Virtualization - Apr 2021 - [PATCH linux-next v2 04/14] vdpa: Introduce query of device config layout

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 at nvidia.com>
Signed-off-by: Eli Cohen <elic at nvidia.com>
---
changelog:
v1->v2:
 - read whole net config layout instead of individual fields
 - added error extack for unmanaged vdpa device
 - fixed several endianness issues
 - introduced vdpa device ops for get config which is synchronized
   with other get/set features ops and config ops
---
 drivers/vdpa/vdpa.c       | 234 +++++++++++++++++++++++++++++++++++++-
 include/linux/vdpa.h      |  42 +++++++
 include/uapi/linux/vdpa.h |  11 ++
 3 files changed, 282 insertions(+), 5 deletions(-)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 116e076c72fd..9da8deb8c0f2 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. */
@@ -60,6 +62,7 @@ static void vdpa_release_dev(struct device *d)
 		ops->free(vdev);
 
 	ida_simple_remove(&vdpa_index_ida, vdev->index);
+	mutex_destroy(&vdev->cf_mutex);
 	kfree(vdev);
 }
 
@@ -114,6 +117,7 @@ struct vdpa_device *__vdpa_alloc_device(struct device
*parent,
 	if (err)
 		goto err_name;
 
+	mutex_init(&vdev->cf_mutex);
 	device_initialize(&vdev->dev);
 
 	return vdev;
@@ -269,10 +273,25 @@ EXPORT_SYMBOL_GPL(vdpa_mgmtdev_register);
  */
 u64 vdpa_get_features(struct vdpa_device *vdev)
 {
-	return vdev->config->get_features(vdev);
+	u64 features;
+
+	mutex_lock(&vdev->cf_mutex);
+	features = vdev->config->get_features(vdev);
+	mutex_unlock(&vdev->cf_mutex);
+	return features;
 }
 EXPORT_SYMBOL_GPL(vdpa_get_features);
 
+static int __vdpa_set_features(struct vdpa_device *vdev, u64 features)
+{
+	const struct vdpa_config_ops *ops = vdev->config;
+	int err;
+
+	vdev->features_valid = true;
+	err = ops->set_features(vdev, features);
+	return err;
+}
+
 /**
  * vdpa_set_features - Set vDPA device features
  * @vdev: vdpa device whose features to set
@@ -282,10 +301,12 @@ EXPORT_SYMBOL_GPL(vdpa_get_features);
  */
 int vdpa_set_features(struct vdpa_device *vdev, u64 features)
 {
-	const struct vdpa_config_ops *ops = vdev->config;
+	int err;
 
-	vdev->features_valid = true;
-	return ops->set_features(vdev, features);
+	mutex_lock(&vdev->cf_mutex);
+	err = __vdpa_set_features(vdev, features);
+	mutex_unlock(&vdev->cf_mutex);
+	return err;
 }
 EXPORT_SYMBOL_GPL(vdpa_set_features);
 
@@ -294,13 +315,15 @@ void vdpa_get_config(struct vdpa_device *vdev, unsigned
int offset,
 {
 	const struct vdpa_config_ops *ops = vdev->config;
 
+	mutex_lock(&vdev->cf_mutex);
 	/*
 	 * Config accesses aren't supposed to trigger before features are set.
 	 * If it does happen we assume a legacy guest.
 	 */
 	if (!vdev->features_valid)
-		vdpa_set_features(vdev, 0);
+		__vdpa_set_features(vdev, 0);
 	ops->get_config(vdev, offset, buf, len);
+	mutex_unlock(&vdev->cf_mutex);
 }
 EXPORT_SYMBOL_GPL(vdpa_get_config);
 
@@ -314,7 +337,9 @@ EXPORT_SYMBOL_GPL(vdpa_get_config);
 void vdpa_set_config(struct vdpa_device *dev, unsigned int offset,
 		     void *buf, unsigned int length)
 {
+	mutex_lock(&dev->cf_mutex);
 	dev->config->set_config(dev, offset, buf, length);
+	mutex_unlock(&dev->cf_mutex);
 }
 EXPORT_SYMBOL_GPL(vdpa_set_config);
 
@@ -664,6 +689,198 @@ 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, u64 features,
+				       const struct vdpa_dev_config *config)
+{
+	if ((features & (1ULL << VIRTIO_NET_F_MQ)) == 0)
+		return 0;
+
+	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP,
+			config->net.max_virtqueue_pairs))
+		return -EMSGSIZE;
+	return 0;
+}
+
+static int vdpa_dev_net_rss_config_fill(struct vdpa_device *vdev,
+					struct sk_buff *msg, u64 features,
+					const struct vdpa_dev_config *config)
+{
+	if ((features & (1ULL << VIRTIO_NET_F_RSS)) == 0)
+		return 0;
+
+	if (nla_put_u8(msg, VDPA_ATTR_DEV_NET_CFG_RSS_MAX_KEY_LEN,
+		       config->net.rss_max_key_size))
+		return -EMSGSIZE;
+	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_RSS_MAX_IT_LEN,
+			config->net.rss_max_key_size))
+		return -EMSGSIZE;
+	if (nla_put_u32(msg, VDPA_ATTR_DEV_NET_CFG_RSS_HASH_TYPES,
+			config->net.supported_hash_types))
+		return -EMSGSIZE;
+	return 0;
+}
+
+static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff
*msg)
+{
+	struct vdpa_dev_config config = {};
+	u64 features;
+	int err;
+
+	mutex_lock(&vdev->cf_mutex);
+	vdev->config->get_ce_config(vdev, &config);
+	mutex_unlock(&vdev->cf_mutex);
+
+	if (nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR, sizeof(config.net.mac),
+		    config.net.mac))
+		return -EMSGSIZE;
+	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_STATUS, config.net.status))
+		return -EMSGSIZE;
+	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, config.net.mtu))
+		return -EMSGSIZE;
+	if (nla_put_u32(msg, VDPA_ATTR_DEV_NET_CFG_SPEED, config.net.speed))
+		return -EMSGSIZE;
+	if (nla_put_u8(msg, VDPA_ATTR_DEV_NET_CFG_DUPLEX, config.net.duplex))
+		return -EMSGSIZE;
+
+	features = vdev->config->get_features(vdev);
+
+	err = vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
+	if (err)
+		return err;
+	return vdpa_dev_net_rss_config_fill(vdev, msg, features, &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;
+
+	if (!vdev->config->get_ce_config) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Configuration layout query is unsupported");
+		return -EOPNOTSUPP;
+	}
+
+	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 },
@@ -695,6 +912,13 @@ 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,
+		.flags = GENL_ADMIN_PERM,
+	},
 };
 
 static struct genl_family vdpa_nl_family __ro_after_init = {
diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 62e68ccc4c96..dcbbecb5dea8 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -6,6 +6,7 @@
 #include <linux/device.h>
 #include <linux/interrupt.h>
 #include <linux/vhost_iotlb.h>
+#include <linux/if_ether.h>
 
 /**
  * struct vdpa_calllback - vDPA callback definition.
@@ -47,6 +48,7 @@ struct vdpa_mgmt_dev;
  * @nvqs: maximum number of supported virtqueues
  * @mdev: management device pointer; caller must setup when registering device
as part
  *	  of dev_add() mgmtdev ops callback before invoking _vdpa_register_device().
+ * @cf_mutex: Protects get and set access to features and configuration layout.
  */
 struct vdpa_device {
 	struct device dev;
@@ -56,6 +58,7 @@ struct vdpa_device {
 	bool features_valid;
 	int nvqs;
 	struct vdpa_mgmt_dev *mdev;
+	struct mutex cf_mutex; /* Protects get/set config and features */
 };
 
 /**
@@ -68,6 +71,39 @@ struct vdpa_iova_range {
 	u64 last;
 };
 
