x86_cpu_id fmpm_cpuids[] = {
+	X86_MATCH_VENDOR_FAM(AMD, 0x19, NULL),
+	{ }
+};
+MODULE_DEVICE_TABLE(x86cpu, fmpm_cpuids);
+
+static int __init fru_mem_poison_init(void)
+{
+	int ret;
+
+	if (!x86_match_cpu(fmpm_cpuids)) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	if (erst_disable) {
+		pr_debug("ERST not available\n");
+		ret = -ENODEV;
+		goto out;
+	}
+
+	ret = get_system_info();
+	if (ret)
+		goto out;
+
+	ret = allocate_records();
+	if (ret)
+		goto out;
+
+	ret = init_fmps();
+	if (ret)
+		goto out_free;
+
+	ret = get_saved_records();
+	if (ret)
+		goto out_free;
+
+	ret = save_new_records();
+	if (ret)
+		goto out_free;
+
+	retire_mem_records();
+
+	mce_register_decode_chain(&fru_mem_poison_nb);
+
+	pr_info("FRU Memory Poison Manager initialized\n");
+	return 0;
+
+out_free:
+	free_records();
+out:
+	return ret;
+}
+
+static void __exit fru_mem_poison_exit(void)
+{
+	mce_unregister_decode_chain(&fru_mem_poison_nb);
+	free_records();
+}
+
+module_init(fru_mem_poison_init);
+module_exit(fru_mem_poison_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("FRU Memory Poison Manager");