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-rw-r--r--virt/kvm/arm/arch_timer.c49
1 files changed, 39 insertions, 10 deletions
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index ea6064696..a7b9022b5 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -86,6 +86,8 @@ static void kvm_timer_inject_irq_work(struct work_struct *work)
vcpu = container_of(work, struct kvm_vcpu, arch.timer_cpu.expired);
vcpu->arch.timer_cpu.armed = false;
+ WARN_ON(!kvm_timer_should_fire(vcpu));
+
/*
* If the vcpu is blocked we want to wake it up so that it will see
* the timer has expired when entering the guest.
@@ -93,10 +95,46 @@ static void kvm_timer_inject_irq_work(struct work_struct *work)
kvm_vcpu_kick(vcpu);
}
+static u64 kvm_timer_compute_delta(struct kvm_vcpu *vcpu)
+{
+ cycle_t cval, now;
+
+ cval = vcpu->arch.timer_cpu.cntv_cval;
+ now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
+
+ if (now < cval) {
+ u64 ns;
+
+ ns = cyclecounter_cyc2ns(timecounter->cc,
+ cval - now,
+ timecounter->mask,
+ &timecounter->frac);
+ return ns;
+ }
+
+ return 0;
+}
+
static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
{
struct arch_timer_cpu *timer;
+ struct kvm_vcpu *vcpu;
+ u64 ns;
+
timer = container_of(hrt, struct arch_timer_cpu, timer);
+ vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu);
+
+ /*
+ * Check that the timer has really expired from the guest's
+ * PoV (NTP on the host may have forced it to expire
+ * early). If we should have slept longer, restart it.
+ */
+ ns = kvm_timer_compute_delta(vcpu);
+ if (unlikely(ns)) {
+ hrtimer_forward_now(hrt, ns_to_ktime(ns));
+ return HRTIMER_RESTART;
+ }
+
queue_work(wqueue, &timer->expired);
return HRTIMER_NORESTART;
}
@@ -170,8 +208,6 @@ static int kvm_timer_update_state(struct kvm_vcpu *vcpu)
void kvm_timer_schedule(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
- u64 ns;
- cycle_t cval, now;
BUG_ON(timer_is_armed(timer));
@@ -191,14 +227,7 @@ void kvm_timer_schedule(struct kvm_vcpu *vcpu)
return;
/* The timer has not yet expired, schedule a background timer */
- cval = timer->cntv_cval;
- now = kvm_phys_timer_read() - vcpu->kvm->arch.timer.cntvoff;
-
- ns = cyclecounter_cyc2ns(timecounter->cc,
- cval - now,
- timecounter->mask,
- &timecounter->frac);
- timer_arm(timer, ns);
+ timer_arm(timer, kvm_timer_compute_delta(vcpu));
}
void kvm_timer_unschedule(struct kvm_vcpu *vcpu)