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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: Alex Bennée <alex.bennee@linaro.org>
This commit is contained in:
Alex Bennée 2017-03-29 16:46:59 +01:00
parent 243c5f77f6
commit 0524838225
1 changed files with 46 additions and 23 deletions
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69
cpus.c
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@ -1179,6 +1179,46 @@ static void handle_icount_deadline(void)
}
}
static void prepare_icount_for_run(CPUState *cpu)
{
if (use_icount) {
int64_t count;
int decr;
/* 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;
}
}
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);
/* 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;
@ -1189,20 +1229,6 @@ static int tcg_cpu_exec(CPUState *cpu)
#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;
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);
@ -1211,15 +1237,6 @@ static int tcg_cpu_exec(CPUState *cpu)
#ifdef CONFIG_PROFILER
tcg_time += profile_getclock() - ti;
#endif
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;
cpu->icount_extra = 0;
replay_account_executed_instructions();
}
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;