Re: [PATCH v1 2/4] virtio: make seg_max virtqueue size dependent

[Michael S. Tsirkin]

On Tue, Nov 05, 2019 at 07:11:03PM +0300, Denis Plotnikov wrote:
> seg_max has a restriction to be less or equal to virtqueue size
> according to Virtio 1.0 specification
> 
> Although seg_max can't be set directly, it's worth to express this
> dependancy directly in the code for sanity purpose.
> 
> Signed-off-by: Denis Plotnikov <address@hidden>

This is guest visible so needs to be machine type dependent, right?

> ---
>  hw/block/virtio-blk.c | 2 +-
>  hw/scsi/virtio-scsi.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 06e57a4d39..21530304cf 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -903,7 +903,7 @@ static void virtio_blk_update_config(VirtIODevice *vdev, 
> uint8_t *config)
>      blk_get_geometry(s->blk, &capacity);
>      memset(&blkcfg, 0, sizeof(blkcfg));
>      virtio_stq_p(vdev, &blkcfg.capacity, capacity);
> -    virtio_stl_p(vdev, &blkcfg.seg_max, 128 - 2);
> +    virtio_stl_p(vdev, &blkcfg.seg_max, s->conf.queue_size - 2);
>      virtio_stw_p(vdev, &blkcfg.geometry.cylinders, conf->cyls);
>      virtio_stl_p(vdev, &blkcfg.blk_size, blk_size);
>      virtio_stw_p(vdev, &blkcfg.min_io_size, conf->min_io_size / blk_size);
> diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
> index 839f120256..f7e5533cd5 100644
> --- a/hw/scsi/virtio-scsi.c
> +++ b/hw/scsi/virtio-scsi.c
> @@ -650,7 +650,7 @@ static void virtio_scsi_get_config(VirtIODevice *vdev,
>      VirtIOSCSICommon *s = VIRTIO_SCSI_COMMON(vdev);
>  
>      virtio_stl_p(vdev, &scsiconf->num_queues, s->conf.num_queues);
> -    virtio_stl_p(vdev, &scsiconf->seg_max, 128 - 2);
> +    virtio_stl_p(vdev, &scsiconf->seg_max, s->conf.virtqueue_size - 2);
>      virtio_stl_p(vdev, &scsiconf->max_sectors, s->conf.max_sectors);
>      virtio_stl_p(vdev, &scsiconf->cmd_per_lun, s->conf.cmd_per_lun);
>      virtio_stl_p(vdev, &scsiconf->event_info_size, sizeof(VirtIOSCSIEvent));
> -- 
> 2.17.0