Patchwork [v3,2/2] virtio-net: introduce a new control to set macaddr

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Submitter Amos Kong
Date Jan. 17, 2013, 10:40 a.m.
Message ID <1358419212-32356-3-git-send-email-akong@redhat.com>
Download mbox | patch
Permalink /patch/213309/
State New
Headers show

Comments

Amos Kong - Jan. 17, 2013, 10:40 a.m.
From: Amos Kong <akong@redhat.com>

Currently we write MAC address to pci config space byte by byte,
this means that we have an intermediate step where mac is wrong.
This patch introduced a new control command to set MAC address,
it's atomic.

VIRTIO_NET_F_CTRL_MAC_ADDR is a new feature bit for compatibility.

Signed-off-by: Amos Kong <akong@redhat.com>
---
 drivers/net/virtio_net.c        | 21 ++++++++++++++++++++-
 include/uapi/linux/virtio_net.h |  8 +++++++-
 2 files changed, 27 insertions(+), 2 deletions(-)
Stefan Hajnoczi - Jan. 18, 2013, 11 a.m.
On Thu, Jan 17, 2013 at 06:40:12PM +0800, akong@redhat.com wrote:
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 395ab4f..837c978 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -802,14 +802,32 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p)
>  	struct virtnet_info *vi = netdev_priv(dev);
>  	struct virtio_device *vdev = vi->vdev;
>  	int ret;
> +	struct scatterlist sg;
> +	char save_addr[ETH_ALEN];
> +	unsigned char save_aatype;
> +
> +	memcpy(save_addr, dev->dev_addr, ETH_ALEN);
> +	save_aatype = dev->addr_assign_type;
>  
>  	ret = eth_mac_addr(dev, p);
>  	if (ret)
>  		return ret;
>  
> -	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
> +		sg_init_one(&sg, dev->dev_addr, dev->addr_len);
> +		if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
> +					  VIRTIO_NET_CTRL_MAC_ADDR_SET,
> +					  &sg, 1, 0)) {
> +			dev_warn(&vdev->dev,
> +				 "Failed to set mac address by vq command.\n");
> +			memcpy(dev->dev_addr, save_addr, ETH_ALEN);
> +			dev->addr_assign_type = save_aatype;
> +			return -EINVAL;
> +		}

eth_mac_addr() doesn't allow callers to implement error handling nicely.
Although you didn't duplicate it's code directly, this patch still leaks
internals of eth_mac_addr().

How about splitting eth_mac_addr() in a separate patch:

int eth_prepare_mac_addr_change(struct net_device *dev, void *p)
{
        struct sockaddr *addr = p;
        if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
                return -EBUSY;
        if (!is_valid_ether_addr(addr->sa_data))
                return -EADDRNOTAVAIL;
	return 0;
}

void eth_commit_mac_addr_change(struct net_device *dev, void *p)
{
        struct sockaddr *addr = p;
        memcpy(dev->dev_addr, addr->sa_data, ETH_ALEN);
        /* if device marked as NET_ADDR_RANDOM, reset it */
        dev->addr_assign_type &= ~NET_ADDR_RANDOM;
}

/* Default implementation of MAC address changing */
int eth_mac_addr(struct net_device *dev, void *p)
{
	int ret;
	ret = eth_prepare_mac_addr_change(dev, p);
	if (ret < 0)
		return ret;
	eth_commit_mac_addr_change(dev, p);
	return 0;
}

Now virtio_net.c does:

ret = eth_prepare_mac_addr_change(dev, p);
if (ret < 0)
	return ret;

if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
	sg_init_one(&sg, dev->dev_addr, dev->addr_len);
	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
				  VIRTIO_NET_CTRL_MAC_ADDR_SET,
				  &sg, 1, 0)) {
		dev_warn(&vdev->dev,
			 "Failed to set mac address by vq command.\n");
		return -EINVAL;
	}
} ...

eth_commit_mac_addr_change(dev, p);
return 0;

Stefan
Amos Kong - Jan. 20, 2013, 2:20 a.m.
On Fri, Jan 18, 2013 at 12:00:42PM +0100, Stefan Hajnoczi wrote:
> On Thu, Jan 17, 2013 at 06:40:12PM +0800, akong@redhat.com wrote:
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 395ab4f..837c978 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -802,14 +802,32 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p)
> >  	struct virtnet_info *vi = netdev_priv(dev);
> >  	struct virtio_device *vdev = vi->vdev;
> >  	int ret;
> > +	struct scatterlist sg;
> > +	char save_addr[ETH_ALEN];
> > +	unsigned char save_aatype;
> > +
> > +	memcpy(save_addr, dev->dev_addr, ETH_ALEN);
> > +	save_aatype = dev->addr_assign_type;
> >  
> >  	ret = eth_mac_addr(dev, p);
> >  	if (ret)
> >  		return ret;
> >  
> > -	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))
> > +	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
> > +		sg_init_one(&sg, dev->dev_addr, dev->addr_len);
> > +		if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
> > +					  VIRTIO_NET_CTRL_MAC_ADDR_SET,
> > +					  &sg, 1, 0)) {
> > +			dev_warn(&vdev->dev,
> > +				 "Failed to set mac address by vq command.\n");
> > +			memcpy(dev->dev_addr, save_addr, ETH_ALEN);
> > +			dev->addr_assign_type = save_aatype;
> > +			return -EINVAL;
> > +		}
> 
> eth_mac_addr() doesn't allow callers to implement error handling nicely.
> Although you didn't duplicate it's code directly, this patch still leaks
> internals of eth_mac_addr().
> 
> How about splitting eth_mac_addr() in a separate patch:

Agree, then we can have nice error handling.
I will send a V4 and include this patch.
Thanks.
 
