KVM: x86: hyperv: do rep check for each hypercall separately

Prepare to support TLB flush hypercalls, some of which are REP hypercalls.
Also, return HV_STATUS_INVALID_HYPERCALL_INPUT as it seems more
appropriate.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

arch/x86/kvm/hyperv.c

@@ -1311,7 +1311,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 {
 	u64 param, ingpa, outgpa, ret = HV_STATUS_SUCCESS;
 	uint16_t code, rep_idx, rep_cnt;
-	bool fast, longmode;
+	bool fast, longmode, rep;
 
 	/*
 	 * hypercall generates UD from non zero cpl and real mode
@@ -1344,28 +1344,31 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
 	fast = !!(param & HV_HYPERCALL_FAST_BIT);
 	rep_cnt = (param >> HV_HYPERCALL_REP_COMP_OFFSET) & 0xfff;
 	rep_idx = (param >> HV_HYPERCALL_REP_START_OFFSET) & 0xfff;
+	rep = !!(rep_cnt || rep_idx);
 
 	trace_kvm_hv_hypercall(code, fast, rep_cnt, rep_idx, ingpa, outgpa);
 
-	/* Hypercall continuation is not supported yet */
-	if (rep_cnt || rep_idx) {
-		ret = HV_STATUS_INVALID_HYPERCALL_CODE;
-		goto set_result;
-	}
-
 	switch (code) {
 	case HVCALL_NOTIFY_LONG_SPIN_WAIT:
+		if (unlikely(rep)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+			break;
+		}
 		kvm_vcpu_on_spin(vcpu, true);
 		break;
 	case HVCALL_SIGNAL_EVENT:
+		if (unlikely(rep)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
+			break;
+		}
 		ret = kvm_hvcall_signal_event(vcpu, fast, ingpa);
 		if (ret != HV_STATUS_INVALID_PORT_ID)
 			break;
 		/* maybe userspace knows this conn_id: fall through */
 	case HVCALL_POST_MESSAGE:
 		/* don't bother userspace if it has no way to handle it */
-		if (!vcpu_to_synic(vcpu)->active) {
-			ret = HV_STATUS_INVALID_HYPERCALL_CODE;
+		if (unlikely(rep || !vcpu_to_synic(vcpu)->active)) {
+			ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
 			break;
 		}
 		vcpu->run->exit_reason = KVM_EXIT_HYPERV;