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vhost: set vring endianness for legacy virtio

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Legacy virtio is native endian: if the guest and host endianness differ,
we have to tell vhost so it can swap bytes where appropriate. This is
done through a vhost ring ioctl.

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>
This commit is contained in:
Greg Kurz 2015-06-17 15:23:39 +02:00 • committed by Michael S. Tsirkin
parent 41d283bdab
commit 04b7a1523d
1 changed files with 49 additions and 1 deletions
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50
hw/virtio/vhost.c
View file

@ -17,9 +17,11 @@
#include "hw/hw.h" #include "hw/hw.h"
#include "qemu/atomic.h" #include "qemu/atomic.h"
#include "qemu/range.h" #include "qemu/range.h"
#include "qemu/error-report.h"
#include <linux/vhost.h> #include <linux/vhost.h>
#include "exec/address-spaces.h" #include "exec/address-spaces.h"
#include "hw/virtio/virtio-bus.h" #include "hw/virtio/virtio-bus.h"
#include "hw/virtio/virtio-access.h"
#include "migration/migration.h" #include "migration/migration.h"
static struct vhost_log *vhost_log; static struct vhost_log *vhost_log;
@ -686,6 +688,27 @@ static void vhost_log_stop(MemoryListener *listener,
/* FIXME: implement */ /* FIXME: implement */
} }
static int vhost_virtqueue_set_vring_endian_legacy(struct vhost_dev *dev,
bool is_big_endian,
int vhost_vq_index)
{
struct vhost_vring_state s = {
.index = vhost_vq_index,
.num = is_big_endian
};
if (!dev->vhost_ops->vhost_call(dev, VHOST_SET_VRING_ENDIAN, &s)) {
return 0;
}
if (errno == ENOTTY) {
error_report("vhost does not support cross-endian");
return -ENOSYS;
}
return -errno;
}
static int vhost_virtqueue_start(struct vhost_dev *dev, static int vhost_virtqueue_start(struct vhost_dev *dev,
struct VirtIODevice *vdev, struct VirtIODevice *vdev,
struct vhost_virtqueue *vq, struct vhost_virtqueue *vq,
@ -716,6 +739,16 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
return -errno; return -errno;
} }
if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1) &&
virtio_legacy_is_cross_endian(vdev)) {
r = vhost_virtqueue_set_vring_endian_legacy(dev,
virtio_is_big_endian(vdev),
vhost_vq_index);
if (r) {
return -errno;
}
}
s = l = virtio_queue_get_desc_size(vdev, idx); s = l = virtio_queue_get_desc_size(vdev, idx);
a = virtio_queue_get_desc_addr(vdev, idx); a = virtio_queue_get_desc_addr(vdev, idx);
vq->desc = cpu_physical_memory_map(a, &l, 0); vq->desc = cpu_physical_memory_map(a, &l, 0);
@ -786,8 +819,9 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
struct vhost_virtqueue *vq, struct vhost_virtqueue *vq,
unsigned idx) unsigned idx)
{ {
int vhost_vq_index = idx - dev->vq_index;
struct vhost_vring_state state = { struct vhost_vring_state state = {
.index = idx - dev->vq_index .index = vhost_vq_index,
}; };
int r; int r;
assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs); assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
@ -798,6 +832,20 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
} }
virtio_queue_set_last_avail_idx(vdev, idx, state.num); virtio_queue_set_last_avail_idx(vdev, idx, state.num);
virtio_queue_invalidate_signalled_used(vdev, idx); virtio_queue_invalidate_signalled_used(vdev, idx);
/* In the cross-endian case, we need to reset the vring endianness to
* native as legacy devices expect so by default.
*/
if (!virtio_has_feature(vdev, VIRTIO_F_VERSION_1) &&
virtio_legacy_is_cross_endian(vdev)) {
r = vhost_virtqueue_set_vring_endian_legacy(dev,
!virtio_is_big_endian(vdev),
vhost_vq_index);
if (r < 0) {
error_report("failed to reset vring endianness");
}
}
assert (r >= 0); assert (r >= 0);
cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx), cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
0, virtio_queue_get_ring_size(vdev, idx)); 0, virtio_queue_get_ring_size(vdev, idx));