From: Greg Kurz <gkurz@linux.vnet.ibm.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>,
Thomas Huth <thuth@redhat.com>,
qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>,
Jason Wang <jasowang@redhat.com>
Subject: [Qemu-devel] [PATCH 3/6] vhost: set vring endianness for legacy virtio
Date: Wed, 17 Jun 2015 15:23:39 +0200 [thread overview]
Message-ID: <20150617132339.6560.67374.stgit@bahia.lab.toulouse-stg.fr.ibm.com> (raw)
In-Reply-To: <20150617132323.6560.29432.stgit@bahia.lab.toulouse-stg.fr.ibm.com>
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>
---
hw/virtio/vhost.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 49 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 2d6c27af8d2a..d9974f49f371 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -17,9 +17,11 @@
#include "hw/hw.h"
#include "qemu/atomic.h"
#include "qemu/range.h"
+#include "qemu/error-report.h"
#include <linux/vhost.h>
#include "exec/address-spaces.h"
#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/virtio-access.h"
#include "migration/migration.h"
static struct vhost_log *vhost_log;
@@ -689,6 +691,27 @@ static void vhost_log_stop(MemoryListener *listener,
/* 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,
struct VirtIODevice *vdev,
struct vhost_virtqueue *vq,
@@ -719,6 +742,16 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
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);
a = virtio_queue_get_desc_addr(vdev, idx);
vq->desc = cpu_physical_memory_map(a, &l, 0);
@@ -789,8 +822,9 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
struct vhost_virtqueue *vq,
unsigned idx)
{
+ int vhost_vq_index = idx - dev->vq_index;
struct vhost_vring_state state = {
- .index = idx - dev->vq_index
+ .index = vhost_vq_index,
};
int r;
assert(idx >= dev->vq_index && idx < dev->vq_index + dev->nvqs);
@@ -801,6 +835,20 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
}
virtio_queue_set_last_avail_idx(vdev, idx, state.num);
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);
cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
0, virtio_queue_get_ring_size(vdev, idx));
next prev parent reply other threads:[~2015-06-17 13:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-17 13:23 [Qemu-devel] [PATCH 0/6] vhost: cross-endian support Greg Kurz
2015-06-17 13:23 ` [Qemu-devel] [PATCH 1/6] linux-headers: sync vhost.h Greg Kurz
2015-06-17 13:23 ` [Qemu-devel] [PATCH 2/6] virtio: introduce virtio_legacy_is_cross_endian() Greg Kurz
2015-06-17 13:23 ` Greg Kurz [this message]
2015-06-17 13:23 ` [Qemu-devel] [PATCH 4/6] tap: add VNET_LE/VNET_BE operations Greg Kurz
2015-06-17 13:23 ` [Qemu-devel] [PATCH 5/6] vhost-net: tell tap backend about the vnet endianness Greg Kurz
2015-06-19 9:16 ` Thomas Huth
2015-06-19 9:45 ` Greg Kurz
2015-06-17 13:23 ` [Qemu-devel] [PATCH 6/6] vhost_net: re-enable when cross endian Greg Kurz
2015-06-17 15:10 ` [Qemu-devel] [PATCH 0/6] vhost: cross-endian support Michael S. Tsirkin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150617132339.6560.67374.stgit@bahia.lab.toulouse-stg.fr.ibm.com \
--to=gkurz@linux.vnet.ibm.com \
--cc=cornelia.huck@de.ibm.com \
--cc=jasowang@redhat.com \
--cc=mst@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=stefanha@redhat.com \
--cc=thuth@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.