KVM: arm64: vgic-v3: Add ICV_HPPIR1_EL1 handler

Add a handler for reading the guest's view of the ICV_HPPIR1_EL1
register. This is a simple parsing of the available LRs, extracting the
highest available interrupt.

Tested-by: Alexander Graf <agraf@suse.de>
Acked-by: David Daney <david.daney@cavium.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>

arch/arm64/include/asm/sysreg.h

@@ -185,6 +185,7 @@
 #define SYS_ICC_SGI1R_EL1		sys_reg(3, 0, 12, 11, 5)
 #define SYS_ICC_IAR1_EL1		sys_reg(3, 0, 12, 12, 0)
 #define SYS_ICC_EOIR1_EL1		sys_reg(3, 0, 12, 12, 1)
+#define SYS_ICC_HPPIR1_EL1		sys_reg(3, 0, 12, 12, 2)
 #define SYS_ICC_BPR1_EL1		sys_reg(3, 0, 12, 12, 3)
 #define SYS_ICC_CTLR_EL1		sys_reg(3, 0, 12, 12, 4)
 #define SYS_ICC_SRE_EL1			sys_reg(3, 0, 12, 12, 5)

virt/kvm/arm/hyp/vgic-v3-sr.c

@@ -790,6 +790,26 @@ static void __hyp_text __vgic_v3_write_apxr3(struct kvm_vcpu *vcpu,
 	__vgic_v3_write_apxrn(vcpu, rt, 3);
 }
 
+static void __hyp_text __vgic_v3_read_hppir(struct kvm_vcpu *vcpu,
+					    u32 vmcr, int rt)
+{
+	u64 lr_val;
+	int lr, lr_grp, grp;
+
+	grp = __vgic_v3_get_group(vcpu);
+
+	lr = __vgic_v3_highest_priority_lr(vcpu, vmcr, &lr_val);
+	if (lr == -1)
+		goto spurious;
+
+	lr_grp = !!(lr_val & ICH_LR_GROUP);
+	if (lr_grp != grp)
+		lr_val = ICC_IAR1_EL1_SPURIOUS;
+
+spurious:
+	vcpu_set_reg(vcpu, rt, lr_val & ICH_LR_VIRTUAL_ID_MASK);
+}
+
 int __hyp_text __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu)
 {
 	int rt;
@@ -854,6 +874,9 @@ int __hyp_text __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu)
 		else
 			fn = __vgic_v3_write_apxr3;
 		break;
+	case SYS_ICC_HPPIR1_EL1:
+		fn = __vgic_v3_read_hppir;
+		break;
 	default:
 		return 0;
 	}