efi_loader: consider no-map property of reserved memory

The device tree may contain a /reserved-memory node. The no-map property
of the sub-nodes signals if the memory may be accessed by the UEFI payload
or not.

In the EBBR specification (https://github.com/arm-software/ebbr) the
modeling of the reserved memory has been clarified.

If a reserved memory node in the device tree has the no-map property map,
create a EfiReservedMemoryType memory map entry else use
EfiBootServicesData.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

1 files changed, 28 insertions, 6 deletions

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index 40d5ef2b3a..fdf909f8da 100644
--- a/cmd/bootefi.c
+++ b/cmd/bootefi.c
@@ -135,12 +135,29 @@ done:
 	return ret;
 }
 
-static void efi_reserve_memory(u64 addr, u64 size)
+/**
+ * efi_reserve_memory() - add reserved memory to memory map
+ *
+ * @addr:	start address of the reserved memory range
+ * @size:	size of the reserved memory range
+ * @nomap:	indicates that the memory range shall not be accessed by the
+ *		UEFI payload
+ */
+static void efi_reserve_memory(u64 addr, u64 size, bool nomap)
 {
+	int type;
+	efi_uintn_t ret;
+
 	/* Convert from sandbox address space. */
 	addr = (uintptr_t)map_sysmem(addr, 0);
-	if (efi_add_memory_map(addr, size,
-			       EFI_RESERVED_MEMORY_TYPE) != EFI_SUCCESS)
+
+	if (nomap)
+		type = EFI_RESERVED_MEMORY_TYPE;
+	else
+		type = EFI_BOOT_SERVICES_DATA;
+
+	ret = efi_add_memory_map(addr, size, type);
+	if (ret != EFI_SUCCESS)
 		log_err("Reserved memory mapping failed addr %llx size %llx\n",
 			addr, size);
 }
@@ -166,7 +183,7 @@ static void efi_carve_out_dt_rsv(void *fdt)
 	for (i = 0; i < nr_rsv; i++) {
 		if (fdt_get_mem_rsv(fdt, i, &addr, &size) != 0)
 			continue;
-		efi_reserve_memory(addr, size);
+		efi_reserve_memory(addr, size, false);
 	}
 
 	/* process reserved-memory */
@@ -186,8 +203,13 @@ static void efi_carve_out_dt_rsv(void *fdt)
 			 * a size instead of a reg property.
 			 */
 			if (fdt_addr != FDT_ADDR_T_NONE &&
-			    fdtdec_get_is_enabled(fdt, subnode))
-				efi_reserve_memory(fdt_addr, fdt_size);
+			    fdtdec_get_is_enabled(fdt, subnode)) {
+				bool nomap;
+
+				nomap = !!fdt_getprop(fdt, subnode, "no-map",
+						      NULL);
+				efi_reserve_memory(fdt_addr, fdt_size, nomap);
+			}
 			subnode = fdt_next_subnode(fdt, subnode);
 		}
 	}