Re: [PATCH v13] virtio-net: support inner header hash

[Heng Qi <hengqi@linux.alibaba.com>]

å 2023/4/26 äå4:28, Parav Pandit åé:
> On 4/23/2023 3:35 AM, Heng Qi wrote:
> > Â Â \subsubsection{Legacy Interface: Feature bits}\label{sec:Device 
> > Types / Network Device / Feature bits / Legacy Interface: Feature bits}
> > @@ -198,6 +202,7 @@ \subsection{Device configuration 
> > layout}\label{sec:Device Types / Network Device
> > ÂÂÂÂÂÂÂÂÂ u8 rss_max_key_size;
> > ÂÂÂÂÂÂÂÂÂ le16 rss_max_indirection_table_length;
> > ÂÂÂÂÂÂÂÂÂ le32 supported_hash_types;
> > +ÂÂÂÂÂÂÂ le32 supported_tunnel_hash_types;
> > Â };
> In v12 I was asking this to move to above field from the config area 
> to the GET command in comment [1] as,
>
> "With that no need to define two fields at two different places in 
> config area and also in cvq."

I'm not sure if this is sufficiently motivated, RSS also has 
supports_hash_types in config space.

We don't actually need cvq and config to sync on 
supported_tunnel_hash_types, since it doesn't need to change (meaning 
supported_tunnel_hash_types doesn't send configuration change 
notifications).

> I am sorry if that was not clear enough.
>
> [1] 
> 569cbaf9-f1fb-0e1f-a2ef-b1d7cd7dbb1f@nvidia.com/">https://lore.kernel.org/virtio-dev/569cbaf9-f1fb-0e1f-a2ef-b1d7cd7dbb1f@nvidia.com/
>
> > Â \subparagraph{Supported/enabled hash types}
> > Â \label{sec:Device Types / Network Device / Device Operation / 
> > Processing of Incoming Packets / Hash calculation for incoming 
> > packets / Supported/enabled hash types}
> > +This paragraph relies on definitions from \hyperref[intro:IP]{[IP]}, 
> > \hyperref[intro:UDP]{[UDP]} and \hyperref[intro:TCP]{[TCP]}.
> > Â Hash types applicable for IPv4 packets:
> > Â \begin{lstlisting}
> > Â #define VIRTIO_NET_HASH_TYPE_IPv4ÂÂÂÂÂÂÂÂÂÂÂÂÂ (1 << 0)
> > @@ -980,6 +993,152 @@ \subsubsection{Processing of Incoming 
> > Packets}\label{sec:Device Types / Network
> > Â (see \ref{sec:Device Types / Network Device / Device Operation / 
> > Processing of Incoming Packets / Hash calculation for incoming 
> > packets / IPv6 packets without extension header}).
> > Â \end{itemize}
> > Â +\paragraph{Inner Header Hash}
> > +\label{sec:Device Types / Network Device / Device Operation / 
> > Processing of Incoming Packets / Inner Header Hash}
> > +
> > +If VIRTIO_NET_F_HASH_TUNNEL has been negotiated, the device supports 
> > inner header hash and the driver can send
> > +commands VIRTIO_NET_CTRL_TUNNEL_HASH_SET and 
> > VIRTIO_NET_CTRL_TUNNEL_HASH_GET for the inner header hash configuration.
> > +
> > +struct virtio_net_hash_tunnel_config {
> Please move field from the config struct to here. Both are RO fields.
>
> le32 supported_hash_tunnel_types;
> > +ÂÂÂ le32 hash_tunnel_types;
> > +};
> > +
> > +#define VIRTIO_NET_CTRL_TUNNEL_HASH 7
> > + #define VIRTIO_NET_CTRL_TUNNEL_HASH_SET 0
> > + #define VIRTIO_NET_CTRL_TUNNEL_HASH_GET 1
> > +
> > +Filed \field{hash_tunnel_types} contains a bitmask of configured 
> > hash tunnel types as
> > +defined in \ref{sec:Device Types / Network Device / Device Operation 
> > / Processing of Incoming Packets / Hash calculation for incoming 
> > packets / Supported/enabled hash tunnel types}.
> > +
> > +The class VIRTIO_NET_CTRL_TUNNEL_HASH has the following commands:
> > +\begin{itemize}
> > +\item VIRTIO_NET_CTRL_TUNNEL_HASH_SET: set the 
> > \field{hash_tunnel_types} to configure the inner header hash 
> > calculation for the device.
> > +\item VIRTIO_NET_CTRL_TUNNEL_HASH_GET: get the 
> > \field{hash_tunnel_types} from the device.
> > +\end{itemize}
> > +
> > +For the command VIRTIO_NET_CTRL_TUNNEL_HASH_SET, the structure 
> > virtio_net_hash_tunnel_config is write-only for the driver.
> > +For the command VIRTIO_NET_CTRL_TUNNEL_HASH_GET, the structure 
> > virtio_net_hash_tunnel_config is read-only for the driver.
> > +
> You need to split the structures to two, one for get and one for set 
> in above description as get and set contains different fields.
> > +
> > +If VIRTIO_NET_HASH_TUNNEL_TYPE_NONE is set or the encapsulation type 
> > is not included in \field{hash_tunnel_types},
> > +the hash of the outer header is calculated for the received 
> > encapsulated packet.
> > +
> > +
> > +For scenarios with sufficient external entropy or no internal 
> > hashing requirements, inner header hash may not be needed:
> > +A tunnel is often expected to isolate the external network from the 
> > internal one. By completely ignoring entropy
> > +in the external header and replacing it with entropy from the 
> > internal header, for hash calculations, this expectation
> You wanted to say inner here like rest of the places.
>
> s/internal header/inner header

I want to make the 'external' and 'internal' correspond, but avoid the 
internal header, and use a unified 'inner header' is also reasonable.:)

> > +The driver MUST NOT set any VIRTIO_NET_HASH_TUNNEL_TYPE_ flags that 
> > are not supported by the device.
> Multiple flags so,
>
> s/flags that are/flags which are/

Will fix.

Thanks!