Preserve memory-backend-memfd memory objects during cpr.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 backends/hostmem-memfd.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c
index 3fc85c3..5097a05 100644
--- a/backends/hostmem-memfd.c
+++ b/backends/hostmem-memfd.c
@@ -14,6 +14,7 @@
 #include "sysemu/hostmem.h"
 #include "qom/object_interfaces.h"
 #include "qemu/memfd.h"
+#include "migration/cpr.h"
 #include "qemu/module.h"
 #include "qapi/error.h"
 #include "qom/object.h"
@@ -36,23 +37,25 @@ memfd_backend_memory_alloc(HostMemoryBackend *backend, Error **errp)
 {
     HostMemoryBackendMemfd *m = MEMORY_BACKEND_MEMFD(backend);
     uint32_t ram_flags;
-    char *name;
-    int fd;
+    char *name = host_memory_backend_get_name(backend);
+    int fd = cpr_find_fd(name, 0);
 
     if (!backend->size) {
         error_setg(errp, "can't create backend with size 0");
         return;
     }
 
-    fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
-                           m->hugetlb, m->hugetlbsize, m->seal ?
-                           F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
-                           errp);
-    if (fd == -1) {
-        return;
+    if (fd < 0) {
+        fd = qemu_memfd_create(TYPE_MEMORY_BACKEND_MEMFD, backend->size,
+                               m->hugetlb, m->hugetlbsize, m->seal ?
+                               F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL : 0,
+                               errp);
+        if (fd == -1) {
+            return;
+        }
+        cpr_save_fd(name, 0, fd);
     }
 
-    name = host_memory_backend_get_name(backend);
     ram_flags = backend->share ? RAM_SHARED : 0;
     ram_flags |= backend->reserve ? 0 : RAM_NORESERVE;
     memory_region_init_ram_from_fd(&backend->mr, OBJECT(backend), name,
-- 
1.8.3.1