[v7,6/6] xl: allow domid to be preserved on save/restore or migrate
diff mbox series

Message ID 20200221112049.3077-7-pdurrant@amazon.com
State New
Headers show
Series
  • xl/libxl: domid allocation/preservation changes
Related show

Commit Message

Paul Durrant Feb. 21, 2020, 11:20 a.m. UTC
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>
---
Cc: Wei Liu <wl@xen.org>
Cc: Anthony PERARD <anthony.perard@citrix.com>

v5:
 - Expand the commit comment to say why it is xl being patched rather
   than libxl

v2:
 - Heavily re-worked based on new libxl_domain_create_info
---
 docs/man/xl.1.pod.in      | 14 ++++++++++++++
 tools/xl/xl.h             |  1 +
 tools/xl/xl_cmdtable.c    |  6 ++++--
 tools/xl/xl_migrate.c     | 15 ++++++++++-----
 tools/xl/xl_saverestore.c | 19 ++++++++++++++-----
 tools/xl/xl_vmcontrol.c   |  3 ++-
 6 files changed, 45 insertions(+), 13 deletions(-)

Patch
diff mbox series

diff --git a/docs/man/xl.1.pod.in b/docs/man/xl.1.pod.in
index 33ad2ebd71..09339282e6 100644
--- 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 2b4709efb2..06569c6c4a 100644
--- 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 3b302b2f20..08335394e5 100644
--- 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 22f0429b84..0813beb801 100644
--- 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 9be033fe65..953d791d1a 100644
--- 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 39292acfe6..2e2d427492 100644
--- 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;