From: "Jonathan (Zhixiong) Zhang" <zjzhang@xxxxxxxxxxxxxx>
If the physical address has memory attributes defined by EFI
memmap as EFI_MEMORY_UC, the page protection type is
PROT_DEVICE_nGnRE. Otherwise, the page protection type is
PAGE_KERNEL.
+#ifdef CONFIG_ACPI_APEI
+/*
+ * 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
+ * corresponding MAIR attribute encoding.
+ */
+static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
+{
+ pgprot_t prot;
+
+ prot = efi_mem_attributes(addr);
+ if (prot & EFI_MEMORY_UC)
+ return PROT_DEVICE_nGnRnE;
+ if (prot & EFI_MEMORY_WC)
+ return PROT_NORMAL_NC;
+ if (prot & EFI_MEMORY_WT)
+ return PROT_NORMAL_WT;
+ return PAGE_KERNEL;
+}