efi_loader: Respect DT reserved regions

With legacy boot (booti, bootz), people can declare memory regions as
reserved using device tree memory reservations. This feature is some
times used to indicate memory regions that should not be touched.

Since in a UEFI world, the DT memory reservations do not get honored,
let's copy them into the UEFI memory map so everyone has a coherent
view of the world and we give people the chance to add reservations
on demand.

Signed-off-by: Alexander Graf <agraf@suse.de>

cmd/bootefi.c

@@ -178,6 +178,27 @@ static efi_status_t efi_run_in_el2(EFIAPI efi_status_t (*entry)(
 }
 #endif
 
+/* Carve out DT reserved memory ranges */
+static efi_status_t efi_carve_out_dt_rsv(void *fdt)
+{
+	int nr_rsv, i;
+	uint64_t addr, size, pages;
+
+	nr_rsv = fdt_num_mem_rsv(fdt);
+
+	/* Look for an existing entry and add it to the efi mem map. */
+	for (i = 0; i < nr_rsv; i++) {
+		if (fdt_get_mem_rsv(fdt, i, &addr, &size) != 0)
+			continue;
+
+		pages = ALIGN(size, EFI_PAGE_SIZE) >> EFI_PAGE_SHIFT;
+		efi_add_memory_map(addr, pages, EFI_RESERVED_MEMORY_TYPE,
+				   false);
+	}
+
+	return EFI_SUCCESS;
+}
+
 static efi_status_t efi_install_fdt(void *fdt)
 {
 	bootm_headers_t img = { 0 };
@@ -199,6 +220,11 @@ static efi_status_t efi_install_fdt(void *fdt)
 		return EFI_LOAD_ERROR;
 	}
 
+	if (efi_carve_out_dt_rsv(fdt) != EFI_SUCCESS) {
+		printf("ERROR: failed to carve out memory\n");
+		return EFI_LOAD_ERROR;
+	}
+
 	/* Link to it in the efi tables */
 	ret = efi_install_configuration_table(&efi_guid_fdt, fdt);
 	if (ret != EFI_SUCCESS)