Re: [Qemu-devel] [PATCH 4/4] s390x/css: fix incorrect length indication

[Cornelia Huck <cohuck@redhat.com>]

On Fri,  8 Sep 2017 17:24:46 +0200
Halil Pasic <pasic@linux.vnet.ibm.com> wrote:

> We report incorrect length via SCSW program check instead of incorrect
> length check (SCWS word 2 bit 10 instead of bit 9). Since we have there
> is no fitting errno for incorrect length, and since I don't like what we
> do with the errno's, as part of the fix, errnos used for control flow in
> ccw interpretation are replaced with an enum using more speaking names.

I'm not sure whether this is the way to go. I mainly dislike the size
of the patch (and the fact that it mixes a fix and a change of function
signature).

Can we instead choose a mapping for incorrect length, and defer a
possible rework?

(Another idea would be to have the callback prepare the scsw via helper
functions. We'd just keep -EAGAIN to keep processing a chain and 0 to
stop.)

> 
> For virtio, if incorrect length checking is suppressed we keep the
> current behavior (channel-program check).

Confused. If it is suppressed, there should not be an error, no?

> 
> Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> ---
>  hw/s390x/3270-ccw.c    |  24 +++++-----
>  hw/s390x/css.c         |  67 +++++++++++++++-----------
>  hw/s390x/virtio-ccw.c  | 128 ++++++++++++++++++++++++-------------------------
>  include/hw/s390x/css.h |  13 ++++-
>  4 files changed, 127 insertions(+), 105 deletions(-)