Re: [PATCH] virtio: remove virtio_tswap16s() call in vring_packed_event_read()

[Peter Maydell]

On Mon, 1 Jul 2024 at 08:52, Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> Commit d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> switched using of address_space_read_cached() to virito_lduw_phys_cached()
> to access packed descriptor event.
>
> When we used address_space_read_cached(), we needed to call
> virtio_tswap16s() to handle the endianess of the field, but
> virito_lduw_phys_cached() already handles it internally, so we no longer
> need to call virtio_tswap16s() (as the commit had done for `off_wrap`,
> but forgot for `flags`).
>
> Fixes: d152cdd6f6 ("virtio: use virtio accessor to access packed event")
> Cc: jasowang@redhat.com
> Cc: qemu-stable@nongnu.org
> Reported-by: Xoykie <xoykie@gmail.com>
> Link: 
> https://lore.kernel.org/qemu-devel/CAFU8RB_pjr77zMLsM0Unf9xPNxfr_--Tjr49F_eX32ZBc5o2zQ@mail.gmail.com
> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
> ---
>  hw/virtio/virtio.c | 1 -
>  1 file changed, 1 deletion(-)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 893a072c9d..2e5e67bdb9 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -323,7 +323,6 @@ static void vring_packed_event_read(VirtIODevice *vdev,
>      /* Make sure flags is seen before off_wrap */
>      smp_rmb();
>      e->off_wrap = virtio_lduw_phys_cached(vdev, cache, off_off);
> -    virtio_tswap16s(vdev, &e->flags);
>  }

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

thanks
-- PMM