Re: [Qemu-devel] [PATCH 6/7] Monitor: Don't allow cont on bad VM state

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2011-08-03 17:17, Luiz Capitulino wrote:
> We have two states where issuing cont before system_reset can be
> catastrophic: QSTATE_SHUTDOWN (when -no-shutdown is used) and
> QSTATE_INTERROR (which only happen with kvm).
> 
> This commit fixes that by making system_reset mandatory before
> issuing cont in those states.
> 
> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> ---
>  cpus.c    |    4 ++++
>  monitor.c |    8 ++++++++
>  qerror.c  |    4 ++++
>  qerror.h  |    3 +++
>  sysemu.h  |    2 +-
>  vl.c      |    1 +
>  6 files changed, 21 insertions(+), 1 deletions(-)
> 
> diff --git a/cpus.c b/cpus.c
> index 65ea503..a61e658 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -125,6 +125,10 @@ static void do_vm_stop(QemuState state)
>          pause_all_vcpus();
>          qemu_state_set(state);
>          vm_state_notify(0, state);
> +        if (state == QSTATE_INTERROR || state == QSTATE_SHUTDOWN) {
> +            /* system_reset is required by 'cont' */
> +            system_reset_required = 1;
> +        }
>          qemu_aio_flush();
>          bdrv_flush_all();
>          monitor_protocol_event(QEVENT_STOP, NULL);
> diff --git a/monitor.c b/monitor.c
> index 3fa2cf7..f1cb5af 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -1312,7 +1312,14 @@ static int do_cont(Monitor *mon, const QDict *qdict, QObject **ret_data)
>      if (qemu_state_get() == QSTATE_INMIGRATE) {
>          qerror_report(QERR_MIGRATION_EXPECTED);
>          return -1;
> +    } else if (qemu_state_get() == QSTATE_INTERROR ||
> +               qemu_state_get() == QSTATE_SHUTDOWN) {
> +        if (system_reset_required) {
> +            qerror_report(QERR_RESET_REQUIRED);
> +            return -1;
> +        }

Why not just enter a proper state, likely QSTATE_PAUSED, when resetting
over INTERROR or SHUTDOWN? Would save you system_reset_required and make
the state machine simpler.

Jan

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