ARM: KVM: abstract SAS decoding away

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@cs.columbia.edu>
diff --git a/arch/arm/kvm/mmio.c b/arch/arm/kvm/mmio.c
index 6495c1c..0b8f499 100644
--- a/arch/arm/kvm/mmio.c
+++ b/arch/arm/kvm/mmio.c
@@ -77,20 +77,9 @@
 		return 1;
 	}
 
-	switch ((kvm_vcpu_get_hsr(vcpu) >> 22) & 0x3) {
-	case 0:
-		len = 1;
-		break;
-	case 1:
-		len = 2;
-		break;
-	case 2:
-		len = 4;
-		break;
-	default:
-		kvm_err("Hardware is weird: SAS 0b11 is reserved\n");
-		return -EFAULT;
-	}
+	len = kvm_vcpu_dabt_get_as(vcpu);
+	if (unlikely(len < 0))
+		return len;
 
 	is_write = kvm_vcpu_dabt_iswrite(vcpu);
 	sign_extend = kvm_vcpu_dabt_issext(vcpu);