Hi, all,
While building stable tree version of 6.10, the following error occurred:
In line 1421 defines:
1421 evtchn_port_t port, *ports;
The ports becomes &port in line 1470, but neither port nor *ports is assigned a value
until line 1486 where port is used:
1485 if (sched_poll.nr_ports == 1)
1486 → vcpu->arch.xen.poll_evtchn = port;
The visual inspection proves that the compiler is again right (GCC 12.3.0).
The linux-next and kvm trees contained the same error.
In line 1507 this error is rectified by setting vcpu->arch.xen.poll_evtchn = 0,
but compiler still prevents build with -Werror.
I don't have familiarity with this section of code.
"arch/x86/kvm/xen.c"
--------------------
1417 static bool kvm_xen_schedop_poll(struct kvm_vcpu *vcpu, bool longmode,
1418 u64 param, u64 *r)
1419 {
1420 struct sched_poll sched_poll;
1421 → evtchn_port_t port, *ports;
1422 struct x86_exception e;
1423 int i;
1424
1425 if (!lapic_in_kernel(vcpu) ||
1426 !(vcpu->kvm->arch.xen_hvm_config.flags & KVM_XEN_HVM_CONFIG_EVTCHN_SEND))
1427 return false;
1428
1429 if (IS_ENABLED(CONFIG_64BIT) && !longmode) {
1430 struct compat_sched_poll sp32;
1431
1432 /* Sanity check that the compat struct definition is correct */
1433 BUILD_BUG_ON(sizeof(sp32) != 16);
1434
1435 if (kvm_read_guest_virt(vcpu, param, &sp32, sizeof(sp32), &e)) {
1436 *r = -EFAULT;
1437 return true;
1438 }
1439
1440 /*
1441 * This is a 32-bit pointer to an array of evtchn_port_t which
1442 * are uint32_t, so once it's converted no further compat
1443 * handling is needed.
1444 */
1445 sched_poll.ports = (void *)(unsigned long)(sp32.ports);
1446 sched_poll.nr_ports = sp32.nr_ports;
1447 sched_poll.timeout = sp32.timeout;
1448 } else {
1449 if (kvm_read_guest_virt(vcpu, param, &sched_poll,
1450 sizeof(sched_poll), &e)) {
1451 *r = -EFAULT;
1452 return true;
1453 }
1454 }
1455
1456 if (unlikely(sched_poll.nr_ports > 1)) {
1457 /* Xen (unofficially) limits number of pollers to 128 */
1458 if (sched_poll.nr_ports > 128) {
1459 *r = -EINVAL;
1460 return true;
1461 }
1462
1463 ports = kmalloc_array(sched_poll.nr_ports,
1464 sizeof(*ports), GFP_KERNEL);
1465 if (!ports) {
1466 *r = -ENOMEM;
1467 return true;
1468 }
1469 } else
1470 → ports = &port;
1471
1472 if (kvm_read_guest_virt(vcpu, (gva_t)sched_poll.ports, ports,
1473 sched_poll.nr_ports * sizeof(*ports), &e)) {
1474 *r = -EFAULT;
1475 return true;
1476 }
1477
1478 for (i = 0; i < sched_poll.nr_ports; i++) {
1479 if (ports[i] >= max_evtchn_port(vcpu->kvm)) {
1480 *r = -EINVAL;
1481 goto out;
1482 }
1483 }
1484
1485 if (sched_poll.nr_ports == 1)
1486 → vcpu->arch.xen.poll_evtchn = port;
1487 else
1488 vcpu->arch.xen.poll_evtchn = -1;
1489
1490 set_bit(vcpu->vcpu_idx, vcpu->kvm->arch.xen.poll_mask);
1491
1492 if (!wait_pending_event(vcpu, sched_poll.nr_ports, ports)) {
1493 vcpu->arch.mp_state = KVM_MP_STATE_HALTED;
1494
1495 if (sched_poll.timeout)
1496 mod_timer(&vcpu->arch.xen.poll_timer,
1497 jiffies + nsecs_to_jiffies(sched_poll.timeout));
1498
1499 kvm_vcpu_halt(vcpu);
1500
1501 if (sched_poll.timeout)
1502 del_timer(&vcpu->arch.xen.poll_timer);
1503
1504 vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
1505 }
1506
1507 → vcpu->arch.xen.poll_evtchn = 0;
1508 *r = 0;
1509 out:
1510 /* Really, this is only needed in case of timeout */
1511 clear_bit(vcpu->vcpu_idx, vcpu->kvm->arch.xen.poll_mask);
1512
1513 if (unlikely(sched_poll.nr_ports > 1))
1514 kfree(ports);
1515 return true;
1516 }
--------------------
Hope this helps.
Best regards,
Mirsad Todorovac
