From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60166) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZACpj-0005Yv-V5 for qemu-devel@nongnu.org; Wed, 01 Jul 2015 03:53:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZACpf-0004Dv-QL for qemu-devel@nongnu.org; Wed, 01 Jul 2015 03:53:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34841) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZACpf-0004Dj-G2 for qemu-devel@nongnu.org; Wed, 01 Jul 2015 03:53:23 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id 49E09B82A0 for ; Wed, 1 Jul 2015 07:53:22 +0000 (UTC) From: Juan Quintela In-Reply-To: <20150617190043.GT2122@work-vm> (David Alan Gilbert's message of "Wed, 17 Jun 2015 20:00:44 +0100") References: <1434505833-11234-1-git-send-email-quintela@redhat.com> <1434505833-11234-4-git-send-email-quintela@redhat.com> <20150617190043.GT2122@work-vm> Date: Wed, 01 Jul 2015 09:53:20 +0200 Message-ID: <87a8vg48lr.fsf@neno.neno> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH 03/11] migration: create new section to store global state Reply-To: quintela@redhat.com List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: amit.shah@redhat.com, qemu-devel@nongnu.org "Dr. David Alan Gilbert" wrote: > * 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 | 1 + >> migration/migration.c | 93 +++++++++++++++++++++++++++++++++++++++++-- >> vl.c | 1 + >> 3 files changed, 92 insertions(+), 3 deletions(-) >> >> diff --git a/include/migration/migration.h b/include/migration/migration.h >> index 9387c8c..1280193 100644 >> --- a/include/migration/migration.h >> +++ b/include/migration/migration.h >> @@ -197,4 +197,5 @@ size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset, >> >> void ram_mig_init(void); >> void savevm_skip_section_footers(void); >> +void register_global_state(void); >> #endif >> diff --git a/migration/migration.c b/migration/migration.c >> index b04b457..01bb90d 100644 >> --- a/migration/migration.c >> +++ b/migration/migration.c >> @@ -25,6 +25,7 @@ >> #include "qemu/thread.h" >> #include "qmp-commands.h" >> #include "trace.h" >> +#include "qapi/util.h" >> >> #define MAX_THROTTLE (32 << 20) /* Migration speed throttling */ >> >> @@ -96,6 +97,81 @@ void migration_incoming_state_destroy(void) >> mis_current = NULL; >> } >> >> + >> +typedef struct { >> + int32_t size; > > Still think that size should be unsigned. changed > >> + uint8_t runstate[100]; >> +} GlobalState; >> + >> +static GlobalState global_state; >> + >> +static void global_state_store(void) >> +{ >> + if (!runstate_store((char *)global_state.runstate, >> + sizeof(global_state.runstate))) { >> + printf("Runstate is too big\n"); >> + exit(-1); > > Hmmmm: > 1) Shouldn't that be an error report? or an assert? > 2) Exit should use EXIT_FAILURE (which is +ve as well) > 3) But you shouldn't kill the guest on an outwards migration > - just fail the migration. > 4) (And anyway this all seems overkill for sending a > status string). moved to a trace & and return -EINVAL. Adjusted only caller to handle the error. > >> + } >> +} >> + >> +static char *global_state_get_runstate(void) >> +{ >> + return (char *)global_state.runstate; >> +} >> + >> +static int global_state_post_load(void *opaque, int version_id) >> +{ >> + GlobalState *s = opaque; >> + int ret = 0; >> + char *runstate = (char *)s->runstate; >> + >> + printf("loaded state: %s\n", runstate); > > trace_..... Done > >> + >> + if (strcmp(runstate, "running") != 0) { >> + Error *local_err = NULL; >> + int r = qapi_enum_parse(RunState_lookup, runstate, RUN_STATE_MAX, >> + -1, &local_err); > > Is there a reason not to do the qapi_enum_parse first, and then > compare it's output to RUN_STATE_RUNNING? Avoid running the enum_parse at all if we are not at running state, I don't really care one way or another. > >> + >> + if (r == -1) { >> + if (local_err) { >> + error_report_err(local_err); >> + } >> + return -1; > > I'm not sure, but shouldn't that be -EINVAL ? > (Not that vmstate is consistent about it) Changed. >> + } >> + ret = vm_stop_force_state(r); > > Kind of going back to adding the state transitions; > don't you need to allow INMIGRATE to * - because it could > be pretty much anything? (Shutdown? Suspended?) good question. Doing the change in the other patch. >> + } >> + >> + return ret; >> +} >> + >> +static void global_state_pre_save(void *opaque) >> +{ >> + GlobalState *s = opaque; >> + >> + s->size = strlen((char *)s->runstate) + 1; >> + printf("saved state: %s\n", s->runstate); > > trace_ Done. >> +} >> + >> +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); >> +} >> + >> /* >> * Called on -incoming with a defer: uri. >> * The migration can be started later after any parameters have been >> @@ -163,10 +239,20 @@ 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(); >> } >> @@ -791,6 +877,7 @@ 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); >> diff --git a/vl.c b/vl.c >> index 555fd88..95acdb1 100644 >> --- a/vl.c >> +++ b/vl.c >> @@ -4473,6 +4473,7 @@ 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); >> -- >> 2.4.3 >> >> > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK