Re: [PATCH v3 4/4] s390x/css: Add passthrough IRB

[Cornelia Huck <cohuck@redhat.com>]

On Wed, Jun 16 2021, Eric Farman <farman@linux.ibm.com> wrote:

> Wire in the subchannel callback for building the IRB
> ESW and ECW space for passthrough devices, and copy
> the hardware's ESW into the IRB we are building.
>
> If the hardware presented concurrent sense, then copy
> that sense data into the IRB's ECW space.
>
> Signed-off-by: Eric Farman <farman@linux.ibm.com>
> ---
>  hw/s390x/css.c         | 13 ++++++++++++-
>  hw/s390x/s390-ccw.c    |  1 +
>  hw/vfio/ccw.c          |  4 ++++
>  include/hw/s390x/css.h |  3 +++
>  4 files changed, 20 insertions(+), 1 deletion(-)
>

(...)

> +void build_irb_passthrough(SubchDev *sch, IRB *irb)
> +{
> +    /* Copy ESW from hardware */
> +    irb->esw = sch->esw;
> +
> +    if (irb->esw.erw & ESW_ERW_SENSE) {
> +        /* Copy ECW from hardware */
> +        build_irb_sense_data(sch, irb);
> +    }

I'm wondering whether we should also copy "Model-dependent information"
(scsw 5 + 14 set, erw 7 unset). Seems more correct, and IIUC the guest
was tripped by the presence of erw 7 without valid sense data.

> +}
> +