diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c
index 0054730f9bae..520a40e5e0e4 100644
--- a/drivers/firmware/efi/fake_mem.c
+++ b/drivers/firmware/efi/fake_mem.c
@@ -52,7 +52,6 @@ static int __init cmp_fake_mem(const void *x1, const void *x2)
 
 void __init efi_fake_memmap(void)
 {
-	struct efi_memory_map_data data;
 	int new_nr_map = efi.memmap.nr_map;
 	efi_memory_desc_t *md;
 	phys_addr_t new_memmap_phy;
@@ -90,13 +89,8 @@ void __init efi_fake_memmap(void)
 
 	/* swap into new EFI memmap */
 	early_memunmap(new_memmap, efi.memmap.desc_size * new_nr_map);
-	efi_memmap_unmap();
 
-	data.phys_map = new_memmap_phy;
-	data.size = efi.memmap.desc_size * new_nr_map;
-	data.desc_version = efi.memmap.desc_version;
-	data.desc_size = efi.memmap.desc_size;
-	efi_memmap_init_early(&data);
+	efi_memmap_install(new_memmap_phy, new_nr_map);
 
 	/* print new EFI memmap */
 	efi_print_memmap();
diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
index 2df7238eb44e..cd96086fd851 100644
--- a/drivers/firmware/efi/memmap.c
+++ b/drivers/firmware/efi/memmap.c
@@ -139,6 +139,31 @@ int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
 	return __efi_memmap_init(&data, true);
 }
 
+/**
+ * efi_memmap_install - Install a new EFI memory map in efi.memmap
+ * @addr: Physical address of the memory map
+ * @nr_map: Number of entries in the memory map
+ *
+ * Unlike efi_memmap_init_*(), this function does not allow the caller
+ * to switch from early to late mappings. It simply uses the existing
+ * mapping function and installs the new memmap.
+ *
+ * Returns zero on success, a negative error code on failure.
+ */
+int __init efi_memmap_install(phys_addr_t addr, unsigned int nr_map)
+{
+	struct efi_memory_map_data data;
+
+	efi_memmap_unmap();
+
+	data.phys_map = addr;
+	data.size = efi.memmap.desc_size * nr_map;
+	data.desc_version = efi.memmap.desc_version;
+	data.desc_size = efi.memmap.desc_size;
+
+	return __efi_memmap_init(&data, efi.memmap.late);
+}
+
 /**
  * efi_memmap_split_count - Count number of additional EFI memmap entries
  * @md: EFI memory descriptor to split
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 84c8638c7a8b..987c18f6fcae 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -923,6 +923,7 @@ extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr);
 extern int __init efi_memmap_init_early(struct efi_memory_map_data *data);
 extern int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size);
 extern void __init efi_memmap_unmap(void);
+extern int __init efi_memmap_install(phys_addr_t addr, unsigned int nr_map);
 extern int __init efi_memmap_split_count(efi_memory_desc_t *md,
 					 struct range *range);
 extern void __init efi_memmap_insert(struct efi_memory_map *old_memmap,