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Re: [Qemu-ppc] [PATCH] virtio-pci: fix host notifiers on bi-endian archi
From: |
Greg Kurz |
Subject: |
Re: [Qemu-ppc] [PATCH] virtio-pci: fix host notifiers on bi-endian architectures |
Date: |
Wed, 11 Mar 2015 23:52:13 +0100 |
On Thu, 12 Mar 2015 09:18:38 +1100
Benjamin Herrenschmidt <address@hidden> 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
> 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);
> > > > }
> > >
> >
>
>