Implement ACPI APEI ERST feature

APEI are ACPI4.0 new features. It consists of ERST, BERT, HEST, and
EINJ.  ERST is used to save fault error log to a platform persistent
storage, so that when reboot os can retrieve the error log and handle
it.

This patch is used to implement ERST feature to Xen.  It consists of
3-level hierarchy: operation level, action level, and instru= ction
level.  Instruction do basic io; Action done by sequential
instructions parsed from ACPI ERST table; Operation done by
sequential actions defined by ACPI spec, providing erst_write/
erst_read/ erst_clear interfaces to MCE/ NMI/ PCIe error handling
mechanism, etc.

Signed-off-by: Liu, Jinsong <jinsong.liu@intel.com>

6 files changed, 1470 insertions, 0 deletions

diff --git a/xen/drivers/acpi/Makefile b/xen/drivers/acpi/Makefile
index 7d108c43a9..f7a693f028 100644
--- a/xen/drivers/acpi/Makefile
+++ b/xen/drivers/acpi/Makefile
@@ -1,5 +1,6 @@
 subdir-y += tables
 subdir-y += utilities
+subdir-y += apei
 
 obj-y += tables.o
 obj-y += numa.o
diff --git a/xen/drivers/acpi/apei/Makefile b/xen/drivers/acpi/apei/Makefile
new file mode 100644
index 0000000000..af6ecb0261
--- /dev/null
+++ b/xen/drivers/acpi/apei/Makefile
@@ -0,0 +1,3 @@
+obj-y += erst.o
+obj-y += apei-base.o
+obj-y += apei-io.o
diff --git a/xen/drivers/acpi/apei/apei-base.c b/xen/drivers/acpi/apei/apei-base.c
new file mode 100644
index 0000000000..e9420f05e7
--- /dev/null
+++ b/xen/drivers/acpi/apei/apei-base.c
@@ -0,0 +1,278 @@
+/*
+ * apei-base.c - ACPI Platform Error Interface (APEI) supporting
+ * infrastructure
+ *
+ * APEI allows to report errors (for example from the chipset) to the
+ * the operating system. This improves NMI handling especially. In
+ * addition it supports error serialization and error injection.
+ *
+ * For more information about APEI, please refer to ACPI Specification
+ * version 4.0, chapter 17.
+ *
+ * This file has Common functions used by more than one APEI table,
+ * including framework of interpreter for ERST and EINJ; resource
+ * management for APEI registers.
+ *
+ * This feature is ported from linux acpi tree
+ * Copyright (C) 2009, Intel Corp.
+ *	Author: Huang Ying <ying.huang@intel.com>
+ *	Ported by: Liu, Jinsong <jinsong.liu@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.
+ *
+ * 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 <xen/kernel.h>
+#include <xen/errno.h>
+#include <xen/delay.h>
+#include <xen/string.h>
+#include <xen/types.h>
+#include <xen/spinlock.h>
+#include <xen/cper.h>
+#include <asm/io.h>
+#include <acpi/acpi.h>
+#include <acpi/apei.h>
+
+#include "apei-internal.h"
+
+/*
+ * APEI ERST (Error Record Serialization Table) and EINJ (Error
+ * INJection) interpreter framework.
+ */
+
+#define APEI_EXEC_PRESERVE_REGISTER	0x1
+
+int apei_exec_ctx_init(struct apei_exec_context *ctx,
+			struct apei_exec_ins_type *ins_table,
+			u32 instructions,
+			struct acpi_whea_header *action_table,
+			u32 entries)
+{
+	if (!ctx)
+		return -EINVAL;
+
+	ctx->ins_table = ins_table;
+	ctx->instructions = instructions;
+	ctx->action_table = action_table;
+	ctx->entries = entries;
+	return 0;
+}
+
+int __apei_exec_read_register(struct acpi_whea_header *entry, u64 *val)
+{
+	int rc;
+
+	rc = apei_read(val, &entry->register_region);
+	if (rc)
+		return rc;
+	*val >>= entry->register_region.bit_offset;
+	*val &= entry->mask;
+
+	return 0;
+}
+
+int apei_exec_read_register(struct apei_exec_context *ctx,
+			    struct acpi_whea_header *entry)
+{
+	int rc;
+	u64 val = 0;
+
+	rc = __apei_exec_read_register(entry, &val);
+	if (rc)
+		return rc;
+	ctx->value = val;
+
+	return 0;
+}
+
+int apei_exec_read_register_value(struct apei_exec_context *ctx,
+				  struct acpi_whea_header *entry)
+{
+	int rc;
+
+	rc = apei_exec_read_register(ctx, entry);
+	if (rc)
+		return rc;
+	ctx->value = (ctx->value == entry->value);
+
+	return 0;
+}
+
+int __apei_exec_write_register(struct acpi_whea_header *entry, u64 val)
+{
+	int rc;
+
+	val &= entry->mask;
+	val <<= entry->register_region.bit_offset;
+	if (entry->flags & APEI_EXEC_PRESERVE_REGISTER) {
+		u64 valr = 0;
+		rc = apei_read(&valr, &entry->register_region);
+		if (rc)
+			return rc;
+		valr &= ~(entry->mask << entry->register_region.bit_offset);
+		val |= valr;
+	}
+	rc = apei_write(val, &entry->register_region);
+
+	return rc;
+}
+
+int apei_exec_write_register(struct apei_exec_context *ctx,
+			     struct acpi_whea_header *entry)
+{
+	return __apei_exec_write_register(entry, ctx->value);
+}
+
+int apei_exec_write_register_value(struct apei_exec_context *ctx,
+				   struct acpi_whea_header *entry)
+{
+	int rc;
+
+	ctx->value = entry->value;
+	rc = apei_exec_write_register(ctx, entry);
+
+	return rc;
+}
+
+int apei_exec_noop(struct apei_exec_context *ctx,
+		   struct acpi_whea_header *entry)
+{
+	return 0;
+}
+
+/*
+ * Interpret the specified action. Go through whole action table,
+ * execute all instructions belong to the action.