+/**
+ * struct vdpa_net_dev_config - vDPA net device config to get/set via
+ *                              management device.
+ * @mac: mac address of the vdpa device
+ * @status: indicates VIRTIO_NET_F_STATUS and VIRTIO_NET_S_*
+ * @max_virtqueue_pairs: Maximum number of each of transmit and receive queues.
+ *			 see VIRTIO_NET_F_MQ and VIRTIO_NET_CTRL_MQ.
+ *			 Legal values are between 1 and 0x8000.
+ * @speed: In units of 1Mb. All values 0 to INT_MAX are legal.
+ * @mtu: Default maximum transmit unit advice.
+ * @duplex: 0x00 - half duplex
+ *	    0x01 - full duplex
+ * @rss_max_key_size: Maximum size of RSS key.
+ * @supported_hash_types: Bitmask of supported VIRTIO_NET_RSS_HASH_ types
+ * @rss_max_indirection_table_length: Maximum number of indirection table
+ *				      entries.
+ */
+struct vdpa_net_dev_config {
+	u8 mac[ETH_ALEN];
+	u16 status;
+	u16 max_virtqueue_pairs;
+	u32 speed;
+	u16 mtu;
+	u8 duplex;
+	u8 rss_max_key_size;
+	u32 supported_hash_types;
+	u16 rss_max_indirection_table_length;
+};
+
+struct vdpa_dev_config {
+	struct vdpa_net_dev_config net;
+};
+
 /**
  * struct vdpa_config_ops - operations for configuring a vDPA device.
  * Note: vDPA device drivers are required to implement all of the
@@ -164,6 +200,10 @@ struct vdpa_iova_range {
  *				@buf: buffer used to write from
  *				@len: the length to write to
  *				configuration space
+ * @get_ce_config:		Read device specific configuration in
+ *				cpu endianness.
+ *				@vdev: vdpa device
+ *				@config: pointer to config buffer used to read to
  * @get_generation:		Get device config generation (optional)
  *				@vdev: vdpa device
  *				Returns u32: device generation
@@ -235,6 +275,8 @@ struct vdpa_config_ops {
 			   void *buf, unsigned int len);
 	void (*set_config)(struct vdpa_device *vdev, unsigned int offset,
 			   const void *buf, unsigned int len);
+	void (*get_ce_config)(struct vdpa_device *vdev,
+			      struct vdpa_dev_config *config);
 	u32 (*get_generation)(struct vdpa_device *vdev);
 	struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev);
 
