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Subject[Question] the check of ioeventfd collision in kvm_*assign_ioeventfd_idx
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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

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