+ */
+int apei_exec_run(struct apei_exec_context *ctx, u8 action)
+{
+	int rc;
+	u32 i, ip;
+	struct acpi_whea_header *entry;
+	apei_exec_ins_func_t run;
+
+	ctx->ip = 0;
+
+	/*
+	 * "ip" is the instruction pointer of current instruction,
+	 * "ctx->ip" specifies the next instruction to executed,
+	 * instruction "run" function may change the "ctx->ip" to
+	 * implement "goto" semantics.
+	 */
+rewind:
+	ip = 0;
+	for (i = 0; i < ctx->entries; i++) {
+		entry = &ctx->action_table[i];
+		if (entry->action != action)
+			continue;
+		if (ip == ctx->ip) {
+			if (entry->instruction >= ctx->instructions ||
+			    !ctx->ins_table[entry->instruction].run) {
+				printk(KERN_WARNING
+				"Invalid action table, unknown instruction "
+				"type: %d\n", entry->instruction);
+				return -EINVAL;
+			}
+			run = ctx->ins_table[entry->instruction].run;
+			rc = run(ctx, entry);
+			if (rc < 0)
+				return rc;
+			else if (rc != APEI_EXEC_SET_IP)
+				ctx->ip++;
+		}
+		ip++;
+		if (ctx->ip < ip)
+			goto rewind;
+	}
+
+	return 0;
+}
+
+typedef int (*apei_exec_entry_func_t)(struct apei_exec_context *ctx,
+				      struct acpi_whea_header *entry,
+				      void *data);
+
+static int apei_exec_for_each_entry(struct apei_exec_context *ctx,
+				    apei_exec_entry_func_t func,
+				    void *data,
+				    int *end)
+{
+	u8 ins;
+	int i, rc;
+	struct acpi_whea_header *entry;
+	struct apei_exec_ins_type *ins_table = ctx->ins_table;
+
+	for (i = 0; i < ctx->entries; i++) {
+		entry = ctx->action_table + i;
+		ins = entry->instruction;
+		if (end)
+			*end = i;
+		if (ins >= ctx->instructions || !ins_table[ins].run) {
+			printk(KERN_WARNING "Invalid action table, "
+			"unknown instruction type: %d\n", ins);
+			return -EINVAL;
+		}
+		rc = func(ctx, entry, data);
+		if (rc)
+			return rc;
+	}
+
+	return 0;
+}
+
+static int pre_map_gar_callback(struct apei_exec_context *ctx,
+				struct acpi_whea_header *entry,
+				void *data)
+{
+	u8 ins = entry->instruction;
+
+	if (ctx->ins_table[ins].flags & APEI_EXEC_INS_ACCESS_REGISTER)
+		return apei_pre_map_gar(&entry->register_region);
+
+	return 0;
+}
+
+/* Pre-map all GARs in action table. */
+int apei_exec_pre_map_gars(struct apei_exec_context *ctx)
+{
+	int rc, end;
+
+	rc = apei_exec_for_each_entry(ctx, pre_map_gar_callback,
+				      NULL, &end);
+	if (rc) {
+		struct apei_exec_context ctx_unmap;
+		memcpy(&ctx_unmap, ctx, sizeof(*ctx));
+		ctx_unmap.entries = end;
+		apei_exec_post_unmap_gars(&ctx_unmap);
+	}
+
+	return rc;
+}
+
+static int post_unmap_gar_callback(struct apei_exec_context *ctx,
+				   struct acpi_whea_header *entry,
+				   void *data)
+{
+	u8 ins = entry->instruction;
+
+	if (ctx->ins_table[ins].flags & APEI_EXEC_INS_ACCESS_REGISTER)
+		apei_post_unmap_gar(&entry->register_region);
+
+	return 0;
+}
+
+/* Post-unmap all GAR in action table. */
+int apei_exec_post_unmap_gars(struct apei_exec_context *ctx)
+{
+	return apei_exec_for_each_entry(ctx, post_unmap_gar_callback,
+					NULL, NULL);
+}
diff --git a/xen/drivers/acpi/apei/apei-internal.h b/xen/drivers/acpi/apei/apei-internal.h
new file mode 100644
index 0000000000..77f31fb993
--- /dev/null
+++ b/xen/drivers/acpi/apei/apei-internal.h
@@ -0,0 +1,73 @@
+/*
+ * apei-internal.h - ACPI Platform Error Interface internal
+ * definations.
