Subject: [PATCH v10 52/59] KVM: arm64: nv: Fold GICv3 host trapping requirements into guest setup

From: Marc Zyngier <[email-masked]>
Date: Mon, 15 May 2023 18:30:56 +0100

Popular HW that is able to use NV also has a broken vgic implementation
that requires trapping.

On such HW, propagate the host trap bits into the guest's shadow
ICH_HCR_EL2 register, making sure we don't allow an L2 guest to bring
the system down.

This involves a bit of tweaking so that the emulation code correctly
poicks up the shadow state as needed, and to only partially sync
ICH_HCR_EL2 back with the guest state to capture EOIcount.

Signed-off-by: Marc Zyngier <[email-masked]>
---
 arch/arm64/kvm/hyp/vgic-v3-sr.c      |  4 ++--
 arch/arm64/kvm/vgic/vgic-v3-nested.c | 21 ++++++++++++++++++---
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/hyp/vgic-v3-sr.c b/arch/arm64/kvm/hyp/vgic-v3-sr.c
index 75152c1ce646..aaaea35099e5 100644
--- a/arch/arm64/kvm/hyp/vgic-v3-sr.c
+++ b/arch/arm64/kvm/hyp/vgic-v3-sr.c
@@ -484,7 +484,7 @@ static int __vgic_v3_get_group(struct kvm_vcpu *vcpu)
 static int __vgic_v3_highest_priority_lr(struct kvm_vcpu *vcpu, u32 vmcr,
 					 u64 *lr_val)
 {
-	unsigned int used_lrs = vcpu->arch.vgic_cpu.vgic_v3.used_lrs;
+	unsigned int used_lrs = kern_hyp_va(vcpu->arch.vgic_cpu.current_cpu_if)->used_lrs;
 	u8 priority = GICv3_IDLE_PRIORITY;
 	int i, lr = -1;
 
@@ -523,7 +523,7 @@ static int __vgic_v3_highest_priority_lr(struct kvm_vcpu *vcpu, u32 vmcr,
 static int __vgic_v3_find_active_lr(struct kvm_vcpu *vcpu, int intid,
 				    u64 *lr_val)
 {
-	unsigned int used_lrs = vcpu->arch.vgic_cpu.vgic_v3.used_lrs;
+	unsigned int used_lrs = kern_hyp_va(vcpu->arch.vgic_cpu.current_cpu_if)->used_lrs;
 	int i;
 
 	for (i = 0; i < used_lrs; i++) {
diff --git a/arch/arm64/kvm/vgic/vgic-v3-nested.c b/arch/arm64/kvm/vgic/vgic-v3-nested.c
index 12937bc86e1c..51f97bd4489d 100644
--- a/arch/arm64/kvm/vgic/vgic-v3-nested.c
+++ b/arch/arm64/kvm/vgic/vgic-v3-nested.c
@@ -149,9 +149,20 @@ void vgic_v3_sync_nested(struct kvm_vcpu *vcpu)
 void vgic_v3_create_shadow_state(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.shadow_vgic_v3;
+	struct vgic_v3_cpu_if *host_if = &vcpu->arch.vgic_cpu.vgic_v3;
+	u64 val = 0;
 	int i;
 
-	cpu_if->vgic_hcr = __vcpu_sys_reg(vcpu, ICH_HCR_EL2);
+	/*
+	 * If we're on a system with a broken vgic that requires
+	 * trapping, propagate the trapping requirements.
+	 *
+	 * Ah, the smell of rotten fruits...
+	 */
+	if (static_branch_unlikely(&vgic_v3_cpuif_trap))
+		val = host_if->vgic_hcr & (ICH_HCR_TALL0 | ICH_HCR_TALL1 |
+					   ICH_HCR_TC | ICH_HCR_TDIR);
+	cpu_if->vgic_hcr = __vcpu_sys_reg(vcpu, ICH_HCR_EL2) | val;
 	cpu_if->vgic_vmcr = __vcpu_sys_reg(vcpu, ICH_VMCR_EL2);
 
 	for (i = 0; i < 4; i++) {
@@ -181,6 +192,7 @@ void vgic_v3_load_nested(struct kvm_vcpu *vcpu)
 void vgic_v3_put_nested(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *s_cpu_if = vcpu_shadow_if(vcpu);
+	u64 val;
 	int i;
 
 	__vgic_v3_save_state(s_cpu_if);
@@ -189,7 +201,10 @@ void vgic_v3_put_nested(struct kvm_vcpu *vcpu)
 	 * Translate the shadow state HW fields back to the virtual ones
 	 * before copying the shadow struct back to the nested one.
 	 */
-	__vcpu_sys_reg(vcpu, ICH_HCR_EL2) = s_cpu_if->vgic_hcr;
+	val = __vcpu_sys_reg(vcpu, ICH_HCR_EL2);
+	val &= ~ICH_HCR_EOIcount_MASK;
+	val |= (s_cpu_if->vgic_hcr & ICH_HCR_EOIcount_MASK);
+	__vcpu_sys_reg(vcpu, ICH_HCR_EL2) = val;
 	__vcpu_sys_reg(vcpu, ICH_VMCR_EL2) = s_cpu_if->vgic_vmcr;
 
 	for (i = 0; i < 4; i++) {
@@ -198,7 +213,7 @@ void vgic_v3_put_nested(struct kvm_vcpu *vcpu)
 	}
 
 	for (i = 0; i < kvm_vgic_global_state.nr_lr; i++) {
-		u64 val = __vcpu_sys_reg(vcpu, ICH_LRN(i));
+		val = __vcpu_sys_reg(vcpu, ICH_LRN(i));
 
 		val &= ~ICH_LR_STATE;
 		val |= s_cpu_if->vgic_lr[i] & ICH_LR_STATE;
-- 
2.34.1

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