On Thu, Aug 04 2022, Heng Qi <[email protected]> wrote:
> 在 2022/8/4 下午2:27, Jason Wang 写道:
>> On Mon, Aug 1, 2022 at 2:59 PM Heng Qi<[email protected]> 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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