KVM: PPC: Fix error in BAT assignment

BATs didn't work. Well, they did, but only up to BAT3. As soon as we
came to BAT4 the offset calculation was screwed up and we ended up
overwriting BAT0-3.

Fortunately, Linux hasn't been using BAT4+. It's still a good
idea to write correct code though.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/kvm/book3s_64_emulate.c

@@ -233,13 +233,13 @@ static void kvmppc_write_bat(struct kvm_vcpu *vcpu, int sprn, u32 val)
 		bat = &vcpu_book3s->ibat[(sprn - SPRN_IBAT0U) / 2];
 		break;
 	case SPRN_IBAT4U ... SPRN_IBAT7L:
-		bat = &vcpu_book3s->ibat[(sprn - SPRN_IBAT4U) / 2];
+		bat = &vcpu_book3s->ibat[4 + ((sprn - SPRN_IBAT4U) / 2)];
 		break;
 	case SPRN_DBAT0U ... SPRN_DBAT3L:
 		bat = &vcpu_book3s->dbat[(sprn - SPRN_DBAT0U) / 2];
 		break;
 	case SPRN_DBAT4U ... SPRN_DBAT7L:
-		bat = &vcpu_book3s->dbat[(sprn - SPRN_DBAT4U) / 2];
+		bat = &vcpu_book3s->dbat[4 + ((sprn - SPRN_DBAT4U) / 2)];
 		break;
 	default:
 		BUG();