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vhost: fix performance on LE hosts

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commit 2751c9882b ("vhost: cross-endian
support for legacy devices") introduced a minor regression: even with
cross-endian disabled, and even on LE host, vhost_is_little_endian is
checking is_le flag so there's always a branch.

To fix, simply check virtio_legacy_is_little_endian first.

Cc: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin 2015-10-27 11:37:39 +02:00 committed by David S. Miller
parent 85ff8a43f3
commit e407f39afd
1 changed files with 7 additions and 0 deletions
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7
drivers/vhost/vhost.h
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@ -183,10 +183,17 @@ static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit)
return vq->acked_features & (1ULL << bit);
}
#ifdef CONFIG_VHOST_CROSS_ENDIAN_LEGACY
static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
{
return vq->is_le;
}
#else
static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq)
{
return virtio_legacy_is_little_endian() || vq->is_le;
}
#endif
/* Memory accessors */
static inline u16 vhost16_to_cpu(struct vhost_virtqueue *vq, __virtio16 val)