xl: allow domid to be preserved on save/restore or migrate

This patch adds a '-D' command line option to save and migrate to allow
the domain id to be incorporated into the saved domain configuration and
hence be preserved.

NOTE: Logically it may seem as though preservation of domid should be
      dealt with by libxl, but the libxl migration stream has no record
      in which to transfer domid and remote domain creation occurs before
      the migration stream is parsed. Hence this patch modifies xl rather
      then libxl.

Signed-off-by: Paul Durrant <pdurrant@amazon.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

diff --git a/docs/man/xl.1.pod.in b/docs/man/xl.1.pod.in
index 33ad2ebd71a65b7b0901173ea654b42a3e1fd1ed..09339282e6bd6809fe135d7200197e90432024af 100644 (file)
--- a/docs/man/xl.1.pod.in
+++ b/docs/man/xl.1.pod.in
@@ -490,6 +490,13 @@ Display huge (!) amount of debug information during the migration process.
 
 Leave the domain on the receive side paused after migration.
 
+=item B<-D>
+
+Preserve the B<domain-id> in the domain coniguration that is transferred
+such that it will be identical on the destination host, unless that
+configuration is overridden using the B<-C> option. Note that it is not
+possible to use this option for a 'localhost' migration.
+
 =back
 
 =item B<remus> [I<OPTIONS>] I<domain-id> I<host>
@@ -692,6 +699,13 @@ Leave the domain running after creating the snapshot.
 
 Leave the domain paused after creating the snapshot.
 
+=item B<-D>
+
+Preserve the B<domain-id> in the domain coniguration that is embedded in
+the state file such that it will be identical when the domain is restored,
+unless that configuration is overridden. (See the B<restore> operation
+above).
+
 =back
 
 =item B<sharing> [I<domain-id>]

diff --git a/tools/xl/xl.h b/tools/xl/xl.h
index 2b4709efb2cfd1f4696a014ff91cce8b80046d6f..06569c6c4a6f8d2fb58fa34be9c489bf2ba7954b 100644 (file)
--- a/tools/xl/xl.h
+++ b/tools/xl/xl.h
@@ -99,6 +99,7 @@ struct save_file_header {
 #define SAVEFILE_BYTEORDER_VALUE ((uint32_t)0x01020304UL)
 
 void save_domain_core_begin(uint32_t domid,
+                            int preserve_domid,
                             const char *override_config_file,
                             uint8_t **config_data_r,
                             int *config_len_r);

diff --git a/tools/xl/xl_cmdtable.c b/tools/xl/xl_cmdtable.c
index 3b302b2f203b0afc5e54a340b0414403fc9dcdde..08335394e53f7c54e5bbac391c0f101cbd04fcc1 100644 (file)
--- a/tools/xl/xl_cmdtable.c
+++ b/tools/xl/xl_cmdtable.c
@@ -153,7 +153,8 @@ struct cmd_spec cmd_table[] = {
       "[options] <Domain> <CheckpointFile> [<ConfigFile>]",
       "-h  Print this help.\n"
       "-c  Leave domain running after creating the snapshot.\n"
-      "-p  Leave domain paused after creating the snapshot."
+      "-p  Leave domain paused after creating the snapshot.\n"
+      "-D  Store the domain id in the configration."
     },
     { "migrate",
       &main_migrate, 0, 1,
@@ -167,7 +168,8 @@ struct cmd_spec cmd_table[] = {
       "-e              Do not wait in the background (on <host>) for the death\n"
       "                of the domain.\n"
       "--debug         Print huge (!) amount of debug during the migration process.\n"
-      "-p              Do not unpause domain after migrating it."
+      "-p              Do not unpause domain after migrating it.\n"
+      "-D              Preserve the domain id"
     },
     { "restore",
       &main_restore, 0, 1,

diff --git a/tools/xl/xl_migrate.c b/tools/xl/xl_migrate.c
index 22f0429b8488ae466a7f3cdeffa5971530372df7..0813beb801819b0047bd4dcf5436c7e143e4a09e 100644 (file)
--- a/tools/xl/xl_migrate.c
+++ b/tools/xl/xl_migrate.c
@@ -176,7 +176,8 @@ static void migrate_do_preamble(int send_fd, int recv_fd, pid_t child,
 
 }
 
-static void migrate_domain(uint32_t domid, const char *rune, int debug,
+static void migrate_domain(uint32_t domid, int preserve_domid,
+                           const char *rune, int debug,
                            const char *override_config_file)
 {
     pid_t child = -1;
@@ -187,7 +188,7 @@ static void migrate_domain(uint32_t domid, const char *rune, int debug,
     uint8_t *config_data;
     int config_len, flags = LIBXL_SUSPEND_LIVE;
 
