[PATCH V1 14/32] savevm: VMS_RESTART and cprsave restart

[Steve Sistare]

Add the VMS_RESTART variant of vmstate, for use when upgrading qemu in place
on the same host without a reboot.  Invoke it using:
  cprsave <filename> restart

VMS_RESTART supports guest ram mapped by private anonymous memory, versus
VMS_REBOOT which requires that guest ram be mapped by persistent shared
memory.  Subsequent patches complete its implementation.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 hmp-commands.hx             | 4 +++-
 include/migration/vmstate.h | 1 +
 migration/savevm.c          | 4 +++-
 monitor/qmp-cmds.c          | 2 +-
 qapi/migration.json         | 1 +
 5 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 7517876..11a2089 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -369,7 +369,7 @@ ERST
     {
         .name       = "cprsave",
         .args_type  = "file:s,mode:s",
-        .params     = "file 'reboot'",
+        .params     = "file 'restart'|'reboot'",
         .help       = "create a checkpoint of the VM in file",
         .cmd        = hmp_cprsave,
     },
@@ -380,6 +380,8 @@ SRST
   in *file*.
   If *mode* is 'reboot', the checkpoint can be cprload'ed after a host kexec
   reboot.
+  If *mode* is 'restart', the checkpoint can be cprload'ed after restarting
+  qemu.
   exec() /usr/bin/qemu-exec if it exists, else exec 
/usr/bin/qemu-system-x86_64,
   passing all the original command line arguments.  The VCPUs remain paused.
 ERST
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index c58551a..8239b84 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -162,6 +162,7 @@ typedef enum {
     VMS_MIGRATE  = (1U << 1),
     VMS_SNAPSHOT = (1U << 2),
     VMS_REBOOT   = (1U << 3),
+    VMS_RESTART  = (1U << 4),
     VMS_MODE_ALL = ~0U
 } VMStateMode;
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 00f493b..38cc63a 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2708,6 +2708,8 @@ void save_cpr_snapshot(const char *file, const char 
*mode, Error **errp)
 
     if (!strcmp(mode, "reboot")) {
         op = VMS_REBOOT;
+    } else if (!strcmp(mode, "restart")) {
+        op = VMS_RESTART;
     } else {
         error_setg(errp, "cprsave: bad mode %s", mode);
         return;
@@ -2973,7 +2975,7 @@ void load_cpr_snapshot(const char *file, Error **errp)
         return;
     }
 
-    ret = qemu_loadvm_state(f, VMS_REBOOT);
+    ret = qemu_loadvm_state(f, VMS_REBOOT | VMS_RESTART);
     qemu_fclose(f);
     if (ret < 0) {
         error_setg(errp, "Error %d while loading VM state", ret);
diff --git a/monitor/qmp-cmds.c b/monitor/qmp-cmds.c
index 8c400e6..8a74c6e 100644
--- a/monitor/qmp-cmds.c
+++ b/monitor/qmp-cmds.c
@@ -164,7 +164,7 @@ void qmp_cont(Error **errp)
 
 char *qmp_cprinfo(Error **errp)
 {
-    return g_strdup("reboot");
+    return g_strdup("reboot restart");
 }
 
 void qmp_cprsave(const char *file, const char *mode, Error **errp)
diff --git a/qapi/migration.json b/qapi/migration.json
index 8190b16..d22992b 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -1639,6 +1639,7 @@
 #
 # @file: name of checkpoint file
 # @mode: 'reboot' : checkpoint can be cprload'ed after a host kexec reboot.
+#        'restart': checkpoint can be cprload'ed after restarting qemu.
 #
 # Since 5.0
 ##
-- 
1.8.3.1