+ */
+
+#ifndef APEI_INTERNAL_H
+#define APEI_INTERNAL_H
+
+struct apei_exec_context;
+
+typedef int (*apei_exec_ins_func_t)(struct apei_exec_context *ctx,
+				    struct acpi_whea_header *entry);
+
+#define APEI_EXEC_INS_ACCESS_REGISTER	0x0001
+
+struct apei_exec_ins_type {
+	u32 flags;
+	apei_exec_ins_func_t run;
+};
+
+struct apei_exec_context {
+	u32 ip;
+	u64 value;
+	u64 var1;
+	u64 var2;
+	u64 src_base;
+	u64 dst_base;
+	struct apei_exec_ins_type *ins_table;
+	u32 instructions;
+	struct acpi_whea_header *action_table;
+	u32 entries;
+};
+
+int apei_exec_ctx_init(struct apei_exec_context *ctx,
+			struct apei_exec_ins_type *ins_table,
+			u32 instructions,
+			struct acpi_whea_header *action_table,
+			u32 entries);
+
+static inline void apei_exec_ctx_set_input(struct apei_exec_context *ctx,
+					   u64 input)
+{
+	ctx->value = input;
+}
+
+static inline u64 apei_exec_ctx_get_output(struct apei_exec_context *ctx)
+{
+	return ctx->value;
+}
+
+int apei_exec_run(struct apei_exec_context *ctx, u8 action);
+
+/* Common instruction implementation */
+
+/* IP has been set in instruction function */
+#define APEI_EXEC_SET_IP	1
+
+int __apei_exec_read_register(struct acpi_whea_header *entry, u64 *val);
+int __apei_exec_write_register(struct acpi_whea_header *entry, u64 val);
+int apei_exec_read_register(struct apei_exec_context *ctx,
+			    struct acpi_whea_header *entry);
+int apei_exec_read_register_value(struct apei_exec_context *ctx,
+				  struct acpi_whea_header *entry);
+int apei_exec_write_register(struct apei_exec_context *ctx,
+			     struct acpi_whea_header *entry);
+int apei_exec_write_register_value(struct apei_exec_context *ctx,
+				   struct acpi_whea_header *entry);
+int apei_exec_noop(struct apei_exec_context *ctx,
+		   struct acpi_whea_header *entry);
+int apei_exec_pre_map_gars(struct apei_exec_context *ctx);
+int apei_exec_post_unmap_gars(struct apei_exec_context *ctx);
+
+#endif
diff --git a/xen/drivers/acpi/apei/apei-io.c b/xen/drivers/acpi/apei/apei-io.c
new file mode 100644
index 0000000000..e77fae8da2
--- /dev/null
+++ b/xen/drivers/acpi/apei/apei-io.c
@@ -0,0 +1,328 @@
+/*
+ * apei-io.c - APEI IO memory pre-mapping/post-unmapping and access
+ *
+ * Copyright (C) 2009-2010, Intel Corp.
+ *	Author: Huang Ying <ying.huang@intel.com>
+ *	Ported by: Liu, Jinsong <jinsong.liu@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.
+ *
+ * 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 <xen/kernel.h>
+#include <xen/errno.h>
+#include <xen/delay.h>
+#include <xen/string.h>
+#include <xen/xmalloc.h>
+#include <xen/types.h>
+#include <xen/spinlock.h>
+#include <xen/list.h>
+#include <xen/cper.h>
+#include <xen/prefetch.h>
+#include <asm/fixmap.h>
+#include <asm/io.h>
+#include <acpi/acpi.h>
+#include <acpi/apei.h>
+
+static LIST_HEAD(apei_iomaps);
+/*
+ * Used for mutual exclusion between writers of apei_iomaps list, for
+ * synchronization between readers and writer.
+ */
+static DEFINE_SPINLOCK(apei_iomaps_lock);
+
+struct apei_iomap {
+	struct list_head list;
+	void __iomem *vaddr;
+	unsigned long size;
+	paddr_t paddr;
+};
+
+static struct apei_iomap *__apei_find_iomap(paddr_t paddr,
+					    unsigned long size)
+{
+	struct apei_iomap *map;
+
+	list_for_each_entry(map, &apei_iomaps, list) {
+		if (map->paddr + map->size >= paddr + size &&
+		    map->paddr <= paddr)
+			return map;
+	}
+	return NULL;
+}
+
+static void __iomem *__apei_ioremap_fast(paddr_t paddr,
+					 unsigned long size)
+{
+	struct apei_iomap *map;
+
+	map = __apei_find_iomap(paddr, size);
+	if (map)
+		return map->vaddr + (paddr - map->paddr);
+	else
+		return NULL;
+}
+
+static int apei_range_nr;
+
+static void __iomem *apei_range_map(paddr_t paddr, unsigned long size)
+{
+	int i, pg;
+	int start_nr, cur_nr;
+
+	pg = ((((paddr + size -1) & PAGE_MASK)
+		 - (paddr & PAGE_MASK)) >> PAGE_SHIFT) + 1;
+	if (apei_range_nr + pg > FIX_APEI_RANGE_MAX)
+		return NULL;
+
+	start_nr = apei_range_nr + pg -1;
+	for (i = 0; i < pg; i++) {
+		cur_nr = start_nr - i;
+		set_fixmap_nocache(FIX_APEI_RANGE_BASE + cur_nr,
+					paddr + (i << PAGE_SHIFT));
+		apei_range_nr++;
+	}
+
+	return (void __iomem *)fix_to_virt(FIX_APEI_RANGE_BASE + start_nr);
+}
+
+/*
+ * Used to pre-map the specified IO memory area. First try to find
+ * whether the area is already pre-mapped, if it is, return; otherwise,
+ * do the real map, and add the mapping into apei_iomaps list.
+ */
+void __iomem *apei_pre_map(paddr_t paddr, unsigned long size)
+{
+	void __iomem *vaddr;
+	struct apei_iomap *map;
+	unsigned long flags;
+
+	spin_lock_irqsave(&apei_iomaps_lock, flags);
+	vaddr = __apei_ioremap_fast(paddr, size);
+	spin_unlock_irqrestore(&apei_iomaps_lock, flags);
+	if (vaddr)
+		return vaddr;
+
+	map = xmalloc(struct apei_iomap);
+	if (!map)
+		return NULL;
+
+	vaddr = apei_range_map(paddr, size);
+	if (!vaddr) {
+		xfree(map);
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&map->list);
+	map->paddr = paddr & PAGE_MASK;
+	map->size = (((paddr + size + PAGE_SIZE -1) & PAGE_MASK)
+					 - (paddr & PAGE_MASK));
+	map->vaddr = vaddr;
+
+	spin_lock_irqsave(&apei_iomaps_lock, flags);
+	list_add_tail(&map->list, &apei_iomaps);
+	spin_unlock_irqrestore(&apei_iomaps_lock, flags);
+
+	return map->vaddr + (paddr - map->paddr);
+}
+
+/*
+ * Used to post-unmap the specified IO memory area.
