On Tue, 07 Jun 2022 15:10:18 +0200, Cornelia Huck <coh...@redhat.com> wrote: > On Mon, Jun 06 2022, Xuan Zhuo <xuanz...@linux.alibaba.com> wrote: > > > The purpose of this feature is to split the header and the payload of > > the packet. > > > > | receive buffer | > > | 0th descriptor | 1th descriptor | > > | virtnet hdr | mac | ip hdr | tcp hdr|<-- hold -->| payload | > > > > We can use a buffer plus a separate page when allocating the receive > > buffer. In this way, we can ensure that all payloads can be > > independently in a page, which is very beneficial for the zerocopy > > implemented by the upper layer. > > > > Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com> > > --- > > > > 1. Fix some syntax issues > > 2. Fix some terminology issues > > 3. It is not unified with ip alignment, so ip alignment is not included > > 4. Make it clear that the device must support four types, in the case of > > successful negotiation. > > > > conformance.tex | 2 ++ > > content.tex | 82 +++++++++++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 84 insertions(+) > > > > (...) > > > diff --git a/content.tex b/content.tex > > index 7508dd1..a5a29d2 100644 > > --- a/content.tex > > +++ b/content.tex > > @@ -3084,6 +3084,9 @@ \subsection{Feature bits}\label{sec:Device Types / > > Network Device / Feature bits > > \item[VIRTIO_NET_F_CTRL_MAC_ADDR(23)] Set MAC address through control > > channel. > > > > +\item[VIRTIO_NET_F_SPLIT_HEADER (55)] Device supports to split the protocol > > + header and the payload. > > Maybe s/supports to split/supports splitting/ ? > > > + > > \item[VIRTIO_NET_F_HOST_USO (56)] Device can receive USO packets. Unlike > > UFO > > (fragmenting the packet) the USO splits large UDP packet > > to several segments when each of these smaller packets has UDP header. > > @@ -3131,6 +3134,7 @@ \subsubsection{Feature bit > > requirements}\label{sec:Device Types / Network Device > > \item[VIRTIO_NET_F_CTRL_MAC_ADDR] Requires VIRTIO_NET_F_CTRL_VQ. > > \item[VIRTIO_NET_F_RSC_EXT] Requires VIRTIO_NET_F_HOST_TSO4 or > > VIRTIO_NET_F_HOST_TSO6. > > \item[VIRTIO_NET_F_RSS] Requires VIRTIO_NET_F_CTRL_VQ. > > +\item[VIRTIO_NET_F_SPLIT_HEADER] Requires VIRTIO_NET_F_CTRL_VQ. > > \end{description} > > > > \subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types / > > Network Device / Feature bits / Legacy Interface: Feature bits} > > @@ -3362,6 +3366,7 @@ \subsection{Device Operation}\label{sec:Device Types > > / Network Device / Device O > > #define VIRTIO_NET_HDR_F_NEEDS_CSUM 1 > > #define VIRTIO_NET_HDR_F_DATA_VALID 2 > > #define VIRTIO_NET_HDR_F_RSC_INFO 4 > > +#define VIRTIO_NET_HDR_F_SPLIT_HEADER 8 > > u8 flags; > > #define VIRTIO_NET_HDR_GSO_NONE 0 > > #define VIRTIO_NET_HDR_GSO_TCPV4 1 > > @@ -4463,6 +4468,83 @@ \subsubsection{Control Virtqueue}\label{sec:Device > > Types / Network Device / Devi > > according to the native endian of the guest rather than > > (necessarily when not using the legacy interface) little-endian. > > > > +\paragraph{Split Header}\label{sec:Device Types / Network Device / Device > > Operation / Control Virtqueue / Split Header} > > + > > +If the VIRTIO_NET_F_SPLIT_HEADER feature is negotiated, > > +the device supports to split the protocol header and the payload. > > s/supports to split/supports splitting/ ? > > > +The protocol header and the payload will be separated into different > > +descriptors. > > + > > +\subparagraph{Split Header}\label{sec:Device Types / Network Device / > > Device Operation / Control Virtqueue / Split Header / Setting Split Header} > > + > > +To configure the split header, the following layout structure and > > definitions > > +are used: > > + > > +\begin{lstlisting} > > +struct virtio_net_split_header_config { > > +#define VIRTIO_NET_SPLIT_HEADER_TYPE_TCP4 1 > > +#define VIRTIO_NET_SPLIT_HEADER_TYPE_TCP6 2 > > +#define VIRTIO_NET_SPLIT_HEADER_TYPE_UDP4 4 > > +#define VIRTIO_NET_SPLIT_HEADER_TYPE_UDP6 8 > > Maybe use the (1 << 0) etc. notation to make it clearer that these are > bits which can be set in different combinations? > > > + le64 type; > > +}; > > + > > +#define VIRTIO_NET_CTRL_SPLIT_HEADER 6 > > + #define VIRTIO_NET_CTRL_SPLIT_HEADER_SET 0 > > +\end{lstlisting} > > + > > +The class VIRTIO_NET_CTRL_SPLIT_HEADER has one command: > > +VIRTIO_NET_CTRL_SPLIT_HEADER_SET applies the new split header > > configuration. > > + > > +The driver can enable or disable the split header by setting or clearing > > Maybe better "The driver can enable or disable split header for > different protocols by..."