[PATCH] efi_loader: consider no-map property of reserved memory

[Heinrich Schuchardt]

If a reserved memory node in the device tree has the property no-map,
remove it from the UEFI memory map provided by GetMemoryMap().

Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
---
 cmd/bootefi.c               | 34 ++++++++++++++++++++++++++++------
 include/efi.h               |  3 +++
 lib/efi_loader/efi_memory.c |  7 +++++--
 3 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/cmd/bootefi.c b/cmd/bootefi.c
index 40d5ef2b3a..f173105251 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 be hidden from the memory
+ *		map
+ */
+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_NO_MAP_MEMORY;
+	else
+		type = EFI_RESERVED_MEMORY_TYPE;
+
+	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);
 		}
 	}
diff --git a/include/efi.h b/include/efi.h
index f986aad877..50190021ef 100644
--- a/include/efi.h
+++ b/include/efi.h
@@ -181,6 +181,9 @@ enum efi_mem_type {

 	EFI_MAX_MEMORY_TYPE,
 	EFI_TABLE_END,	/* For efi_build_mem_table() */
+
+	/* Memory that shall not be mapped */
+	EFI_NO_MAP_MEMORY,
 };

 /* Attribute values */
diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index 7be756e370..d156b9533c 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -251,7 +251,7 @@ static efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
 	EFI_PRINT("%s: 0x%llx 0x%llx %d %s\n", __func__,
 		  start, pages, memory_type, overlap_only_ram ? "yes" : "no");

-	if (memory_type >= EFI_MAX_MEMORY_TYPE)
+	if (memory_type >= EFI_MAX_MEMORY_TYPE && memory_type != EFI_NO_MAP_MEMORY)
 		return EFI_INVALID_PARAMETER;

 	if (!pages)
@@ -327,7 +327,10 @@ static efi_status_t efi_add_memory_map_pg(u64 start, u64 pages,
 	}

 	/* Add our new map */
-        list_add_tail(&newlist->link, &efi_mem);
+	if (memory_type == EFI_NO_MAP_MEMORY)
+		free(newlist);
+	else
+		list_add_tail(&newlist->link, &efi_mem);

 	/* And make sure memory is listed in descending order */
 	efi_mem_sort();
--
2.28.0