Commit 05248382 authored by Alex Bennée's avatar Alex Bennée
Browse files

cpus: move icount preparation out of tcg_exec_cpu 



As icount is only supported for single-threaded execution due to the
requirement for determinism let's remove it from the common
tcg_exec_cpu path.

Also remove the additional fiddling which shouldn't be required as the
icount counters should all be rectified as you enter the loop.

Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
parent 243c5f77

cpus.c

+45 −22
Original line number Diff line number Diff line
@@ -1179,47 +1179,64 @@ static void handle_icount_deadline(void) 
    }

}



static int tcg_cpu_exec(CPUState *cpu)

static void prepare_icount_for_run(CPUState *cpu)

{

    int ret;

#ifdef CONFIG_PROFILER

    int64_t ti;

#endif



#ifdef CONFIG_PROFILER

    ti = profile_getclock();

#endif

    if (use_icount) {

        int64_t count;

        int decr;

        timers_state.qemu_icount -= (cpu->icount_decr.u16.low

                                    + cpu->icount_extra);

        cpu->icount_decr.u16.low = 0;

        cpu->icount_extra = 0;



        /* These should always be cleared by process_icount_data after

         * each vCPU execution. However u16.high can be raised

         * asynchronously by cpu_exit/cpu_interrupt/tcg_handle_interrupt

         */

        g_assert(cpu->icount_decr.u16.low == 0);

        g_assert(cpu->icount_extra == 0);





        count = tcg_get_icount_limit();



        timers_state.qemu_icount += count;

        decr = (count > 0xffff) ? 0xffff : count;

        count -= decr;

        cpu->icount_decr.u16.low = decr;

        cpu->icount_extra = count;

    }

    qemu_mutex_unlock_iothread();

    cpu_exec_start(cpu);

    ret = cpu_exec(cpu);

    cpu_exec_end(cpu);

    qemu_mutex_lock_iothread();

#ifdef CONFIG_PROFILER

    tcg_time += profile_getclock() - ti;

#endif

}



static void process_icount_data(CPUState *cpu)

{

    if (use_icount) {

        /* Fold pending instructions back into the

           instruction counter, and clear the interrupt flag.  */

        timers_state.qemu_icount -= (cpu->icount_decr.u16.low

                        + cpu->icount_extra);

        cpu->icount_decr.u32 = 0;



        /* Reset the counters */

        cpu->icount_decr.u16.low = 0;

        cpu->icount_extra = 0;

        replay_account_executed_instructions();

    }

}





static int tcg_cpu_exec(CPUState *cpu)

{

    int ret;

#ifdef CONFIG_PROFILER

    int64_t ti;

#endif



#ifdef CONFIG_PROFILER

    ti = profile_getclock();

#endif

    qemu_mutex_unlock_iothread();

    cpu_exec_start(cpu);

    ret = cpu_exec(cpu);

    cpu_exec_end(cpu);

    qemu_mutex_lock_iothread();

#ifdef CONFIG_PROFILER

    tcg_time += profile_getclock() - ti;

#endif

    return ret;

}
@@ -1306,7 +1323,13 @@ static void *qemu_tcg_rr_cpu_thread_fn(void *arg) 


            if (cpu_can_run(cpu)) {

                int r;



                prepare_icount_for_run(cpu);



                r = tcg_cpu_exec(cpu);



                process_icount_data(cpu);



                if (r == EXCP_DEBUG) {

                    cpu_handle_guest_debug(cpu);

                    break;