-    save_domain_core_begin(domid, override_config_file,
+    save_domain_core_begin(domid, preserve_domid, override_config_file,
                            &config_data, &config_len);
 
     if (!config_len) {
@@ -537,13 +538,14 @@ int main_migrate(int argc, char **argv)
     char *rune = NULL;
     char *host;
     int opt, daemonize = 1, monitor = 1, debug = 0, pause_after_migration = 0;
+    int preserve_domid = 0;
     static struct option opts[] = {
         {"debug", 0, 0, 0x100},
         {"live", 0, 0, 0x200},
         COMMON_LONG_OPTS
     };
 
-    SWITCH_FOREACH_OPT(opt, "FC:s:ep", opts, "migrate", 2) {
+    SWITCH_FOREACH_OPT(opt, "FC:s:epD", opts, "migrate", 2) {
     case 'C':
         config_filename = optarg;
         break;
@@ -560,6 +562,9 @@ int main_migrate(int argc, char **argv)
     case 'p':
         pause_after_migration = 1;
         break;
+    case 'D':
+        preserve_domid = 1;
+        break;
     case 0x100: /* --debug */
         debug = 1;
         break;
@@ -596,7 +601,7 @@ int main_migrate(int argc, char **argv)
                   pause_after_migration ? " -p" : "");
     }
 
-    migrate_domain(domid, rune, debug, config_filename);
+    migrate_domain(domid, preserve_domid, rune, debug, config_filename);
     return EXIT_SUCCESS;
 }
 
@@ -716,7 +721,7 @@ int main_remus(int argc, char **argv)
             }
         }
 
-        save_domain_core_begin(domid, NULL, &config_data, &config_len);
+        save_domain_core_begin(domid, 0, NULL, &config_data, &config_len);
 
         if (!config_len) {
             fprintf(stderr, "No config file stored for running domain and "

diff --git a/tools/xl/xl_saverestore.c b/tools/xl/xl_saverestore.c
index 9be033fe65e4557c849d5dd57a2cf6a307397d01..953d791d1a6de59ab182f7788dcd81062b8cab30 100644 (file)
--- a/tools/xl/xl_saverestore.c
+++ b/tools/xl/xl_saverestore.c
@@ -32,6 +32,7 @@
 #ifndef LIBXL_HAVE_NO_SUSPEND_RESUME
 
 void save_domain_core_begin(uint32_t domid,
+                            int preserve_domid,
                             const char *override_config_file,
                             uint8_t **config_data_r,
                             int *config_len_r)
@@ -62,6 +63,8 @@ void save_domain_core_begin(uint32_t domid,
             fprintf(stderr, "unable to retrieve domain configuration\n");
             exit(EXIT_FAILURE);
         }
+
+        d_config.c_info.domid = preserve_domid ? domid : 0;
     }
 
     config_c = libxl_domain_config_to_json(ctx, &d_config);
@@ -120,14 +123,15 @@ void save_domain_core_writeconfig(int fd, const char *source,
             hdr.optional_data_len);
 }
 
-static int save_domain(uint32_t domid, const char *filename, int checkpoint,
-                            int leavepaused, const char *override_config_file)
+static int save_domain(uint32_t domid, int preserve_domid,
+                       const char *filename, int checkpoint,
+                       int leavepaused, const char *override_config_file)
 {
     int fd;
     uint8_t *config_data;
     int config_len;
 
-    save_domain_core_begin(domid, override_config_file,
+    save_domain_core_begin(domid, preserve_domid, override_config_file,
                            &config_data, &config_len);
 
     if (!config_len) {
@@ -236,15 +240,19 @@ int main_save(int argc, char **argv)
     const char *config_filename = NULL;
     int checkpoint = 0;
     int leavepaused = 0;
+    int preserve_domid = 0;
     int opt;
 
-    SWITCH_FOREACH_OPT(opt, "cp", NULL, "save", 2) {
+    SWITCH_FOREACH_OPT(opt, "cpD", NULL, "save", 2) {
     case 'c':
         checkpoint = 1;
         break;
     case 'p':
         leavepaused = 1;
         break;
+    case 'D':
+        preserve_domid = 1;
+        break;
     }
 
     if (argc-optind > 3) {
@@ -257,7 +265,8 @@ int main_save(int argc, char **argv)
     if ( argc - optind >= 3 )
         config_filename = argv[optind + 2];
 
-    save_domain(domid, filename, checkpoint, leavepaused, config_filename);
+    save_domain(domid, preserve_domid, filename, checkpoint, leavepaused,
+                config_filename);
     return EXIT_SUCCESS;
 }
 

diff --git a/tools/xl/xl_vmcontrol.c b/tools/xl/xl_vmcontrol.c
index 39292acfe66ed11fc55dc2fb1ac36ab357177383..2e2d427492fea23863409c8f23561a2abb4ff057 100644 (file)
--- a/tools/xl/xl_vmcontrol.c
+++ b/tools/xl/xl_vmcontrol.c
@@ -899,7 +899,8 @@ start:
         autoconnect_console_how = 0;
     }
 
-    d_config.c_info.domid = domid_policy;
+    if (!libxl_domid_valid_guest(d_config.c_info.domid))
+        d_config.c_info.domid = domid_policy;
 
     if ( restoring ) {
         libxl_domain_restore_params params;