| Message ID | 20160205104559.21017.3686.stgit@bahia.huguette.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 05 Feb 2016 11:46:04 +0100 Greg Kurz <gkurz@linux.vnet.ibm.com> wrote: > After the call to virtio_vdev_has_feature(), we only care for legacy > devices, so we don't need the extra check in virtio_is_big_endian(). > > Also the device_endian field is always set (VIRTIO_DEVICE_ENDIAN_UNKNOWN > may only happen on a virtio_load() path that cannot lead here), so we > don't need the assert() either. > > This open codes the device_endian checking in vhost_needs_vring_endian(). > It also adds a comment to explain the logic, as recent reviews showed the > cross-endian tweaks aren't that obvious. > > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> > --- > hw/virtio/vhost.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
On 05/02/2016 11:46, Greg Kurz wrote: > After the call to virtio_vdev_has_feature(), we only care for legacy > devices, so we don't need the extra check in virtio_is_big_endian(). > > Also the device_endian field is always set (VIRTIO_DEVICE_ENDIAN_UNKNOWN > may only happen on a virtio_load() path that cannot lead here), so we > don't need the assert() either. > > This open codes the device_endian checking in vhost_needs_vring_endian(). > It also adds a comment to explain the logic, as recent reviews showed the > cross-endian tweaks aren't that obvious. > > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Reviewed-by: Laurent Vivier <lvivier@redhat.com> > --- > hw/virtio/vhost.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c > index bb17177f5e7e..9f8ac38ccf2d 100644 > --- a/hw/virtio/vhost.c > +++ b/hw/virtio/vhost.c > @@ -749,6 +749,11 @@ static void vhost_log_stop(MemoryListener *listener, > /* FIXME: implement */ > } > > +/* The vhost driver natively knows how to handle the vrings of non > + * cross-endian legacy devices and modern devices. Only legacy devices > + * exposed to a bi-endian guest may require the vhost driver to use a > + * specific endianness. > + */ > static inline bool vhost_needs_vring_endian(VirtIODevice *vdev) > { > if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) { > @@ -756,9 +761,9 @@ static inline bool vhost_needs_vring_endian(VirtIODevice *vdev) > } > #ifdef TARGET_IS_BIENDIAN > #ifdef HOST_WORDS_BIGENDIAN > - return !virtio_is_big_endian(vdev); > + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE; > #else > - return virtio_is_big_endian(vdev); > + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG; > #endif > #else > return false; > >
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index bb17177f5e7e..9f8ac38ccf2d 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -749,6 +749,11 @@ static void vhost_log_stop(MemoryListener *listener, /* FIXME: implement */ } +/* The vhost driver natively knows how to handle the vrings of non + * cross-endian legacy devices and modern devices. Only legacy devices + * exposed to a bi-endian guest may require the vhost driver to use a + * specific endianness. + */ static inline bool vhost_needs_vring_endian(VirtIODevice *vdev) { if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) { @@ -756,9 +761,9 @@ static inline bool vhost_needs_vring_endian(VirtIODevice *vdev) } #ifdef TARGET_IS_BIENDIAN #ifdef HOST_WORDS_BIGENDIAN - return !virtio_is_big_endian(vdev); + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_LITTLE; #else - return virtio_is_big_endian(vdev); + return vdev->device_endian == VIRTIO_DEVICE_ENDIAN_BIG; #endif #else return false;
After the call to virtio_vdev_has_feature(), we only care for legacy devices, so we don't need the extra check in virtio_is_big_endian(). Also the device_endian field is always set (VIRTIO_DEVICE_ENDIAN_UNKNOWN may only happen on a virtio_load() path that cannot lead here), so we don't need the assert() either. This open codes the device_endian checking in vhost_needs_vring_endian(). It also adds a comment to explain the logic, as recent reviews showed the cross-endian tweaks aren't that obvious. Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> --- hw/virtio/vhost.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)