libxl: domain restore: reshuffle, preparing for ao

We are going to arrange that libxl, instead of calling
xc_domain_restore, calls a stub function which forks and execs a
helper program, so that restore can be asynchronous rather than
blocking the whole toolstack.

This stub function will be called libxl__xc_domain_restore.

However, its prospective call site is unsuitable for a function which
needs to make a callback, and is buried in two nested single-call-site
functions which are logically part of the domain creation procedure.

So we first abolish those single-call-site functions, integrate their
contents into domain creation in their proper temporal order, and
break out libxl__xc_domain_restore ready for its reimplementation.

No functional change - just the following reorganisation:

* Abolish libxl__domain_restore_common, as it had only one caller.
  Move its contents into (what was) domain_restore.

* There is a new stage function domcreate_rebuild_done containing what
  used to be the bulk of domcreate_bootloader_done, since
  domcreate_bootloader_done now simply starts the restore (or does the
  rebuild) and arranges to call the next stage.

* Move the contents of domain_restore into its correct place in the
  domain creation sequence.  We put it inside
  domcreate_bootloader_done, which now either calls
  libxl__xc_domain_restore which will call the new function
  domcreate_rebuild_done, or calls domcreate_rebuild_done directly.

* Various general-purpose local variables (`i' etc.) and convenience
  alias variables need to be shuffled about accordingly.

* Consequently libxl__toolstack_restore needs to gain external linkage
  as it is now in a different file to its user.

* Move the xc_domain_save callbacks struct from the stack into
  libxl__domain_create_state.

In general the moved code remains almost identical.  Two returns in
what used to be libxl__domain_restore_common have been changed to set
the return value and "goto out", and the call sites for the abolished
and new functions have been adjusted.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

1 files changed, 15 insertions, 4 deletions

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 37e0d098da..7a3b7f8722 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -46,6 +46,7 @@
 
 #include <xenstore.h>
 #include <xenctrl.h>
+#include <xenguest.h>
 
 #include "xentoollog.h"
 
@@ -782,10 +783,8 @@ _hidden int libxl__domain_rename(libxl__gc *gc, uint32_t domid,
                                  const char *old_name, const char *new_name,
                                  xs_transaction_t trans);
 
-_hidden int libxl__domain_restore_common(libxl__gc *gc, uint32_t domid,
-                                         libxl_domain_build_info *info,
-                                         libxl__domain_build_state *state,
-                                         int fd);
+_hidden int libxl__toolstack_restore(uint32_t domid, const uint8_t *buf,
+                                     uint32_t size, void *data);
 _hidden const char *libxl__device_model_savefile(libxl__gc *gc, uint32_t domid);
 _hidden int libxl__domain_suspend_device_model(libxl__gc *gc, uint32_t domid);
 _hidden int libxl__domain_resume_device_model(libxl__gc *gc, uint32_t domid);
@@ -1899,6 +1898,7 @@ struct libxl__domain_create_state {
     libxl__stub_dm_spawn_state dmss;
         /* If we're not doing stubdom, we use only dmss.dm,
          * for the non-stubdom device model. */
+    struct restore_callbacks callbacks;
 };
 
 /*----- Domain suspend (save) functions -----*/
@@ -1908,6 +1908,17 @@ _hidden int libxl__domain_suspend_common(libxl__gc *gc, uint32_t domid, int fd,
                                          int live, int debug,
                                          const libxl_domain_remus_info *r_info);
 
+/* calls libxl__xc_domain_restore_done when done */
+_hidden void libxl__xc_domain_restore(libxl__egc *egc,
+                                      libxl__domain_create_state *dcs,
+                                      int hvm, int pae, int superpages,
+                                      int no_incr_generationid);
+/* If rc==0 then retval is the return value from xc_domain_save
+ * and errnoval is the errno value it provided.
+ * If rc!=0, retval and errnoval are undefined. */
+_hidden void libxl__xc_domain_restore_done(libxl__egc *egc,
+                                           libxl__domain_create_state *dcs,
+                                           int rc, int retval, int errnoval);
 
 
 /*