+ */
+static void apei_post_unmap(paddr_t paddr, unsigned long size)
+{
+	struct apei_iomap *map;
+	unsigned long flags;
+
+	spin_lock_irqsave(&apei_iomaps_lock, flags);
+	map = __apei_find_iomap(paddr, size);
+	if (!map);
+		return;
+
+	list_del(&map->list);
+	spin_unlock_irqrestore(&apei_iomaps_lock, flags);
+
+	xfree(map);
+}
+
+/* In NMI handler, should set silent = 1 */
+static int apei_check_gar(struct acpi_generic_address *reg,
+			  u64 *paddr, int silent)
+{
+	u32 width, space_id;
+
+	width = reg->bit_width;
+	space_id = reg->space_id;
+	/* Handle possible alignment issues */
+	memcpy(paddr, &reg->address, sizeof(*paddr));
+	if (!*paddr) {
+		if (!silent)
+			printk(KERN_WARNING
+			"Invalid physical address in GAR\n");
+		return -EINVAL;
+	}
+
+	if ((width != 8) && (width != 16) && (width != 32) && (width != 64)) {
+		if (!silent)
+			printk(KERN_WARNING
+			"Invalid bit width in GAR\n");
+		return -EINVAL;
+	}
+
+	if (space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY &&
+	    space_id != ACPI_ADR_SPACE_SYSTEM_IO) {
+		if (!silent)
+			printk(KERN_WARNING
+			"Invalid address space type in GAR\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* Pre-map, working on GAR */
+int apei_pre_map_gar(struct acpi_generic_address *reg)
+{
+	u64 paddr;
+	void __iomem *vaddr;
+	int rc;
+
+	if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
+		return 0;
+
+	rc = apei_check_gar(reg, &paddr, 0);
+	if (rc)
+		return rc;
+
+	vaddr = apei_pre_map(paddr, reg->bit_width / 8);
+	if (!vaddr)
+		return -EIO;
+
+	return 0;
+}
+
+/* Post-unmap, working on GAR */
+int apei_post_unmap_gar(struct acpi_generic_address *reg)
+{
+	u64 paddr;
+	int rc;
+
+	if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY)
+		return 0;
+
+	rc = apei_check_gar(reg, &paddr, 0);
+	if (rc)
+		return rc;
+
+	apei_post_unmap(paddr, reg->bit_width / 8);
+
+	return 0;
+}
+
+static int apei_read_mem(u64 paddr, u64 *val, u32 width)
+{
+	void __iomem *addr;
+	u64 tmpval;
+
+	addr = __apei_ioremap_fast(paddr, width);
+	switch (width) {
+	case 8:
+		*val = readb(addr);
+		break;
+	case 16:
+		*val = readw(addr);
+		break;
+	case 32:
+		*val = readl(addr);
+		break;
+	case 64:
+		tmpval = (u64)readl(addr);
+		tmpval |= ((u64)readl(addr+4)) << 32;
+		*val = tmpval;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int apei_write_mem(u64 paddr, u64 val, u32 width)
+{
+	void __iomem *addr;
+	u32 tmpval;
+
+	addr = __apei_ioremap_fast(paddr, width);
+	switch (width) {
+	case 8:
+		writeb(val, addr);
+		break;
+	case 16:
+		writew(val, addr);
+		break;
+	case 32:
+		writel(val, addr);
+		break;
+	case 64:
+		tmpval = (u32)val;
+		writel(tmpval, addr);
+		tmpval = (u32)(val >> 32);
+		writel(tmpval, addr+4);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int apei_read(u64 *val, struct acpi_generic_address *reg)
+{
+	u64 paddr;
+	int rc;
+
+	rc = apei_check_gar(reg, &paddr, 1);
+	if (rc)
+		return rc;
+
+	*val = 0;
+
+	/* currently all erst implementation take bit_width as real range */
+	switch (reg->space_id) {
+	case ACPI_ADR_SPACE_SYSTEM_MEMORY:
+		return apei_read_mem(paddr, val, reg->bit_width);
+	case ACPI_ADR_SPACE_SYSTEM_IO:
+		return acpi_os_read_port(paddr, (u32 *)val, reg->bit_width);
+	default:
+		return -EINVAL;
+	}
+}
+
+int apei_write(u64 val, struct acpi_generic_address *reg)
+{
+	u64 paddr;
+	int rc;
+
+	rc = apei_check_gar(reg, &paddr, 1);
+	if (rc)
+		return rc;
+
+	switch (reg->space_id) {
+	case ACPI_ADR_SPACE_SYSTEM_MEMORY:
+		return apei_write_mem(paddr, val, reg->bit_width);
+	case ACPI_ADR_SPACE_SYSTEM_IO:
+		return acpi_os_write_port(paddr, val, reg->bit_width);
+	default:
+		return -EINVAL;
+	}
+}
diff --git a/xen/drivers/acpi/apei/erst.c b/xen/drivers/acpi/apei/erst.c
new file mode 100644
index 0000000000..0aeb8f2501
--- /dev/null
+++ b/xen/drivers/acpi/apei/erst.c
@@ -0,0 +1,787 @@
+/*
+ * APEI Error Record Serialization Table support
+ *
+ * ERST is a way provided by APEI to save and retrieve hardware error
+ * infomation to and from a persistent store.
+ *
+ * For more information about ERST, please refer to ACPI Specification
+ * version 4.0, section 17.4.
+ *
+ * This feature is ported from linux acpi tree
+ * Copyright 2010 Intel Corp.
