1 files changed, 117 insertions, 56 deletions

diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index b9d3a32cbc04..21a0ab2d8919 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -28,6 +28,8 @@
 #include <kvm/arm_vgic.h>
 #include <kvm/arm_arch_timer.h>
 
+#include "trace.h"
+
 static struct timecounter *timecounter;
 static struct workqueue_struct *wqueue;
 static unsigned int host_vtimer_irq;
@@ -59,18 +61,6 @@ static void timer_disarm(struct arch_timer_cpu *timer)
 	}
 }
 
-static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
-{
-	int ret;
-	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
-
-	kvm_vgic_set_phys_irq_active(timer->map, true);
-	ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
-					 timer->map,
-					 timer->irq->level);
-	WARN_ON(ret);
-}
-
 static irqreturn_t kvm_arch_timer_handler(int irq, void *dev_id)
 {
 	struct kvm_vcpu *vcpu = *(struct kvm_vcpu **)dev_id;
@@ -111,14 +101,20 @@ static enum hrtimer_restart kvm_timer_expire(struct hrtimer *hrt)
 	return HRTIMER_NORESTART;
 }
 
+static bool kvm_timer_irq_can_fire(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+	return !(timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) &&
+		(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE);
+}
+
 bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
 {
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 	cycle_t cval, now;
 
-	if ((timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) ||
-	    !(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE) ||
-	    kvm_vgic_get_phys_irq_active(timer->map))
+	if (!kvm_timer_irq_can_fire(vcpu))
 		return false;
 
 	cval = timer->cntv_cval;
@@ -127,12 +123,94 @@ bool kvm_timer_should_fire(struct kvm_vcpu *vcpu)
 	return cval <= now;
 }
 
+static void kvm_timer_update_irq(struct kvm_vcpu *vcpu, bool new_level)
+{
+	int ret;
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+	BUG_ON(!vgic_initialized(vcpu->kvm));
+
+	timer->irq.level = new_level;
+	trace_kvm_timer_update_irq(vcpu->vcpu_id, timer->map->virt_irq,
+				   timer->irq.level);
+	ret = kvm_vgic_inject_mapped_irq(vcpu->kvm, vcpu->vcpu_id,
+					 timer->map,
+					 timer->irq.level);
+	WARN_ON(ret);
+}
+
+/*
+ * Check if there was a change in the timer state (should we raise or lower
+ * the line level to the GIC).
+ */
+static void kvm_timer_update_state(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+
+	/*
+	 * If userspace modified the timer registers via SET_ONE_REG before
+	 * the vgic was initialized, we mustn't set the timer->irq.level value
+	 * because the guest would never see the interrupt.  Instead wait
+	 * until we call this function from kvm_timer_flush_hwstate.
+	 */
+	if (!vgic_initialized(vcpu->kvm))
+	    return;
+
+	if (kvm_timer_should_fire(vcpu) != timer->irq.level)
+		kvm_timer_update_irq(vcpu, !timer->irq.level);
+}
+
+/*
+ * Schedule the background timer before calling kvm_vcpu_block, so that this
+ * thread is removed from its waitqueue and made runnable when there's a timer
+ * interrupt to handle.
+ */
+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));
+
+	/*
+	 * No need to schedule a background timer if the guest timer has
+	 * already expired, because kvm_vcpu_block will return before putting
+	 * the thread to sleep.
+	 */
+	if (kvm_timer_should_fire(vcpu))
+		return;
+
+	/*
+	 * If the timer is not capable of raising interrupts (disabled or
+	 * masked), then there's no more work for us to do.
+	 */
+	if (!kvm_timer_irq_can_fire(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);
+}
+
+void kvm_timer_unschedule(struct kvm_vcpu *vcpu)
+{
+	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
+	timer_disarm(timer);
+}
+
 /**
  * kvm_timer_flush_hwstate - prepare to move the virt timer to the cpu
  * @vcpu: The vcpu pointer
  *
- * Disarm any pending soft timers, since the world-switch code will write the
- * virtual timer state back to the physical CPU.
+ * Check if the virtual timer has expired while we were running in the host,
+ * and inject an interrupt if that was the case.
  */
 void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 {
@@ -140,28 +218,20 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 	bool phys_active;
 	int ret;
 
-	/*
-	 * We're about to run this vcpu again, so there is no need to
-	 * keep the background timer running, as we're about to
-	 * populate the CPU timer again.
-	 */
-	timer_disarm(timer);
+	kvm_timer_update_state(vcpu);
 
 	/*
-	 * If the timer expired while we were not scheduled, now is the time
-	 * to inject it.
+	 * If we enter the guest with the virtual input level to the VGIC
+	 * asserted, then we have already told the VGIC what we need to, and
+	 * we don't need to exit from the guest until the guest deactivates
+	 * the already injected interrupt, so therefore we should set the
+	 * hardware active state to prevent unnecessary exits from the guest.
+	 *
+	 * Conversely, if the virtual input level is deasserted, then always
+	 * clear the hardware active state to ensure that hardware interrupts
+	 * from the timer triggers a guest exit.
 	 */
-	if (kvm_timer_should_fire(vcpu))
-		kvm_timer_inject_irq(vcpu);
-
-	/*
-	 * We keep track of whether the edge-triggered interrupt has been
-	 * signalled to the vgic/guest, and if so, we mask the interrupt and
-	 * the physical distributor to prevent the timer from raising a
-	 * physical interrupt whenever we run a guest, preventing forward
-	 * VCPU progress.
-	 */
-	if (kvm_vgic_get_phys_irq_active(timer->map))
+	if (timer->irq.level)
 		phys_active = true;
 	else
 		phys_active = false;
@@ -176,32 +246,20 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
  * kvm_timer_sync_hwstate - sync timer state from cpu
  * @vcpu: The vcpu pointer
  *
- * Check if the virtual timer was armed and either schedule a corresponding
- * soft timer or inject directly if already expired.
+ * Check if the virtual timer has expired while we were running in the guest,
+ * and inject an interrupt if that was the case.
  */
 void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
 {
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
-	cycle_t cval, now;
-	u64 ns;
 
 	BUG_ON(timer_is_armed(timer));
 
-	if (kvm_timer_should_fire(vcpu)) {
-		/*
-		 * Timer has already expired while we were not
-		 * looking. Inject the interrupt and carry on.
-		 */
-		kvm_timer_inject_irq(vcpu);
-		return;
-	}
-
-	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);
+	/*
+	 * The guest could have modified the timer registers or the timer
+	 * could have expired, update the timer state.
+	 */
+	kvm_timer_update_state(vcpu);
 }
 
 int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
@@ -216,7 +274,7 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
 	 * kvm_vcpu_set_target(). To handle this, we determine
 	 * vcpu timer irq number when the vcpu is reset.
 	 */
-	timer->irq = irq;
+	timer->irq.irq = irq->irq;
 
 	/*
 	 * The bits in CNTV_CTL are architecturally reset to UNKNOWN for ARMv8
@@ -225,6 +283,7 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
 	 * the ARMv7 architecture.
 	 */
 	timer->cntv_ctl = 0;
+	kvm_timer_update_state(vcpu);
 
 	/*
 	 * Tell the VGIC that the virtual interrupt is tied to a
@@ -269,6 +328,8 @@ int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
 	default:
 		return -1;
 	}
+
+	kvm_timer_update_state(vcpu);
 	return 0;
 }