[RFC 31/55] KVM: arm/arm64: Inject maintenance interrupts to the guest hypervisor

[Jintack Lim]

From: Christoffer Dall <christoffer.dall at linaro.org>

If we exit a nested VM with a pending maintenance interrupt from the
GIC, then we need to forward this to the guest hypervisor so that it can
re-sync the appropriate LRs and sample level triggered interrupts again.

Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
Signed-off-by: Jintack Lim <jintack at cs.columbia.edu>
---
 arch/arm64/kvm/context.c           |  3 +++
 include/kvm/arm_vgic.h             |  2 ++
 virt/kvm/arm/vgic/vgic-v2-nested.c | 16 ++++++++++++++++
 3 files changed, 21 insertions(+)

diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c
index 7a94c9d..a93ffe4 100644
--- a/arch/arm64/kvm/context.c
+++ b/arch/arm64/kvm/context.c
@@ -140,6 +140,9 @@ static void sync_shadow_el1_state(struct kvm_vcpu *vcpu, bool setup)
 void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
+
+	vgic_handle_nested_maint_irq(vcpu);
+
 	if (unlikely(vcpu_mode_el2(vcpu))) {
 		ctxt->hw_pstate = *vcpu_cpsr(vcpu) & ~PSR_MODE_MASK;
 
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 484f6b1..fc882d6 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -315,9 +315,11 @@ int kvm_vgic_inject_mapped_irq(struct kvm *kvm, int cpuid, unsigned int intid,
 #ifdef CONFIG_KVM_ARM_NESTED_HYP
 void vgic_v2_setup_shadow_state(struct kvm_vcpu *vcpu);
 void vgic_v2_restore_shadow_state(struct kvm_vcpu *vcpu);
+void vgic_handle_nested_maint_irq(struct kvm_vcpu *vcpu);
 #else
 static inline void vgic_v2_setup_shadow_state(struct kvm_vcpu *vcpu) { }
 static inline void vgic_v2_restore_shadow_state(struct kvm_vcpu *vcpu) { }
+static inline void vgic_handle_nested_maint_irq(struct kvm_vcpu *vcpu) { }
 #endif
 
 #define irqchip_in_kernel(k)	(!!((k)->arch.vgic.in_kernel))
diff --git a/virt/kvm/arm/vgic/vgic-v2-nested.c b/virt/kvm/arm/vgic/vgic-v2-nested.c
index a992da5..85f646b 100644
--- a/virt/kvm/arm/vgic/vgic-v2-nested.c
+++ b/virt/kvm/arm/vgic/vgic-v2-nested.c
@@ -300,6 +300,22 @@ void vgic_v2_restore_shadow_state(struct kvm_vcpu *vcpu)
 	vgic_cpu->nested_vgic_v2 = vgic_cpu->shadow_vgic_v2;
 }
 
+void vgic_handle_nested_maint_irq(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v2_cpu_if *cpu_if = vcpu_nested_if(vcpu);
+
+	/*
+	 * If we exit a nested VM with a pending maintenance interrupt from the
+	 * GIC, then we need to forward this to the guest hypervisor so that it
+	 * can re-sync the appropriate LRs and sample level triggered interrupts
+	 * again.
+	 */
+	if (vcpu_el2_imo_is_set(vcpu) && !vcpu_mode_el2(vcpu) &&
+	    (cpu_if->vgic_hcr & GICH_HCR_EN) &&
+	    vgic_mmio_read_v2_misr(vcpu, 0, 0))
+		kvm_inject_nested_irq(vcpu);
+}
+
 void vgic_init_nested(struct kvm_vcpu *vcpu)
 {
 	vgic_v2_setup_shadow_state(vcpu);
-- 
1.9.1