Re: [Qemu-devel] [patch 09/11] qemu: handle vmstop from cpu context

[Anthony Liguori]

Marcelo Tosatti wrote:
> There are certain cases where cpu context requests a vm stop, such as
> -ENOSPC handling.
>
> IMO its simpler to handle vmstop only through the iothread.
>
> Note there is change in behaviour: now the cpu thread which requested vm_stop
> will actually only stop when it exits back to cpu_main_loop. It might cause
> further damage in between vmstop and cpu_main_loop.
>   

Missing SoB line.

Regards,

Anthony Liguori

> Index: trunk/vl.c
> ===================================================================
> --- trunk.orig/vl.c
> +++ trunk/vl.c
> @@ -3551,7 +3551,22 @@ void vm_start(void)
>      }
>  }
>  
> -void vm_stop(int reason)
> +static int vmstop_requested;
> +
> +static int qemu_vmstop_requested(void)
> +{
> +    int r = vmstop_requested;
> +    vmstop_requested = 0;
> +    return r;
> +}
> +
> +static void qemu_system_vmstop_request(int reason)
> +{
> +    vmstop_requested = reason;
> +    main_loop_break();
> +}
> +
> +static void __vm_stop(int reason)
>  {
>      if (vm_running) {
>          cpu_disable_ticks();
> @@ -3561,6 +3576,21 @@ void vm_stop(int reason)
>      }
>  }
>  
> +void vm_stop(int reason)
> +{
> +    QemuThread me;
> +    qemu_thread_self(&me);
> +
> +    if (!qemu_thread_equal(&me, &io_thread)) {
> +        qemu_system_vmstop_request(reason);
> +        /* make sure we can't return to cpu_exec */
> +        if (cpu_single_env)
> +            cpu_single_env->stop = 1;
> +        return;
> +    }
> +    __vm_stop(reason);
> +}
> +
>  /* reset/shutdown handler */
>  
>  typedef struct QEMUResetEntry {
> @@ -3758,6 +3788,8 @@ static int cpu_can_run(CPUState *env)
>          return 0;
>      if (reset_requested)
>          return 0;
> +    if (vmstop_requested)
> +        return 0;
>      return 1;
>  }
>  
> @@ -4204,6 +4236,8 @@ static void qemu_init_state(void)
>  
>  static void main_loop(void)
>  {
> +    int r;
> +
>      qemu_thread_self(&io_thread);
>      setup_iothread_fd();
>  
> @@ -4220,12 +4254,14 @@ static void main_loop(void)
>                  no_shutdown = 0;
>              else
>                      break;
> -        } else if (qemu_powerdown_requested())
> +        } else if (qemu_powerdown_requested()) {
>              qemu_system_powerdown();
> -        else if (qemu_reset_requested()) {
> +        } else if (qemu_reset_requested()) {
>              pause_all_vcpus();
>              qemu_system_reset();
>              resume_all_vcpus();
> +        } else if ((r = qemu_vmstop_requested())) {
> +            vm_stop(r);
>          }
>      }
>  }
>
>   


--
Regards,

Anthony Liguori