From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: [PATCH] vhost: fix performance on LE hosts Date: Tue, 27 Oct 2015 11:37:39 +0200 Message-ID: <1445938640-32673-1-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org To: linux-kernel@vger.kernel.org Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org commit 2751c9882b947292fcfb084c4f604e01724af804 ("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 Signed-off-by: Michael S. Tsirkin --- drivers/vhost/vhost.h | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index 4772862..d3f7674 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -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) -- MST