? > > > +corresponding bits in \field{type}. > > + > > +The protocol header contains all headers before level 4 payload. For ip > > +fragmented packets, except for the first fragment, the protocol header only > > +contains all headers before level 3 payload. > > + > > +\devicenormative{\subparagraph}{Setting Split Header}{Device Types / > > Network Device / Device Operation / Control Virtqueue / Split Header} > > + > > +Split header MUST be disabled upon device reset. > > Maybe "A device MUST initialize \field{type} to 0, and MUST set it to 0 > upon device reset." ? > > > + > > +If VIRTIO_NET_F_SPLIT_HEADER is negotiated, the device MUST support > > +VIRTIO_NET_SPLIT_HEADER_TYPE_TCP4, VIRTIO_NET_SPLIT_HEADER_TYPE_TCP6, > > +VIRTIO_NET_SPLIT_HEADER_TYPE_UDP4, VIRTIO_NET_SPLIT_HEADER_TYPE_UDP6. > > + > > +A device MUST NOT perform split header in the following cases: > > Maybe s/perform split header/split the header/ ? > > > +\begin{itemize} > > + \item device does not recognize the protocol of the packet. > > + \item \field{type} does not include the protocol of the packet. > > + \item the buffer consists of only one descriptor. > > + \item the virtio net header and the protocol header exceeds the size > > + of the first descriptor. > > The sum of both, or either of them? > > > + \item If VIRTIO_NET_F_MRG_RXBUF is not negotiated and the size of the > > s/If/when/ ? > > > + payload exceeds the size of the buffer chain starting from the 2nd > > + descriptor. > > +\end{itemize} > > + > > +If the header is split by the device, the \field{flags} of structure > > +virtio_net_hdr MUST contains VIRTIO_NET_HDR_F_SPLIT_HEADER. The protocol > > header > > +MUST be on the buffer specified by the first descriptor, following the > > virtio > > +net header. The payload MUST starts from the buffer of the second > > descriptor. > > +The device MUST set \field{hdr_len} of structure virtio_net_hdr to the > > length of > > +the protocol header. > > + > > +If the header is split by the device, VIRTIO_NET_F_MRG_RXBUF is negotiated, > > +and the receive packet is spread over multiple buffers, when the device > > uses a > > +buffer other than the first, if the buffer consists of multiple > > descriptors, the > > +device MUST skip the buffer of the first descriptor, because the buffer of > > the > > +first descriptor is used to carry the protocol header. > > + > > +\drivernormative{\subparagraph}{Setting Split Header}{Device Types / > > Network Device / Device Operation / Control Virtqueue / Split Header} > > + > > +If VIRTIO_NET_HDR_F_SPLIT_HEADER bit in \field{flags} is set, the driver > > MUST > > s/If/If the/ > > > +trust \field{hdr_len}. > > What does "trust" mean? Something like "the driver MUST treat the > contents of \field{hdr_len} as the length of the packet"? > > > + > > +If the split header is enabled, the buffers submitted to receiveq by the > > +driver SHOULD at least be composed of two descriptors. The buffer > > specified by > > "SHOULD be composed of at least two descriptors"
Thanks. The next version will fix these issues. > > > +the first descriptor SHOULD be able to accommodate the virtio net header > > and the > > +protocol header. > > > > \subsubsection{Legacy Interface: Framing Requirements}\label{sec:Device > > Types / Network Device / Legacy Interface: Framing Requirements} > --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org