From: Sean Christopherson <seanjc@google.com>
To: Wei Wang <wei.w.wang@intel.com>
Cc: pbonzini@redhat.com, mhal@rbox.co, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] KVM: destruct kvm_io_device while unregistering it from kvm_io_bus
Date: Thu, 23 Mar 2023 08:43:34 -0700 [thread overview]
Message-ID: <ZBxzphnyLPwBimKL@google.com> (raw)
In-Reply-To: <20230207123713.3905-2-wei.w.wang@intel.com>
On Tue, Feb 07, 2023, Wei Wang wrote:
> Current usage of kvm_io_device requires users to destruct it with an extra
> call of kvm_iodevice_destructor after the device gets unregistered from
> kvm_io_bus. This is not necessary and can cause errors if a user forgot
> to make the extra call.
>
> Simplify the usage by combining kvm_iodevice_destructor into
> kvm_io_bus_unregister_dev. This reduces LOCs a bit for users and can
> avoid the leakage of destructing the device explicitly.
The changelog should really call out that coalesced_mmio_ops and ioeventfd_ops
are the only kvm_io_device_ops instances that implement ->destructor. Without
that info, this change looks super dangerous as it's not obvious other paths won't
end up with a use-after-free.
Paolo, if/when you take this, can you tack on something like:
Note, coalesced_mmio_ops and ioeventfd_ops are the only instances of
kvm_io_device_ops that implement a destructor, all other callers of
kvm_io_bus_unregister_dev() are unaffected by this change.
> Signed-off-by: Wei Wang <wei.w.wang@intel.com>
> ---
Reviewed-by: Sean Christopherson <seanjc@google.com>
next prev parent reply other threads:[~2023-03-23 15:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-07 12:37 [PATCH v2 0/2] kvm_io_bus_unregister_dev cleanup Wei Wang
2023-02-07 12:37 ` [PATCH v2 1/2] KVM: destruct kvm_io_device while unregistering it from kvm_io_bus Wei Wang
2023-03-23 15:43 ` Sean Christopherson [this message]
2023-02-07 12:37 ` [PATCH v2 2/2] kvm/eventfd: use list_for_each_entry when deassign ioeventfd Wei Wang
2023-03-23 15:30 ` Sean Christopherson
2023-06-13 23:21 ` [PATCH v2 0/2] kvm_io_bus_unregister_dev cleanup Sean Christopherson
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