[Qemu-devel] [PATCH v3 2/3] Revert "vhost-net: tell tap backend about the vnet endianness"

[Greg Kurz]

This reverts commit 5be7d9f1b1452613b95c6ba70b8d7ad3d0797991.

Cross-endian is now configured by the core virtio-net code. We simply
fall back on full emulation if the net backend cannot support the
requested endianness for vnet headers.

Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
---
 hw/net/vhost_net.c  |   33 +--------------------------------
 hw/net/virtio-net.c |    7 +++++++
 2 files changed, 8 insertions(+), 32 deletions(-)

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index d91b7b155ea7..fd7ea47fd38d 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -38,7 +38,6 @@
 #include "standard-headers/linux/virtio_ring.h"
 #include "hw/virtio/vhost.h"
 #include "hw/virtio/virtio-bus.h"
-#include "hw/virtio/virtio-access.h"
 
 struct vhost_net {
     struct vhost_dev dev;
@@ -205,27 +204,6 @@ static void vhost_net_set_vq_index(struct vhost_net *net, 
int vq_index)
     net->dev.vq_index = vq_index;
 }
 
-static int vhost_net_set_vnet_endian(VirtIODevice *dev, NetClientState *peer,
-                                     bool set)
-{
-    int r = 0;
-
-    if (virtio_vdev_has_feature(dev, VIRTIO_F_VERSION_1) ||
-        (virtio_legacy_is_cross_endian(dev) && !virtio_is_big_endian(dev))) {
-        r = qemu_set_vnet_le(peer, set);
-        if (r) {
-            error_report("backend does not support LE vnet headers");
-        }
-    } else if (virtio_legacy_is_cross_endian(dev)) {
-        r = qemu_set_vnet_be(peer, set);
-        if (r) {
-            error_report("backend does not support BE vnet headers");
-        }
-    }
-
-    return r;
-}
-
 static int vhost_net_start_one(struct vhost_net *net,
                                VirtIODevice *dev)
 {
@@ -320,11 +298,6 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
         goto err;
     }
 
-    r = vhost_net_set_vnet_endian(dev, ncs[0].peer, true);
-    if (r < 0) {
-        goto err;
-    }
-
     for (i = 0; i < total_queues; i++) {
         vhost_net_set_vq_index(get_vhost_net(ncs[i].peer), i * 2);
     }
@@ -332,7 +305,7 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
     r = k->set_guest_notifiers(qbus->parent, total_queues * 2, true);
     if (r < 0) {
         error_report("Error binding guest notifier: %d", -r);
-        goto err_endian;
+        goto err;
     }
 
     for (i = 0; i < total_queues; i++) {
@@ -354,8 +327,6 @@ err_start:
         fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", e);
         fflush(stderr);
     }
-err_endian:
-    vhost_net_set_vnet_endian(dev, ncs[0].peer, false);
 err:
     return r;
 }
@@ -378,8 +349,6 @@ void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
         fflush(stderr);
     }
     assert(r >= 0);
-
-    assert(vhost_net_set_vnet_endian(dev, ncs[0].peer, false) >= 0);
 }
 
 void vhost_net_cleanup(struct vhost_net *net)
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index d4cc94ea5e55..5a0ab6ad5bb5 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -128,6 +128,13 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t 
status)
     if (!n->vhost_started) {
         int r, i;
 
+        if (n->needs_vnet_hdr_swap) {
+            error_report("backend does not support %s vnet headers."
+                         "falling back on userspace virtio",
+                         virtio_is_big_endian(vdev) ? "BE" : "LE");
+            return;
+        }
+
         /* Any packets outstanding? Purge them to avoid touching rings
          * when vhost is running.
          */