Re: [RFC PATCH 2/2] virtio-net: introduce a new control to set macaddr

Michael S. Tsirkin
2013-01-10T15:26:50Z

On Thu, Jan 10, 2013 at 10:45:41PM +0800, akong@redhat.com wrote:
> 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
> in one time.
>
> 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 | 16 +++++++++++++++-
> include/uapi/linux/virtio_net.h | 8 +++++++-
> 2 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 395ab4f..ff22bcd 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -803,13 +803,26 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p)
> struct virtio_device *vdev = vi->vdev;
> int ret;
>
> + struct scatterlist sg;
> +
> 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)) {
> + /* Set MAC address by sending vq command */
> + sg_init_one(&sg, dev->dev_addr, dev->addr_len);
> + virtnet_send_command(vi, VIRTIO_NET_CTRL_MAC,
> + VIRTIO_NET_CTRL_MAC_ADDR_SET,
> + &sg, 1, 0);

I think we should check status and return an error if the command failed.
Also, delay eth_mac_addr until after it passes.

> + return 0;
> + }
> +
> + if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
> + /* Set MAC address by writing config space */
> vdev->config->set(vdev, offsetof(struct virtio_net_config, mac),
> dev->dev_addr, dev->addr_len);
> + }
>

By the way, why don't we fail the command if VIRTIO_NET_F_MAC is off?
Rusty?

> return 0;
> }
> @@ -1627,6 +1640,7 @@ 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
> --
> 1.7.11.7