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cpu-exec: unify icount_decr and tcg_exit_req

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The icount interrupt flag and tcg_exit_req serve almost the same
purpose, let's make them completely the same.

The former TB_EXIT_REQUESTED and TB_EXIT_ICOUNT_EXPIRED cases are
unified, since we can distinguish them from the value of the
interrupt flag.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2017-01-27 11:25:33 +01:00
parent a1cf5fac2b
commit 1aab16c28a
7 changed files with 71 additions and 85 deletions
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70
cpu-exec.c
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@ -185,12 +185,6 @@ static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock *itb)
cc->set_pc(cpu, last_tb->pc);
}
}
if (tb_exit == TB_EXIT_REQUESTED) {
/* We were asked to stop executing TBs (probably a pending
* interrupt. We've now stopped, so clear the flag.
*/
atomic_set(&cpu->tcg_exit_req, 0);
}
return ret;
}
@ -537,6 +531,7 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
SyncClocks *sc)
{
uintptr_t ret;
int32_t insns_left;
if (unlikely(atomic_read(&cpu->exit_request))) {
return;
@ -546,8 +541,15 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
ret = cpu_tb_exec(cpu, tb);
tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK);
*tb_exit = ret & TB_EXIT_MASK;
switch (*tb_exit) {
case TB_EXIT_REQUESTED:
if (*tb_exit != TB_EXIT_REQUESTED) {
*last_tb = tb;
return;
}
*last_tb = NULL;
insns_left = atomic_read(&cpu->icount_decr.u32);
atomic_set(&cpu->icount_decr.u16.high, 0);
if (insns_left < 0) {
/* Something asked us to stop executing
* chained TBs; just continue round the main
* loop. Whatever requested the exit will also
@ -559,38 +561,30 @@ static inline void cpu_loop_exec_tb(CPUState *cpu, TranslationBlock *tb,
* or cpu->interrupt_request.
*/
smp_mb();
*last_tb = NULL;
break;
case TB_EXIT_ICOUNT_EXPIRED:
{
/* Instruction counter expired. */
#ifdef CONFIG_USER_ONLY
abort();
#else
int insns_left = cpu->icount_decr.u32;
*last_tb = NULL;
if (cpu->icount_extra && insns_left >= 0) {
/* Refill decrementer and continue execution. */
cpu->icount_extra += insns_left;
insns_left = MIN(0xffff, cpu->icount_extra);
cpu->icount_extra -= insns_left;
cpu->icount_decr.u16.low = insns_left;
} else {
if (insns_left > 0) {
/* Execute remaining instructions. */
cpu_exec_nocache(cpu, insns_left, tb, false);
align_clocks(sc, cpu);
}
cpu->exception_index = EXCP_INTERRUPT;
cpu_loop_exit(cpu);
return;
}
/* Instruction counter expired. */
assert(use_icount);
#ifndef CONFIG_USER_ONLY
if (cpu->icount_extra) {
/* Refill decrementer and continue execution. */
cpu->icount_extra += insns_left;
insns_left = MIN(0xffff, cpu->icount_extra);
cpu->icount_extra -= insns_left;
cpu->icount_decr.u16.low = insns_left;
} else {
/* Execute any remaining instructions, then let the main loop
* handle the next event.
*/
if (insns_left > 0) {
cpu_exec_nocache(cpu, insns_left, tb, false);
align_clocks(sc, cpu);
}
break;
cpu->exception_index = EXCP_INTERRUPT;
cpu_loop_exit(cpu);
}
#endif
}
default:
*last_tb = tb;
break;
}
}
/* main execution loop */