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Date: Fri, 13 Mar 2015 09:03:12 +0100
From: Greg Kurz <gkurz@linux.vnet.ibm.com>
Message-ID: <20150313090312.742d135c@bahia.local>
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Subject: Re: [Qemu-devel] [PATCH] virtio-pci: fix host notifiers on
 bi-endian architectures
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>, qemu-ppc@nongnu.org, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, "Michael S. Tsirkin" <mst@redhat.com>

On Thu, 12 Mar 2015 17:25:15 +0100
Paolo Bonzini <pbonzini@redhat.com> wrote:
> 
> 
> On 12/03/2015 08:08, Michael S. Tsirkin wrote:
> > But common header format is simple, it's always LE.
> > It does not depend on target.
> > To me this looks like a bug in memory_region_add_eventfd,
> > it should do the right thing depending on device
> > endian-ness.
> 
> I agree it seems to be a QEMU bug.
> 
> Paolo
> 

Yes you're right ! QEMU swaps the virtqueue id (adjust_endianness) according
to TARGET_WORDS, like it was coming from the guest but in fact it comes from
the host. The id should be fixed according to HOST_WORDS instead. Of course
this went unnoticed until TARGET_WORDS_BIGENDIAN != HOST_WORDS_BIGENDIAN,
which we have now with ppc64le hosts.

Patches to follow.

Thanks.

--
Greg