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>
diff --git a/cpus.c b/cpus.c
index 0ecb0b8..a5125d7 100644
--- a/cpus.c
+++ b/cpus.c
@@ -232,12 +232,31 @@
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 @@
{
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;