Re: [virtio-comment] Re: [virtio-dev] Re: [virtio-comment] Re: [PATCH v5] virtio-net: device does not deliver partially checksummed packet and may validate the checksum

[Jason Wang <jasowang@redhat.com>]

On Thu, Dec 21, 2023 at 11:45âAM Heng Qi <hengqi@linux.alibaba.com> wrote:
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> å 2023/12/21 äå9:34, Jason Wang åé:
> > On Wed, Dec 20, 2023 at 3:35âPM Michael S. Tsirkin <mst@redhat.com> wrote:
> >> On Wed, Dec 20, 2023 at 02:30:01PM +0800, Heng Qi wrote:
> >>> But why are we discussing this?
> >> I think basically at this point everyone is confused about what
> >> the feature does. right now we have packets
> >> with
> >> #define VIRTIO_NET_HDR_F_NEEDS_CSUM     1       -> partial
> >> #define VIRTIO_NET_HDR_F_DATA_VALID     2       -> unnecessary
> >> and packets without either                      -> none
> >>
> >> if both 1 and 2 are set then linux uses VIRTIO_NET_HDR_F_NEEDS_CSUM but
> >> I am not sure it's not a mistake. Maybe it does not matter.
> >>
> >> What does this new thing do? So far all we have is "XDP will turn it on"
> >> which is not really sufficient. I assumed it somehow replaces
> >> partial with complete.
> > It looks not? CHECKSUM_COMPLETE is less optimal than
> > CHECKSUM_UNNCESSARY as validation is still needed.
> >
> > If I understand correctly, this new thing wants DATA_VALID only.
>
> Disable NEEDS_CSUM or calculate fully checksummed packets to fully
> checksummed packets (how this is done does not matter).
> The driver will only receive two types of packets: CHECKSUM_NONE and
> DATA_VALID (CHECKSUM_UNNECESSARY).

Right, this is my understanding as well.

Thanks

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> Thanksï
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> >
> > Thanks
> >
> >
> >
> >> That would make sense for many reasons,
> >> for example the checksum fields in the header can be reused
> >> for other purposes. But maybe not?
> >>
> >>
> >> --
> >> MST
> >>
>