Re: [PATCH linux-next 2/9] vdpa: Introduce query of device config layout

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Feb 24, 2021 at 08:18:37AM +0200, Parav Pandit wrote:
> Introduce a command to query a device config layout.
> 
> An example query of network vdpa device:
> 
> $ vdpa dev add name bar mgmtdev vdpasim_net
> 
> $ vdpa dev config show
> bar: mac 00:35:09:19:48:05 link up link_announce false mtu 1500 speed 0 duplex 0
> 
> $ vdpa dev config show -jp
> {
>     "config": {
>         "bar": {
>             "mac": "00:35:09:19:48:05",
>             "link ": "up",
>             "link_announce ": false,
>             "mtu": 1500,
>             "speed": 0,
>             "duplex": 0
>         }
>     }
> }
> 
> Signed-off-by: Parav Pandit <parav@nvidia.com>
> Reviewed-by: Eli Cohen <elic@nvidia.com>
> ---
> changelog:
> v1->v2:
>  - read whole net config layout instead of individual fields
>  - added error extack for unmanaged vdpa device
> ---
>  drivers/vdpa/vdpa.c       | 181 ++++++++++++++++++++++++++++++++++++++
>  include/uapi/linux/vdpa.h |  11 +++
>  2 files changed, 192 insertions(+)
> 
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 3d997b389345..cebbba500638 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -14,6 +14,8 @@
>  #include <uapi/linux/vdpa.h>
>  #include <net/genetlink.h>
>  #include <linux/mod_devicetable.h>
> +#include <linux/virtio_net.h>
> +#include <linux/virtio_ids.h>
>  
>  static LIST_HEAD(mdev_head);
>  /* A global mutex that protects vdpa management device and device level operations. */
> @@ -603,6 +605,179 @@ static int vdpa_nl_cmd_dev_get_dumpit(struct sk_buff *msg, struct netlink_callba
>  	return msg->len;
>  }
>  
> +static int vdpa_dev_net_mq_config_fill(struct vdpa_device *vdev,
> +				       struct sk_buff *msg,
> +				       const struct virtio_net_config *config)
> +{
> +	u32 hash_types;
> +	u16 rss_field;
> +	u64 features;
> +
> +	features = vdev->config->get_features(vdev);
> +	if ((features & (1ULL << VIRTIO_NET_F_MQ)) == 0)
> +		return 0;
> +
> +	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP,
> +			config->max_virtqueue_pairs))
> +		return -EMSGSIZE;
> +	if (nla_put_u8(msg, VDPA_ATTR_DEV_NET_CFG_RSS_MAX_KEY_LEN,
> +		       config->rss_max_key_size))

Why is it ok to poke at RSS fields without checking the relevant feature bits?

> +		return -EMSGSIZE;

Did you check this with sparse?
max_virtqueue_pairs is __virtio16.

> +
> +	rss_field = le16_to_cpu(config->rss_max_key_size);
> +	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_RSS_MAX_IT_LEN, rss_field))
> +		return -EMSGSIZE;
> +
> +	hash_types = le32_to_cpu(config->supported_hash_types);

unused variable

> +	if (nla_put_u32(msg, VDPA_ATTR_DEV_NET_CFG_RSS_HASH_TYPES,
> +			config->supported_hash_types))
> +		return -EMSGSIZE;
> +	return 0;
> +}
> +
> +static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *msg)
> +{
> +	struct virtio_net_config config = {};
> +
> +	vdev->config->get_config(vdev, 0, &config, sizeof(config));
> +	if (nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR, sizeof(config.mac), config.mac))
> +		return -EMSGSIZE;
> +	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_STATUS, config.status))
> +		return -EMSGSIZE;
> +	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, config.mtu))
> +		return -EMSGSIZE;
> +	if (nla_put_u32(msg, VDPA_ATTR_DEV_NET_CFG_SPEED, config.speed))
> +		return -EMSGSIZE;

looks like a bunch of endian-ness/sparse errors to me, and
a bunch of fields checked without checking the feature bits.

