From: Ruslan Ruslichenko <Ruslan_Ruslichenko@epam.com>

The patch registers FDT compatibility handlers and
QOM aliases of memory subsystem, so that memory
regions can be created from a device tree model.

The alias 'qemu:system-memory' could be used to attach
subregion to root address space.
The system memory can also be attached to another
container with other priority, which may be used
for implementing secure memory structures.

Also 'qemu-memory-region' types can be used to create
new memory regions.

Signed-off-by: Ruslan Ruslichenko <Ruslan_Ruslichenko@epam.com>
---
 system/memory.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/system/memory.c b/system/memory.c
index b3d981dc0c..bd8b6e06ad 100644
--- a/system/memory.c
+++ b/system/memory.c
@@ -4024,3 +4024,81 @@ static void memory_register_types(void)
 }
 
 type_init(memory_register_types)
+
+static int sysmem_fdt_init(char *node_path, FDTMachineInfo *fdti,
+                           void *priv)
+{
+    int i, ret = 0, priority = 0;
+    uint32_t container_phandle;
+    MemoryRegion *container;
+    char container_node_path[DT_PATH_LENGTH];
+    FDTGenericRegPropInfo *reg;
+    Error *errp = NULL;
+
+    fdt_init_set_opaque(fdti, node_path, OBJECT(get_system_memory()));
+
+    /* allow to set system_memory region as subregion */
+    container_phandle = qemu_fdt_getprop_cell(fdti->fdt, node_path,
+                                            "container",
+                                            0, &errp);
+    if (errp) {
+        /* container is an optional property */
+        error_free(errp);
+        return 0;
+    }
+
+    if (qemu_devtree_get_node_by_phandle(fdti->fdt, container_node_path,
+                                            container_phandle)) {
+        error_report("failed to get container node");
+        return -1;
+    }
+
+    while (!fdt_init_has_opaque(fdti, container_node_path)) {
+        fdt_init_yield(fdti);
+    }
+
+    container = MEMORY_REGION(fdt_init_get_opaque(fdti,
+                                                    container_node_path));
+    reg = fdt_get_reg_info(fdti, node_path, OBJECT(get_system_memory()));
+    if (reg && reg->n > 0) {
+        if (reg->x[0][0] || reg->x[1][0]) {
+            error_report("can't change sysmem address or size");
+            ret = -1;
+            goto out;
+        }
+        priority = reg->x[3][0];
+    }
+
+    memory_region_add_subregion_overlap(container, 0,
+                                        get_system_memory(), priority);
+
+out:
+    if (reg) {
+        g_free(reg->parents);
+
+        for (i = 0; i < FDT_GENERIC_REG_TUPLE_LENGTH; ++i) {
+            g_free(reg->x[i]);
+        }
+
+        g_free(reg);
+    }
+    return ret;
+}
+
+fdt_register_compatibility(sysmem_fdt_init, "compatible:qemu:system-memory");
+
+static const TypeInfo fdt_qom_aliases[] = {
+    {   .name = "qemu-memory-region",       .parent = "memory-region"  },
+    {   .name = "simple-bus",               .parent = "memory-region"  },
+};
+
+static void fdt_memory_types(void)
+{
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(fdt_qom_aliases); ++i) {
+        type_register_static(&fdt_qom_aliases[i]);
+    }
+}
+
+type_init(fdt_memory_types)
-- 
2.43.0