Preserve memory-backend-memfd memory objects during cpr.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 backends/hostmem-memfd.c | 21 ++++++++++++---------
 hmp-commands.hx          |  2 +-
 qapi/cpr.json            |  2 +-
 3 files changed, 14 insertions(+), 11 deletions(-)

diff --git a/backends/hostmem-memfd.c b/backends/hostmem-memfd.c
index c9d8001..2aeb5d1 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;
     ram_flags |= RAM_ANON;
diff --git a/hmp-commands.hx b/hmp-commands.hx
index da5dd60..540f9be 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -380,7 +380,7 @@ SRST
 
   If *mode* is 'restart', the checkpoint remains valid after restarting
   qemu using a subsequent cpr-exec.  Guest RAM must be backed by a
-  memory-backend-file with share=on.
+  memory-backend-memfd or memory-backend-file object with share=on.
   To resume from the checkpoint, issue the cpr-load command.
 ERST
 
diff --git a/qapi/cpr.json b/qapi/cpr.json
index 47ee4ff..1ec5aae 100644
--- a/qapi/cpr.json
+++ b/qapi/cpr.json
@@ -41,7 +41,7 @@
 #
 # If @mode is 'restart', the checkpoint remains valid after restarting
 # qemu using a subsequent cpr-exec.  Guest RAM must be backed by a
-# memory-backend-file with share=on.
+# memory-backend-memfd or memory-backend-file object with share=on.
 # To resume from the checkpoint, issue the cpr-load command.
 #
 # @filename: name of checkpoint file
-- 
1.8.3.1