From 512d3c807177b5cfff6b5a4925d71ae1b5521093 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Wed, 5 Apr 2017 12:32:37 +0100 Subject: cpus: introduce cpu_update_icount helper MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 --- cpus.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) (limited to 'cpus.c') diff --git a/cpus.c b/cpus.c index 0ecb0b87f0..a5125d7167 100644 --- a/cpus.c +++ b/cpus.c @@ -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; -- cgit v1.2.1