Re: [Qemu-devel] [virtio-dev] [PATCH v18 1/2] virtio-crypto: Add virtio crypto device specification

[Stefan Hajnoczi]

On Sat, Apr 22, 2017 at 02:23:50PM +0800, Gonglei wrote:
> +Dataq requests for both session and stateless modes are as follows:
> +
> +\begin{lstlisting}
> +struct virtio_crypto_op_data_req_mux {
> +    struct virtio_crypto_op_header header;
> +
> +    union {
> +        struct virtio_crypto_sym_data_req   sym_req;
> +        struct virtio_crypto_hash_data_req  hash_req;
> +        struct virtio_crypto_mac_data_req   mac_req;
> +        struct virtio_crypto_aead_data_req  aead_req;
> +        struct virtio_crypto_sym_data_req_stateless   sym_stateless_req;
> +        struct virtio_crypto_hash_data_req_stateless  hash_stateless_req;
> +        struct virtio_crypto_mac_data_req_stateless   mac_stateless_req;
> +        struct virtio_crypto_aead_data_req_stateless  aead_stateless_req;
> +    } u;
> +};
> +\end{lstlisting}

Halil touched on this in the discussion: this spec uses a C-like struct
syntax but does not define whether unions really affect sizeof(mystruct)
like they would in C or whether you just mean that any of the union
fields can be used.  This distinction is important so device and driver
authors understand the exact memory layout of requests and responses.

Please include an explanation about the meaning of "union" in the text.

> +Session mode MAC service requests are as follows:
> +
> +\begin{lstlisting}
> +struct virtio_crypto_mac_para {
> +    struct virtio_crypto_hash_para hash;
> +};
> +
> +struct virtio_crypto_mac_data_req {
> +    /* Device-readable part */
> +    struct virtio_crypto_mac_para para;
> +    /* Source data */
> +    u8 src_data[src_data_len];
> +
> +    /* Device-writable part */
> +    /* Hash result data */
> +    u8 hash_result[hash_result_len];
> +    struct virtio_crypto_inhdr inhdr;
> +};
> +\end{lstlisting}
> +
> +Each data request uses virtio_crypto_mac_data_req structure to store 
> information

"Each request uses the virtio_crypto_mac_data_req structure to store
information"

> +Session mode requests of symmetric algorithm are as follows:
> +
> +\begin{lstlisting}
> +struct virtio_crypto_sym_data_req {
> +    union {
> +        struct virtio_crypto_cipher_data_req cipher;
> +        struct virtio_crypto_alg_chain_data_req chain;
> +    } u;
> +
> +    /* Device-readable part */
> +
> +    /* See above VIRTIO_CRYPTO_SYM_OP_* */
> +    le32 op_type;
> +    le32 padding;
> +};
> +\end{lstlisting}
> +
> +Each data request uses virtio_crypto_sym_data_req structure to store 
> information

s/virtio_crypto_sym_data_req structure/the virtio_crypto_sym_data_req structure/

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