memory: Introduce memory_region_init_ram_guest_memfd()

Introduce memory_region_init_ram_guest_memfd() to allocate private
guset memfd on the MemoryRegion initialization. It's for the use case of
TDVF, which must be private on TDX case.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Pankaj Gupta <pankaj.gupta@amd.com>
Message-ID: <20240530111643.1091816-4-pankaj.gupta@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/exec/memory.h

@@ -1638,6 +1638,12 @@ bool memory_region_init_ram(MemoryRegion *mr,
                             uint64_t size,
                             Error **errp);
 
+bool memory_region_init_ram_guest_memfd(MemoryRegion *mr,
+                                        Object *owner,
+                                        const char *name,
+                                        uint64_t size,
+                                        Error **errp);
+
 /**
  * memory_region_init_rom: Initialize a ROM memory region.
  *

system/memory.c

@@ -3649,6 +3649,30 @@ bool memory_region_init_ram(MemoryRegion *mr,
     return true;
 }
 
+bool memory_region_init_ram_guest_memfd(MemoryRegion *mr,
+                                        Object *owner,
+                                        const char *name,
+                                        uint64_t size,
+                                        Error **errp)
+{
+    DeviceState *owner_dev;
+
+    if (!memory_region_init_ram_flags_nomigrate(mr, owner, name, size,
+                                                RAM_GUEST_MEMFD, errp)) {
+        return false;
+    }
+    /* This will assert if owner is neither NULL nor a DeviceState.
+     * We only want the owner here for the purposes of defining a
+     * unique name for migration. TODO: Ideally we should implement
+     * a naming scheme for Objects which are not DeviceStates, in
+     * which case we can relax this restriction.
+     */
+    owner_dev = DEVICE(owner);
+    vmstate_register_ram(mr, owner_dev);
+
+    return true;
+}
+
 bool memory_region_init_rom(MemoryRegion *mr,
                             Object *owner,
                             const char *name,