From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34162) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YuICx-00019V-2Q for qemu-devel@nongnu.org; Mon, 18 May 2015 06:23:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YuICs-0006fN-SW for qemu-devel@nongnu.org; Mon, 18 May 2015 06:23:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38155) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YuICs-0006fF-Ks for qemu-devel@nongnu.org; Mon, 18 May 2015 06:23:34 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t4IANYVI031019 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Mon, 18 May 2015 06:23:34 -0400 Date: Mon, 18 May 2015 11:23:30 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20150518102329.GD2201@work-vm> References: <1431620920-19710-1-git-send-email-quintela@redhat.com> <1431620920-19710-7-git-send-email-quintela@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1431620920-19710-7-git-send-email-quintela@redhat.com> Subject: Re: [Qemu-devel] [PATCH 6/9] migration: create new section to store global state List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juan Quintela Cc: qemu-devel@nongnu.org * Juan Quintela (quintela@redhat.com) wrote: > This includes a new section that for now just stores the current qemu state. > > Right now, there are only one way to control what is the state of the > target after migration. > > - If you run the target qemu with -S, it would start stopped. > - If you run the target qemu without -S, it would run just after migration finishes. > > The problem here is what happens if we start the target without -S and > there happens one error during migration that puts current state as > -EIO. Migration would ends (notice that the error happend doing block > IO, network IO, i.e. nothing related with migration), and when > migration finish, we would just "continue" running on destination, > probably hanging the guest/corruption data, whatever. > > Signed-off-by: Juan Quintela > --- > include/migration/migration.h | 4 ++ > migration/migration.c | 85 +++++++++++++++++++++++++++++++++++++++++-- > vl.c | 1 + > 3 files changed, 87 insertions(+), 3 deletions(-) > > diff --git a/include/migration/migration.h b/include/migration/migration.h > index a6e025a..785c2dc 100644 > --- a/include/migration/migration.h > +++ b/include/migration/migration.h > @@ -180,4 +180,8 @@ size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset, > ram_addr_t offset, size_t size, > uint64_t *bytes_sent); > > +void register_global_state(void); > +void global_state_store(void); > +char *global_state_get_runstate(void); > + > #endif > diff --git a/migration/migration.c b/migration/migration.c > index 732d229..ab69f81 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -133,10 +133,20 @@ static void process_incoming_migration_co(void *opaque) > exit(EXIT_FAILURE); > } > > - if (autostart) { > + /* runstate == "" means that we haven't received it through the > + * wire, so we obey autostart. runstate == runing means that we > + * need to run it, we need to make sure that we do it after > + * everything else has finished. Every other state change is done > + * at the post_load function */ > + > + if (strcmp(global_state_get_runstate(), "running") == 0) { > vm_start(); > - } else { > - runstate_set(RUN_STATE_PAUSED); > + } else if (strcmp(global_state_get_runstate(), "") == 0) { > + if (autostart) { > + vm_start(); > + } else { > + runstate_set(RUN_STATE_PAUSED); > + } > } > migrate_decompress_threads_join(); > } > @@ -760,6 +770,7 @@ static void *migration_thread(void *opaque) > qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER); > old_vm_running = runstate_is_running(); > > + global_state_store(); > ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE); > if (ret >= 0) { > qemu_file_set_rate_limit(s->file, INT64_MAX); > @@ -855,3 +866,71 @@ void migrate_fd_connect(MigrationState *s) > qemu_thread_create(&s->thread, "migration", migration_thread, s, > QEMU_THREAD_JOINABLE); > } > + > +typedef struct { > + int32_t size; > + uint8_t runstate[100]; > +} GlobalState; unsigned for size? Could use something smaller than a int32_t I guess for a 100 byte buffer. > + > +static GlobalState global_state; > + > +void global_state_store(void) > +{ > + if (runstate_store((char *)global_state.runstate, > + sizeof(global_state.runstate)) == -1) { > + error_report("Runstate is too big: %s\n", global_state.runstate); error_report's don't need the \n > + exit(-1); > + } > +} > + > +char *global_state_get_runstate(void) > +{ > + return (char *)global_state.runstate; > +} Is that needed outside of this file - if not then just make it static or use the data directly? > + > +static int global_state_post_load(void *opaque, int version_id) > +{ > + GlobalState *s = opaque; > + int ret = 0; > + char *runstate = (char *)s->runstate; > + > + if (strcmp(runstate, "running") != 0) { > + > + RunState r = runstate_index(runstate); > + > + if (r == -1) { > + error_report("Unknown received state %s\n", runstate); error_report's don't need the \n > + return -1; > + } > + ret = vm_stop_force_state(r); Why do this here, rather than in process_incoming_migration_co; that would seem neater to keep the state change in one place. Dave > + } > + > + return ret; > +} > + > +static void global_state_pre_save(void *opaque) > +{ > + GlobalState *s = opaque; > + > + s->size = strlen((char *)s->runstate) + 1; > +} > + > +static const VMStateDescription vmstate_globalstate = { > + .name = "globalstate", > + .version_id = 1, > + .minimum_version_id = 1, > + .post_load = global_state_post_load, > + .pre_save = global_state_pre_save, > + .fields = (VMStateField[]) { > + VMSTATE_INT32(size, GlobalState), > + VMSTATE_BUFFER(runstate, GlobalState), > + VMSTATE_END_OF_LIST() > + }, > +}; > + > +void register_global_state(void) > +{ > + /* We would use it independently that we receive it */ > + strcpy((char *)&global_state.runstate, ""); > + vmstate_register(NULL, 0, &vmstate_globalstate, &global_state); > +} > diff --git a/vl.c b/vl.c > index b8844f6..8af6c79 100644 > --- a/vl.c > +++ b/vl.c > @@ -4387,6 +4387,7 @@ int main(int argc, char **argv, char **envp) > return 0; > } > > + register_global_state(); > if (incoming) { > Error *local_err = NULL; > qemu_start_incoming_migration(incoming, &local_err); > -- > 2.4.0 > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK