Re: [Qemu-devel] [PATCH 3/5] virtio-ccw: use ccw data stream

[Cornelia Huck <cohuck@redhat.com>]

On Tue,  5 Sep 2017 13:16:43 +0200
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> Replace direct access which implicitly assumes no IDA
> or MIDA with the new ccw data stream interface which should
> cope with these transparently in the future.
> 
> Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> 
> ---
> 
> Error handling: At the moment we ignore errors reported
> by stream ops to keep the change minimal. It might make sense
> to change this.

Do that as an add-on patch?

> ---
>  hw/s390x/virtio-ccw.c | 158 +++++++++++++++-----------------------------------
>  1 file changed, 48 insertions(+), 110 deletions(-)
> 
> diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
> index b1976fdd19..72dd129a15 100644
> --- a/hw/s390x/virtio-ccw.c
> +++ b/hw/s390x/virtio-ccw.c
> @@ -287,49 +287,19 @@ static int virtio_ccw_handle_set_vq(SubchDev *sch, CCW1 ccw, bool check_len,
>          return -EFAULT;
>      }
>      if (is_legacy) {
> -        linfo.queue = address_space_ldq_be(&address_space_memory, ccw.cda,
> -                                           MEMTXATTRS_UNSPECIFIED, NULL);
> -        linfo.align = address_space_ldl_be(&address_space_memory,
> -                                           ccw.cda + sizeof(linfo.queue),
> -                                           MEMTXATTRS_UNSPECIFIED,
> -                                           NULL);
> -        linfo.index = address_space_lduw_be(&address_space_memory,
> -                                            ccw.cda + sizeof(linfo.queue)
> -                                            + sizeof(linfo.align),
> -                                            MEMTXATTRS_UNSPECIFIED,
> -                                            NULL);
> -        linfo.num = address_space_lduw_be(&address_space_memory,
> -                                          ccw.cda + sizeof(linfo.queue)
> -                                          + sizeof(linfo.align)
> -                                          + sizeof(linfo.index),
> -                                          MEMTXATTRS_UNSPECIFIED,
> -                                          NULL);
> +        ccw_dstream_read(&sch->cds, linfo);
> +        be64_to_cpus(&linfo.queue);
> +        be32_to_cpus(&linfo.align);
> +        be16_to_cpus(&linfo.index);
> +        be16_to_cpus(&linfo.num);

That's a very nice contraction :)

>          ret = virtio_ccw_set_vqs(sch, NULL, &linfo);
>      } else {
> -        info.desc = address_space_ldq_be(&address_space_memory, ccw.cda,
> -                                           MEMTXATTRS_UNSPECIFIED, NULL);
> -        info.index = address_space_lduw_be(&address_space_memory,
> -                                           ccw.cda + sizeof(info.desc)
> -                                           + sizeof(info.res0),
> -                                           MEMTXATTRS_UNSPECIFIED, NULL);
> -        info.num = address_space_lduw_be(&address_space_memory,
> -                                         ccw.cda + sizeof(info.desc)
> -                                         + sizeof(info.res0)
> -                                         + sizeof(info.index),
> -                                         MEMTXATTRS_UNSPECIFIED, NULL);
> -        info.avail = address_space_ldq_be(&address_space_memory,
> -                                          ccw.cda + sizeof(info.desc)
> -                                          + sizeof(info.res0)
> -                                          + sizeof(info.index)
> -                                          + sizeof(info.num),
> -                                          MEMTXATTRS_UNSPECIFIED, NULL);
> -        info.used = address_space_ldq_be(&address_space_memory,
> -                                         ccw.cda + sizeof(info.desc)
> -                                         + sizeof(info.res0)
> -                                         + sizeof(info.index)
> -                                         + sizeof(info.num)
> -                                         + sizeof(info.avail),
> -                                         MEMTXATTRS_UNSPECIFIED, NULL);
> +        ccw_dstream_read(&sch->cds, info);
> +        be64_to_cpus(&info.desc);
> +        be16_to_cpus(&info.index);
> +        be16_to_cpus(&info.num);
> +        be64_to_cpus(&info.avail);
> +        be64_to_cpus(&info.used);
>          ret = virtio_ccw_set_vqs(sch, &info, NULL);
>      }
>      sch->curr_status.scsw.count = 0;

(...)

> @@ -488,7 +446,8 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
>          } else {
>              virtio_bus_get_vdev_config(&dev->bus, vdev->config);
>              /* XXX config space endianness */

Unrelated: That should be fine, I guess?

> -            cpu_physical_memory_write(ccw.cda, vdev->config, len);
> +            /* TODO we may have made -EINVAL out of -EFAULT */

Eek.

> +            ccw_dstream_write_buf(&sch->cds, vdev->config, len);
>              sch->curr_status.scsw.count = ccw.count - len;
>              ret = 0;
>          }

Looks fine in general.