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Message-ID: <bbece68b-fb39-d599-9ba7-a8ee8be16525@huawei.com>
Date: Thu, 30 Jul 2020 22:19:49 +0800
From: Zhenyu Ye <yezhenyu2@...wei.com>
To: <pbonzini@...hat.com>, <mst@...hat.com>, <gleb@...hat.com>,
<linux-kernel@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>, <kvm@...r.kernel.org>,
<kvmarm@...ts.cs.columbia.edu>,
Xiexiangyou <xiexiangyou@...wei.com>, <ghaskins@...ell.com>
Subject: [Question] the check of ioeventfd collision in
kvm_*assign_ioeventfd_idx
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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