On Wed, 21 Jan 2015 12:23:18 +0100
Cornelia Huck <cornelia.huck@xxxxxxxxxx> wrote:
> On Tue, 20 Jan 2015 11:08:24 +0000
> Stefan Hajnoczi <stefanha@xxxxxxxxx> wrote:
>
> > On Thu, Dec 11, 2014 at 02:25:12PM +0100, Cornelia Huck wrote:
> > > @@ -608,6 +631,25 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
> > > }
> > > }
> > > break;
> > > + case CCW_CMD_SET_VIRTIO_REV:
> > > + len = sizeof(revinfo);
> > > + if (ccw.count < len || (check_len && ccw.count > len)) {
> > > + ret = -EINVAL;
> > > + break;
> > > + }
> > > + if (!ccw.cda) {
> > > + ret = -EFAULT;
> > > + break;
> > > + }
> > > + cpu_physical_memory_read(ccw.cda, &revinfo, len);
> > > + if (dev->revision >= 0 ||
> > > + revinfo.revision > virtio_ccw_rev_max(dev)) {
> >
> > In the next patch virtio_ccw_handle_set_vq() uses big-endian memory
> > access functions to load a struct from guest memory.
> >
> > Here you just copy the struct in without byteswaps.
> >
> > Are the byteswaps missing here? (I guess this normally runs big-endian
> > guests on big-endian hosts so it's not noticable.)
>
> Indeed, these are supposed to be big-endian. I'll double check the
> other payloads.
Right. Cornelia, can you take care of this or shall I rework the patch?
NB: Actually, there are a couple of "XXX config space endianness"
comments in that virtio_ccw_cb() function, so there are likely a bunch
of problems when this code should be run on little endian hosts one day.
So far, this code only runs with big-endian guests on big-endian hosts
since the virtio-ccw machine is currently KVM-only as far as I know,
that's likely why nobody complained about this yet.
Thomas
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