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

? 2021/4/7 ??1:04, Parav Pandit ??:
> 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 at nvidia.com>
> Signed-off-by: Eli Cohen <elic at nvidia.com>
> ---
> changelog:
> v1->v2:
>   - read whole net config layout instead of individual fields
>   - added error extack for unmanaged vdpa device
>   - fixed several endianness issues
>   - introduced vdpa device ops for get config which is synchronized
>     with other get/set features ops and config ops
> ---
>   drivers/vdpa/vdpa.c       | 234 +++++++++++++++++++++++++++++++++++++-
>   include/linux/vdpa.h      |  42 +++++++
>   include/uapi/linux/vdpa.h |  11 ++
>   3 files changed, 282 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 116e076c72fd..9da8deb8c0f2 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. */
> @@ -60,6 +62,7 @@ static void vdpa_release_dev(struct device *d)
>   		ops->free(vdev);
>   
>   	ida_simple_remove(&vdpa_index_ida, vdev->index);
> +	mutex_destroy(&vdev->cf_mutex);
>   	kfree(vdev);
>   }
>   
> @@ -114,6 +117,7 @@ struct vdpa_device *__vdpa_alloc_device(struct device
*parent,
>   	if (err)
>   		goto err_name;
>   
> +	mutex_init(&vdev->cf_mutex);
>   	device_initialize(&vdev->dev);
>   
>   	return vdev;
> @@ -269,10 +273,25 @@ EXPORT_SYMBOL_GPL(vdpa_mgmtdev_register);
>    */
>   u64 vdpa_get_features(struct vdpa_device *vdev)
>   {
> -	return vdev->config->get_features(vdev);
> +	u64 features;
> +
> +	mutex_lock(&vdev->cf_mutex);
> +	features = vdev->config->get_features(vdev);
> +	mutex_unlock(&vdev->cf_mutex);
> +	return features;
>   }
>   EXPORT_SYMBOL_GPL(vdpa_get_features);
>   
> +static int __vdpa_set_features(struct vdpa_device *vdev, u64 features)
> +{
> +	const struct vdpa_config_ops *ops = vdev->config;
> +	int err;
> +
> +	vdev->features_valid = true;
> +	err = ops->set_features(vdev, features);
> +	return err;
> +}
> +
>   /**
>    * vdpa_set_features - Set vDPA device features
>    * @vdev: vdpa device whose features to set
> @@ -282,10 +301,12 @@ EXPORT_SYMBOL_GPL(vdpa_get_features);
>    */
>   int vdpa_set_features(struct vdpa_device *vdev, u64 features)
>   {
> -	const struct vdpa_config_ops *ops = vdev->config;
> +	int err;
>   
> -	vdev->features_valid = true;
> -	return ops->set_features(vdev, features);
> +	mutex_lock(&vdev->cf_mutex);
> +	err = __vdpa_set_features(vdev, features);
> +	mutex_unlock(&vdev->cf_mutex);
> +	return err;
>   }
>   EXPORT_SYMBOL_GPL(vdpa_set_features);
>   
> @@ -294,13 +315,15 @@ void vdpa_get_config(struct vdpa_device *vdev,
unsigned int offset,
>   {
>   	const struct vdpa_config_ops *ops = vdev->config;
>   
> +	mutex_lock(&vdev->cf_mutex);
>   	/*
>   	 * Config accesses aren't supposed to trigger before features are
set.
>   	 * If it does happen we assume a legacy guest.
>   	 */
>   	if (!vdev->features_valid)
> -		vdpa_set_features(vdev, 0);
> +		__vdpa_set_features(vdev, 0);
>   	ops->get_config(vdev, offset, buf, len);
> +	mutex_unlock(&vdev->cf_mutex);
>   }
>   EXPORT_SYMBOL_GPL(vdpa_get_config);
>   
> @@ -314,7 +337,9 @@ EXPORT_SYMBOL_GPL(vdpa_get_config);
>   void vdpa_set_config(struct vdpa_device *dev, unsigned int offset,
>   		     void *buf, unsigned int length)
>   {
> +	mutex_lock(&dev->cf_mutex);
>   	dev->config->set_config(dev, offset, buf, length);
> +	mutex_unlock(&dev->cf_mutex);
>   }
>   EXPORT_SYMBOL_GPL(vdpa_set_config);
>   
> @@ -664,6 +689,198 @@ 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, u64 features,
> +				       const struct vdpa_dev_config *config)
> +{
> +	if ((features & (1ULL << VIRTIO_NET_F_MQ)) == 0)
> +		return 0;
> +
> +	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MAX_VQP,
> +			config->net.max_virtqueue_pairs))
> +		return -EMSGSIZE;
> +	return 0;
