[PATCH v4 48/66] KVM: arm64: nv: vgic: Emulate the HW bit in software

[Marc Zyngier]

From: Christoffer Dall <christoffer.dall at arm.com>

Should the guest hypervisor use the HW bit in the LRs, we need to
emulate the deactivation from the L2 guest into the L1 distributor
emulation, which is handled by L0.

It's all good fun.

Signed-off-by: Christoffer Dall <christoffer.dall at arm.com>
Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/include/asm/kvm_hyp.h     |  2 ++
 arch/arm64/kvm/hyp/vgic-v3-sr.c      |  2 +-
 arch/arm64/kvm/vgic/vgic-v3-nested.c | 32 ++++++++++++++++++++++++++++
 arch/arm64/kvm/vgic/vgic.c           |  6 ++++--
 include/kvm/arm_vgic.h               |  1 +
 5 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_hyp.h b/arch/arm64/include/asm/kvm_hyp.h
index 9d60b3006efc..67c3f76ad274 100644
--- a/arch/arm64/include/asm/kvm_hyp.h
+++ b/arch/arm64/include/asm/kvm_hyp.h
@@ -57,6 +57,8 @@ DECLARE_PER_CPU(struct kvm_nvhe_init_params, kvm_init_params);
 
 int __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu);
 
+u64 __gic_v3_get_lr(unsigned int lr);
+
 void __vgic_v3_save_state(struct vgic_v3_cpu_if *cpu_if);
 void __vgic_v3_restore_state(struct vgic_v3_cpu_if *cpu_if);
 void __vgic_v3_activate_traps(struct vgic_v3_cpu_if *cpu_if);
diff --git a/arch/arm64/kvm/hyp/vgic-v3-sr.c b/arch/arm64/kvm/hyp/vgic-v3-sr.c
index 39f8f7f9227c..89b0ffa55424 100644
--- a/arch/arm64/kvm/hyp/vgic-v3-sr.c
+++ b/arch/arm64/kvm/hyp/vgic-v3-sr.c
@@ -18,7 +18,7 @@
 #define vtr_to_nr_pre_bits(v)		((((u32)(v) >> 26) & 7) + 1)
 #define vtr_to_nr_apr_regs(v)		(1 << (vtr_to_nr_pre_bits(v) - 5))
 
-static u64 __gic_v3_get_lr(unsigned int lr)
+u64 __gic_v3_get_lr(unsigned int lr)
 {
 	switch (lr & 0xf) {
 	case 0:
diff --git a/arch/arm64/kvm/vgic/vgic-v3-nested.c b/arch/arm64/kvm/vgic/vgic-v3-nested.c
index bfe0ccde514f..3ee3438b5e22 100644
--- a/arch/arm64/kvm/vgic/vgic-v3-nested.c
+++ b/arch/arm64/kvm/vgic/vgic-v3-nested.c
@@ -138,6 +138,38 @@ static void vgic_v3_fixup_shadow_lr_state(struct kvm_vcpu *vcpu)
 	}
 }
 
+void vgic_v3_sync_nested(struct kvm_vcpu *vcpu)
+{
+	struct vgic_v3_cpu_if *cpu_if = vcpu_nested_if(vcpu);
+	struct vgic_v3_cpu_if *s_cpu_if = vcpu_shadow_if(vcpu);
+	struct vgic_irq *irq;
+	int i;
+
+	for (i = 0; i < s_cpu_if->used_lrs; i++) {
+		u64 lr = cpu_if->vgic_lr[i];
+		int l1_irq;
+
+		if (!(lr & ICH_LR_HW) || !(lr & ICH_LR_STATE))
+			continue;
+
+		/*
+		 * If we had a HW lr programmed by the guest hypervisor, we
+		 * need to emulate the HW effect between the guest hypervisor
+		 * and the nested guest.
+		 */
+		l1_irq = (lr & ICH_LR_PHYS_ID_MASK) >> ICH_LR_PHYS_ID_SHIFT;
+		irq = vgic_get_irq(vcpu->kvm, vcpu, l1_irq);
+		if (!irq)
+			continue; /* oh well, the guest hyp is broken */
+
+		lr = __gic_v3_get_lr(i);
+		if (!(lr & ICH_LR_STATE))
+			irq->active = false;
+
+		vgic_put_irq(vcpu->kvm, irq);
+	}
+}
+
 void vgic_v3_load_nested(struct kvm_vcpu *vcpu)
 {
 	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index b06b993c4c7e..3df8d9139999 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -877,9 +877,11 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
 {
 	int used_lrs;
 
-	/* If nesting, this is a load/put affair, not flush/sync. */
-	if (vgic_state_is_nested(vcpu))
+	/* If nesting, emulate the HW effect from L0 to L1 */
+	if (vgic_state_is_nested(vcpu)) {
+		vgic_v3_sync_nested(vcpu);
 		return;
+	}
 
 	/* An empty ap_list_head implies used_lrs == 0 */
 	if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head))
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 10f63112e785..26586283c8f4 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -372,6 +372,7 @@ void kvm_vgic_load(struct kvm_vcpu *vcpu);
 void kvm_vgic_put(struct kvm_vcpu *vcpu);
 void kvm_vgic_vmcr_sync(struct kvm_vcpu *vcpu);
 
+void vgic_v3_sync_nested(struct kvm_vcpu *vcpu);
 void vgic_v3_load_nested(struct kvm_vcpu *vcpu);
 void vgic_v3_put_nested(struct kvm_vcpu *vcpu);
 void vgic_v3_handle_nested_maint_irq(struct kvm_vcpu *vcpu);
-- 
2.29.2