arm64/efi: mark UEFI reserved regions as MEMBLOCK_NOMAP

Change the EFI memory reservation logic to use memblock_mark_nomap()
rather than memblock_reserve() to mark UEFI reserved regions as
occupied. In addition to reserving them against allocations done by
memblock, this will also prevent them from being covered by the linear
mapping.
Reviewed-by: NMatt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: NArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/kernel/efi.c

@@ -187,7 +187,7 @@ static __init void reserve_regions(void)
 			early_init_dt_add_memory_arch(paddr, size);
 
 		if (is_reserve_region(md)) {
-			memblock_reserve(paddr, size);
+			memblock_mark_nomap(paddr, size);
 			if (efi_enabled(EFI_DBG))
 				pr_cont("*");
 		}
@@ -209,8 +209,6 @@ void __init efi_init(void)
 
 	efi_system_table = params.system_table;
 
-	memblock_reserve(params.mmap & PAGE_MASK,
-			 PAGE_ALIGN(params.mmap_size + (params.mmap & ~PAGE_MASK)));
 	memmap.phys_map = params.mmap;
 	memmap.map = early_memremap(params.mmap, params.mmap_size);
 	if (memmap.map == NULL) {
@@ -230,6 +228,9 @@ void __init efi_init(void)
 
 	reserve_regions();
 	early_memunmap(memmap.map, params.mmap_size);
+	memblock_mark_nomap(params.mmap & PAGE_MASK,
+			    PAGE_ALIGN(params.mmap_size +
+				       (params.mmap & ~PAGE_MASK)));
 }
 
 static bool __init efi_virtmap_init(void)