KVM: arm64: vgic-v3: Add ICV_RPR_EL1 handler

Add a handler for reading the guest's view of the ICV_RPR_EL1
register, returning the highest active priority.

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

arch/arm64/include/asm/sysreg.h

@@ -187,6 +187,7 @@
 #define SYS_ICC_AP0Rn_EL1(n)		sys_reg(3, 0, 12, 8, 4 | n)
 #define SYS_ICC_AP1Rn_EL1(n)		sys_reg(3, 0, 12, 9, n)
 #define SYS_ICC_DIR_EL1			sys_reg(3, 0, 12, 11, 1)
+#define SYS_ICC_RPR_EL1			sys_reg(3, 0, 12, 11, 3)
 #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)

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

@@ -884,6 +884,13 @@ spurious:
 	vcpu_set_reg(vcpu, rt, lr_val & ICH_LR_VIRTUAL_ID_MASK);
 }
 
+static void __hyp_text __vgic_v3_read_rpr(struct kvm_vcpu *vcpu,
+					  u32 vmcr, int rt)
+{
+	u32 val = __vgic_v3_get_highest_active_priority();
+	vcpu_set_reg(vcpu, rt, val);
+}
+
 int __hyp_text __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu)
 {
 	int rt;
@@ -973,6 +980,9 @@ int __hyp_text __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu)
 	case SYS_ICC_DIR_EL1:
 		fn = __vgic_v3_write_dir;
 		break;
+	case SYS_ICC_RPR_EL1:
+		fn = __vgic_v3_read_rpr;
+		break;
 	default:
 		return 0;
 	}