Re: [Qemu-devel] [PATCH] s390-ccw: Fix alignment for CCW1

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 28 Aug 2017 08:56:42 -0400
Farhan Ali <alifm@linux.vnet.ibm.com> wrote:

> On 08/28/2017 04:22 AM, Cornelia Huck wrote:
> > On Fri, 25 Aug 2017 11:05:30 -0400
> > Farhan Ali <alifm@linux.vnet.ibm.com> wrote:
> >  
> >> On 08/25/2017 10:04 AM, Cornelia Huck wrote:  
> >>> On Fri, 25 Aug 2017 09:24:46 -0400
> >>> Farhan Ali <alifm@linux.vnet.ibm.com> wrote:
> >>>  
> >>>> The commit 198c0d1f9df8c4 s390x/css: check ccw address validity
> >>>> exposes an alignment issue in ccw bios.
> >>>>
> >>>> According to PoP the CCW must be doubleword aligned. Let's fix
> >>>> this in the bios.
> >>>>
> >>>> Cc: qemu-stable@nongnu.org
> >>>> Signed-off-by: Farhan Ali <alifm@linux.vnet.ibm.com>
> >>>> Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> >>>> Reviewed-by: Eric Farman <farman@linux.vnet.ibm.com>
> >>>> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> >>>> ---
> >>>>  pc-bios/s390-ccw/cio.h | 2 +-
> >>>>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>>>
> >>>> diff --git a/pc-bios/s390-ccw/cio.h b/pc-bios/s390-ccw/cio.h
> >>>> index f5b4549..55eaeee 100644
> >>>> --- a/pc-bios/s390-ccw/cio.h
> >>>> +++ b/pc-bios/s390-ccw/cio.h
> >>>> @@ -133,7 +133,7 @@ struct ccw1 {
> >>>>      __u8 flags;
> >>>>      __u16 count;
> >>>>      __u32 cda;
> >>>> -} __attribute__ ((packed));
> >>>> +} __attribute__ ((packed, aligned(8)));
> >>>>
> >>>>  #define CCW_FLAG_DC              0x80
> >>>>  #define CCW_FLAG_CC              0x40  
> >>>
> >>> Currently testing.
> >>>
> >>> This looks obviously right, but did you figure out what the (probably
> >>> unrelated) other failure was?
> >>>  
> >>
> >> That is still under investigation, for some reason it only fails for an
> >> LDL DASD and it works for SCSIs and CDL DASD.  
> >
> > Which are the symptoms of the failure? I'd like to understand this
> > before I update the (currently working by accident) bios with an
> > updated version.
> >
> > I'll just apply the patch for now.
> >  
> 
> Well it's seems like the failure for LDL DASD could be a disk setup 
> failure. We tried the test on a different environment with LDL disks and 
> everything worked fine with the patch applied.

Odd that it breaks after this change, though. Do you get command
rejects, or what happens?