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-rw-r--r--virt/kvm/arm/arch_timer.c75
1 files changed, 51 insertions, 24 deletions
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 7f4f12d48a1a..20e56c420632 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -202,7 +202,27 @@ static enum hrtimer_restart kvm_bg_timer_expire(struct hrtimer *hrt)
static enum hrtimer_restart kvm_phys_timer_expire(struct hrtimer *hrt)
{
- WARN(1, "Timer only used to ensure guest exit - unexpected event.");
+ struct arch_timer_context *ptimer;
+ struct arch_timer_cpu *timer;
+ struct kvm_vcpu *vcpu;
+ u64 ns;
+
+ timer = container_of(hrt, struct arch_timer_cpu, phys_timer);
+ vcpu = container_of(timer, struct kvm_vcpu, arch.timer_cpu);
+ ptimer = vcpu_ptimer(vcpu);
+
+ /*
+ * Check that the timer has really expired from the guest's
+ * PoV (NTP on the host may have forced it to expire
+ * early). If not ready, schedule for a later time.
+ */
+ ns = kvm_timer_compute_delta(ptimer);
+ if (unlikely(ns)) {
+ hrtimer_forward_now(hrt, ns_to_ktime(ns));
+ return HRTIMER_RESTART;
+ }
+
+ kvm_timer_update_irq(vcpu, true, ptimer);
return HRTIMER_NORESTART;
}
@@ -256,24 +276,28 @@ static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level,
}
/* Schedule the background timer for the emulated timer. */
-static void phys_timer_emulate(struct kvm_vcpu *vcpu,
- struct arch_timer_context *timer_ctx)
+static void phys_timer_emulate(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+ struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
- if (kvm_timer_should_fire(timer_ctx))
- return;
-
- if (!kvm_timer_irq_can_fire(timer_ctx))
+ /*
+ * If the timer can fire now we have just raised the IRQ line and we
+ * don't need to have a soft timer scheduled for the future. If the
+ * timer cannot fire at all, then we also don't need a soft timer.
+ */
+ if (kvm_timer_should_fire(ptimer) || !kvm_timer_irq_can_fire(ptimer)) {
+ soft_timer_cancel(&timer->phys_timer, NULL);
return;
+ }
- /* The timer has not yet expired, schedule a background timer */
- soft_timer_start(&timer->phys_timer, kvm_timer_compute_delta(timer_ctx));
+ soft_timer_start(&timer->phys_timer, kvm_timer_compute_delta(ptimer));
}
/*
- * Check if there was a change in the timer state (should we raise or lower
- * the line level to the GIC).
+ * Check if there was a change in the timer state, so that we should either
+ * raise or lower the line level to the GIC or schedule a background timer to
+ * emulate the physical timer.
*/
static void kvm_timer_update_state(struct kvm_vcpu *vcpu)
{
@@ -295,6 +319,8 @@ static void kvm_timer_update_state(struct kvm_vcpu *vcpu)
if (kvm_timer_should_fire(ptimer) != ptimer->irq.level)
kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer);
+
+ phys_timer_emulate(vcpu);
}
static void vtimer_save_state(struct kvm_vcpu *vcpu)
@@ -441,6 +467,9 @@ void kvm_timer_vcpu_load(struct kvm_vcpu *vcpu)
if (has_vhe())
disable_el1_phys_timer_access();
+
+ /* Set the background timer for the physical timer emulation. */
+ phys_timer_emulate(vcpu);
}
bool kvm_timer_should_notify_user(struct kvm_vcpu *vcpu)
@@ -476,12 +505,6 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
if (unlikely(!timer->enabled))
return;
-
- if (kvm_timer_should_fire(ptimer) != ptimer->irq.level)
- kvm_timer_update_irq(vcpu, !ptimer->irq.level, ptimer);
-
- /* Set the background timer for the physical timer emulation. */
- phys_timer_emulate(vcpu, vcpu_ptimer(vcpu));
}
void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
@@ -497,6 +520,17 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
vtimer_save_state(vcpu);
/*
+ * Cancel the physical timer emulation, because the only case where we
+ * need it after a vcpu_put is in the context of a sleeping VCPU, and
+ * in that case we already factor in the deadline for the physical
+ * timer when scheduling the bg_timer.
+ *
+ * In any case, we re-schedule the hrtimer for the physical timer when
+ * coming back to the VCPU thread in kvm_timer_vcpu_load().
+ */
+ soft_timer_cancel(&timer->phys_timer, NULL);
+
+ /*
* The kernel may decide to run userspace after calling vcpu_put, so
* we reset cntvoff to 0 to ensure a consistent read between user
* accesses to the virtual counter and kernel access to the physical
@@ -538,16 +572,9 @@ static void unmask_vtimer_irq(struct kvm_vcpu *vcpu)
*/
void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
{
- struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
struct arch_timer_context *vtimer = vcpu_vtimer(vcpu);
/*
- * This is to cancel the background timer for the physical timer
- * emulation if it is set.
- */
- soft_timer_cancel(&timer->phys_timer, NULL);
-
- /*
* If we entered the guest with the vtimer output asserted we have to
* check if the guest has modified the timer so that we should lower
* the line at this point.