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author | Greg Kurz <gkurz@linux.vnet.ibm.com> | 2016-02-05 11:46:18 +0100 |
---|---|---|
committer | Timothy Pearson <tpearson@raptorengineering.com> | 2019-11-29 19:45:28 -0600 |
commit | 6e91acefa01d248ebc0b80056498b392aa6b27c6 (patch) | |
tree | a00645c5314f46e04df932966558d5287a2eb890 /include | |
parent | 9844cdd25e443b59826cd92ad188665d7019c3ec (diff) | |
download | hqemu-6e91acefa01d248ebc0b80056498b392aa6b27c6.zip hqemu-6e91acefa01d248ebc0b80056498b392aa6b27c6.tar.gz |
virtio: optimize virtio_access_is_big_endian() for little-endian targets
When adding cross-endian support, we introduced the TARGET_IS_BIENDIAN macro
and the virtio_access_is_big_endian() helper to have a branchless fast path
in the virtio memory accessors for targets that don't switch endian.
This was considered as a strong requirement at the time.
Now we have added a runtime check for virtio 1.0, which ruins the benefit
of the virtio_access_is_big_endian() helper for always little-endian targets.
With this patch, always little-endian targets stop checking for virtio 1.0,
since the result is little-endian in all cases.
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
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>
Diffstat (limited to 'include')
-rw-r--r-- | include/hw/virtio/virtio-access.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/hw/virtio/virtio-access.h b/include/hw/virtio/virtio-access.h index f1f12af..8dc84f5 100644 --- a/include/hw/virtio/virtio-access.h +++ b/include/hw/virtio/virtio-access.h @@ -19,13 +19,13 @@ static inline bool virtio_access_is_big_endian(VirtIODevice *vdev) { +#if defined(TARGET_IS_BIENDIAN) + return virtio_is_big_endian(vdev); +#elif defined(TARGET_WORDS_BIGENDIAN) if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) { /* Devices conforming to VIRTIO 1.0 or later are always LE. */ return false; } -#if defined(TARGET_IS_BIENDIAN) - return virtio_is_big_endian(vdev); -#elif defined(TARGET_WORDS_BIGENDIAN) return true; #else return false; |