linux-kernel - [RFC PATCH 9/9] KVM: arm: timer: make the interrupt state part of the timer state

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Date:	Wed, 25 Jun 2014 10:28:50 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc:	Will Deacon <will.deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Thomas Gleixner <tglx@...utronix.de>, eric.auger@...aro.org,
	Christoffer Dall <christoffer.dall@...aro.org>
Subject: [RFC PATCH 9/9] KVM: arm: timer: make the interrupt state part of the timer state

In order to remove the crude hack where we sneak the masked bit
into the timer's control register, make use of the forwarded
interrupt API to save/restore the active state of the interrupt.

Signed-off-by: Marc Zyngier <marc.zyngier@....com>
---
 include/kvm/arm_arch_timer.h |  3 +++
 virt/kvm/arm/arch_timer.c    | 31 ++++++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/include/kvm/arm_arch_timer.h b/include/kvm/arm_arch_timer.h
index 6d9aedd..6a69f42 100644
--- a/include/kvm/arm_arch_timer.h
+++ b/include/kvm/arm_arch_timer.h
@@ -53,6 +53,9 @@ struct arch_timer_cpu {
 	/* Background timer active */
 	bool				armed;
 
+	/* Is interrupt active at the distributor level */
+	u32				irq_active;
+
 	/* Timer IRQ */
 	const struct kvm_irq_level	*irq;
 #endif
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 22fa819..57817c5 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -63,7 +63,7 @@ static void kvm_timer_inject_irq(struct kvm_vcpu *vcpu)
 {
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 
-	timer->cntv_ctl |= ARCH_TIMER_CTRL_IT_MASK;
+	timer->irq_active = IRQ_FWD_STATE_ACTIVE;
 	kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
 			    timer->irq->irq,
 			    timer->irq->level);
@@ -117,6 +117,16 @@ void kvm_timer_flush_hwstate(struct kvm_vcpu *vcpu)
 	 * populate the CPU timer again.
 	 */
 	timer_disarm(timer);
+
+	if (timer->irq_active) {
+		int ret;
+
+		ret = irq_set_fwd_state(host_vtimer_irq,
+					timer->irq_active,
+					IRQ_FWD_STATE_ACTIVE);
+		if (ret)
+			kvm_err("unable to restore timer state");
+	}
 }
 
 /**
@@ -130,8 +140,16 @@ void kvm_timer_sync_hwstate(struct kvm_vcpu *vcpu)
 {
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 	cycle_t cval, now;
+	int ret;
 	u64 ns;
 
+	ret = irq_get_fwd_state(host_vtimer_irq, &timer->irq_active,
+				IRQ_FWD_STATE_ACTIVE);
+	if (ret)
+		kvm_err("unable to retrieve timer state");
+	if (timer->irq_active)
+		irq_set_fwd_state(host_vtimer_irq, 0, IRQ_FWD_STATE_ACTIVE);
+
 	if ((timer->cntv_ctl & ARCH_TIMER_CTRL_IT_MASK) ||
 		!(timer->cntv_ctl & ARCH_TIMER_CTRL_ENABLE))
 		return;
@@ -166,6 +184,12 @@ void kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu,
 	 * vcpu timer irq number when the vcpu is reset.
 	 */
 	timer->irq = irq;
+
+	/*
+	 * Tell the VGIC that the virtual interrupt is tied to a
+	 * physical interrupt. We do that once per VCPU.
+	 */
+	vgic_map_phys_irq(vcpu, irq->irq, host_vtimer_irq);
 }
 
 void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
@@ -290,6 +314,10 @@ int kvm_timer_hyp_init(void)
 	}
 
 	kvm_info("%s IRQ%d\n", np->name, ppi);
+
+	/* Tell the GIC we're forwarding the interrupt to a guest */
+	irqd_set_irq_forwarded(irq_get_irq_data(host_vtimer_irq));
+
 	on_each_cpu(kvm_timer_init_interrupt, NULL, 1);
 
 	goto out;
@@ -305,6 +333,7 @@ void kvm_timer_vcpu_terminate(struct kvm_vcpu *vcpu)
 	struct arch_timer_cpu *timer = &vcpu->arch.timer_cpu;
 
 	timer_disarm(timer);
+	vgic_unmap_phys_irq(vcpu, timer->irq->irq, host_vtimer_irq);
 }
 
 int kvm_timer_init(struct kvm *kvm)
-- 
1.8.3.4

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