fred.kon...@greensocs.com writes:
> From: KONRAD Frederic <fred.kon...@greensocs.com>
>
> This removes exit_request global and adds a variable in CPUState for this.
> Only the flag for the first cpu is used for the moment as we are still with
> one
> TCG thread.
>
> Signed-off-by: KONRAD Frederic <fred.kon...@greensocs.com>
> ---
> cpu-exec.c | 15 ---------------
> cpus.c | 17 ++++++++++++++---
> 2 files changed, 14 insertions(+), 18 deletions(-)
>
> diff --git a/cpu-exec.c b/cpu-exec.c
> index 5d9b518..0644383 100644
> --- a/cpu-exec.c
> +++ b/cpu-exec.c
> @@ -364,8 +364,6 @@ static void cpu_handle_debug_exception(CPUArchState *env)
>
> /* main execution loop */
>
> -volatile sig_atomic_t exit_request;
> -
> int cpu_exec(CPUArchState *env)
> {
> CPUState *cpu = ENV_GET_CPU(env);
> @@ -394,20 +392,8 @@ int cpu_exec(CPUArchState *env)
>
> current_cpu = cpu;
>
> - /* As long as current_cpu is null, up to the assignment just above,
> - * requests by other threads to exit the execution loop are expected to
> - * be issued using the exit_request global. We must make sure that our
> - * evaluation of the global value is performed past the current_cpu
> - * value transition point, which requires a memory barrier as well as
> - * an instruction scheduling constraint on modern architectures. */
> - smp_mb();
> -
> rcu_read_lock();
>
> - if (unlikely(exit_request)) {
> - cpu->exit_request = 1;
> - }
> -
> cc->cpu_exec_enter(cpu);
>
> /* Calculate difference between guest clock and host clock.
> @@ -496,7 +482,6 @@ int cpu_exec(CPUArchState *env)
> }
> }
> if (unlikely(cpu->exit_request)) {
> - cpu->exit_request = 0;
> cpu->exception_index = EXCP_INTERRUPT;
> cpu_loop_exit(cpu);
> }
> diff --git a/cpus.c b/cpus.c
> index 23c316c..2541c56 100644
> --- a/cpus.c
> +++ b/cpus.c
> @@ -137,6 +137,8 @@ typedef struct TimersState {
> } TimersState;
>
> static TimersState timers_state;
> +/* CPU associated to this thread. */
> +static __thread CPUState *tcg_thread_cpu;
>
> int64_t cpu_get_icount_raw(void)
> {
> @@ -661,12 +663,18 @@ static void cpu_handle_guest_debug(CPUState *cpu)
> cpu->stopped = true;
> }
>
> +/**
> + * cpu_signal
> + * Signal handler when using TCG.
> + */
> static void cpu_signal(int sig)
> {
> if (current_cpu) {
> cpu_exit(current_cpu);
> }
> - exit_request = 1;
> +
> + /* FIXME: We might want to check if the cpu is running? */
> + tcg_thread_cpu->exit_request = true;
I guess the potential problem is race conditions here? What happens if
the cpu is signalled by two different threads for two different reasons?
> }
>
> #ifdef CONFIG_LINUX
> @@ -1031,6 +1039,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg)
> {
> CPUState *cpu = arg;
>
> + tcg_thread_cpu = cpu;
> qemu_tcg_init_cpu_signals();
> qemu_thread_get_self(cpu->thread);
>
> @@ -1393,7 +1402,8 @@ static void tcg_exec_all(void)
> if (next_cpu == NULL) {
> next_cpu = first_cpu;
> }
> - for (; next_cpu != NULL && !exit_request; next_cpu = CPU_NEXT(next_cpu))
> {
> + for (; next_cpu != NULL && !first_cpu->exit_request;
> + next_cpu = CPU_NEXT(next_cpu)) {
> CPUState *cpu = next_cpu;
> CPUArchState *env = cpu->env_ptr;
>
> @@ -1410,7 +1420,8 @@ static void tcg_exec_all(void)
> break;
> }
> }
> - exit_request = 0;
> +
> + first_cpu->exit_request = 0;
> }
>
> void list_cpus(FILE *f, fprintf_function cpu_fprintf, const char *optarg)
--
Alex Bennée
