[RFC 2/2] Send KVM_EXIT_IRQ from timer if irqchip is not used

[Pavel Fedin <p.fedin@samsung.com>]

Signed-off-by: Pavel Fedin <p.fedin@samsung.com>
---
 arch/arm/kvm/arm.c        | 18 +++++++++++-------
 include/linux/kvm_host.h  |  7 +++++++
 virt/kvm/arm/arch_timer.c |  6 ++++++
 3 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 7e389fd..67545bd 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -461,13 +461,7 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu)
 			return ret;
 	}
 
-	/*
-	 * Enable the arch timers only if we have an in-kernel VGIC
-	 * and it has been properly initialized, since we cannot handle
-	 * interrupts from the virtual timer with a userspace gic.
-	 */
-	if (irqchip_in_kernel(kvm) && vgic_initialized(kvm))
-		kvm_timer_enable(kvm);
+	kvm_timer_enable(kvm);
 
 	return 0;
 }
@@ -547,6 +541,16 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 			run->exit_reason = KVM_EXIT_INTR;
 		}
 
+		if (vcpu->irq) {
+			ret = 0;
+			run->exit_reason = KVM_EXIT_IRQ;
+			run->irq.irq = vcpu->irq->irq;
+			run->irq.level = vcpu->irq->level;
+
+			vcpu->irq = NULL;
+			continue;
+		}
+
 		if (ret <= 0 || need_new_vmid_gen(vcpu->kvm)) {
 			local_irq_enable();
 			kvm_timer_sync_hwstate(vcpu);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ad45054..3907e79 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -267,6 +267,13 @@ struct kvm_vcpu {
 	} spin_loop;
 #endif
 	bool preempted;
+
+	/*
+	 * IRQ pending to the userspace on this CPU.
+	 * Currently we support only one slot, used only by ARM architecture.
+	 */
+	const struct kvm_irq_level *irq;
+
 	struct kvm_vcpu_arch arch;
 };
 
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 98c95f2..e1b0aa9 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -65,6 +65,12 @@ 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;
+
+	if (!irqchip_in_kernel(vcpu->kvm)) {
+		vcpu->irq = timer->irq;
+		return;
+	}
+
 	ret = kvm_vgic_inject_irq(vcpu->kvm, vcpu->vcpu_id,
 				  timer->irq->irq,
 				  timer->irq->level);
-- 
2.4.4