> +	if (nla_put_u8(msg, VDPA_ATTR_DEV_NET_CFG_DUPLEX, config.duplex))
> +		return -EMSGSIZE;
> +
> +	return vdpa_dev_net_mq_config_fill(vdev, msg, &config);
> +}
> +
> +static int
> +vdpa_dev_config_fill(struct vdpa_device *vdev, struct sk_buff *msg, u32 portid, u32 seq,
> +		     int flags, struct netlink_ext_ack *extack)
> +{
> +	u32 device_id;
> +	void *hdr;
> +	int err;
> +
> +	hdr = genlmsg_put(msg, portid, seq, &vdpa_nl_family, flags,
> +			  VDPA_CMD_DEV_CONFIG_GET);
> +	if (!hdr)
> +		return -EMSGSIZE;
> +
> +	if (nla_put_string(msg, VDPA_ATTR_DEV_NAME, dev_name(&vdev->dev))) {
> +		err = -EMSGSIZE;
> +		goto msg_err;
> +	}
> +
> +	device_id = vdev->config->get_device_id(vdev);
> +	if (nla_put_u32(msg, VDPA_ATTR_DEV_ID, device_id)) {
> +		err = -EMSGSIZE;
> +		goto msg_err;
> +	}
> +
> +	switch (device_id) {
> +	case VIRTIO_ID_NET:
> +		err = vdpa_dev_net_config_fill(vdev, msg);
> +		break;
> +	default:
> +		err = -EOPNOTSUPP;
> +		break;
> +	}
> +	if (err)
> +		goto msg_err;
> +
> +	genlmsg_end(msg, hdr);
> +	return 0;
> +
> +msg_err:
> +	genlmsg_cancel(msg, hdr);
> +	return err;
> +}
> +
> +static int vdpa_nl_cmd_dev_config_get_doit(struct sk_buff *skb, struct genl_info *info)
> +{
> +	struct vdpa_device *vdev;
> +	struct sk_buff *msg;
> +	const char *devname;
> +	struct device *dev;
> +	int err;
> +
> +	if (!info->attrs[VDPA_ATTR_DEV_NAME])
> +		return -EINVAL;
> +	devname = nla_data(info->attrs[VDPA_ATTR_DEV_NAME]);
> +	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
> +	if (!msg)
> +		return -ENOMEM;
> +
> +	mutex_lock(&vdpa_dev_mutex);
> +	dev = bus_find_device(&vdpa_bus, NULL, devname, vdpa_name_match);
> +	if (!dev) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "device not found");
> +		err = -ENODEV;
> +		goto dev_err;
> +	}
> +	vdev = container_of(dev, struct vdpa_device, dev);
> +	if (!vdev->mdev) {
> +		NL_SET_ERR_MSG_MOD(info->extack, "unmanaged vdpa device");
> +		err = -EINVAL;
> +		goto mdev_err;
> +	}
> +	err = vdpa_dev_config_fill(vdev, msg, info->snd_portid, info->snd_seq,
> +				   0, info->extack);
> +	if (!err)
> +		err = genlmsg_reply(msg, info);
> +
> +mdev_err:
> +	put_device(dev);
> +dev_err:
> +	mutex_unlock(&vdpa_dev_mutex);
> +	if (err)
> +		nlmsg_free(msg);
> +	return err;
> +}
> +
> +static int vdpa_dev_config_dump(struct device *dev, void *data)
> +{
> +	struct vdpa_device *vdev = container_of(dev, struct vdpa_device, dev);
> +	struct vdpa_dev_dump_info *info = data;
> +	int err;
> +
> +	if (!vdev->mdev)
> +		return 0;
> +	if (info->idx < info->start_idx) {
> +		info->idx++;
> +		return 0;
> +	}
> +	err = vdpa_dev_config_fill(vdev, info->msg, NETLINK_CB(info->cb->skb).portid,
> +				   info->cb->nlh->nlmsg_seq, NLM_F_MULTI,
> +				   info->cb->extack);
> +	if (err)
> +		return err;
> +
> +	info->idx++;
> +	return 0;
> +}
> +
> +static int
> +vdpa_nl_cmd_dev_config_get_dumpit(struct sk_buff *msg, struct netlink_callback *cb)
> +{
> +	struct vdpa_dev_dump_info info;
> +
> +	info.msg = msg;
> +	info.cb = cb;
> +	info.start_idx = cb->args[0];
> +	info.idx = 0;
> +
> +	mutex_lock(&vdpa_dev_mutex);
> +	bus_for_each_dev(&vdpa_bus, NULL, &info, vdpa_dev_config_dump);
> +	mutex_unlock(&vdpa_dev_mutex);
> +	cb->args[0] = info.idx;
> +	return msg->len;
> +}
> +
>  static const struct nla_policy vdpa_nl_policy[VDPA_ATTR_MAX + 1] = {
>  	[VDPA_ATTR_MGMTDEV_BUS_NAME] = { .type = NLA_NUL_STRING },
>  	[VDPA_ATTR_MGMTDEV_DEV_NAME] = { .type = NLA_STRING },
> @@ -634,6 +809,12 @@ static const struct genl_ops vdpa_nl_ops[] = {
>  		.doit = vdpa_nl_cmd_dev_get_doit,
>  		.dumpit = vdpa_nl_cmd_dev_get_dumpit,
>  	},
> +	{
> +		.cmd = VDPA_CMD_DEV_CONFIG_GET,
> +		.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
> +		.doit = vdpa_nl_cmd_dev_config_get_doit,
> +		.dumpit = vdpa_nl_cmd_dev_config_get_dumpit,
> +	},
>  };
>  
>  static struct genl_family vdpa_nl_family __ro_after_init = {
> diff --git a/include/uapi/linux/vdpa.h b/include/uapi/linux/vdpa.h
> index 66a41e4ec163..5c31ecc3b956 100644
> --- a/include/uapi/linux/vdpa.h
> +++ b/include/uapi/linux/vdpa.h
> @@ -17,6 +17,7 @@ enum vdpa_command {
>  	VDPA_CMD_DEV_NEW,
>  	VDPA_CMD_DEV_DEL,
>  	VDPA_CMD_DEV_GET,		/* can dump */
> +	VDPA_CMD_DEV_CONFIG_GET,	/* can dump */
>  };
>  
>  enum vdpa_attr {
> @@ -33,6 +34,16 @@ enum vdpa_attr {
>  	VDPA_ATTR_DEV_MAX_VQS,			/* u32 */
>  	VDPA_ATTR_DEV_MAX_VQ_SIZE,		/* u16 */
>  
> +	VDPA_ATTR_DEV_NET_CFG_MACADDR,		/* binary */
> +	VDPA_ATTR_DEV_NET_STATUS,		/* u8 */
> +	VDPA_ATTR_DEV_NET_CFG_MAX_VQP,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_MTU,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_SPEED,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_DUPLEX,		/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_RSS_MAX_KEY_LEN,	/* u8 */
> +	VDPA_ATTR_DEV_NET_CFG_RSS_MAX_IT_LEN,	/* u16 */
> +	VDPA_ATTR_DEV_NET_CFG_RSS_HASH_TYPES,	/* u32 */
> +
>  	/* new attributes must be added above here */
>  	VDPA_ATTR_MAX,
>  };
> -- 
> 2.26.2

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