efi: Add efi_memmap_install() for installing new EFI memory maps

While efi_memmap_init_{early,late}() exist for architecture code to
install memory maps from firmware data and for the virtual memory
regions respectively, drivers don't care which stage of the boot we're
at and just want to swap the existing memmap for a modified one.

efi_memmap_install() abstracts the details of how the new memory map
should be mapped and the existing one unmapped.

Tested-by: Dave Young <dyoung@redhat.com> [kexec/kdump]
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> [arm]
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>

2 files changed, 26 insertions, 7 deletions

diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c
index 0054730..520a40e 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 2df7238..cd96086 100644
--- a/drivers/firmware/efi/memmap.c
+++ b/drivers/firmware/efi/memmap.c
@@ -140,6 +140,31 @@ int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
 }
 
 /**
+ * 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
  * @range: Address range (start, end) to split around