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[Qemu-devel] [PULL 05/13] vhost: simplify vhost_needs_vring_endian()
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] [PULL 05/13] vhost: simplify vhost_needs_vring_endian() |
Date: |
Fri, 19 Feb 2016 10:00:21 +0200 |
From: Greg Kurz <address@hidden>
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 <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>
Reviewed-by: Laurent Vivier <address@hidden>
Reviewed-by: Cornelia Huck <address@hidden>
---
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 bb17177..9f8ac38 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;
--
MST
- [Qemu-devel] [PULL 00/13] vhost, virtio, pci, pxe, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 01/13] virtio-net: use the backend cross-endian capabilities, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 02/13] vhost-net: revert support of cross-endian vnet headers, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 03/13] virtio: move cross-endian helper to vhost, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 05/13] vhost: simplify vhost_needs_vring_endian(),
Michael S. Tsirkin <=
- [Qemu-devel] [PULL 04/13] vhost: move virtio 1.0 check to cross-endian helper, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 06/13] virtio: optimize virtio_access_is_big_endian() for little-endian targets, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 07/13] msix: fix msix_vector_masked, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 08/13] tests: add pxe e1000 and virtio-pci tests, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 09/13] dec: convert to realize(), Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 10/13] change type of pci_bridge_initfn() to void, Michael S. Tsirkin, 2016/02/19
- [Qemu-devel] [PULL 11/13] rules: filter out irrelevant files, Michael S. Tsirkin, 2016/02/19