* Halil Pasic <pa...@linux.vnet.ibm.com> [2017-09-25 12:57:31 +0200]:
[restored Cc:] > > > On 09/25/2017 09:31 AM, Dong Jia Shi wrote: > > * Cornelia Huck <coh...@redhat.com> [2017-09-08 11:59:50 +0200]: > > > >> On Fri, 8 Sep 2017 11:21:57 +0200 > >> Halil Pasic <pa...@linux.vnet.ibm.com> wrote: > >> > >>> On 09/08/2017 05:41 AM, Dong Jia Shi wrote: > >>>> Let' me summarize here, in case I misunderstand things. Now we have > >>>> two ways to choose: > >>>> > >>>> A. Kernel: no change. > >>>> Qemu : handle -EFAULT as option 2 by generating a program check. > >>>> > >>>> B. Kernel: return -EFAULT > >>>> + > >>>> update the IRB area in the I/O region for option 1 to present > >>>> a unit check SCSW (with proper sense byte ECW), and for option > >>>> 2 to present a program check. > >>>> Qemu : handle -EFAULT according to the information that the IRB area > >>>> provided. > >>> > >>> This is not what I was trying to say. You got my message regarding A, but > >>> B was supposed to be understood like this. > >>> > >>> Keep the current handling for option 1, that is return -EFAULT. For option > >>> 2 do what the spec says, execute the program until the bad address and > >>> then > >>> generate a program-check (SCSW) once the bad stuff has it's turn. Thus > >>> the only change in QEMU would be handling -EFAULT with an unit check > >>> (because > >>> now it's just option 1). > > Let me adding some context information here by copying some words from the > > previous mail in this thread: > > The only option 2 case in the kernel is ccwchain_fetch_idal() finding a > > bad idaw_iova. > > > > What you propose to do for this case is (correct me if I get it wrong): > > In ccwchain_fetch_idal(), we do not return -EFAULT, instead we return 0, > > and issuing the incompletely translated channel program with the bad > > address to the physical device. And QEMU will eventually get the SCSW > > with the program-check from the physical device I/O result, and inject > > it to guest for further handling. > > > > I guess that would be the cleanest. I would also be fine with not making > the physical device program-check (issuing a shortened channel program, > and doing the program check in software) but that's probably more > complicated to implement. That's far more complicated. I will try the simple approach. > > Is this understanding right? If so, I'm fine with that, and I can > > provide the fix in the kernel. > > > > That would be nice. Ok. -- Dong Jia Shi
