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Date: Wed, 10 Dec 2008 18:34:44 +0000
From: Mark McLoughlin <markmc@...hat.com>
To: Anthony Liguori <anthony@...emonkey.ws>
Cc: Rusty Russell <rusty@...tcorp.com.au>,
netdev <netdev@...r.kernel.org>, kvm <kvm@...r.kernel.org>
Subject: Re: [PATCH] virtio_net: add link status handling
On Tue, 2008-12-09 at 21:11 -0600, Anthony Liguori wrote:
> Rusty Russell wrote:
> > On Wednesday 10 December 2008 08:02:14 Anthony Liguori wrote:
> >
> >> Mark McLoughlin wrote:
> >>
> >>> Allow the host to inform us that the link is down by adding
> >>> a VIRTIO_NET_F_STATUS which indicates that device status is
> >>> available in virtio_net config.
> >>>
> >>> This is currently useful for simulating link down conditions
> >>> (e.g. using proposed qemu 'set_link' monitor command) but
> >>> would also be needed if we were to support device assignment
> >>> via virtio.
> >>>
> >> It would be nice if the virtio-net card wrote some acknowledgement that
> >> it has received the link status down/up events.
> >>
> >
> > How about of every status change event? ie. a generic virtio_pci solution?
> >
>
> A really simple way to do it would just be to have another status field
> that was the guest's status (verses the host requested status which the
> current field is). All config reads/writes result in exits so it's easy
> to track.
>
> Adding YA virtio event may be a little overkill.
Sounds very reasonable; that and Rusty's "mask out unknown bits"
suggestion in the version below.
Cheers,
Mark.
From: Mark McLoughlin <markmc@...hat.com>
Subject: [PATCH] virtio_net: add link status handling
Allow the host to inform us that the link is down by adding
a VIRTIO_NET_F_STATUS which indicates that device status is
available in virtio_net config.
This is currently useful for simulating link down conditions
(e.g. using proposed qemu 'set_link' monitor command) but
would also be needed if we were to support device assignment
via virtio.
Signed-off-by: Mark McLoughlin <markmc@...hat.com>
---
drivers/net/virtio_net.c | 49 +++++++++++++++++++++++++++++++++++++++++++-
include/linux/virtio_net.h | 8 +++++++
2 files changed, 56 insertions(+), 1 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 71ca29c..40f02a1 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -42,6 +42,7 @@ struct virtnet_info
struct virtqueue *rvq, *svq;
struct net_device *dev;
struct napi_struct napi;
+ unsigned int status;
/* The skb we couldn't send because buffers were full. */
struct sk_buff *last_xmit_skb;
@@ -611,6 +612,7 @@ static struct ethtool_ops virtnet_ethtool_ops = {
.set_tx_csum = virtnet_set_tx_csum,
.set_sg = ethtool_op_set_sg,
.set_tso = ethtool_op_set_tso,
+ .get_link = ethtool_op_get_link,
};
#define MIN_MTU 68
@@ -624,6 +626,47 @@ static int virtnet_change_mtu(struct net_device *dev, int new_mtu)
return 0;
}
+static void virtnet_update_status(struct virtnet_info *vi)
+{
+ u16 v;
+
+ if (!virtio_has_feature(vi->vdev, VIRTIO_NET_F_STATUS))
+ return;
+
+ vi->vdev->config->get(vi->vdev,
+ offsetof(struct virtio_net_config, status),
+ &v, sizeof(v));
+
+ /* Ignore unknown (future) status bits */
+ v &= VIRTIO_NET_S_LINK_UP;
+
+ if (vi->status == v)
+ return;
+
+ vi->status = v;
+
+ if (vi->status & VIRTIO_NET_S_LINK_UP) {
+ netif_carrier_on(vi->dev);
+ netif_wake_queue(vi->dev);
+ } else {
+ netif_carrier_off(vi->dev);
+ netif_stop_queue(vi->dev);
+ }
+
+ /* acknowledge the status change */
+ vi->vdev->config->set(vi->vdev,
+ offsetof(struct virtio_net_config, status_ack),
+ &vi->status, sizeof(vi->status));
+
+}
+
+static void virtnet_config_changed(struct virtio_device *vdev)
+{
+ struct virtnet_info *vi = vdev->priv;
+
+ virtnet_update_status(vi);
+}
+
static int virtnet_probe(struct virtio_device *vdev)
{
int err;
@@ -732,6 +775,9 @@ static int virtnet_probe(struct virtio_device *vdev)
goto unregister;
}
+ vi->status = VIRTIO_NET_S_LINK_UP;
+ virtnet_update_status(vi);
+
pr_debug("virtnet: registered device %s\n", dev->name);
return 0;
@@ -787,7 +833,7 @@ static unsigned int features[] = {
VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6,
VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
VIRTIO_NET_F_GUEST_ECN, /* We don't yet handle UFO input. */
- VIRTIO_NET_F_MRG_RXBUF,
+ VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS,
VIRTIO_F_NOTIFY_ON_EMPTY,
};
@@ -799,6 +845,7 @@ static struct virtio_driver virtio_net = {
.id_table = id_table,
.probe = virtnet_probe,
.remove = __devexit_p(virtnet_remove),
+ .config_changed = virtnet_config_changed,
};
static int __init init(void)
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 5cdd0aa..67a37f8 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -21,11 +21,19 @@
#define VIRTIO_NET_F_HOST_ECN 13 /* Host can handle TSO[6] w/ ECN in. */
#define VIRTIO_NET_F_HOST_UFO 14 /* Host can handle UFO in. */
#define VIRTIO_NET_F_MRG_RXBUF 15 /* Host can merge receive buffers. */
+#define VIRTIO_NET_F_STATUS 16 /* virtio_net_config.status available */
+
+#define VIRTIO_NET_S_LINK_UP 1 /* Link is up */
struct virtio_net_config
{
/* The config defining mac address (if VIRTIO_NET_F_MAC) */
__u8 mac[6];
+ /* Status supplied by host; see VIRTIO_NET_F_STATUS and VIRTIO_NET_S_*
+ * bits above */
+ __u16 status;
+ /* The guest acks the status by writing it back here */
+ __u16 status_ack;
} __attribute__((packed));
/* This is the first element of the scatter-gather list. If you don't
--
1.6.0.3
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