+ *   Author: Huang Ying <ying.huang@intel.com>
+ *   Ported by: Liu, Jinsong <jinsong.liu@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.
+ *
+ * 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 <xen/kernel.h>
+#include <xen/errno.h>
+#include <xen/delay.h>
+#include <xen/string.h>
+#include <xen/types.h>
+#include <xen/spinlock.h>
+#include <xen/cper.h>
+#include <asm/fixmap.h>
+#include <asm/io.h>
+#include <acpi/acpi.h>
+#include <acpi/apei.h>
+
+#include "apei-internal.h"
+
+/* ERST command status */
+#define ERST_STATUS_SUCCESS			0x0
+#define ERST_STATUS_NOT_ENOUGH_SPACE		0x1
+#define ERST_STATUS_HARDWARE_NOT_AVAILABLE	0x2
+#define ERST_STATUS_FAILED			0x3
+#define ERST_STATUS_RECORD_STORE_EMPTY		0x4
+#define ERST_STATUS_RECORD_NOT_FOUND		0x5
+
+#define ERST_TAB_ENTRY(tab)						\
+	((struct acpi_whea_header *)((char *)(tab) +			\
+				     sizeof(struct acpi_table_erst)))
+
+#define SPIN_UNIT		1			/* 1us */
+/* Firmware should respond within 1 miliseconds */
+#define FIRMWARE_TIMEOUT	(1 * 1000)
+#define FIRMWARE_MAX_STALL	50			/* 50us */
+
+static struct acpi_table_erst *erst_tab;
+static int erst_enabled;
+
+/* ERST Error Log Address Range atrributes */
+#define ERST_RANGE_RESERVED	0x0001
+#define ERST_RANGE_NVRAM	0x0002
+#define ERST_RANGE_SLOW		0x0004
+
+/*
+ * ERST Error Log Address Range, used as buffer for reading/writing
+ * error records.
+ */
+static struct erst_erange {
+	u64 base;
+	u64 size;
+	void __iomem *vaddr;
+	u32 attr;
+} erst_erange;
+
+/*
+ * Prevent ERST interpreter to run simultaneously, because the
+ * corresponding firmware implementation may not work properly when
+ * invoked simultaneously.
+ *
+ * It is used to provide exclusive accessing for ERST Error Log
+ * Address Range too.
+ */
+static DEFINE_SPINLOCK(erst_lock);
+
+static inline int erst_errno(int command_status)
+{
+	switch (command_status) {
+	case ERST_STATUS_SUCCESS:
+		return 0;
+	case ERST_STATUS_HARDWARE_NOT_AVAILABLE:
+		return -ENODEV;
+	case ERST_STATUS_NOT_ENOUGH_SPACE:
+		return -ENOSPC;
+	case ERST_STATUS_RECORD_STORE_EMPTY:
+	case ERST_STATUS_RECORD_NOT_FOUND:
+		return -ENOENT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int erst_timedout(u64 *t, u64 spin_unit)
+{
+	if ((s64)*t < spin_unit) {
+		printk(XENLOG_WARNING "Firmware does not respond in time\n");
+		return 1;
+	}
+	*t -= spin_unit;
+	udelay(spin_unit);
+	return 0;
+}
+
+static int erst_exec_load_var1(struct apei_exec_context *ctx,
+			       struct acpi_whea_header *entry)
+{
+	return __apei_exec_read_register(entry, &ctx->var1);
+}
+
+static int erst_exec_load_var2(struct apei_exec_context *ctx,
+			       struct acpi_whea_header *entry)
+{
+	return __apei_exec_read_register(entry, &ctx->var2);
+}
+
+static int erst_exec_store_var1(struct apei_exec_context *ctx,
+				struct acpi_whea_header *entry)
+{
+	return __apei_exec_write_register(entry, ctx->var1);
+}
+
+static int erst_exec_add(struct apei_exec_context *ctx,
+			 struct acpi_whea_header *entry)
+{
+	ctx->var1 += ctx->var2;
+	return 0;
+}
+
+static int erst_exec_subtract(struct apei_exec_context *ctx,
+			      struct acpi_whea_header *entry)
+{
+	ctx->var1 -= ctx->var2;
+	return 0;
+}
+
+static int erst_exec_add_value(struct apei_exec_context *ctx,
+			       struct acpi_whea_header *entry)
+{
+	int rc;
+	u64 val;
+
+	rc = __apei_exec_read_register(entry, &val);
+	if (rc)
+		return rc;
+	val += ctx->value;
+	rc = __apei_exec_write_register(entry, val);
+	return rc;
+}
+
+static int erst_exec_subtract_value(struct apei_exec_context *ctx,
+				    struct acpi_whea_header *entry)
+{
+	int rc;
+	u64 val;
+
+	rc = __apei_exec_read_register(entry, &val);
+	if (rc)
+		return rc;
+	val -= ctx->value;
+	rc = __apei_exec_write_register(entry, val);
+	return rc;
+}
+
+static int erst_exec_stall(struct apei_exec_context *ctx,
+			   struct acpi_whea_header *entry)
+{
+	udelay((ctx->var1 > FIRMWARE_MAX_STALL) ? 
+			FIRMWARE_MAX_STALL : 
+			ctx->var1);
+	return 0;
+}
+
+static int erst_exec_stall_while_true(struct apei_exec_context *ctx,
+				      struct acpi_whea_header *entry)
+{
+	int rc;
+	u64 val;
+	u64 timeout = FIRMWARE_TIMEOUT;
+	u64 stall_time = (ctx->var1 > FIRMWARE_MAX_STALL) ? 
