Commit c788ada8 authored by Peter Xu's avatar Peter Xu Committed by Juan Quintela
Browse files

migration: add "return-path" capability 



When this capability is enabled, QEMU will use the return path even for
precopy migration. This is helpful at least in one case when destination
failed to load the image while source quited without confirmation. With
return path, source will wait for the last response from destination,
and if destination fails, it'll fail the migration on source, then the
guest can be run again on the source (rather than assuming to be good,
then the guest will be lost after source quits).

It needs to be enabled explicitly on source, otherwise disabled.

Signed-off-by: default avatarPeter Xu <peterx@redhat.com>
Message-Id: <1498472935-14461-1-git-send-email-peterx@redhat.com>
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Reviewed-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent d2164ad3

migration/migration.c

+13 −3
Original line number Diff line number Diff line
@@ -1311,6 +1311,15 @@ bool migrate_use_block(void) 
    return s->enabled_capabilities[MIGRATION_CAPABILITY_BLOCK];

}



bool migrate_use_return_path(void)

{

    MigrationState *s;



    s = migrate_get_current();



    return s->enabled_capabilities[MIGRATION_CAPABILITY_RETURN_PATH];

}



bool migrate_use_block_incremental(void)

{

    MigrationState *s;
@@ -1975,10 +1984,11 @@ void migrate_fd_connect(MigrationState *s) 
    notifier_list_notify(&migration_state_notifiers, s);



    /*

     * Open the return path; currently for postcopy but other things might

     * also want it.

     * Open the return path. For postcopy, it is used exclusively. For

     * precopy, only if user specified "return-path" capability would

     * QEMU uses the return path.

     */

    if (migrate_postcopy_ram()) {

    if (migrate_postcopy_ram() || migrate_use_return_path()) {

        if (open_return_path_on_source(s)) {

            error_report("Unable to open return-path for postcopy");

            migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,

migration/migration.h

+1 −0
Original line number Diff line number Diff line
@@ -177,6 +177,7 @@ bool migrate_colo_enabled(void); 


bool migrate_use_block(void);

bool migrate_use_block_incremental(void);

bool migrate_use_return_path(void);



bool migrate_use_compression(void);

int migrate_compress_level(void);

qapi-schema.json

+4 −1
Original line number Diff line number Diff line
@@ -900,12 +900,15 @@ 
#          offers more flexibility.

#          (Since 2.10)

#

# @return-path: If enabled, migration will use the return path even

#               for precopy. (since 2.10)

#

# Since: 1.2

##

{ 'enum': 'MigrationCapability',

  'data': ['xbzrle', 'rdma-pin-all', 'auto-converge', 'zero-blocks',

           'compress', 'events', 'postcopy-ram', 'x-colo', 'release-ram',

           'block' ] }

           'block', 'return-path' ] }



##

# @MigrationCapabilityStatus: