[Xen-devel] [PATCH v3 COLOPre 11/26] tools/libxl: introduce a new API libxl__domain_restore() to load qemu state

[Yang Hongyang <yanghy@xxxxxxxxxxxxxx>]

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. Introduce a new API libxl__domain_restore()
to do it. This API should be called before resuming
secondary vm.

Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
Cc: Anthony Perard <anthony.perard@xxxxxxxxxx>
---
 tools/libxl/libxl_dom_save.c | 49 ++++++++++++++++++++++++++++++++++++++++++++
 tools/libxl/libxl_internal.h |  3 +++
 tools/libxl/libxl_qmp.c      | 10 +++++++++
 3 files changed, 62 insertions(+)

diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c
index 8fe1625..0ad2894 100644
--- a/tools/libxl/libxl_dom_save.c
+++ b/tools/libxl/libxl_dom_save.c
@@ -639,6 +639,55 @@ int libxl__toolstack_restore(uint32_t domid, const uint8_t 
*buf,
     }
     return 0;
 }
+
+static int libxl__domain_restore_device_model(libxl__gc *gc, uint32_t domid);
+
+int libxl__domain_restore(libxl__gc *gc, uint32_t domid)
+{
+    int rc = 0;
+
+    libxl_domain_type type = libxl__domain_type(gc, domid);
+    if (type != LIBXL_DOMAIN_TYPE_HVM) {
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    rc = libxl__domain_restore_device_model(gc, domid);
+    if (rc)
+        LOG(ERROR, "failed to restore device mode for domain %u:%d",
+            domid, rc);
+out:
+    return rc;
+}
+
+static int libxl__domain_restore_device_model(libxl__gc *gc, uint32_t domid)
+{
+    char *state_file;
+    int rc;
+
+    switch (libxl__device_model_version_running(gc, domid)) {
+    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL:
+        /* not supported now */
+        rc = ERROR_INVAL;
+        break;
+    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
+        /*
+         * This function may be called too many times for the same gc,
+         * so we use NOGC, and free the memory before return to avoid
+         * OOM.
+         */
+        state_file = libxl__sprintf(NOGC,
+                                    XC_DEVICE_MODEL_RESTORE_FILE".%d",
+                                    domid);
+        rc = libxl__qmp_restore(gc, domid, state_file);
+        free(state_file);
+        break;
+    default:
+        rc = ERROR_INVAL;
+    }
+
+    return rc;
+}
 /*
  * Local variables:
  * mode: C
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 573c844..0adc9b4 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1043,6 +1043,7 @@ _hidden int libxl__userdata_store(libxl__gc *gc, uint32_t 
domid,
                                   const char *userdata_userid,
                                   const uint8_t *data, int datalen);
 
+_hidden int libxl__domain_restore(libxl__gc *gc, uint32_t domid);
 _hidden int libxl__domain_resume(libxl__gc *gc, uint32_t domid,
                                  int suspend_cancel);
 
@@ -1654,6 +1655,8 @@ _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 9aa7e2e..a6f1a21 100644
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -892,6 +892,16 @@ 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", 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)
 {
-- 
1.9.1


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