machine: introduce convenience MachineState::ram

the new field will be used by boards to get access to main
RAM memory region and will help to save boiler plate in
boards which often introduce a field or variable just for
this purpose.

Memory region will be equivalent to what currently used
memory_region_allocate_system_memory() is returning apart
from that it will come from hostmem backend.
Followup patches will incrementally switch boards to using
RAM from MachineState::ram.

Patch takes care of non-NUMA case and follow up patch will
initialize MachineState::ram for NUMA case.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20200219160953.13771-5-imammedo@redhat.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 8e536cafb2..ae2b60fb5e 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -73,7 +73,12 @@ void machine_set_cpu_numa_node(MachineState *machine,
                                Error **errp);
 
 void machine_class_allow_dynamic_sysbus_dev(MachineClass *mc, const char *type);
-
+/*
+ * Checks that backend isn't used, preps it for exclusive usage and
+ * returns migratable MemoryRegion provided by backend.
+ */
+MemoryRegion *machine_consume_memdev(MachineState *machine,
+                                     HostMemoryBackend *backend);
 
 /**
  * CPUArchId:
@@ -295,6 +300,11 @@ struct MachineState {
     bool enable_graphics;
     char *memory_encryption;
     char *ram_memdev_id;
+    /*
+     * convenience alias to ram_memdev_id backend memory region
+     * or to numa container memory region
+     */
+    MemoryRegion *ram;
     DeviceMemoryState *device_memory;
 
     ram_addr_t ram_size;