1 files changed, 17 insertions, 15 deletions

diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c
index e0a511d4074f..8efe13075c92 100644
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -26,9 +26,9 @@
 
 u64 efi_system_table;
 
-static int __init is_normal_ram(efi_memory_desc_t *md)
+static int __init is_memory(efi_memory_desc_t *md)
 {
-        if (md->attribute & EFI_MEMORY_WB)
+        if (md->attribute & (EFI_MEMORY_WB|EFI_MEMORY_WT|EFI_MEMORY_WC))
                 return 1;
         return 0;
 }
@@ -152,9 +152,9 @@ out:
 }
 
 /*
- * Return true for RAM regions we want to permanently reserve.
+ * Return true for regions that can be used as System RAM.
  */
-static __init int is_reserve_region(efi_memory_desc_t *md)
+static __init int is_usable_memory(efi_memory_desc_t *md)
 {
         switch (md->type) {
         case EFI_LOADER_CODE:
@@ -163,18 +163,22 @@ static __init int is_reserve_region(efi_memory_desc_t *md)
         case EFI_BOOT_SERVICES_DATA:
         case EFI_CONVENTIONAL_MEMORY:
         case EFI_PERSISTENT_MEMORY:
-                return 0;
+                /*
+                 * According to the spec, these regions are no longer reserved
+                 * after calling ExitBootServices(). However, we can only use
+                 * them as System RAM if they can be mapped writeback cacheable.
+                 */
+                return (md->attribute & EFI_MEMORY_WB);
         default:
                 break;
         }
-        return is_normal_ram(md);
+        return false;
 }
 
 static __init void reserve_regions(void)
 {
         efi_memory_desc_t *md;
         u64 paddr, npages, size;
-        int resv;
 
         if (efi_enabled(EFI_DBG))
                 pr_info("Processing EFI memory map:\n");
@@ -191,25 +195,23 @@ static __init void reserve_regions(void)
                 paddr = md->phys_addr;
                 npages = md->num_pages;
 
-                resv = is_reserve_region(md);
                 if (efi_enabled(EFI_DBG)) {
                         char buf[64];
 
-                        pr_info("  0x%012llx-0x%012llx %s%s\n",
+                        pr_info("  0x%012llx-0x%012llx %s\n",
                                 paddr, paddr + (npages << EFI_PAGE_SHIFT) - 1,
-                                efi_md_typeattr_format(buf, sizeof(buf), md),
-                                resv ? "*" : "");
+                                efi_md_typeattr_format(buf, sizeof(buf), md));
                 }
 
                 memrange_efi_to_native(&paddr, &npages);
                 size = npages << PAGE_SHIFT;
 
-                if (is_normal_ram(md))
+                if (is_memory(md)) {
                         early_init_dt_add_memory_arch(paddr, size);
 
-                if (resv)
-                        memblock_mark_nomap(paddr, size);
-
+                        if (!is_usable_memory(md))
+                                memblock_mark_nomap(paddr, size);
+                }
         }
 }