2 files changed, 34 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index 406485ed110a..5aa892a12a0d 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -92,4 +92,9 @@ static inline const char *acpi_get_enable_method(int cpu)
 {
         return acpi_psci_present() ? "psci" : NULL;
 }
+
+#ifdef  CONFIG_ACPI_APEI
+pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr);
+#endif
+
 #endif /*_ASM_ACPI_H*/
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 19de7537e7d3..137d537ddceb 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -29,6 +29,11 @@
 #include <asm/cpu_ops.h>
 #include <asm/smp_plat.h>
 
+#ifdef CONFIG_ACPI_APEI
+# include <linux/efi.h>
+# include <asm/pgtable.h>
+#endif
+
 int acpi_noirq = 1;             /* skip ACPI IRQ initialization */
 int acpi_disabled = 1;
 EXPORT_SYMBOL(acpi_disabled);
@@ -230,3 +235,27 @@ void __init acpi_gic_init(void)
 
         early_acpi_os_unmap_memory((char *)table, tbl_size);
 }
+
+#ifdef CONFIG_ACPI_APEI
+pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
+{
+        /*
+         * According to "Table 8 Map: EFI memory types to AArch64 memory
+         * types" of UEFI 2.5 section 2.3.6.1, each EFI memory type is
+         * mapped to a corresponding MAIR attribute encoding.
+         * The EFI memory attribute advises all possible capabilities
+         * of a memory region. We use the most efficient capability.
+         */
+
+        u64 attr;
+
+        attr = efi_mem_attributes(addr);
+        if (attr & EFI_MEMORY_WB)
+                return PAGE_KERNEL;
+        if (attr & EFI_MEMORY_WT)
+                return __pgprot(PROT_NORMAL_WT);
+        if (attr & EFI_MEMORY_WC)
+                return __pgprot(PROT_NORMAL_NC);
+        return __pgprot(PROT_DEVICE_nGnRnE);
+}
+#endif