[Qemu-devel] [PATCHv3 0/2] vhost: fix tap link down

[Qemu-devel] [PATCHv3 0/2] vhost: fix tap link down

[Michael S. Tsirkin]

qemu makes it possible to disable link at tap
which is not communicated to the guest but
causes all packets to be dropped.

With vhost-net at the moment it just keeps going.
Fix by communicating to virtio net and have that
stop vhost-net.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: pradeep <psuriset@linux.vnet.ibm.com>

Changes from v2:
	comment tweaked
	split to two patches

Changes from v1:
	fix link down after guest link is up



Michael S. Tsirkin (2):
  net: notify peer about link status change
  vhost: disable on tap link down

 hw/virtio-net.c |    3 ++-
 net.c           |   11 +++++++++++
 2 files changed, 13 insertions(+), 1 deletions(-)

-- 
1.7.3.2.91.g446ac

[Qemu-devel] [PATCHv3 1/2] net: notify peer about link status change

[Michael S. Tsirkin]

qemu makes it possible to disable link at tap
which is not communicated to the guest but
causes all packets to be dropped.

This works for virtio userspace, as qemu
stops giving it packets, but not for
virtio-net connected to vhost-net
as that does not get notified about this change.

Notify peer when this happens, which will then be used
by the follow-up patch to stop/start vhost-net.

Note: it might be a good idea to make peer link status match
tap in this case, so the guest gets an event
and updates the carrier state. For now
stay bug for bug compatible with what we used to have
in userspace.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: pradeep <psuriset@linux.vnet.ibm.com>
---
 net.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/net.c b/net.c
index 9ba5be2..ec4745d 100644
--- a/net.c
+++ b/net.c
@@ -1324,6 +1324,17 @@ done:
     if (vc->info->link_status_changed) {
         vc->info->link_status_changed(vc);
     }
+
+    /* Notify peer. Don't update peer link status: this makes it possible to
+     * disconnect from host network without notifying the guest.
+     * FIXME: is disconnected link status change operation useful?
+     *
+     * Current behaviour is compatible with qemu vlans where there could be
+     * multiple clients that can still communicate with each other in
+     * disconnected mode. For now maintain this compatibility. */
+    if (vc->peer && vc->peer->info->link_status_changed) {
+        vc->peer->info->link_status_changed(vc->peer);
+    }
     return 0;
 }
 
-- 
1.7.3.2.91.g446ac

[Qemu-devel] [PATCHv3 2/2] vhost: disable on tap link down

[Michael S. Tsirkin]

qemu makes it possible to disable link at tap
which is not communicated to the guest but
causes all packets to be dropped.

When vhost-net is enabled, vhost needs to be aware of both the virtio
link_down and the peer link_down. we switch to userspace emulation when
either is down.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reported-by: pradeep <psuriset@linux.vnet.ibm.com>
---
 hw/virtio-net.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 671d952..20cf680 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -115,7 +115,8 @@ static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
     if (!tap_get_vhost_net(n->nic->nc.peer)) {
         return;
     }
-    if (!!n->vhost_started == virtio_net_started(n, status)) {
+    if (!!n->vhost_started == virtio_net_started(n, status) &&
+                              !n->nic->nc.peer->link_down) {
         return;
     }
     if (!n->vhost_started) {
-- 
1.7.3.2.91.g446ac

[Qemu-devel] Re: [PATCHv3 0/2] vhost: fix tap link down

[Alex Williamson]

On Wed, 2011-02-09 at 18:44 +0200, Michael S. Tsirkin wrote:
> qemu makes it possible to disable link at tap
> which is not communicated to the guest but
> causes all packets to be dropped.
> 
> With vhost-net at the moment it just keeps going.
> Fix by communicating to virtio net and have that
> stop vhost-net.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Reported-by: pradeep <psuriset@linux.vnet.ibm.com>
> 
> Changes from v2:
> 	comment tweaked
> 	split to two patches
> 
> Changes from v1:
> 	fix link down after guest link is up
> 
> 
> 
> Michael S. Tsirkin (2):
>   net: notify peer about link status change
>   vhost: disable on tap link down
> 
>  hw/virtio-net.c |    3 ++-
>  net.c           |   11 +++++++++++
>  2 files changed, 13 insertions(+), 1 deletions(-)
> 

Thanks

Acked-by: Alex Williamson <alex.williamson@redhat.com>

[Qemu-devel] [PATCHv3 0/2] vhost: fix tap link down

[Jason Wang]

Michael S. Tsirkin writes:
 > qemu makes it possible to disable link at tap
 > which is not communicated to the guest but
 > causes all packets to be dropped.
 > 
 > With vhost-net at the moment it just keeps going.
 > Fix by communicating to virtio net and have that
 > stop vhost-net.
 > 
 > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
 > Reported-by: pradeep <psuriset@linux.vnet.ibm.com>
 > 
 > Changes from v2:
 > 	comment tweaked
 > 	split to two patches
 > 
 > Changes from v1:
 > 	fix link down after guest link is up
 > 
 > 
 > 
 > Michael S. Tsirkin (2):
 >   net: notify peer about link status change
 >   vhost: disable on tap link down
 > 
 >  hw/virtio-net.c |    3 ++-
 >  net.c           |   11 +++++++++++
 >  2 files changed, 13 insertions(+), 1 deletions(-)
 > 

Acked-by: Jason Wang <jasowang@redhat.com>

 > -- 
 > 1.7.3.2.91.g446ac
 > 

Re: [Qemu-devel] [PATCHv3 0/2] vhost: fix tap link down

[Aurelien Jarno]

On Wed, Feb 09, 2011 at 06:44:59PM +0200, Michael S. Tsirkin wrote:
> qemu makes it possible to disable link at tap
> which is not communicated to the guest but
> causes all packets to be dropped.
> 
> With vhost-net at the moment it just keeps going.
> Fix by communicating to virtio net and have that
> stop vhost-net.
> 
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Reported-by: pradeep <psuriset@linux.vnet.ibm.com>
> 
> Changes from v2:
> 	comment tweaked
> 	split to two patches
> 
> Changes from v1:
> 	fix link down after guest link is up
> 
> 
> 
> Michael S. Tsirkin (2):
>   net: notify peer about link status change
>   vhost: disable on tap link down
> 
>  hw/virtio-net.c |    3 ++-
>  net.c           |   11 +++++++++++
>  2 files changed, 13 insertions(+), 1 deletions(-)
> 

Thanks, both applied.


-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net