[Qemu-devel] Re: [PATCH 1/4] Add virtio disk identification support

[Anthony Liguori]

On 03/25/2010 12:32 AM, john cooper wrote:
> Add virtio-blk device id (s/n) support via virtio request.
> Remove artifacts of pci and ATA_IDENTIFY implementation
> relative to prior versions.
>
> Signed-off-by: john cooper<address@hidden>
> ---
>
> diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
> index 9915840..358b0af 100644
> --- a/hw/virtio-blk.c
> +++ b/hw/virtio-blk.c
> @@ -19,6 +19,8 @@
>   # include<scsi/sg.h>
>   #endif
>
> +#define min(a,b) ((a)<  (b) ? (a) : (b))
>    

We already have MIN().

> +
>   typedef struct VirtIOBlock
>   {
>       VirtIODevice vdev;
> @@ -28,6 +30,7 @@ typedef struct VirtIOBlock
>       QEMUBH *bh;
>       BlockConf *conf;
>       unsigned short sector_mask;
> +    char sn[BLOCK_SERIAL_STRLEN];
>   } VirtIOBlock;
>
>   static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
> @@ -317,6 +320,12 @@ static void virtio_blk_handle_request(VirtIOBlockReq *req,
>           virtio_blk_handle_flush(req);
>       } else if (req->out->type&  VIRTIO_BLK_T_SCSI_CMD) {
>           virtio_blk_handle_scsi(req);
> +    } else if (req->out->type&  VIRTIO_BLK_T_GET_ID) {
> +        VirtIOBlock *s = req->dev;
> +
> +        memcpy(req->elem.in_sg[0].iov_base, s->sn,
> +               min(req->elem.in_sg[0].iov_len, sizeof(s->sn)));
> +        virtio_blk_req_complete(req, VIRTIO_BLK_S_OK);
>       } else if (req->out->type&  VIRTIO_BLK_T_OUT) {
>           qemu_iovec_init_external(&req->qiov,&req->elem.out_sg[1],
>                                    req->elem.out_num - 1);
> @@ -496,6 +505,8 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, BlockConf 
> *conf)
>       bdrv_guess_geometry(s->bs,&cylinders,&heads,&secs);
>       bdrv_set_geometry_hint(s->bs, cylinders, heads, secs);
>
> +    strncpy(s->sn, drive_get_serial(s->bs), sizeof (s->sn));
> +
>    

Friends don't let friends use strncpy().

This actually will result in a non-NULL terminated string if 
drive_get_serial() returns a string larger than s->sn.  Use snprintf() 
instead.

Regards,

Anthony Liguori

>       s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
>
>       qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
> diff --git a/hw/virtio-blk.h b/hw/virtio-blk.h
> index 7a7ece3..fff46da 100644
> --- a/hw/virtio-blk.h
> +++ b/hw/virtio-blk.h
> @@ -59,6 +59,9 @@ struct virtio_blk_config
>   /* Flush the volatile write cache */
>   #define VIRTIO_BLK_T_FLUSH      4
>
> +/* return the device ID string */
> +#define VIRTIO_BLK_T_GET_ID     8
> +
>   /* Barrier before this op. */
>   #define VIRTIO_BLK_T_BARRIER    0x80000000
>
>