Re: [Qemu-devel] [PATCH 5/5] s390x/ccs: add ccw-tester emulated device

[Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>]

* Cornelia Huck <cohuck@redhat.com> [2017-09-07 12:52:20 +0200]:

> On Thu, 7 Sep 2017 12:21:50 +0200
> Halil Pasic <pasic@linux.vnet.ibm.com> wrote:
> 
> > On 09/07/2017 10:08 AM, Cornelia Huck wrote:
> > > On Thu, 7 Sep 2017 15:31:09 +0800
> > > Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com> wrote:
> 
> > >> I'm thinking of a method these days:
> > >> Could passing through an fully emulated ccw device (e.g. 3270), or a
> > >> virtio ccw device, in the level 1 kvm guest to a level 2 guest be a test
> > >> method for this?
> > >>
> > >> All of the CCWs will be translated to IDAL CCWs by vfio-ccw in the level
> > >> 1 guest (which is the level 2 kvm host) and issued to the level 1 kvm
> > >> host. So, those IDALs will eventually be handled by the emulated device,
> > >> or the virtio ccw device, on the level 1 kvm host...
> > >>
> > >> Some days ago, one of my colleague tried the emulated 3270 passing
> > >> through. She stucked with the problem that the level 1 kvm host handling
> > >> a senseid IDAL ccw as a Direct ccw.
> > >>
> > >> Maybe I could try to pass through a virtio ccw device. I don't think of
> > >> any obvious problem that would lead to fail. Any comment?
> > >>  
> > > 
> > > That actually looks like a good thing to try! Cool idea.
> > >   
> > 
> > I'm afraid that it would not work without some extra work.
> > AFAIR Connie we said that the 3270 does not use any IDA, so
> > I did not touch the 3270 emulation code in QEMU. To make
> > the scenario viable one should convert the 3270 emulation
> > to ccw data stream (unless the original implementation
> > already took care of IDA, which I doubt).
> 
> But the vfio-ccw code uses idals... no need to touch the 3270 emulation.
> 
What Halil pointed out is that the ccw_cb implementation of 3270
emulation does not take care of IDALs. This is true.

I can also do that right after this series, if Halil agrees.
(The 3270 emulation authors are busy of other stuff these days. :()

-- 
Dong Jia Shi