On Wed, Mar 11, 2015 at 11:52:13PM +0100, Greg Kurz wrote:
> On Thu, 12 Mar 2015 09:18:38 +1100
> Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > On Wed, 2015-03-11 at 23:03 +0100, Greg Kurz wrote:
> >
> > > /* The host notifier will be swapped in adjust_endianness() according to the
> > > * target default endianness. We need to negate this swap if the device uses
> > > * an endianness that is not the default (ppc64le for example).
> > > */
> > >
> > > > > +static uint16_t cpu_to_host_notifier16(VirtIODevice *vdev, uint16_t val)
> > > > > +{
> > > > > + return virtio_is_big_endian(vdev) ? val : bswap16(val);
> > > > > +}
> >
> > But but but ... The above ... won't it do things like break x86 ? Ie,
> > shouldn't we swap only if TARGET_BIG_ENDIAN and !virtio_is_big_endian ?
> > Or better, "fixed target endian" ^ "virtio endian" to cover all cases ?
> >
>
> Yeah you're right, it's a mess :)
>
> To avoid virtio-pci.o being built per target, we can use virtio_default_endian()
> instead (to be exported from virtio.c):
>
> return vdev->device_endian() != virtio_default_endian() ? val : bswap16(val);
>
> I shall test on x86 and post a v2.
>
> Thanks.
>
> --
> G
It's a mess because the issue is not in virtio I think.
virtio common region is just a simple device, using
fixed LE format.
It's some bug in ioeventfd support. Need to understand
whether it's in kernel (and maybe do a work-around)
or in qemu memory core.
> > Cheers,
> > Ben.
> >
> > > > > static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
> > > > > int n, bool assign, bool set_handler)
> > > > > {
> > > > > @@ -150,10 +155,12 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
> > > > > }
> > > > > virtio_queue_set_host_notifier_fd_handler(vq, true, set_handler);
> > > > > memory_region_add_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
> > > > > - true, n, notifier);
> > > > > + true, cpu_to_host_notifier16(vdev, n),
> > > > > + notifier);
> > > > > } else {
> > > > > memory_region_del_eventfd(&proxy->bar, VIRTIO_PCI_QUEUE_NOTIFY, 2,
> > > > > - true, n, notifier);
> > > > > + true, cpu_to_host_notifier16(vdev, n),
> > > > > + notifier);
> > > > > virtio_queue_set_host_notifier_fd_handler(vq, false, false);
> > > > > event_notifier_cleanup(notifier);
> > > > > }
> > > >
> > >
> >
> >
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