On Fri, 13 Mar 2015 12:06:06 +0100
Paolo Bonzini <pbonz...@redhat.com> wrote:
>
>
> On 13/03/2015 09:11, Greg Kurz wrote:
> > The data argument is a host entity. It is not related to the target
> > endianness. Let's introduce a HOST_WORDS_BIGENDIAN based helper for
> > that.
> >
> > This patch fixes ioeventfd and vhost for a ppc64le host running a ppc64le
> > guest (only virtqueue 0 was handled, all others being byteswapped because
> > of TARGET_WORDS_BIGENDIAN). It doesn't change functionnality for fixed
> > endian architectures (i.e. doesn't break x86).
> >
> > Reported-by: Cédric Le Goater <c...@fr.ibm.com>
> > Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
> > ---
> > memory.c | 13 +++++++++++--
> > 1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/memory.c b/memory.c
> > index 6291cc0..1e29d40 100644
> > --- a/memory.c
> > +++ b/memory.c
> > @@ -1549,6 +1549,15 @@ void
> > memory_region_clear_flush_coalesced(MemoryRegion *mr)
> > }
> > }
> >
> > +static bool eventfd_wrong_endianness(MemoryRegion *mr)
> > +{
> > +#ifdef HOST_WORDS_BIGENDIAN
> > + return mr->ops->endianness == DEVICE_LITTLE_ENDIAN;
> > +#else
> > + return mr->ops->endianness == DEVICE_BIG_ENDIAN;
> > +#endif
> > +}
> > +
> > void memory_region_add_eventfd(MemoryRegion *mr,
> > hwaddr addr,
> > unsigned size,
> > @@ -1565,7 +1574,7 @@ void memory_region_add_eventfd(MemoryRegion *mr,
> > };
> > unsigned i;
> >
> > - adjust_endianness(&mrfd.data, size,
> > memory_region_wrong_endianness(mr));
> > + adjust_endianness(&mrfd.data, size, eventfd_wrong_endianness(mr));
>
> Strictly speaking, the place to do this would be kvm_set_ioeventfd_mmio.
FWIW the swap is being done in memory.c since commit:
commit 28f362be6e7f45ea9b7a57a08555c4c784f36198
Author: Alexander Graf <ag...@suse.de>
Date: Mon Oct 15 20:30:28 2012 +0200
memory: Make eventfd adhere to device endianness
Are you asking to revert this commit and to pass the device endianness to
kvm_set_ioeventfd_mmio() so it can fix the ordering ?
> A hypothetical userspace ioeventfd emulation would not need the swap.
>
I don't understand why "would not need the swap"...
> I can accept the patch, but it's better to add a comment.
>
... and so I don't know what to write. :)
Please enlight !
--
Greg
> Paolo
>
> > memory_region_transaction_begin();
> > for (i = 0; i < mr->ioeventfd_nb; ++i) {
> > if (memory_region_ioeventfd_before(mrfd, mr->ioeventfds[i])) {
> > @@ -1598,7 +1607,7 @@ void memory_region_del_eventfd(MemoryRegion *mr,
> > };
> > unsigned i;
> >
> > - adjust_endianness(&mrfd.data, size,
> > memory_region_wrong_endianness(mr));
> > + adjust_endianness(&mrfd.data, size, eventfd_wrong_endianness(mr));
> > memory_region_transaction_begin();
> > for (i = 0; i < mr->ioeventfd_nb; ++i) {
> > if (memory_region_ioeventfd_equal(mrfd, mr->ioeventfds[i])) {
> >
>
