| Message ID | 20150220100746.18608.15083.stgit@bahia.local (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Feb 20, 2015 at 11:14:47AM +0100, Greg Kurz wrote: > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> > --- > drivers/vhost/vhost.h | 20 ++++++++++++++------ > 1 file changed, 14 insertions(+), 6 deletions(-) > > Michael, > > The vhost_is_little_endian() helper adds unconditionnal overhead to fixed > endian architectures: that is all architectures except arm and ppc64. This > was addressed in QEMU with a TARGET_IS_BIENDIAN macro. Please give an > advice about how to address this in the vhost code. > > Thanks. I suggest creating a config option for this, default to off. When disabled the flag won't be set so userspace can discover it's availability. > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h > index ce2c68e..21e7d6a 100644 > --- a/drivers/vhost/vhost.h > +++ b/drivers/vhost/vhost.h > @@ -176,34 +176,42 @@ static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit) > return vq->acked_features & (1ULL << bit); > } > > +static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq) > +{ > + if (vhost_has_feature(vq, VIRTIO_F_VERSION_1)) > + return true; > + else > + return !vq->legacy_big_endian; > +} > + > /* Memory accessors */ > static inline u16 vhost16_to_cpu(struct vhost_virtqueue *vq, __virtio16 val) > { > - return __virtio16_to_cpu(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); > + return __virtio16_to_cpu(vhost_is_little_endian(vq), val); > } > > static inline __virtio16 cpu_to_vhost16(struct vhost_virtqueue *vq, u16 val) > { > - return __cpu_to_virtio16(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); > + return __cpu_to_virtio16(vhost_is_little_endian(vq), val); > } > > static inline u32 vhost32_to_cpu(struct vhost_virtqueue *vq, __virtio32 val) > { > - return __virtio32_to_cpu(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); > + return __virtio32_to_cpu(vhost_is_little_endian(vq), val); > } > > static inline __virtio32 cpu_to_vhost32(struct vhost_virtqueue *vq, u32 val) > { > - return __cpu_to_virtio32(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); > + return __cpu_to_virtio32(vhost_is_little_endian(vq), val); > } > > static inline u64 vhost64_to_cpu(struct vhost_virtqueue *vq, __virtio64 val) > { > - return __virtio64_to_cpu(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); > + return __virtio64_to_cpu(vhost_is_little_endian(vq), val); > } > > static inline __virtio64 cpu_to_vhost64(struct vhost_virtqueue *vq, u64 val) > { > - return __cpu_to_virtio64(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); > + return __cpu_to_virtio64(vhost_is_little_endian(vq), val); > } > #endif -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h index ce2c68e..21e7d6a 100644 --- a/drivers/vhost/vhost.h +++ b/drivers/vhost/vhost.h @@ -176,34 +176,42 @@ static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit) return vq->acked_features & (1ULL << bit); } +static inline bool vhost_is_little_endian(struct vhost_virtqueue *vq) +{ + if (vhost_has_feature(vq, VIRTIO_F_VERSION_1)) + return true; + else + return !vq->legacy_big_endian; +} + /* Memory accessors */ static inline u16 vhost16_to_cpu(struct vhost_virtqueue *vq, __virtio16 val) { - return __virtio16_to_cpu(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); + return __virtio16_to_cpu(vhost_is_little_endian(vq), val); } static inline __virtio16 cpu_to_vhost16(struct vhost_virtqueue *vq, u16 val) { - return __cpu_to_virtio16(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); + return __cpu_to_virtio16(vhost_is_little_endian(vq), val); } static inline u32 vhost32_to_cpu(struct vhost_virtqueue *vq, __virtio32 val) { - return __virtio32_to_cpu(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); + return __virtio32_to_cpu(vhost_is_little_endian(vq), val); } static inline __virtio32 cpu_to_vhost32(struct vhost_virtqueue *vq, u32 val) { - return __cpu_to_virtio32(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); + return __cpu_to_virtio32(vhost_is_little_endian(vq), val); } static inline u64 vhost64_to_cpu(struct vhost_virtqueue *vq, __virtio64 val) { - return __virtio64_to_cpu(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); + return __virtio64_to_cpu(vhost_is_little_endian(vq), val); } static inline __virtio64 cpu_to_vhost64(struct vhost_virtqueue *vq, u64 val) { - return __cpu_to_virtio64(vhost_has_feature(vq, VIRTIO_F_VERSION_1), val); + return __cpu_to_virtio64(vhost_is_little_endian(vq), val); } #endif
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> --- drivers/vhost/vhost.h | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-) Michael, The vhost_is_little_endian() helper adds unconditionnal overhead to fixed endian architectures: that is all architectures except arm and ppc64. This was addressed in QEMU with a TARGET_IS_BIENDIAN macro. Please give an advice about how to address this in the vhost code. Thanks. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html