On Mon, Mar 12, 2018 at 02:11:09PM +0100, Igor Mammedov wrote: > This option allows pausing QEMU in the new RUN_STATE_PRECONFIG state, > allowing the configuration of QEMU from QMP before the machine jumps > into board initialization code of machine_run_board_init() > > Intent is to allow management to query machine state and additionally > configure it using previous query results within one QEMU instance > (i.e. eliminate need to start QEMU twice, 1st to query board specific > parameters and 2nd for actual VM start using query results for > additional parameters). > > New option complements -S option and could be used with or without > it. Difference is that -S pauses QEMU when machine is completely > build with all devices wired up and ready run (QEMU need only to > unpause CPUs to let guest execute its code). > And "preconfig" option pauses QEMU early before board specific init > callback (machine_run_board_init) is executed and will allow to > configure machine parameters which will be used by board init code. > > When early introspection/configuration is done, command 'cont' should > be used to exit RUN_STATE_PRECONFIG and transition to the next > requested state (i.e. if -S is used then QEMU will pause the second > time when board/device initialization is completed or start guest > execution if -S isn't provided on CLI) > > PS: > Initially 'preconfig' is planned to be used for configuring numa > topology depending on board specified possible cpus layout. > > Signed-off-by: Igor Mammedov <imamm...@redhat.com> > --- > v4: > * Explain more on behaviour in commit message and use suggested > wording in message and patch (Eric Blake <ebl...@redhat.com>) > --- > include/sysemu/sysemu.h | 1 + > qapi/run-state.json | 5 ++++- > qemu-options.hx | 13 +++++++++++++ > qmp.c | 5 +++++ > vl.c | 35 ++++++++++++++++++++++++++++++++++- > 5 files changed, 57 insertions(+), 2 deletions(-) > > diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h > index 356bfdc..996bc38 100644 > --- a/include/sysemu/sysemu.h > +++ b/include/sysemu/sysemu.h > @@ -66,6 +66,7 @@ typedef enum WakeupReason { > QEMU_WAKEUP_REASON_OTHER, > } WakeupReason; > > +void qemu_exit_preconfig_request(void); > void qemu_system_reset_request(ShutdownCause reason); > void qemu_system_suspend_request(void); > void qemu_register_suspend_notifier(Notifier *notifier); > diff --git a/qapi/run-state.json b/qapi/run-state.json > index 1c9fff3..ce846a5 100644 > --- a/qapi/run-state.json > +++ b/qapi/run-state.json > @@ -49,12 +49,15 @@ > # @colo: guest is paused to save/restore VM state under colo checkpoint, > # VM can not get into this state unless colo capability is enabled > # for migration. (since 2.8) > +# @preconfig: QEMU is paused before board specific init callback is executed. > +# The state is reachable only if -preconfig CLI option is used. > +# (Since 2.12) > ## > { 'enum': 'RunState', > 'data': [ 'debug', 'inmigrate', 'internal-error', 'io-error', 'paused', > 'postmigrate', 'prelaunch', 'finish-migrate', 'restore-vm', > 'running', 'save-vm', 'shutdown', 'suspended', 'watchdog', > - 'guest-panicked', 'colo' ] } > + 'guest-panicked', 'colo', 'preconfig' ] } > > ## > # @StatusInfo: > diff --git a/qemu-options.hx b/qemu-options.hx > index 6585058..7c8aaa5 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -3302,6 +3302,19 @@ STEXI > Run the emulation in single step mode. > ETEXI > > +DEF("preconfig", 0, QEMU_OPTION_preconfig, \ > + "-preconfig pause QEMU before machine is initialized\n", > + QEMU_ARCH_ALL) > +STEXI > +@item -preconfig > +@findex -preconfig > +Pause QEMU for interactive configuration before the machine is created, > +which allows querying and configuring properties that will affect > +machine initialization. Use the QMP command 'cont' to exit the preconfig > +state and move to the next state (ie. run guest if -S isn't used or > +pause the second time is -S is used). > +ETEXI > + > DEF("S", 0, QEMU_OPTION_S, \ > "-S freeze CPU at startup (use 'c' to