Re: [PATCH 09/10] virtio/s390: use DMA memory for ccw I/O and classic notifiers

Halil Pasic
2019-05-09T18:30:28Z

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