Re: [PATCH] virtio-spec: add field for scsi command size

[Paolo Bonzini <pbonzini@redhat.com>]

Il 14/03/2013 12:10, Michael S. Tsirkin ha scritto:
> Add field for guest to specify command size for virtio-blk.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  virtio-spec.lyx | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 78 insertions(+), 5 deletions(-)
> 
> diff --git a/virtio-spec.lyx b/virtio-spec.lyx
> index a8ce3f9..fea97ed 100644
> --- a/virtio-spec.lyx
> +++ b/virtio-spec.lyx
> @@ -5826,6 +5826,16 @@ VIRTIO_BLK_F_TOPOLOGY (10) Device exports information on optimal I/O alignment.
>  \change_inserted 1531152142 1341302349
>  VIRTIO_BLK_F_CONFIG_WCE (11) Device can toggle its cache between writeback
>   and writethrough modes.
> +\change_inserted 1986246365 1363257418
> +
> +\end_layout
> +
> +\begin_layout Description
> +
> +\change_inserted 1986246365 1363258629
> +VIRTIO_BLK_F_CMD_SIZE (12) cmd_size field is valid.

SCSI_CMD_SIZE and scsi_cmd_size please.

> +\change_inserted 1531152142 1341302349
> +
>  \end_layout
>  
>  \end_deeper
> @@ -5994,6 +6004,30 @@ struct virtio_blk_config {
>  \change_inserted 1531152142 1341301918
>  
>      u8 writeback;
> +\change_inserted 1986246365 1363257385
> +
> +\end_layout
> +
> +\begin_layout Plain Layout
> +
> +\change_inserted 1986246365 1363258610
> +
> +    u8 reserved[3];
> +\end_layout
> +
> +\begin_layout Plain Layout
> +
> +\change_inserted 1986246365 1363259147
> +
> +    // buffer length for cmd field in requests.

size of the cmd field in VIRTIO_BLK_T_SCSI_CMD requests.

> + reset value 0.
> +\end_layout
> +
> +\begin_layout Plain Layout
> +
> +\change_inserted 1986246365 1363257810
> +
> +    u32 cmd_size;

scsi_cmd_size

>  \change_unchanged
>  
>  \end_layout
> @@ -6085,6 +6119,21 @@ Until version 1.1, QEMU remained in writeback mode even after a guest announced
>  \end_inset
>  
>  .
> +\change_inserted 1986246365 1363258989
> +
> +\end_layout
> +
> +\begin_layout Enumerate
> +
> +\change_inserted 1986246365 1363259237
> +If VIRTIO_BLK_F_SCSI_CMD_SIZE is negotiated, Guest should set the desired
> + size for scsi commands to the 

If both VIRTIO_BLK_F_SCSI and VIRTIO_BLK_F_SCSI_CMD_SIZE are negotiated,
the driver should write a non-zero value to the scsi_cmd_size field
before sending a VIRTIO_BLK_T_SCSI_CMD request.

> +\emph on
> +cmd_size 
> +\emph default
> +field.
> +\change_unchanged
> +
>  \end_layout
>  
>  \begin_layout Section*
> @@ -6369,8 +6418,33 @@ cmd
>  \emph default
>   field is only present for scsi packet command requests, and indicates the
>   command to perform.
> - This field must reside in a single, separate read-only buffer; command
> - length can be derived from the length of this buffer.
> + 
> +\change_inserted 1986246365 1363258881
> +If VIRTIO_BLK_F_SCSI_CMD_SIZE feature bit is negotiated, Guest must set
> + the command length by writing it to the cmd_size field in configuration
> + space

If the VIRTIO_BLK_F_SCSI_CMD_SIZE feature bit is negotiated, the driver
should write the length of the cmd field to the scsi_cmd_size field of
the configuration space.

(please make sure bold and emphasis are consistent)

> +\begin_inset Foot
> +status open
> +
> +\begin_layout Plain Layout
> +
> +\change_inserted 1986246365 1363258931
> +Guest should always set cmd_size during initialization.

scsi_cmd_size

> +\change_unchanged
> +
> +\end_layout
> +
> +\end_inset
> +
> +.
> + If VIRTIO_BLK_F_SCSI_CMD_SIZE is not negotiated, 
> +\change_deleted 1986246365 1363258703
> +T
> +\change_inserted 1986246365 1363258703
> +t
> +\change_unchanged
> +his field must reside in a single, separate read-only buffer; command length
> + can be derived from the length of this buffer.

the command length...

>   
>  \end_layout
>  
> 

Thanks,

Paolo