+				FIRMWARE_MAX_STALL : 
+				ctx->var1;
+
+	for (;;) {
+		rc = __apei_exec_read_register(entry, &val);
+		if (rc)
+			return rc;
+		if (val != ctx->value)
+			break;
+		if (erst_timedout(&timeout, stall_time))
+			return -EIO;
+	}
+	return 0;
+}
+
+static int erst_exec_skip_next_instruction_if_true(
+	struct apei_exec_context *ctx,
+	struct acpi_whea_header *entry)
+{
+	int rc;
+	u64 val;
+
+	rc = __apei_exec_read_register(entry, &val);
+	if (rc)
+		return rc;
+	if (val == ctx->value) {
+		ctx->ip += 2;
+		return APEI_EXEC_SET_IP;
+	}
+
+	return 0;
+}
+
+static int erst_exec_goto(struct apei_exec_context *ctx,
+			  struct acpi_whea_header *entry)
+{
+	ctx->ip = ctx->value;
+	return APEI_EXEC_SET_IP;
+}
+
+static int erst_exec_set_src_address_base(struct apei_exec_context *ctx,
+					  struct acpi_whea_header *entry)
+{
+	return __apei_exec_read_register(entry, &ctx->src_base);
+}
+
+static int erst_exec_set_dst_address_base(struct apei_exec_context *ctx,
+					  struct acpi_whea_header *entry)
+{
+	return __apei_exec_read_register(entry, &ctx->dst_base);
+}
+
+static int erst_exec_move_data(struct apei_exec_context *ctx,
+			       struct acpi_whea_header *entry)
+{
+	int rc;
+	u64 offset;
+
+	rc = __apei_exec_read_register(entry, &offset);
+	if (rc)
+		return rc;
+	memmove((void *)(unsigned long)(ctx->dst_base + offset),
+		(void *)(unsigned long)(ctx->src_base + offset),
+		ctx->var2);
+
+	return 0;
+}
+
+static struct apei_exec_ins_type erst_ins_type[] = {
+	[ACPI_ERST_READ_REGISTER] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = apei_exec_read_register,
+	},
+	[ACPI_ERST_READ_REGISTER_VALUE] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = apei_exec_read_register_value,
+	},
+	[ACPI_ERST_WRITE_REGISTER] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = apei_exec_write_register,
+	},
+	[ACPI_ERST_WRITE_REGISTER_VALUE] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = apei_exec_write_register_value,
+	},
+	[ACPI_ERST_NOOP] = {
+		.flags = 0,
+		.run = apei_exec_noop,
+	},
+	[ACPI_ERST_LOAD_VAR1] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_load_var1,
+	},
+	[ACPI_ERST_LOAD_VAR2] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_load_var2,
+	},
+	[ACPI_ERST_STORE_VAR1] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_store_var1,
+	},
+	[ACPI_ERST_ADD] = {
+		.flags = 0,
+		.run = erst_exec_add,
+	},
+	[ACPI_ERST_SUBTRACT] = {
+		.flags = 0,
+		.run = erst_exec_subtract,
+	},
+	[ACPI_ERST_ADD_VALUE] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_add_value,
+	},
+	[ACPI_ERST_SUBTRACT_VALUE] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_subtract_value,
+	},
+	[ACPI_ERST_STALL] = {
+		.flags = 0,
+		.run = erst_exec_stall,
+	},
+	[ACPI_ERST_STALL_WHILE_TRUE] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_stall_while_true,
+	},
+	[ACPI_ERST_SKIP_NEXT_IF_TRUE] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_skip_next_instruction_if_true,
+	},
+	[ACPI_ERST_GOTO] = {
+		.flags = 0,
+		.run = erst_exec_goto,
+	},
+	[ACPI_ERST_SET_SRC_ADDRESS_BASE] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_set_src_address_base,
+	},
+	[ACPI_ERST_SET_DST_ADDRESS_BASE] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_set_dst_address_base,
+	},
+	[ACPI_ERST_MOVE_DATA] = {
+		.flags = APEI_EXEC_INS_ACCESS_REGISTER,
+		.run = erst_exec_move_data,
+	},
+};
+
+static inline void erst_exec_ctx_init(struct apei_exec_context *ctx)
+{
+	apei_exec_ctx_init(ctx, erst_ins_type, ARRAY_SIZE(erst_ins_type),
+			   ERST_TAB_ENTRY(erst_tab), erst_tab->entries);
+}
+
+static int erst_get_erange(struct erst_erange *range)
+{
+	struct apei_exec_context ctx;
+	int rc;
+
+	erst_exec_ctx_init(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_RANGE);
+	if (rc)
+		return rc;
+	range->base = apei_exec_ctx_get_output(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_LENGTH);
+	if (rc)
+		return rc;
+	range->size = apei_exec_ctx_get_output(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_GET_ERROR_ATTRIBUTES);
+	if (rc)
+		return rc;
+	range->attr = apei_exec_ctx_get_output(&ctx);
+
+	return 0;
+}
+
+static size_t __erst_get_record_count(void)
+{
+	struct apei_exec_context ctx;
+	int rc;
+
+	erst_exec_ctx_init(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_GET_RECORD_COUNT);
+	if (rc)
+		return rc;
+	return apei_exec_ctx_get_output(&ctx);
+}
+
+size_t erst_get_record_count(void)
+{
+	size_t count;
+	unsigned long flags;
+
+	if (!erst_enabled)
+		return -ENODEV;
+
+	spin_lock_irqsave(&erst_lock, flags);
+	count = __erst_get_record_count();
+	spin_unlock_irqrestore(&erst_lock, flags);
+
+	return count;
+}
+
+static int __erst_get_next_record_id(u64 *record_id)
+{
+	struct apei_exec_context ctx;
+	int rc;
+
+	erst_exec_ctx_init(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_GET_RECORD_ID);
+	if (rc)
+		return rc;
+	*record_id = apei_exec_ctx_get_output(&ctx);
+
+	return 0;
+}
+
+/*
+ * Get the record ID of an existing error record on the persistent
+ * storage. If there is no error record on the persistent storage, the
+ * returned record_id is APEI_ERST_INVALID_RECORD_ID.
