machine: make memory-backend a link property

Handle HostMemoryBackend creation and setting of ms->ram entirely in
machine_run_board_init.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20220414165300.555321-5-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

5 files changed, 74 insertions, 69 deletions

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 46b8d0e..8aab541 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -36,6 +36,7 @@
 #include "exec/confidential-guest-support.h"
 #include "hw/virtio/virtio.h"
 #include "hw/virtio/virtio-pci.h"
+#include "qom/object_interfaces.h"
 
 GlobalProperty hw_compat_7_0[] = {};
 const size_t hw_compat_7_0_len = G_N_ELEMENTS(hw_compat_7_0);
@@ -653,21 +654,6 @@ bool device_type_is_dynamic_sysbus(MachineClass *mc, const char *type)
     return allowed;
 }
 
-static char *machine_get_memdev(Object *obj, Error **errp)
-{
-    MachineState *ms = MACHINE(obj);
-
-    return g_strdup(ms->ram_memdev_id);
-}
-
-static void machine_set_memdev(Object *obj, const char *value, Error **errp)
-{
-    MachineState *ms = MACHINE(obj);
-
-    g_free(ms->ram_memdev_id);
-    ms->ram_memdev_id = g_strdup(value);
-}
-
 HotpluggableCPUList *machine_query_hotpluggable_cpus(MachineState *machine)
 {
     int i;
@@ -1020,8 +1006,9 @@ static void machine_class_init(ObjectClass *oc, void *data)
     object_class_property_set_description(oc, "memory-encryption",
         "Set memory encryption object to use");
 
-    object_class_property_add_str(oc, "memory-backend",
-                                  machine_get_memdev, machine_set_memdev);
+    object_class_property_add_link(oc, "memory-backend", TYPE_MEMORY_BACKEND,
+                                   offsetof(MachineState, memdev), object_property_allow_set_link,
+                                   OBJ_PROP_LINK_STRONG);
     object_class_property_set_description(oc, "memory-backend",
                                           "Set RAM backend"
                                           "Valid value is ID of hostmem based backend");
@@ -1270,7 +1257,40 @@ MemoryRegion *machine_consume_memdev(MachineState *machine,
     return ret;
 }
 
-void machine_run_board_init(MachineState *machine)
+static bool create_default_memdev(MachineState *ms, const char *path, Error **errp)
+{
+    Object *obj;
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
+    bool r = false;
+
+    obj = object_new(path ? TYPE_MEMORY_BACKEND_FILE : TYPE_MEMORY_BACKEND_RAM);
+    if (path) {
+        if (!object_property_set_str(obj, "mem-path", path, errp)) {
+            goto out;
+        }
+    }
+    if (!object_property_set_int(obj, "size", ms->ram_size, errp)) {
+        goto out;
+    }
+    object_property_add_child(object_get_objects_root(), mc->default_ram_id,
+                              obj);
+    /* Ensure backend's memory region name is equal to mc->default_ram_id */
+    if (!object_property_set_bool(obj, "x-use-canonical-path-for-ramblock-id",
+                             false, errp)) {
+        goto out;
+    }
+    if (!user_creatable_complete(USER_CREATABLE(obj), errp)) {
+        goto out;
+    }
+    r = object_property_set_link(OBJECT(ms), "memory-backend", obj, errp);
+
+out:
+    object_unref(obj);
+    return r;
+}
+
+
+void machine_run_board_init(MachineState *machine, const char *mem_path, Error **errp)
 {
     MachineClass *machine_class = MACHINE_GET_CLASS(machine);
     ObjectClass *oc = object_class_by_name(machine->cpu_type);
@@ -1281,11 +1301,11 @@ void machine_run_board_init(MachineState *machine)
        clock values from the log. */
     replay_checkpoint(CHECKPOINT_INIT);
 
