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vhost: simplify vhost_needs_vring_endian()

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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: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
This commit is contained in:
Greg Kurz 2016-02-05 11:46:04 +01:00 committed by Michael S. Tsirkin
parent e58481234e
commit 46f70ff148
1 changed files with 7 additions and 2 deletions
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9
hw/virtio/vhost.c
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@ -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;