Re: [Qemu-devel] [PATCH 2/5] disk_deadlines: add request to resume Virtual Machine

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Sep 08, 2015 at 11:00:25AM +0300, Denis V. Lunev wrote:
> From: Raushaniya Maksudova <rmaksudova@virtuozzo.com>
> 
> In some cases one needs to pause and resume a Virtual Machine from inside
> of Qemu. Currently there are request functions to pause VM (vmstop), but
> there are no respective ones to resume VM.
> 
> Signed-off-by: Raushaniya Maksudova <rmaksudova@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Stefan Hajnoczi <stefanha@redhat.com>
> CC: Kevin Wolf <kwolf@redhat.com>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  include/sysemu/sysemu.h |  1 +
>  stubs/vm-stop.c         |  5 +++++
>  vl.c                    | 18 ++++++++++++++++++
>  3 files changed, 24 insertions(+)

Why can't vm_start() be used?

> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index 44570d1..a382ae1 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -62,6 +62,7 @@ void qemu_system_shutdown_request(void);
>  void qemu_system_powerdown_request(void);
>  void qemu_register_powerdown_notifier(Notifier *notifier);
>  void qemu_system_debug_request(void);
> +void qemu_system_vmstart_request(void);
>  void qemu_system_vmstop_request(RunState reason);
>  void qemu_system_vmstop_request_prepare(void);
>  int qemu_shutdown_requested_get(void);
> diff --git a/stubs/vm-stop.c b/stubs/vm-stop.c
> index 69fd86b..c8e2cdd 100644
> --- a/stubs/vm-stop.c
> +++ b/stubs/vm-stop.c
> @@ -10,3 +10,8 @@ void qemu_system_vmstop_request(RunState state)
>  {
>      abort();
>  }
> +
> +void qemu_system_vmstart_request(void)
> +{
> +    abort();
> +}
> diff --git a/vl.c b/vl.c
> index 584ca88..63f10d3 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -563,6 +563,7 @@ static RunState current_run_state = RUN_STATE_PRELAUNCH;
>  /* We use RUN_STATE_MAX but any invalid value will do */
>  static RunState vmstop_requested = RUN_STATE_MAX;
>  static QemuMutex vmstop_lock;
> +static bool vmstart_requested;
>  
>  typedef struct {
>      RunState from;
> @@ -723,6 +724,19 @@ void qemu_system_vmstop_request(RunState state)
>      qemu_notify_event();
>  }
>  
> +static bool qemu_vmstart_requested(void)
> +{
> +    bool r = vmstart_requested;
> +    vmstart_requested = false;
> +    return r;
> +}
> +
> +void qemu_system_vmstart_request(void)
> +{
> +    vmstart_requested = true;
> +    qemu_notify_event();
> +}
> +
>  void vm_start(void)
>  {
>      RunState requested;
> @@ -1884,6 +1898,10 @@ static bool main_loop_should_exit(void)
>      if (qemu_vmstop_requested(&r)) {
>          vm_stop(r);
>      }
> +    if (qemu_vmstart_requested()) {
> +        vm_start();
> +    }
> +
>      return false;
>  }
>  
> -- 
> 2.1.4
> 
>