@@ -2270,7 +2270,7 @@ static enum hrtimer_restart apic_timer_fn(struct hrtimer *data)
return HRTIMER_NORESTART;
}
-int kvm_create_lapic(struct kvm_vcpu *vcpu, u32 timer_advance_ns)
+int kvm_create_lapic(struct kvm_vcpu *vcpu, int timer_advance_ns)
{
struct kvm_lapic *apic;
@@ -2294,7 +2294,14 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu, u32 timer_advance_ns)
hrtimer_init(&apic->lapic_timer.timer, CLOCK_MONOTONIC,
HRTIMER_MODE_ABS_PINNED);
apic->lapic_timer.timer.function = apic_timer_fn;
- apic->lapic_timer.timer_advance_ns = timer_advance_ns;
+ if (timer_advance_ns == -1) {
+ apic->lapic_timer.timer_advance_ns = 1000;
+ apic->lapic_timer.timer_advance_adjust_done = false;
+ } else {
+ apic->lapic_timer.timer_advance_ns = timer_advance_ns;
+ apic->lapic_timer.timer_advance_adjust_done = true;
+ }
+
/*
* APIC is created enabled. This will prevent kvm_lapic_set_base from
@@ -64,7 +64,7 @@ struct kvm_lapic {
struct dest_map;
-int kvm_create_lapic(struct kvm_vcpu *vcpu, u32 timer_advance_ns);
+int kvm_create_lapic(struct kvm_vcpu *vcpu, int timer_advance_ns);
void kvm_free_lapic(struct kvm_vcpu *vcpu);
int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu);
@@ -136,8 +136,13 @@ EXPORT_SYMBOL_GPL(kvm_default_tsc_scaling_ratio);
static u32 __read_mostly tsc_tolerance_ppm = 250;
module_param(tsc_tolerance_ppm, uint, S_IRUGO | S_IWUSR);
-/* lapic timer advance (tscdeadline mode only) in nanoseconds */
-static u32 __read_mostly lapic_timer_advance_ns = 1000;
+/*
+ * lapic timer advance (tscdeadline mode only) in nanoseconds. '-1' enables
+ * adaptive tuning starting from default advancment of 1000ns. '0' disables
+ * advancement entirely. Any other value is used as-is and disables adaptive
+ * tuning, i.e. allows priveleged userspace to set an exact advancement time.
+ */
+static int __read_mostly lapic_timer_advance_ns = -1;
module_param(lapic_timer_advance_ns, uint, S_IRUGO | S_IWUSR);
static bool __read_mostly vector_hashing = true;