start execution)\n", > QEMU_ARCH_ALL) > diff --git a/qmp.c b/qmp.c > index 8c7d1cc..b38090d 100644 > --- a/qmp.c > +++ b/qmp.c > @@ -166,6 +166,11 @@ void qmp_cont(Error **errp) > BlockBackend *blk; > Error *local_err = NULL; > > + if (runstate_check(RUN_STATE_PRECONFIG)) { > + qemu_exit_preconfig_request(); > + return; > + } > + > /* if there is a dump in background, we should wait until the dump > * finished */ > if (dump_in_progress()) { > diff --git a/vl.c b/vl.c > index 3ef04ce..69b1997 100644 > --- a/vl.c > +++ b/vl.c > @@ -593,7 +593,7 @@ static int default_driver_check(void *opaque, QemuOpts > *opts, Error **errp) > /***********************************************************/ > /* QEMU state */ > > -static RunState current_run_state = RUN_STATE_PRELAUNCH; > +static RunState current_run_state = RUN_STATE_PRECONFIG; > > /* We use RUN_STATE__MAX but any invalid value will do */ > static RunState vmstop_requested = RUN_STATE__MAX; > @@ -606,6 +606,9 @@ typedef struct { > > static const RunStateTransition runstate_transitions_def[] = { > /* from -> to */ > + { RUN_STATE_PRECONFIG, RUN_STATE_PRELAUNCH }, > + { RUN_STATE_PRECONFIG, RUN_STATE_INMIGRATE },
Don't this mean -preconfig and -incoming could work together? > + > { RUN_STATE_DEBUG, RUN_STATE_RUNNING }, > { RUN_STATE_DEBUG, RUN_STATE_FINISH_MIGRATE }, > { RUN_STATE_DEBUG, RUN_STATE_PRELAUNCH }, > @@ -1629,6 +1632,7 @@ static pid_t shutdown_pid; > static int powerdown_requested; > static int debug_requested; > static int suspend_requested; > +static bool preconfig_exit_requested = true; > static WakeupReason wakeup_reason; > static NotifierList powerdown_notifiers = > NOTIFIER_LIST_INITIALIZER(powerdown_notifiers); > @@ -1713,6 +1717,11 @@ static int qemu_debug_requested(void) > return r; > } > > +void qemu_exit_preconfig_request(void) > +{ > + preconfig_exit_requested = true; > +} > + > /* > * Reset the VM. Issue an event unless @reason is SHUTDOWN_CAUSE_NONE. > */ > @@ -1886,6 +1895,13 @@ static bool main_loop_should_exit(void) > RunState r; > ShutdownCause request; > > + if (preconfig_exit_requested) { > + if (runstate_check(RUN_STATE_PRECONFIG)) { Is it possible to have preconfig_exit_request set outside of RUN_STATE_PRECONFIG? When and why? > + runstate_set(RUN_STATE_PRELAUNCH); > + } > + preconfig_exit_requested = false; > + return true; > + } > if (qemu_debug_requested()) { > vm_stop(RUN_STATE_DEBUG); > } > @@ -3697,6 +3713,14 @@ int main(int argc, char **argv, char **envp) > exit(1); > } > break; > + case QEMU_OPTION_preconfig: > + if (runstate_check(RUN_STATE_INMIGRATE)) { > + error_report("option can not be used with " > + "-incoming option"); > + exit(EXIT_FAILURE); > + } So -incoming changes runstate as soon as the option is parsed? Ouch. I would rather not rely on that behavior and just do "if (incoming)". Why exactly it's not possible to use -incoming with -preconfig? > + preconfig_exit_requested = false; > + break; > case QEMU_OPTION_enable_kvm: > olist = qemu_find_opts("machine"); > qemu_opts_parse_noisily(olist, "accel=kvm", false); > @@ -3902,6 +3926,11 @@ int main(int argc, char **argv, char **envp) > } > break; > case QEMU_OPTION_incoming: > + if (!preconfig_exit_requested) { > + error_report("option can not be used with " > + "-preconfig option"); > + exit(EXIT_FAILURE); > + } Instead of reimplementing the same check in two separate places, why not validate options and check for (incoming && preconfig) after the option parsing loop? > if (!incoming) { > runstate_set(RUN_STATE_INMIGRATE); > } > @@ -4594,6 +4623,10 @@ int main(int argc, char **argv, char **envp) > } > parse_numa_opts(current_machine); > > + /* do monitor/qmp handling at preconfig state if requested */ > + main_loop(); Wouldn't it be simpler to do "if (!preconfig) { main_loop(); }" instead of entering main_loop() just to exit immediately? > + > + /* from here on runstate is RUN_STATE_PRELAUNCH */ > machine_run_board_init(current_machine); > > realtime_init(); > -- > 2.7.4 > > -- Eduardo