-    if (machine->ram_memdev_id) {
-        Object *o;
-        o = object_resolve_path_type(machine->ram_memdev_id,
-                                     TYPE_MEMORY_BACKEND, NULL);
-        machine->ram = machine_consume_memdev(machine, MEMORY_BACKEND(o));
+    if (machine_class->default_ram_id && machine->ram_size &&
+        numa_uses_legacy_mem() && !machine->memdev) {
+        if (!create_default_memdev(current_machine, mem_path, errp)) {
+            return;
+        }
     }
 
     if (machine->numa_state) {
@@ -1295,6 +1315,10 @@ void machine_run_board_init(MachineState *machine)
         }
     }
 
+    if (!machine->ram && machine->memdev) {
+        machine->ram = machine_consume_memdev(machine, machine->memdev);
+    }
+
     /* If the machine supports the valid_cpu_types check and the user
      * specified a CPU with -cpu check here that the user CPU is supported.
      */
diff --git a/hw/core/numa.c b/hw/core/numa.c
index 1aa05dc..26d8e5f 100644
--- a/hw/core/numa.c
+++ b/hw/core/numa.c
@@ -695,7 +695,7 @@ void numa_complete_configuration(MachineState *ms)
         }
 
         if (!numa_uses_legacy_mem() && mc->default_ram_id) {
-            if (ms->ram_memdev_id) {
+            if (ms->memdev) {
                 error_report("'-machine memory-backend' and '-numa memdev'"
                              " properties are mutually exclusive");
                 exit(1);
diff --git a/hw/sparc/sun4m.c b/hw/sparc/sun4m.c
index 9d57491..d928832 100644
--- a/hw/sparc/sun4m.c
+++ b/hw/sparc/sun4m.c
@@ -831,8 +831,7 @@ static void sun4m_hw_init(MachineState *machine)
     SysBusDevice *s;
     unsigned int smp_cpus = machine->smp.cpus;
     unsigned int max_cpus = machine->smp.max_cpus;
-    Object *ram_memdev = object_resolve_path_type(machine->ram_memdev_id,
-                                                  TYPE_MEMORY_BACKEND, NULL);
+    HostMemoryBackend *ram_memdev = machine->memdev;
     NICInfo *nd = &nd_table[0];
 
     if (machine->ram_size > hwdef->max_mem) {
@@ -852,7 +851,7 @@ static void sun4m_hw_init(MachineState *machine)
 
     /* Create and map RAM frontend */
     dev = qdev_new("memory");
-    object_property_set_link(OBJECT(dev), "memdev", ram_memdev, &error_fatal);
+    object_property_set_link(OBJECT(dev), "memdev", OBJECT(ram_memdev), &error_fatal);
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
     sysbus_mmio_map(SYS_BUS_DEVICE(dev), 0, 0);
 
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 910c3ff..7b416c9 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -25,7 +25,7 @@ OBJECT_DECLARE_TYPE(MachineState, MachineClass, MACHINE)
 
 extern MachineState *current_machine;
 
-void machine_run_board_init(MachineState *machine);
+void machine_run_board_init(MachineState *machine, const char *mem_path, Error **errp);
 bool machine_usb(MachineState *machine);
 int machine_phandle_start(MachineState *machine);
 bool machine_dump_guest_core(MachineState *machine);
@@ -339,7 +339,7 @@ struct MachineState {
     bool suppress_vmdesc;
     bool enable_graphics;
     ConfidentialGuestSupport *cgs;
-    char *ram_memdev_id;
+    HostMemoryBackend *memdev;
     /*
      * convenience alias to ram_memdev_id backend memory region
      * or to numa container memory region
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 65a665e..f6deec9 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -160,6 +160,7 @@ static const char *incoming;
 static const char *loadvm;
 static const char *accelerators;
 static bool have_custom_ram_size;
+static const char *ram_memdev_id;
 static QDict *machine_opts_dict;
 static QTAILQ_HEAD(, ObjectOption) object_opts = QTAILQ_HEAD_INITIALIZER(object_opts);
 static QTAILQ_HEAD(, DeviceOption) device_opts = QTAILQ_HEAD_INITIALIZER(device_opts);
@@ -1768,6 +1769,19 @@ static void qemu_apply_legacy_machine_options(QDict *qdict)
         qdict_del(qdict, "kernel-irqchip");
     }
 
+    value = qdict_get_try_str(qdict, "memory-backend");
+    if (value) {
+        if (mem_path) {
+            error_report("'-mem-path' can't be used together with"
+                         "'-machine memory-backend'");
+            exit(EXIT_FAILURE);
+        }
+
+        /* Resolved later.  */
+        ram_memdev_id = g_strdup(value);
+        qdict_del(qdict, "memory-backend");
+    }
+
     prop = qdict_get(qdict, "memory");
     if (prop) {
         have_custom_ram_size =
@@ -2003,29 +2017,25 @@ static void qemu_create_late_backends(void)
 
 static void qemu_resolve_machine_memdev(void)
 {
-    if (current_machine->ram_memdev_id) {
+    if (ram_memdev_id) {
         Object *backend;
         ram_addr_t backend_size;
 
-        backend = object_resolve_path_type(current_machine->ram_memdev_id,
+        backend = object_resolve_path_type(ram_memdev_id,
                                            TYPE_MEMORY_BACKEND, NULL);
         if (!backend) {
-            error_report("Memory backend '%s' not found",
-                         current_machine->ram_memdev_id);
+            error_report("Memory backend '%s' not found", ram_memdev_id);
             exit(EXIT_FAILURE);
         }
         backend_size = object_property_get_uint(backend, "size",  &error_abort);
         if (have_custom_ram_size && backend_size != current_machine->ram_size) {
-                error_report("Size specified by -m option must match size of "
-                             "explicitly specified 'memory-backend' property");
-                exit(EXIT_FAILURE);
-        }
-        if (mem_path) {
-            error_report("'-mem-path' can't be used together with"
-                         "'-machine memory-backend'");
+            error_report("Size specified by -m option must match size of "
+                         "explicitly specified 'memory-backend' property");
             exit(EXIT_FAILURE);
         }
         current_machine->ram_size = backend_size;
+        object_property_set_link(OBJECT(current_machine),
+                                 "memory-backend", backend, &error_fatal);
     }
 
     if (!xen_enabled()) {
@@ -2376,27 +2386,6 @@ static void configure_accelerators(const char *progname)
     }
 }
 
-static void create_default_memdev(MachineState *ms, const char *path)
-{
-    Object *obj;
-    MachineClass *mc = MACHINE_GET_CLASS(ms);
-
-    obj = object_new(path ? TYPE_MEMORY_BACKEND_FILE : TYPE_MEMORY_BACKEND_RAM);
-    if (path) {
-        object_property_set_str(obj, "mem-path", path, &error_fatal);
-    }
-    object_property_set_int(obj, "size", ms->ram_size, &error_fatal);
-    object_property_add_child(object_get_objects_root(), mc->default_ram_id,
-                              obj);
-    /* Ensure backend's memory region name is equal to mc->default_ram_id */
-    object_property_set_bool(obj, "x-use-canonical-path-for-ramblock-id",
-                             false, &error_fatal);
-    user_creatable_complete(USER_CREATABLE(obj), &error_fatal);
-    object_unref(obj);
-    object_property_set_str(OBJECT(ms), "memory-backend", mc->default_ram_id,
-                            &error_fatal);
-}
-
 static void qemu_validate_options(const QDict *machine_opts)
 {
     const char *kernel_filename = qdict_get_try_str(machine_opts, "kernel");
@@ -2581,18 +2570,11 @@ static void qemu_init_displays(void)
 
 static void qemu_init_board(void)
 {
-    MachineClass *machine_class = MACHINE_GET_CLASS(current_machine);
-
-    if (machine_class->default_ram_id && current_machine->ram_size &&
-        numa_uses_legacy_mem() && !current_machine->ram_memdev_id) {
-        create_default_memdev(current_machine, mem_path);
-    }
-
     /* process plugin before CPUs are created, but once -smp has been parsed */
     qemu_plugin_load_list(&plugin_list, &error_fatal);
 
     /* From here on we enter MACHINE_PHASE_INITIALIZED.  */
-    machine_run_board_init(current_machine);
+    machine_run_board_init(current_machine, mem_path, &error_fatal);
 
     drive_check_orphaned();