+ */
+int erst_get_next_record_id(u64 *record_id)
+{
+	int rc;
+	unsigned long flags;
+
+	if (!erst_enabled)
+		return -ENODEV;
+
+	spin_lock_irqsave(&erst_lock, flags);
+	rc = __erst_get_next_record_id(record_id);
+	spin_unlock_irqrestore(&erst_lock, flags);
+
+	return rc;
+}
+
+static int __erst_write_to_storage(u64 offset)
+{
+	struct apei_exec_context ctx;
+	u64 timeout = FIRMWARE_TIMEOUT;
+	u64 val;
+	int rc;
+
+	erst_exec_ctx_init(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_BEGIN_WRITE);
+	if (rc)
+		return rc;
+	apei_exec_ctx_set_input(&ctx, offset);
+	rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_OFFSET);
+	if (rc)
+		return rc;
+	rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
+	if (rc)
+		return rc;
+	for (;;) {
+		rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
+		if (rc)
+			return rc;
+		val = apei_exec_ctx_get_output(&ctx);
+		if (!val)
+			break;
+		if (erst_timedout(&timeout, SPIN_UNIT))
+			return -EIO;
+	}
+	rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
+	if (rc)
+		return rc;
+	val = apei_exec_ctx_get_output(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_END);
+	if (rc)
+		return rc;
+
+	return erst_errno(val);
+}
+
+static int __erst_read_from_storage(u64 record_id, u64 offset)
+{
+	struct apei_exec_context ctx;
+	u64 timeout = FIRMWARE_TIMEOUT;
+	u64 val;
+	int rc;
+
+	erst_exec_ctx_init(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_BEGIN_READ);
+	if (rc)
+		return rc;
+	apei_exec_ctx_set_input(&ctx, offset);
+	rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_OFFSET);
+	if (rc)
+		return rc;
+	apei_exec_ctx_set_input(&ctx, record_id);
+	rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_ID);
+	if (rc)
+		return rc;
+	rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
+	if (rc)
+		return rc;
+	for (;;) {
+		rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
+		if (rc)
+			return rc;
+		val = apei_exec_ctx_get_output(&ctx);
+		if (!val)
+			break;
+		if (erst_timedout(&timeout, SPIN_UNIT))
+			return -EIO;
+	};
+	rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
+	if (rc)
+		return rc;
+	val = apei_exec_ctx_get_output(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_END);
+	if (rc)
+		return rc;
+
+	return erst_errno(val);
+}
+
+static int __erst_clear_from_storage(u64 record_id)
+{
+	struct apei_exec_context ctx;
+	u64 timeout = FIRMWARE_TIMEOUT;
+	u64 val;
+	int rc;
+
+	erst_exec_ctx_init(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_BEGIN_CLEAR);
+	if (rc)
+		return rc;
+	apei_exec_ctx_set_input(&ctx, record_id);
+	rc = apei_exec_run(&ctx, ACPI_ERST_SET_RECORD_ID);
+	if (rc)
+		return rc;
+	rc = apei_exec_run(&ctx, ACPI_ERST_EXECUTE_OPERATION);
+	if (rc)
+		return rc;
+	for (;;) {
+		rc = apei_exec_run(&ctx, ACPI_ERST_CHECK_BUSY_STATUS);
+		if (rc)
+			return rc;
+		val = apei_exec_ctx_get_output(&ctx);
+		if (!val)
+			break;
+		if (erst_timedout(&timeout, SPIN_UNIT))
+			return -EIO;
+	}
+	rc = apei_exec_run(&ctx, ACPI_ERST_GET_COMMAND_STATUS);
+	if (rc)
+		return rc;
+	val = apei_exec_ctx_get_output(&ctx);
+	rc = apei_exec_run(&ctx, ACPI_ERST_END);
+	if (rc)
+		return rc;
+
+	return erst_errno(val);
+}
+
+/* NVRAM ERST Error Log Address Range is not supported yet */
+static int __erst_write_to_nvram(const struct cper_record_header *record)
+{
+	/* do not print message, because printk is not safe for NMI */
+	return -ENOSYS;
+}
+
+static int __erst_read_to_erange_from_nvram(u64 record_id, u64 *offset)
+{
+	printk(KERN_WARNING
+		"NVRAM ERST Log Address Range is not implemented yet\n");
+	return -ENOSYS;
+}
+
+static int __erst_clear_from_nvram(u64 record_id)
+{
+	printk(KERN_WARNING
+		"NVRAM ERST Log Address Range is not implemented yet\n");
+	return -ENOSYS;
+}
+
+int erst_write(const struct cper_record_header *record)
+{
+	int rc;
+	unsigned long flags;
+	struct cper_record_header *rcd_erange;
+
+	if (!record)
+		return -EINVAL;
+
+	if (!erst_enabled)
+		return -ENODEV;
+
+	if (memcmp(record->signature, CPER_SIG_RECORD, CPER_SIG_SIZE))
+		return -EINVAL;
+
+	if (erst_erange.attr & ERST_RANGE_NVRAM) {
+		if (!spin_trylock_irqsave(&erst_lock, flags))
+			return -EBUSY;
+		rc = __erst_write_to_nvram(record);
+		spin_unlock_irqrestore(&erst_lock, flags);
+		return rc;
+	}
+
+	if (record->record_length > erst_erange.size)
+		return -EINVAL;
+
+	if (!spin_trylock_irqsave(&erst_lock, flags))
+		return -EBUSY;
