From: Cornelia Huck <cohuck@redhat.com>
To: Heng Qi <hengqi@linux.alibaba.com>, Jason Wang <jasowang@redhat.com>
Cc: mst@redhat.com, xuanzhuo@linux.alibaba.com,
kangjie.xu@linux.alibaba.com, virtio-dev@lists.oasis-open.org
Subject: Re: [virtio-dev] Re: [PATCH] virtio_net: support split header
Date: Thu, 04 Aug 2022 15:50:16 +0200 [thread overview]
Message-ID: <87bkt086ef.fsf@redhat.com> (raw)
In-Reply-To: <8ab46a3e-8f00-e05f-0dca-d0009164aa16@linux.alibaba.com>
On Thu, Aug 04 2022, Heng Qi <hengqi@linux.alibaba.com> wrote:
> 在 2022/8/4 下午2:27, Jason Wang 写道:
>> On Mon, Aug 1, 2022 at 2:59 PM Heng Qi<hengqi@linux.alibaba.com> wrote:
>>> @@ -3820,9 +3826,13 @@ \subsubsection{Processing of Incoming Packets}\label{sec:Device Types / Network
>>> driver MUST NOT use the \field{csum_start} and \field{csum_offset}.
>>>
>>> If one of the VIRTIO_NET_F_GUEST_TSO4, TSO6, UFO, USO4 or USO6 options have
>>> -been negotiated, the driver MAY use \field{hdr_len} only as a hint about the
>>> +been negotiated and the VIRTIO_NET_HDR_F_SPLIT_HEADER bit in \field{flags}
>>> +is not set, the driver MAY use \field{hdr_len} only as a hint about the
>>> transport header size.
>>> -The driver MUST NOT rely on \field{hdr_len} to be correct.
>>> +
>>> +If the VIRTIO_NET_HDR_F_SPLIT_HEADER bit in \field{flags} is not set, the driver
>>> +MUST NOT rely on \field{hdr_len} to be correct.
>> I think we should keep the above description as-is. For whatever case,
>> the driver must not trust the metadata set by the device and must
>> perform necessary sanity tests on them.
>
>
> My idea is to keep the current description as it is,
> but to emphasize in the next version:
> "If the VIRTIO_NET_HDR_F_SPLIT_HEADER bit in \field{flags} is set,
> the driver MAY treat the \field{hdr_len} as the length of the
> protocol header inside the first descriptor."
Just to be clear, you suggest using
"If one of the VIRTIO_NET_F_GUEST_TSO4, TSO6, UFO, USO4 or USO6 options have
been negotiated, the driver MAY use \field{hdr_len} only as a hint about the
transport header size.
The driver MUST NOT rely on \field{hdr_len} to be correct.
If the VIRTIO_NET_HDR_F_SPLIT_HEADER bit in \field{flags} is set,
the driver MAY treat the \field{hdr_len} as the length of the
protocol header inside the first descriptor."
(Maybe "...the driver MAY use \field{hdr_len} as a hint about the length
of the protocol header..."? It's still not reliable, right?)
>
>
>>
>>> +
>>> \begin{note}
>>> This is due to various bugs in implementations.
>>> \end{note}
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next prev parent reply other threads:[~2022-08-04 13:50 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-01 6:59 [virtio-dev] [PATCH] virtio_net: support split header Heng Qi
2022-08-01 8:28 ` [virtio-dev] " Heng Qi
2022-08-04 6:27 ` Jason Wang
2022-08-04 13:01 ` Heng Qi
2022-08-04 13:50 ` Cornelia Huck [this message]
2022-08-05 5:59 ` Heng Qi
2022-08-09 15:33 ` Cornelia Huck
2022-08-11 9:01 ` Xuan Zhuo
[not found] ` <4ea77b4a-2571-2b12-433c-2f1a8ceaeff8@linux.alibaba.com>
[not found] ` <CACGkMEvTr44xhziEwMhCpAVp4dWDPvGHfkwGm+o4WRqsKBX=gw@mail.gmail.com>
2022-08-10 9:10 ` Heng Qi
-- strict thread matches above, loose matches on Subject: below --
2022-02-16 3:01 [virtio-dev] " Xuan Zhuo
2022-02-16 4:32 ` [virtio-dev] " Jason Wang
2022-02-16 6:05 ` Xuan Zhuo
2022-02-17 7:01 ` Jason Wang
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