RE: [PATCH] net: pad virtio_net_ff_cap_data

> From: Michael S. Tsirkin <[email protected]>
> Sent: 19 November 2025 01:54 PM
> 
> struct virtio_net_ff_cap_data has 4 byte fields but the size is not a multiple of
> 4.  drivers can easily get it wrong since compilers tend to add padding to align
> such structures.
> 
> Since we are always allowed to pad or truncate admin commands, let's do just
> that here.
> 
> Fixes: 899bb0c ("virtio-net: Add flow filter capability")
> Cc: "Parav Pandit" <[email protected]>
> Signed-off-by: Michael S. Tsirkin <[email protected]>
> ---
>  device-types/net/description.tex | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/device-types/net/description.tex b/device-
> types/net/description.tex
> index 9833d16..0b4fcac 100644
> --- a/device-types/net/description.tex
> +++ b/device-types/net/description.tex
> @@ -3055,6 +3055,7 @@ \subsubsection{Flow filter}\label{sec:Device Types
> / Network Device / Device Ope
>          le32 rules_per_group_limit;
>          u8 last_rule_priority;
>          u8 selectors_per_classifier_limit;
> +        u8 reserved[2];
>  };
>  \end{lstlisting}
> 
Thanks for the fix.
We should align to the 8B boundary instead of 4B.
It should be reserved[6].

> @@ -3071,6 +3072,8 @@ \subsubsection{Flow filter}\label{sec:Device Types
> / Network Device / Device Ope  \field{selectors_per_classifier_limit} is the
> maximum number of selectors  that a classifier can have.
> 
> +\field{reserved} is reserved and set to zero.
> +
>  \subparagraph{VIRTIO_NET_FF_SELECTOR_CAP}
>  \label{par:Device Types / Network Device / Device Operation / Flow filter /
> Device and driver capabilities / VIRTIO-NET-FF-SELECTOR-CAP}
> 
> --
> MST