Re: [PATCH v2 2/2] s390x/pci: Fix memory_region_access_valid call

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 21 Dec 2020 09:50:23 +0100
Pierre Morel <pmorel@linux.ibm.com> wrote:

> On 12/18/20 6:05 PM, Pierre Morel wrote:
> > 
> > 
> > On 12/18/20 5:51 PM, Cornelia Huck wrote:  
> >> On Fri, 18 Dec 2020 17:40:50 +0100
> >> Pierre Morel <pmorel@linux.ibm.com> wrote:
> >>  
> >>> On 12/18/20 4:32 PM, Cornelia Huck wrote:  
> >>>> On Fri, 18 Dec 2020 15:32:08 +0100
> >>>> Pierre Morel <pmorel@linux.ibm.com> wrote:  
> >>>>> On 12/18/20 12:04 PM, Cornelia Huck wrote:  
> >>>>>> On Fri, 18 Dec 2020 10:37:38 +0100
> >>>>>> Pierre Morel <pmorel@linux.ibm.com> wrote:  
> >>>>>>> On 12/17/20 11:16 PM, Matthew Rosato wrote:  
> >>>>>>>> In pcistb_service_handler, a call is made to validate that the 
> >>>>>>>> memory
> >>>>>>>> region can be accessed.  However, the call is made using the 
> >>>>>>>> entire length
> >>>>>>>> of the pcistb operation, which can be larger than the allowed 
> >>>>>>>> memory
> >>>>>>>> access size (8).  Since we already know that the provided buffer 
> >>>>>>>> is a
> >>>>>>>> multiple of 8, fix the call to memory_region_access_valid to 
> >>>>>>>> iterate
> >>>>>>>> over the memory region in the same way as the subsequent call to
> >>>>>>>> memory_region_dispatch_write.
> >>>>>>>>
> >>>>>>>> Fixes: 863f6f52b7 ("s390: implement pci instructions")
> >>>>>>>> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> >>>>>>>> ---  
> 
> ...snip...
> 
> >>>>  
> >>>
> >>> The ops already exist, I thought adding a dedicated callback for s390 on
> >>> every regions used by vfio_pci instead of the default.
> >>> But it does not add a lot, just looks cleaner to me.  
> >>
> >> But we end up here for every pci device, not just for vfio devices,
> >> don't we?
> >>
> >>  
> > 
> > Yes, but isn't what is done here?
> >   
> 
> It was not my intention to slow the integration process.
> We can start with this fix and eventually move the code to the callback 
> in another series when/if we all agree.

Yeah, I also fear that we might have been talking past each other. It's
late in the year :)

> 
> Acked-by: Pierre Morel <pmorel@linux.ibm.com>

Thanks!