diff options
Diffstat (limited to 'target/arm/cpu.c')
| -rw-r--r-- | target/arm/cpu.c | 65 |
1 files changed, 57 insertions, 8 deletions
diff --git a/target/arm/cpu.c b/target/arm/cpu.c index dd51adac05..d62fd5fdc6 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -976,6 +976,10 @@ static void arm_cpu_initfn(Object *obj) } } +static Property arm_cpu_gt_cntfrq_property = + DEFINE_PROP_UINT64("cntfrq", ARMCPU, gt_cntfrq_hz, + NANOSECONDS_PER_SECOND / GTIMER_SCALE); + static Property arm_cpu_reset_cbar_property = DEFINE_PROP_UINT64("reset-cbar", ARMCPU, reset_cbar, 0); @@ -1055,6 +1059,30 @@ static void arm_set_init_svtor(Object *obj, Visitor *v, const char *name, visit_type_uint32(v, name, &cpu->init_svtor, errp); } +unsigned int gt_cntfrq_period_ns(ARMCPU *cpu) +{ + /* + * The exact approach to calculating guest ticks is: + * + * muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL), cpu->gt_cntfrq_hz, + * NANOSECONDS_PER_SECOND); + * + * We don't do that. Rather we intentionally use integer division + * truncation below and in the caller for the conversion of host monotonic + * time to guest ticks to provide the exact inverse for the semantics of + * the QEMUTimer scale factor. QEMUTimer's scale facter is an integer, so + * it loses precision when representing frequencies where + * `(NANOSECONDS_PER_SECOND % cpu->gt_cntfrq) > 0` holds. Failing to + * provide an exact inverse leads to scheduling timers with negative + * periods, which in turn leads to sticky behaviour in the guest. + * + * Finally, CNTFRQ is effectively capped at 1GHz to ensure our scale factor + * cannot become zero. + */ + return NANOSECONDS_PER_SECOND > cpu->gt_cntfrq_hz ? + NANOSECONDS_PER_SECOND / cpu->gt_cntfrq_hz : 1; +} + void arm_cpu_post_init(Object *obj) { ARMCPU *cpu = ARM_CPU(obj); @@ -1172,6 +1200,11 @@ void arm_cpu_post_init(Object *obj) qdev_property_add_static(DEVICE(obj), &arm_cpu_cfgend_property, &error_abort); + + if (arm_feature(&cpu->env, ARM_FEATURE_GENERIC_TIMER)) { + qdev_property_add_static(DEVICE(cpu), &arm_cpu_gt_cntfrq_property, + &error_abort); + } } static void arm_cpu_finalizefn(Object *obj) @@ -1251,14 +1284,30 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp) } } - cpu->gt_timer[GTIMER_PHYS] = timer_new(QEMU_CLOCK_VIRTUAL, GTIMER_SCALE, - arm_gt_ptimer_cb, cpu); - cpu->gt_timer[GTIMER_VIRT] = timer_new(QEMU_CLOCK_VIRTUAL, GTIMER_SCALE, - arm_gt_vtimer_cb, cpu); - cpu->gt_timer[GTIMER_HYP] = timer_new(QEMU_CLOCK_VIRTUAL, GTIMER_SCALE, - arm_gt_htimer_cb, cpu); - cpu->gt_timer[GTIMER_SEC] = timer_new(QEMU_CLOCK_VIRTUAL, GTIMER_SCALE, - arm_gt_stimer_cb, cpu); + + { + uint64_t scale; + + if (arm_feature(env, ARM_FEATURE_GENERIC_TIMER)) { + if (!cpu->gt_cntfrq_hz) { + error_setg(errp, "Invalid CNTFRQ: %"PRId64"Hz", + cpu->gt_cntfrq_hz); + return; + } + scale = gt_cntfrq_period_ns(cpu); + } else { + scale = GTIMER_SCALE; + } + + cpu->gt_timer[GTIMER_PHYS] = timer_new(QEMU_CLOCK_VIRTUAL, scale, + arm_gt_ptimer_cb, cpu); + cpu->gt_timer[GTIMER_VIRT] = timer_new(QEMU_CLOCK_VIRTUAL, scale, + arm_gt_vtimer_cb, cpu); + cpu->gt_timer[GTIMER_HYP] = timer_new(QEMU_CLOCK_VIRTUAL, scale, + arm_gt_htimer_cb, cpu); + cpu->gt_timer[GTIMER_SEC] = timer_new(QEMU_CLOCK_VIRTUAL, scale, + arm_gt_stimer_cb, cpu); + } #endif cpu_exec_realizefn(cs, &local_err); |