> int eth_prepare_mac_addr_change(struct net_device *dev, void *p)
> {
>         struct sockaddr *addr = p;
>         if (!(dev->priv_flags & IFF_LIVE_ADDR_CHANGE) && netif_running(dev))
>                 return -EBUSY;
>         if (!is_valid_ether_addr(addr->sa_data))
>                 return -EADDRNOTAVAIL;
> 	return 0;
> }

...

> Now virtio_net.c does:
> 
> ret = eth_prepare_mac_addr_change(dev, p);
> if (ret < 0)
> 	return ret;
> 
> if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
> 	sg_init_one(&sg, dev->dev_addr, dev->addr_len);

         trivial issue, %s/dev->dev_addr/addr->sa_data

> 	if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
> 				  VIRTIO_NET_CTRL_MAC_ADDR_SET,
> 				  &sg, 1, 0)) {
> 		dev_warn(&vdev->dev,
> 			 "Failed to set mac address by vq command.\n");
> 		return -EINVAL;
> 	}
> } ...
> 
> eth_commit_mac_addr_change(dev, p);
> return 0;
> 
> Stefan

Patch

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 395ab4f..837c978 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -802,14 +802,32 @@  static int virtnet_set_mac_address(struct net_device *dev, void *p)
 	struct virtnet_info *vi = netdev_priv(dev);
 	struct virtio_device *vdev = vi->vdev;
 	int ret;
+	struct scatterlist sg;
+	char save_addr[ETH_ALEN];
+	unsigned char save_aatype;
+
+	memcpy(save_addr, dev->dev_addr, ETH_ALEN);
+	save_aatype = dev->addr_assign_type;
 
 	ret = eth_mac_addr(dev, p);
 	if (ret)
 		return ret;
 
-	if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC))
+	if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR)) {
+		sg_init_one(&sg, dev->dev_addr, dev->addr_len);
+		if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
+					  VIRTIO_NET_CTRL_MAC_ADDR_SET,
+					  &sg, 1, 0)) {
+			dev_warn(&vdev->dev,
+				 "Failed to set mac address by vq command.\n");
+			memcpy(dev->dev_addr, save_addr, ETH_ALEN);
+			dev->addr_assign_type = save_aatype;
+			return -EINVAL;
+		}
+	} else if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
 		vdev->config->set(vdev, offsetof(struct virtio_net_config, mac),
 		                  dev->dev_addr, dev->addr_len);
+	}
 
 	return 0;
 }
@@ -1627,6 +1645,7 @@  static unsigned int features[] = {
 	VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ,
 	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN,
 	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ,
+	VIRTIO_NET_F_CTRL_MAC_ADDR,
 };
 
 static struct virtio_driver virtio_net_driver = {
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index 848e358..a5a8c88 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -53,6 +53,7 @@ 
 					 * network */
 #define VIRTIO_NET_F_MQ	22	/* Device supports Receive Flow
 					 * Steering */
+#define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
 
 #define VIRTIO_NET_S_LINK_UP	1	/* Link is up */
 #define VIRTIO_NET_S_ANNOUNCE	2	/* Announcement is needed */
@@ -127,7 +128,7 @@  typedef __u8 virtio_net_ctrl_ack;
  #define VIRTIO_NET_CTRL_RX_NOBCAST      5
 
 /*
- * Control the MAC filter table.
+ * Control the MAC
  *
  * The MAC filter table is managed by the hypervisor, the guest should
  * assume the size is infinite.  Filtering should be considered
@@ -140,6 +141,10 @@  typedef __u8 virtio_net_ctrl_ack;
  * first sg list contains unicast addresses, the second is for multicast.
  * This functionality is present if the VIRTIO_NET_F_CTRL_RX feature
  * is available.
+ *
+ * The ADDR_SET command requests one out scatterlist, it contains a
+ * 6 bytes MAC address. This functionality is present if the
+ * VIRTIO_NET_F_CTRL_MAC_ADDR feature is available.
  */
 struct virtio_net_ctrl_mac {
 	__u32 entries;
@@ -148,6 +153,7 @@  struct virtio_net_ctrl_mac {
 
 #define VIRTIO_NET_CTRL_MAC    1
  #define VIRTIO_NET_CTRL_MAC_TABLE_SET        0
+ #define VIRTIO_NET_CTRL_MAC_ADDR_SET         1
 
 /*
  * Control VLAN filtering