Hi all,

There are checks of ioeventfd collision in both kvm_assign_ioeventfd_idx()
and kvm_deassign_ioeventfd_idx(), however, with different logic.

In kvm_assign_ioeventfd_idx(), this is done by ioeventfd_check_collision():
---8<---
        if (_p->bus_idx == p->bus_idx &&
            _p->addr == p->addr &&
            (!_p->length || !p->length ||
             (_p->length == p->length &&
              (_p->wildcard || p->wildcard ||
               _p->datamatch == p->datamatch))))
                // then we consider the two are the same
---8<---

The logic in kvm_deassign_ioeventfd_idx() is as follows:
---8<---
        if (p->bus_idx != bus_idx ||
            p->eventfd != eventfd  ||
            p->addr != args->addr  ||
            p->length != args->len ||
            p->wildcard != wildcard)
                continue;

        if (!p->wildcard && p->datamatch != args->datamatch)
                continue;

        // then we consider the two are the same
---8<---

As we can see, there is extra check of p->eventfd in

().  Why we don't check p->eventfd
in kvm_assign_ioeventfd_idx()? Or should we delete this in
kvm_deassign_ioeventfd_idx()?


Thanks,
Zhenyu