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Date: Thu, 9 May 2019 20:30:28 +0200
From: Halil Pasic <pasic@linux.ibm.com>
Subject: Re: [PATCH 09/10] virtio/s390: use DMA memory for ccw I/O and
 classic notifiers
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To: Pierre Morel <pmorel@linux.ibm.com>
Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, Cornelia Huck <cohuck@redhat.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Sebastian Ott <sebott@linux.ibm.com>, virtualization@lists.linux-foundation.org, "Michael S. Tsirkin" <mst@redhat.com>, Christoph Hellwig <hch@infradead.org>, Thomas Huth <thuth@redhat.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Viktor Mihajlovski <mihajlov@linux.ibm.com>, Vasily Gorbik <gor@linux.ibm.com>, Janosch Frank <frankja@linux.ibm.com>, Claudio Imbrenda <imbrenda@linux.ibm.com>, Farhan Ali <alifm@linux.ibm.com>, Eric Farman <farman@linux.ibm.com>
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On Thu, 9 May 2019 15:30:08 +0200
Pierre Morel <pmorel@linux.ibm.com> wrote:

> On 08/05/2019 16:46, Pierre Morel wrote:
> > On 26/04/2019 20:32, Halil Pasic wrote:
> >> Before virtio-ccw could get away with not using DMA API for the pieces of
> >> memory it does ccw I/O with. With protected virtualization this has to
> >> change, since the hypervisor needs to read and sometimes also write these
> >> pieces of memory.
> >>
> >> The hypervisor is supposed to poke the classic notifiers, if these are
> >> used, out of band with regards to ccw I/O. So these need to be allocated
> >> as DMA memory (which is shared memory for protected virtualization
> >> guests).
> >>
> >> Let us factor out everything from struct virtio_ccw_device that needs to
> >> be DMA memory in a satellite that is allocated as such.
> >>
> ...
> >> +                       sizeof(indicators(vcdev)));
> > 
> > should be sizeof(long) ?

If something different then sizeof(u64) IMHO.
> > 
> > This is a recurrent error, but it is not an issue because the size of
> > the indicators is unsigned long as the size of the pointer.

I don't think there is an error, let alone a recurrent one.

> > 
> > Regards,
> > Pierre
> > 
> 
> Here too, with the problem of the indicator size handled:

I've laid out my view in a response to your comment on patch #8.

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

Thanks!
Halil