Commit aed807c8 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

tcg: synchronize exit_request and tcg_current_cpu accesses 



Synchronize the remaining pair of accesses in cpu_signal.  These should
be necessary on Windows as well, at least in theory.  Probably
SuspendProcess and ResumeProcess introduce some implicit memory
barrier.

Reviewed-by: default avatarRichard Henderson <rth@twiddle.net>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ab096a75

cpu-exec.c

+1 −1
Original line number Diff line number Diff line
@@ -372,7 +372,7 @@ int cpu_exec(CPUState *cpu) 
    atomic_mb_set(&tcg_current_cpu, cpu);

    rcu_read_lock();



    if (unlikely(exit_request)) {

    if (unlikely(atomic_mb_read(&exit_request))) {

        cpu->exit_request = 1;

    }

cpus.c

+10 −4
Original line number Diff line number Diff line
@@ -663,11 +663,15 @@ static void cpu_handle_guest_debug(CPUState *cpu) 


static void cpu_signal(int sig)

{

    CPUState *cpu = atomic_mb_read(&tcg_current_cpu);

    CPUState *cpu;

    /* Ensure whatever caused the exit has reached the CPU threads before

     * writing exit_request.

     */

    atomic_mb_set(&exit_request, 1);

    cpu = atomic_mb_read(&tcg_current_cpu);

    if (cpu) {

        cpu_exit(cpu);

    }

    exit_request = 1;

}



#ifdef CONFIG_LINUX
@@ -1063,7 +1067,7 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) 
    }



    /* process any pending work */

    exit_request = 1;

    atomic_mb_set(&exit_request, 1);



    while (1) {

        tcg_exec_all();
@@ -1441,7 +1445,9 @@ static void tcg_exec_all(void) 
            break;

        }

    }

    exit_request = 0;



    /* Pairs with smp_wmb in qemu_cpu_kick.  */

    atomic_mb_set(&exit_request, 0);

}



void list_cpus(FILE *f, fprintf_function cpu_fprintf, const char *optarg)