On Thu, 23 Apr 2015 17:29:06 +0200
Greg Kurz <gkurz@xxxxxxxxxxxxxxxxxx> wrote:
> The current memory accessors logic is:
> - little endian if little_endian
> - native endian (i.e. no byteswap) if !little_endian
>
> If we want to fully support cross-endian vhost, we also need to be
> able to convert to big endian.
>
> Instead of changing the little_endian argument to some 3-value enum, this
> patch changes the logic to:
> - little endian if little_endian
> - big endian if !little_endian
>
> The native endian case is handled by all users with a trivial helper. This
> patch doesn't change any functionality, nor it does add overhead.
>
> Signed-off-by: Greg Kurz <gkurz@xxxxxxxxxxxxxxxxxx>
> ---
>
> Changes since v4:
> - style fixes (I have chosen if ... else in most places to stay below
> 80 columns, with the notable exception of the vhost helper which gets
> shorten in a later patch)
>
> drivers/net/macvtap.c | 5 ++++-
> drivers/net/tun.c | 5 ++++-
> drivers/vhost/vhost.h | 2 +-
> include/linux/virtio_byteorder.h | 24 ++++++++++++++----------
> include/linux/virtio_config.h | 5 ++++-
> include/linux/vringh.h | 2 +-
> 6 files changed, 28 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index a2f2958..6cf6b3e 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -51,7 +51,10 @@ struct macvtap_queue {
>
> static inline bool macvtap_is_little_endian(struct macvtap_queue *q)
> {
> - return q->flags & MACVTAP_VNET_LE;
> + if (q->flags & MACVTAP_VNET_LE)
> + return true;
> + else
> + return virtio_legacy_is_little_endian();
simply:
return (q->flags & MACVTAP_VNET_LE) ||
virtio_legacy_is_little_endian();
?
> }
>
> static inline u16 macvtap16_to_cpu(struct macvtap_queue *q, __virtio16 val)
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 3c3d6c0..5b044d4 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -208,7 +208,10 @@ struct tun_struct {
>
> static inline bool tun_is_little_endian(struct tun_struct *tun)
> {
> - return tun->flags & TUN_VNET_LE;
> + if (tun->flags & TUN_VNET_LE)
> + return true;
> + else
> + return virtio_legacy_is_little_endian();
dito?
> }
>
> static inline u16 tun16_to_cpu(struct tun_struct *tun, __virtio16 val)
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index 6a49960..954c657 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -175,7 +175,7 @@ static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit)
>
> static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
> {
> - return vhost_has_feature(vq, VIRTIO_F_VERSION_1);
> + return vhost_has_feature(vq, VIRTIO_F_VERSION_1) ? true : virtio_legacy_is_little_endian();
> }
That line is way longer than 80 characters ... may I suggest to switch
at least here to:
return vhost_has_feature(vq, VIRTIO_F_VERSION_1) ||
virtio_legacy_is_little_endian();
?
Apart from the cosmetics, the patch looks good to me.
Thomas
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