Re: [Qemu-devel] [PULL 26/47] cpu-exec: reset exception_index correctly

[Eduardo Habkost]

On Mon, Dec 15, 2014 at 05:38:10PM +0100, Paolo Bonzini wrote:
> From: Pavel Dovgalyuk <address@hidden>
> 
> Exception index is reset at every entry at every entry into cpu_exec()
> function. This may cause missing the exceptions while replaying them.
> This patch moves exception_index reset to the locations where they are
> processed.
> 
> Signed-off-by: Pavel Dovgalyuk <address@hidden>
> Signed-off-by: Paolo Bonzini <address@hidden>

x86_64-linux-user is broken after applying this patch:

  [qemu/(e511b4d...)|BISECTING]$ ./install/bin/qemu-x86_64 /bin/true
  qemu: uncaught target signal 8 (Floating point exception) - core dumped
  Floating point exception (core dumped)


> ---
>  cpu-exec.c | 3 ++-
>  cpus.c     | 3 +++
>  2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/cpu-exec.c b/cpu-exec.c
> index 8830255..4df9856 100644
> --- a/cpu-exec.c
> +++ b/cpu-exec.c
> @@ -358,7 +358,6 @@ int cpu_exec(CPUArchState *env)
>      }
>  
>      cc->cpu_exec_enter(cpu);
> -    cpu->exception_index = -1;
>  
>      /* Calculate difference between guest clock and host clock.
>       * This delay includes the delay of the last cycle, so
> @@ -378,6 +377,7 @@ int cpu_exec(CPUArchState *env)
>                      if (ret == EXCP_DEBUG) {
>                          cpu_handle_debug_exception(env);
>                      }
> +                    cpu->exception_index = -1;
>                      break;
>                  } else {
>  #if defined(CONFIG_USER_ONLY)
> @@ -388,6 +388,7 @@ int cpu_exec(CPUArchState *env)
>                      cc->do_interrupt(cpu);
>  #endif
>                      ret = cpu->exception_index;
> +                    cpu->exception_index = -1;
>                      break;
>  #else
>                      cc->do_interrupt(cpu);
> diff --git a/cpus.c b/cpus.c
> index 0c33458..91119bb 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -934,6 +934,7 @@ static void *qemu_kvm_cpu_thread_fn(void *arg)
>      qemu_mutex_lock(&qemu_global_mutex);
>      qemu_thread_get_self(cpu->thread);
>      cpu->thread_id = qemu_get_thread_id();
> +    cpu->exception_index = -1;
>      current_cpu = cpu;
>  
>      r = kvm_init_vcpu(cpu);
> @@ -974,6 +975,7 @@ static void *qemu_dummy_cpu_thread_fn(void *arg)
>      qemu_mutex_lock_iothread();
>      qemu_thread_get_self(cpu->thread);
>      cpu->thread_id = qemu_get_thread_id();
> +    cpu->exception_index = -1;
>  
>      sigemptyset(&waitset);
>      sigaddset(&waitset, SIG_IPI);
> @@ -1016,6 +1018,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
>      CPU_FOREACH(cpu) {
>          cpu->thread_id = qemu_get_thread_id();
>          cpu->created = true;
> +        cpu->exception_index = -1;
>      }
>      qemu_cond_signal(&qemu_cpu_cond);
>  
> -- 
> 1.8.3.1
> 
> 
> 

-- 
Eduardo