diff options
Diffstat (limited to 'cpus.c')
| -rw-r--r-- | cpus.c | 113 |
1 files changed, 81 insertions, 32 deletions
diff --git a/cpus.c b/cpus.c index 167d9615e1..740b8dc3f8 100644 --- a/cpus.c +++ b/cpus.c @@ -202,14 +202,14 @@ void qemu_tcg_configure(QemuOpts *opts, Error **errp) } else if (use_icount) { error_setg(errp, "No MTTCG when icount is enabled"); } else { -#ifndef TARGET_SUPPORT_MTTCG +#ifndef TARGET_SUPPORTS_MTTCG error_report("Guest not yet converted to MTTCG - " "you may get unexpected results"); #endif if (!check_tcg_memory_orders_compatible()) { error_report("Guest expects a stronger memory ordering " "than the host provides"); - error_printf("This may cause strange/hard to debug errors"); + error_printf("This may cause strange/hard to debug errors\n"); } mttcg_enabled = true; } @@ -223,20 +223,51 @@ void qemu_tcg_configure(QemuOpts *opts, Error **errp) } } +/* The current number of executed instructions is based on what we + * originally budgeted minus the current state of the decrementing + * icount counters in extra/u16.low. + */ +static int64_t cpu_get_icount_executed(CPUState *cpu) +{ + return cpu->icount_budget - (cpu->icount_decr.u16.low + cpu->icount_extra); +} + +/* + * Update the global shared timer_state.qemu_icount to take into + * account executed instructions. This is done by the TCG vCPU + * thread so the main-loop can see time has moved forward. + */ +void cpu_update_icount(CPUState *cpu) +{ + int64_t executed = cpu_get_icount_executed(cpu); + cpu->icount_budget -= executed; + +#ifdef CONFIG_ATOMIC64 + atomic_set__nocheck(&timers_state.qemu_icount, + atomic_read__nocheck(&timers_state.qemu_icount) + + executed); +#else /* FIXME: we need 64bit atomics to do this safely */ + timers_state.qemu_icount += executed; +#endif +} + int64_t cpu_get_icount_raw(void) { - int64_t icount; CPUState *cpu = current_cpu; - icount = timers_state.qemu_icount; - if (cpu) { + if (cpu && cpu->running) { if (!cpu->can_do_io) { fprintf(stderr, "Bad icount read\n"); exit(1); } - icount -= (cpu->icount_decr.u16.low + cpu->icount_extra); + /* Take into account what has run */ + cpu_update_icount(cpu); } - return icount; +#ifdef CONFIG_ATOMIC64 + return atomic_read__nocheck(&timers_state.qemu_icount); +#else /* FIXME: we need 64bit atomics to do this safely */ + return timers_state.qemu_icount; +#endif } /* Return the virtual CPU time, based on the instruction counter. */ @@ -1179,6 +1210,41 @@ static void handle_icount_deadline(void) } } +static void prepare_icount_for_run(CPUState *cpu) +{ + if (use_icount) { + int insns_left; + + /* 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); + + cpu->icount_budget = tcg_get_icount_limit(); + insns_left = MIN(0xffff, cpu->icount_budget); + cpu->icount_decr.u16.low = insns_left; + cpu->icount_extra = cpu->icount_budget - insns_left; + } +} + +static void process_icount_data(CPUState *cpu) +{ + if (use_icount) { + /* Account for executed instructions */ + cpu_update_icount(cpu); + + /* Reset the counters */ + cpu->icount_decr.u16.low = 0; + cpu->icount_extra = 0; + cpu->icount_budget = 0; + + replay_account_executed_instructions(); + } +} + + static int tcg_cpu_exec(CPUState *cpu) { int ret; @@ -1189,20 +1255,6 @@ 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 +1263,6 @@ 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 +1349,13 @@ 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; @@ -1392,6 +1441,8 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) { CPUState *cpu = arg; + g_assert(!use_icount); + rcu_register_thread(); qemu_mutex_lock_iothread(); @@ -1434,8 +1485,6 @@ static void *qemu_tcg_cpu_thread_fn(void *arg) } } - handle_icount_deadline(); - atomic_mb_set(&cpu->exit_request, 0); qemu_tcg_wait_io_event(cpu); } |