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| author | Alex Bennée | 2017-04-05 13:32:37 +0200 |
|---|---|---|
| committer | Alex Bennée | 2017-04-10 11:23:38 +0200 |
| commit | 512d3c807177b5cfff6b5a4925d71ae1b5521093 (patch) | |
| tree | e28725655ab542d8a7e0c5eab665c009a0ea6727 | |
| parent | cpus: don't credit executed instructions before they have run (diff) | |
| download | qemu-512d3c807177b5cfff6b5a4925d71ae1b5521093.tar.gz qemu-512d3c807177b5cfff6b5a4925d71ae1b5521093.tar.xz qemu-512d3c807177b5cfff6b5a4925d71ae1b5521093.zip | |
cpus: introduce cpu_update_icount helper
By holding off updates to timer_state.qemu_icount we can run into
trouble when the non-vCPU thread needs to know the time. This helper
ensures we atomically update timers_state.qemu_icount based on what
has been currently executed.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
| -rw-r--r-- | cpus.c | 23 | ||||
| -rw-r--r-- | include/qemu/timer.h | 1 |
2 files changed, 22 insertions, 2 deletions
@@ -232,12 +232,31 @@ 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; + icount = atomic_read(&timers_state.qemu_icount); if (cpu && cpu->running) { if (!cpu->can_do_io) { fprintf(stderr, "Bad icount read\n"); @@ -1220,7 +1239,7 @@ static void process_icount_data(CPUState *cpu) { if (use_icount) { /* Account for executed instructions */ - timers_state.qemu_icount += cpu_get_icount_executed(cpu); + cpu_update_icount(cpu); /* Reset the counters */ cpu->icount_decr.u16.low = 0; diff --git a/include/qemu/timer.h b/include/qemu/timer.h index e1742f2f3d..8a1eb74839 100644 --- a/include/qemu/timer.h +++ b/include/qemu/timer.h @@ -869,6 +869,7 @@ int64_t cpu_get_icount_raw(void); int64_t cpu_get_icount(void); int64_t cpu_get_clock(void); int64_t cpu_icount_to_ns(int64_t icount); +void cpu_update_icount(CPUState *cpu); /*******************************************/ /* host CPU ticks (if available) */ |