[RFC Patch 08/25] Update libxl__domain_resume() for colo

[Wen Congyang <wency@cn.fujitsu.com>]

Secondary vm is running in colo mode. So we will do
the following things again and again:
1. suspend both primay vm and secondary vm
2. sync the state
3. resume both primary vm and secondary vm
We will send qemu's state each time in step2, and
slave's qemu should read it each time before resuming
secondary vm. libxl__domain_resume() doesn't
read qemu's state. Add a new parameter to
control whether we need to read qemu's state
before resuming.

Note: we should update qemu to support it.
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 tools/libxl/libxl.c          |  7 ++++---
 tools/libxl/libxl_dom.c      | 24 +++++++++++++++++++++---
 tools/libxl/libxl_internal.h |  8 ++++++--
 tools/libxl/libxl_qmp.c      | 10 ++++++++++
 4 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index fc60bb1..7ff1cb6 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -466,7 +466,8 @@ int libxl_domain_rename(libxl_ctx *ctx, uint32_t domid,
     return rc;
 }
 
-int libxl__domain_resume(libxl__gc *gc, uint32_t domid, int suspend_cancel)
+int libxl__domain_resume(libxl__gc *gc, uint32_t domid,
+                         int suspend_cancel, int read_savefile)
 {
     int rc = 0;
 
@@ -483,7 +484,7 @@ int libxl__domain_resume(libxl__gc *gc, uint32_t domid, int suspend_cancel)
     }
 
     if (type == LIBXL_DOMAIN_TYPE_HVM) {
-        rc = libxl__domain_resume_device_model(gc, domid);
+        rc = libxl__domain_resume_device_model(gc, domid, read_savefile);
         if (rc) {
             LOG(ERROR, "failed to resume device model for domain %u:%d",
                 domid, rc);
@@ -503,7 +504,7 @@ int libxl_domain_resume(libxl_ctx *ctx, uint32_t domid, int suspend_cancel,
                         const libxl_asyncop_how *ao_how)
 {
     AO_CREATE(ctx, domid, ao_how);
-    int rc = libxl__domain_resume(gc, domid, suspend_cancel);
+    int rc = libxl__domain_resume(gc, domid, suspend_cancel, 0);
     libxl__ao_complete(egc, ao, rc);
     return AO_INPROGRESS;
 }
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 035d25a..206c1dd 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -1046,16 +1046,34 @@ int libxl__domain_suspend_device_model(libxl__gc *gc,
     return ret;
 }
 
-int libxl__domain_resume_device_model(libxl__gc *gc, uint32_t domid)
+int libxl__domain_resume_device_model(libxl__gc *gc, uint32_t domid,
+                                      int read_savefile)
 {
 
     switch (libxl__device_model_version_running(gc, domid)) {
     case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL: {
-        libxl__qemu_traditional_cmd(gc, domid, "continue");
+        if (read_savefile)
+            libxl__qemu_traditional_cmd(gc, domid, "resume");
+        else
+            libxl__qemu_traditional_cmd(gc, domid, "continue");
         libxl__wait_for_device_model_deprecated(gc, domid, "running", NULL, NULL, NULL);
         break;
     }
     case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
+        if (read_savefile) {
+            char *state_file;
+            int rc;
+
+            state_file = libxl__sprintf(NOGC,
+                                        XC_DEVICE_MODEL_RESTORE_FILE".%d",
+                                        domid);
+            /* This command only restores the device state */
+            rc = libxl__qmp_restore(gc, domid, state_file);
+            free(state_file);
+            if (rc)
+                return ERROR_FAIL;
+        }
+
         if (libxl__qmp_resume(gc, domid))
             return ERROR_FAIL;
         break;
@@ -1540,7 +1558,7 @@ static void remus_device_preresume_cb(libxl__egc *egc,
 
     if (!rc) {
         /* Resumes the domain and the device model */
-        if (!libxl__domain_resume(gc, dss->domid, /* Fast Suspend */1))
+        if (!libxl__domain_resume(gc, dss->domid, /* Fast Suspend */1, 0))
             ok = 1;
     }
     libxl__xc_domain_saverestore_async_callback_done(egc, &dss->shs, ok);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 881f3b9..35227d3 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -994,12 +994,14 @@ _hidden int libxl__domain_rename(libxl__gc *gc, uint32_t domid,
 
 _hidden int libxl__toolstack_restore(uint32_t domid, const uint8_t *buf,
                                      uint32_t size, void *data);
-_hidden int libxl__domain_resume_device_model(libxl__gc *gc, uint32_t domid);
+_hidden int libxl__domain_resume_device_model(libxl__gc *gc,
+                                              uint32_t domid,
+                                              int read_savefile);
 
 _hidden void libxl__userdata_destroyall(libxl__gc *gc, uint32_t domid);
 
 _hidden int libxl__domain_resume(libxl__gc *gc, uint32_t domid,
-                                 int suspend_cancel);
+                                 int suspend_cancel, int read_savefile);
 
 /* returns 0 or 1, or a libxl error code */
 _hidden int libxl__domain_pvcontrol_available(libxl__gc *gc, uint32_t domid);
@@ -1585,6 +1587,8 @@ _hidden int libxl__qmp_stop(libxl__gc *gc, int domid);
 _hidden int libxl__qmp_resume(libxl__gc *gc, int domid);
 /* Save current QEMU state into fd. */
 _hidden int libxl__qmp_save(libxl__gc *gc, int domid, const char *filename);
+/* Load current QEMU state from fd. */
+_hidden int libxl__qmp_restore(libxl__gc *gc, int domid, const char *filename);
 /* Set dirty bitmap logging status */
 _hidden int libxl__qmp_set_global_dirty_log(libxl__gc *gc, int domid, bool enable);
 _hidden int libxl__qmp_insert_cdrom(libxl__gc *gc, int domid, const libxl_device_disk *disk);
diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
index 5cc56b1..60a119d 100644
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -876,6 +876,16 @@ int libxl__qmp_save(libxl__gc *gc, int domid, const char *filename)
                            NULL, NULL);
 }
 
+int libxl__qmp_restore(libxl__gc *gc, int domid, const char *state_file)
+{
+    libxl__json_object *args = NULL;
+
+    qmp_parameters_add_string(gc, &args, "filename", (char *)state_file);
+
+    return qmp_run_command(gc, domid, "xen-load-devices-state", args,
+                           NULL, NULL);
+}
+
 static int qmp_change(libxl__gc *gc, libxl__qmp_handler *qmp,
                       char *device, char *target, char *arg)
 {
-- 
1.9.3