[PATCH v2 6/9] KVM: arm/arm64: use a vcpu request on irq injection

[Andrew Jones <drjones@redhat.com>]

Don't use request-less VCPU kicks when injecting IRQs, as a VCPU
kick meant to trigger the interrupt injection could be sent while
the VCPU is outside guest mode, which means no IPI is sent, and
after it has called kvm_vgic_flush_hwstate(), meaning it won't see
the updated GIC state until its next exit some time later for some
other reason.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 arch/arm/include/asm/kvm_host.h   |  1 +
 arch/arm/kvm/arm.c                |  1 +
 arch/arm64/include/asm/kvm_host.h |  1 +
 virt/kvm/arm/arch_timer.c         |  1 +
 virt/kvm/arm/vgic/vgic.c          | 12 ++++++++++--
 5 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index afed5d44634d..0b8a6d6b3cb3 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -47,6 +47,7 @@
 
 #define KVM_REQ_PAUSE		8
 #define KVM_REQ_POWER_OFF	9
+#define KVM_REQ_IRQ_PENDING	10
 
 u32 *kvm_vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num, u32 mode);
 int __attribute_const__ kvm_target_cpu(void);
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 7ed39060b1cf..a106feccf314 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -768,6 +768,7 @@ static int vcpu_interrupt_line(struct kvm_vcpu *vcpu, int number, bool level)
 	 * trigger a world-switch round on the running physical CPU to set the
 	 * virtual IRQ/FIQ fields in the HCR appropriately.
 	 */
+	kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
 	kvm_vcpu_kick(vcpu);
 
 	return 0;
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e78895f675d0..7057512b3474 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -44,6 +44,7 @@
 
 #define KVM_REQ_PAUSE		8
 #define KVM_REQ_POWER_OFF	9
+#define KVM_REQ_IRQ_PENDING	10
 
 int __attribute_const__ kvm_target_cpu(void);
 int kvm_reset_vcpu(struct kvm_vcpu *vcpu);
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 35d7100e0815..3c48abbf951b 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -95,6 +95,7 @@ static void kvm_timer_inject_irq_work(struct work_struct *work)
 	 * If the vcpu is blocked we want to wake it up so that it will see
 	 * the timer has expired when entering the guest.
 	 */
+	kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
 	kvm_vcpu_kick(vcpu);
 }
 
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 654dfd40e449..31fb89057f0c 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -283,8 +283,10 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
 		 * won't see this one until it exits for some other
 		 * reason.
 		 */
-		if (vcpu)
+		if (vcpu) {
+			kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
 			kvm_vcpu_kick(vcpu);
+		}
 		return false;
 	}
 
@@ -330,6 +332,7 @@ bool vgic_queue_irq_unlock(struct kvm *kvm, struct vgic_irq *irq)
 	spin_unlock(&irq->irq_lock);
 	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
 
+	kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
 	kvm_vcpu_kick(vcpu);
 
 	return true;
@@ -654,6 +657,9 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
 	spin_lock(&vcpu->arch.vgic_cpu.ap_list_lock);
 	vgic_flush_lr_state(vcpu);
 	spin_unlock(&vcpu->arch.vgic_cpu.ap_list_lock);
+
+	/* The GIC is now ready to deliver the IRQ. */
+	clear_bit(KVM_REQ_IRQ_PENDING, &vcpu->requests);
 }
 
 int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu)
@@ -691,8 +697,10 @@ void vgic_kick_vcpus(struct kvm *kvm)
 	 * a good kick...
 	 */
 	kvm_for_each_vcpu(c, vcpu, kvm) {
-		if (kvm_vgic_vcpu_pending_irq(vcpu))
+		if (kvm_vgic_vcpu_pending_irq(vcpu)) {
+			kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
 			kvm_vcpu_kick(vcpu);
+		}
 	}
 }
 
-- 
2.9.3