Re: [PATCH 2/5] virtio: Don't expose legacy block features when VIRTIO_BLK_NO_LEGACY defined.

[Michael S. Tsirkin]

On Fri, Feb 06, 2015 at 03:36:53PM +1030, Rusty Russell wrote:
> This allows modern implementations to ensure they don't use legacy
> feature bits or SCSI commands (which are not used in v1.0 non-legacy).
> 
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

> ---
>  include/uapi/linux/virtio_blk.h | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h
> index 247c8ba8544a..3c53eec4ae22 100644
> --- a/include/uapi/linux/virtio_blk.h
> +++ b/include/uapi/linux/virtio_blk.h
> @@ -31,22 +31,25 @@
>  #include <linux/virtio_types.h>
>  
>  /* Feature bits */
> -#define VIRTIO_BLK_F_BARRIER	0	/* Does host support barriers? */
>  #define VIRTIO_BLK_F_SIZE_MAX	1	/* Indicates maximum segment size */
>  #define VIRTIO_BLK_F_SEG_MAX	2	/* Indicates maximum # of segments */
>  #define VIRTIO_BLK_F_GEOMETRY	4	/* Legacy geometry available  */
>  #define VIRTIO_BLK_F_RO		5	/* Disk is read-only */
>  #define VIRTIO_BLK_F_BLK_SIZE	6	/* Block size of disk is available*/
> -#define VIRTIO_BLK_F_SCSI	7	/* Supports scsi command passthru */
> -#define VIRTIO_BLK_F_WCE	9	/* Writeback mode enabled after reset */
>  #define VIRTIO_BLK_F_TOPOLOGY	10	/* Topology information is available */
> -#define VIRTIO_BLK_F_CONFIG_WCE	11	/* Writeback mode available in config */
>  #define VIRTIO_BLK_F_MQ		12	/* support more than one vq */
>  
> +/* Legacy feature bits */
> +#ifndef VIRTIO_BLK_NO_LEGACY
> +#define VIRTIO_BLK_F_BARRIER	0	/* Does host support barriers? */
> +#define VIRTIO_BLK_F_SCSI	7	/* Supports scsi command passthru */
> +#define VIRTIO_BLK_F_WCE	9	/* Writeback mode enabled after reset */
> +#define VIRTIO_BLK_F_CONFIG_WCE	11	/* Writeback mode available in config */
>  #ifndef __KERNEL__
>  /* Old (deprecated) name for VIRTIO_BLK_F_WCE. */
>  #define VIRTIO_BLK_F_FLUSH VIRTIO_BLK_F_WCE
>  #endif
> +#endif /* !VIRTIO_BLK_NO_LEGACY */
>  
>  #define VIRTIO_BLK_ID_BYTES	20	/* ID string length */
>  
> @@ -100,8 +103,10 @@ struct virtio_blk_config {
>  #define VIRTIO_BLK_T_IN		0
>  #define VIRTIO_BLK_T_OUT	1
>  
> +#ifndef VIRTIO_BLK_NO_LEGACY
>  /* This bit says it's a scsi command, not an actual read or write. */
>  #define VIRTIO_BLK_T_SCSI_CMD	2
> +#endif /* VIRTIO_BLK_NO_LEGACY */
>  
>  /* Cache flush command */
>  #define VIRTIO_BLK_T_FLUSH	4
> @@ -109,8 +114,10 @@ struct virtio_blk_config {
>  /* Get device ID command */
>  #define VIRTIO_BLK_T_GET_ID    8
>  
> +#ifndef VIRTIO_BLK_NO_LEGACY
>  /* Barrier before this op. */
>  #define VIRTIO_BLK_T_BARRIER	0x80000000
> +#endif /* !VIRTIO_BLK_NO_LEGACY */
>  
>  /* This is the first element of the read scatter-gather list. */
>  struct virtio_blk_outhdr {
> @@ -122,12 +129,14 @@ struct virtio_blk_outhdr {
>  	__virtio64 sector;
>  };
>  
> +#ifndef VIRTIO_BLK_NO_LEGACY
>  struct virtio_scsi_inhdr {
>  	__virtio32 errors;
>  	__virtio32 data_len;
>  	__virtio32 sense_len;
>  	__virtio32 residual;
>  };
> +#endif /* !VIRTIO_BLK_NO_LEGACY */
>  
>  /* And this is the final byte of the write scatter-gather list. */
>  #define VIRTIO_BLK_S_OK		0
> -- 
> 2.1.0
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