Re: [Qemu-devel] [PATCH v2 0/3] s390x/sclp: 64 bit event masks

[Cornelia Huck <cohuck@redhat.com>]

On Thu, 22 Feb 2018 17:22:56 +0100
Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> wrote:

> Until 67915de9f0383ccf4a ("s390x/event-facility: variable-length event masks")
> we only supported 32bit sclp event masks, even though the archiecture
> allows the guests to set up sclp event masks up to 1021 bytes in length.
> With that patch the behaviour was almost compliant, but some issues were
> still remaining, in particular regarding the handling of selective reads
> and migration.
> 
> This patchset fixes migration and the handling of selective reads, and
> puts in place the support for 64-bit sclp event masks internally.
> 
> A new property of the sclp-event device switches between the 32bit masks
> and the compliant behaviour. The property is bound to the machine
> version, so older machines keep the old broken behaviour, allowing for
> migration, but the default is the compliant implementation.
> 
> Fixes: 67915de9f0383ccf4a ("s390x/event-facility: variable-length event masks")
> 
> v1 -> v2 
> * improved comments and patch descriptions to better explain why we need
>   this, including better description of the old broken behaviour
> * rename SCLPEVMSK to SCLP_EVMASK to improve readability
> * removed some unneded variable initializations
> * fixed a pre-existing typo
> 
> Claudio Imbrenda (3):
>   s390x/sclp: proper support of larger send and receive masks
>   s390x/sclp: clean up sclp masks
>   s390x/sclp: extend SCLP event masks to 64 bits
> 
>  hw/char/sclpconsole-lm.c          |   4 +-
>  hw/char/sclpconsole.c             |   4 +-
>  hw/s390x/event-facility.c         | 150 +++++++++++++++++++++++++++++++-------
>  hw/s390x/s390-virtio-ccw.c        |   8 +-
>  hw/s390x/sclpcpu.c                |   4 +-
>  hw/s390x/sclpquiesce.c            |   4 +-
>  include/hw/s390x/event-facility.h |  22 +++---
>  7 files changed, 151 insertions(+), 45 deletions(-)
> 

This looks sane as far as I can see without having access to the
documentation.

BTW, I saw you also extended the masks in the Linux (guest) code (at
least, I see patches queued on the s390 features branch...) You also
might want to adjust the "Linux uses 4 byte masks" comment in the code
in the future.

Before I queue this, I'd like some r-bs/a-bs by folks with access to
the documentation.