From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marcelo Tosatti <mtosatti@redhat.com>
Subject: Re: [PATCH 1/2] Complete cpu initialization before signaling main
	thread.
Date: Tue, 13 Oct 2009 15:19:08 -0300
Message-ID: <20091013181908.GA14313@amt.cnet>
References: <1255436240-994-1-git-send-email-gleb@redhat.com>
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Cc: kvm@vger.kernel.org
To: Gleb Natapov <gleb@redhat.com>
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On Tue, Oct 13, 2009 at 02:17:19PM +0200, Gleb Natapov wrote:
> Otherwise some cpus may start executing code before others
> are fully initialized.
> 
> Signed-off-by: Gleb Natapov <gleb@redhat.com>
> ---
>  qemu-kvm.c |   26 ++++++++++++--------------
>  1 files changed, 12 insertions(+), 14 deletions(-)
> 
> diff --git a/qemu-kvm.c b/qemu-kvm.c
> index 62ca050..3765818 100644
> --- a/qemu-kvm.c
> +++ b/qemu-kvm.c
> @@ -1954,18 +1954,6 @@ static void process_irqchip_events(CPUState *env)
>  
>  static int kvm_main_loop_cpu(CPUState *env)
>  {
> -    setup_kernel_sigmask(env);
> -
> -    pthread_mutex_lock(&qemu_mutex);
> -
> -    kvm_arch_init_vcpu(env);
> -#ifdef TARGET_I386
> -    kvm_tpr_vcpu_start(env);
> -#endif
> -
> -    cpu_single_env = env;
> -    kvm_arch_load_regs(env);
> -
>      while (1) {
>          int run_cpu = !is_cpu_stopped(env);
>          if (run_cpu && !kvm_irqchip_in_kernel(kvm_context)) {
> @@ -2003,15 +1991,25 @@ static void *ap_main_loop(void *_env)
>          on_vcpu(env, kvm_arch_do_ioperm, data);
>  #endif
>  
> -    /* signal VCPU creation */
> +    setup_kernel_sigmask(env);
> +
>      pthread_mutex_lock(&qemu_mutex);
> +    cpu_single_env = env;
> +
> +    kvm_arch_init_vcpu(env);
> +#ifdef TARGET_I386
> +    kvm_tpr_vcpu_start(env);
> +#endif
> +
> +    kvm_arch_load_regs(env);
> +
> +    /* signal VCPU creation */
>      current_env->created = 1;
>      pthread_cond_signal(&qemu_vcpu_cond);
>  
>      /* and wait for machine initialization */
>      while (!qemu_system_ready)
>          qemu_cond_wait(&qemu_system_cond);
> -    pthread_mutex_unlock(&qemu_mutex);

You don't set cpu_single_env after reacquiring 
qemu_mutex here (via qemu_cond_wait).