Re: [PATCH] virtio-net: Fix save/load

[Alex Williamson <alex.williamson@hp.com>]

On Wed, 2009-05-06 at 10:21 +0300, Avi Kivity wrote:
> Alex Williamson wrote:
> > We can't rely on build switches to tell us if a save image
> > includes a given field.  We also need to save status since
> > it's visible to the guest.  Draw another line in the sand
> > for broken save versions.  The version number should always
> > be updated when new values are saved and load should make
> > an attempt to set reasonable defaults for lower version save
> > images.
> >   
> 
> I applied the the first part of this ancient patch.  Can't tell from the 
> thread what the consensus is for the rest.

Thanks Avi, I think you got the important bits.  I might recommend the
following change to keep this contained to a version_id 7 load and bail
if vnet header support is required, but not available.  Thanks,

Alex


kvm: virtio-net: Cleanup load from vnet header saved image

Bail if the saved image requires vnet header support.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
---

 hw/virtio-net.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)


diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 6dfe758..4beb16d 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -663,14 +663,15 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
     if (version_id >= 6)
         qemu_get_buffer(f, (uint8_t *)n->vlans, MAX_VLAN >> 3);
 
-#ifdef TAP_VNET_HDR
     if (version_id == 7 && qemu_get_be32(f)) {
+#ifdef TAP_VNET_HDR
         tap_using_vnet_hdr(n->vc->vlan->first_client, 1);
-    }
 #else
-    /* FIXME: error out if nonzero? */
-    qemu_get_be32(f);
+        fprintf(stderr,
+                "virtio-net: saved image requires vnet header support\n");
+        exit(1);
 #endif
+    }
 
     if (n->tx_timer_active) {
         qemu_mod_timer(n->tx_timer,