+	memcpy(erst_erange.vaddr, record, record->record_length);
+	rcd_erange = erst_erange.vaddr;
+	/* signature for serialization system */
+	memcpy(&rcd_erange->persistence_information, "ER", 2);
+
+	rc = __erst_write_to_storage(0);
+	spin_unlock_irqrestore(&erst_lock, flags);
+
+	return rc;
+}
+
+static int __erst_read_to_erange(u64 record_id, u64 *offset)
+{
+	int rc;
+
+	if (erst_erange.attr & ERST_RANGE_NVRAM)
+		return __erst_read_to_erange_from_nvram(
+			record_id, offset);
+
+	rc = __erst_read_from_storage(record_id, 0);
+	if (rc)
+		return rc;
+	*offset = 0;
+
+	return 0;
+}
+
+static size_t __erst_read(u64 record_id, struct cper_record_header *record,
+			   size_t buflen)
+{
+	int rc;
+	u64 offset, len = 0;
+	struct cper_record_header *rcd_tmp;
+
+	rc = __erst_read_to_erange(record_id, &offset);
+	if (rc)
+		return rc;
+	rcd_tmp = erst_erange.vaddr + offset;
+	len = rcd_tmp->record_length;
+	if (len <= buflen)
+		memcpy(record, rcd_tmp, len);
+
+	return len;
+}
+
+/*
+ * If return value > buflen, the buffer size is not big enough,
+ * else if return value < 0, something goes wrong,
+ * else everything is OK, and return value is record length
+ */
+size_t erst_read(u64 record_id, struct cper_record_header *record,
+		  size_t buflen)
+{
+	size_t len;
+	unsigned long flags;
+
+	if (!erst_enabled)
+		return -ENODEV;
+
+	spin_lock_irqsave(&erst_lock, flags);
+	len = __erst_read(record_id, record, buflen);
+	spin_unlock_irqrestore(&erst_lock, flags);
+	return len;
+}
+
+/*
+ * If return value > buflen, the buffer size is not big enough,
+ * else if return value = 0, there is no more record to read,
+ * else if return value < 0, something goes wrong,
+ * else everything is OK, and return value is record length
+ */
+size_t erst_read_next(struct cper_record_header *record, size_t buflen)
+{
+	int rc;
+	size_t len;
+	unsigned long flags;
+	u64 record_id;
+
+	if (!erst_enabled)
+		return -ENODEV;
+
+	spin_lock_irqsave(&erst_lock, flags);
+	rc = __erst_get_next_record_id(&record_id);
+	if (rc) {
+		spin_unlock_irqrestore(&erst_lock, flags);
+		return rc;
+	}
+	/* no more record */
+	if (record_id == APEI_ERST_INVALID_RECORD_ID) {
+		spin_unlock_irqrestore(&erst_lock, flags);
+		return 0;
+	}
+
+	len = __erst_read(record_id, record, buflen);
+	spin_unlock_irqrestore(&erst_lock, flags);
+
+	return len;
+}
+
+int erst_clear(u64 record_id)
+{
+	int rc;
+	unsigned long flags;
+
+	if (!erst_enabled)
+		return -ENODEV;
+
+	spin_lock_irqsave(&erst_lock, flags);
+	if (erst_erange.attr & ERST_RANGE_NVRAM)
+		rc = __erst_clear_from_nvram(record_id);
+	else
+		rc = __erst_clear_from_storage(record_id);
+	spin_unlock_irqrestore(&erst_lock, flags);
+
+	return rc;
+}
+
+static int erst_check_table(struct acpi_table_erst *erst_tab)
+{
+	if (erst_tab->header_length != sizeof(struct acpi_table_erst))
+		return -EINVAL;
+	if (erst_tab->header.length < sizeof(struct acpi_table_erst))
+		return -EINVAL;
+	if (erst_tab->entries !=
+	    (erst_tab->header.length - sizeof(struct acpi_table_erst)) /
+	    sizeof(struct acpi_erst_entry))
+		return -EINVAL;
+
+	return 0;
+}
+
+int erst_init(void)
+{
+	int rc = 0;
+	acpi_status status;
+	struct apei_exec_context ctx;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	status = acpi_get_table(ACPI_SIG_ERST, 0,
+				(struct acpi_table_header **)&erst_tab);
+	if (status == AE_NOT_FOUND) {
+		printk(KERN_ERR "Table is not found!\n");
+		return -ENODEV;
+	} else if (ACPI_FAILURE(status)) {
+		const char *msg = acpi_format_exception(status);
+		printk(KERN_ERR "Failed to get table, %s\n", msg);
+		return -EINVAL;
+	}
+
+	rc = erst_check_table(erst_tab);
+	if (rc) {
+		printk(KERN_ERR "ERST table is invalid\n");
+		return rc;
+	}
+
+	erst_exec_ctx_init(&ctx);
+	rc = apei_exec_pre_map_gars(&ctx);
+	if (rc)
+		return rc;
+
+	rc = erst_get_erange(&erst_erange);
+	if (rc) {
+		if (rc == -ENODEV)
+			printk(KERN_INFO
+			"The corresponding hardware device or firmware "
+			"implementation is not available.\n");
+		else
+			printk(KERN_ERR
+			       "Failed to get Error Log Address Range.\n");
+		goto err_unmap_reg;
+	}
+
+	erst_erange.vaddr = apei_pre_map(erst_erange.base, erst_erange.size);
+	if (!erst_erange.vaddr) {
+		rc = -ENOMEM;
+		goto err_unmap_reg;
+	}
+
+	printk(KERN_INFO "Xen ERST support is initialized.\n");
+	erst_enabled = 1;
+
+	return 0;
+
+err_unmap_reg:
+	apei_exec_post_unmap_gars(&ctx);
+	return rc;
+}