Re: [PATCH] vdpa: Fix endian bugs in shadow virtqueue

[Eugenio Perez Martin <eperezma@redhat.com>]

On Wed, Feb 12, 2025 at 4:37 PM Konstantin Shkolnyy <kshk@linux.ibm.com> wrote:
>
> On 2/12/2025 09:06, Eugenio Perez Martin wrote:
> >> -        i = cpu_to_le16(svq->desc_next[i]);
> >> +        i = le16_to_cpu(svq->desc_next[i]);
> >
> > Both svq->desc_next and "i" are in QEMU. We can skip the conversion
> > and assign directly.
>
> Are you saying that desc_next[] should be in "CPU" and not LE format?
>
> The original code contained statements (below) that led me to think that
> desc_next[] was designed to be LE...
>
> vhost_svq_last_desc_of_chain()
>          i = le16_to_cpu(svq->desc_next[i]);
>
> vhost_svq_start()
>          svq->desc_next[i] = cpu_to_le16(i + 1);
>

Yes, I did a mess with the endianness back then :(. But we can remove
both conversions, and add the conversion at
vhost_svq_vring_write_descs instead.