> +}
> +
> +static int vdpa_dev_net_rss_config_fill(struct vdpa_device *vdev,
> +					struct sk_buff *msg, u64 features,
> +					const struct vdpa_dev_config *config)
> +{
> +	if ((features & (1ULL << VIRTIO_NET_F_RSS)) == 0)
> +		return 0;
> +
> +	if (nla_put_u8(msg, VDPA_ATTR_DEV_NET_CFG_RSS_MAX_KEY_LEN,
> +		       config->net.rss_max_key_size))
> +		return -EMSGSIZE;
> +	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_RSS_MAX_IT_LEN,
> +			config->net.rss_max_key_size))
> +		return -EMSGSIZE;
> +	if (nla_put_u32(msg, VDPA_ATTR_DEV_NET_CFG_RSS_HASH_TYPES,
> +			config->net.supported_hash_types))
> +		return -EMSGSIZE;
> +	return 0;
> +}
> +
> +static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct
sk_buff *msg)
> +{
> +	struct vdpa_dev_config config = {};
> +	u64 features;
> +	int err;
> +
> +	mutex_lock(&vdev->cf_mutex);
> +	vdev->config->get_ce_config(vdev, &config);
> +	mutex_unlock(&vdev->cf_mutex);
> +
> +	if (nla_put(msg, VDPA_ATTR_DEV_NET_CFG_MACADDR, sizeof(config.net.mac),
> +		    config.net.mac))
> +		return -EMSGSIZE;
> +	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_STATUS, config.net.status))
> +		return -EMSGSIZE;
> +	if (nla_put_u16(msg, VDPA_ATTR_DEV_NET_CFG_MTU, config.net.mtu))
> +		return -EMSGSIZE;
> +	if (nla_put_u32(msg, VDPA_ATTR_DEV_NET_CFG_SPEED, config.net.speed))
> +		return -EMSGSIZE;
> +	if (nla_put_u8(msg, VDPA_ATTR_DEV_NET_CFG_DUPLEX, config.net.duplex))
> +		return -EMSGSIZE;
> +
> +	features = vdev->config->get_features(vdev);
> +
> +	err = vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
> +	if (err)
> +		return err;
> +	return vdpa_dev_net_rss_config_fill(vdev, msg, features, &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;
> +
> +	if (!vdev->config->get_ce_config) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "Configuration layout query is unsupported");
> +		return -EOPNOTSUPP;
> +	}
> +
> +	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 },
> @@ -695,6 +912,13 @@ 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,
> +		.flags = GENL_ADMIN_PERM,
> +	},
>   };
>   
>   static struct genl_family vdpa_nl_family __ro_after_init = {
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 62e68ccc4c96..dcbbecb5dea8 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -6,6 +6,7 @@
>   #include <linux/device.h>
>   #include <linux/interrupt.h>
>   #include <linux/vhost_iotlb.h>
> +#include <linux/if_ether.h>
>   
>   /**
>    * struct vdpa_calllback - vDPA callback definition.
> @@ -47,6 +48,7 @@ struct vdpa_mgmt_dev;
>    * @nvqs: maximum number of supported virtqueues
>    * @mdev: management device pointer; caller must setup when registering
device as part
>    *	  of dev_add() mgmtdev ops callback before invoking
_vdpa_register_device().
> + * @cf_mutex: Protects get and set access to features and configuration
layout.
>    */
>   struct vdpa_device {
>   	struct device dev;
> @@ -56,6 +58,7 @@ struct vdpa_device {
>   	bool features_valid;
>   	int nvqs;
>   	struct vdpa_mgmt_dev *mdev;
> +	struct mutex cf_mutex; /* Protects get/set config and features */
>   };
>   
>   /**
> @@ -68,6 +71,39 @@ struct vdpa_iova_range {
>   	u64 last;
>   };
>   
> +/**
> + * struct vdpa_net_dev_config - vDPA net device config to get/set via
> + *                              management device.
> + * @mac: mac address of the vdpa device
> + * @status: indicates VIRTIO_NET_F_STATUS and VIRTIO_NET_S_*
> + * @max_virtqueue_pairs: Maximum number of each of transmit and receive
queues.
> + *			 see VIRTIO_NET_F_MQ and VIRTIO_NET_CTRL_MQ.
> + *			 Legal values are between 1 and 0x8000.
> + * @speed: In units of 1Mb. All values 0 to INT_MAX are legal.
> + * @mtu: Default maximum transmit unit advice.
> + * @duplex: 0x00 - half duplex
> + *	    0x01 - full duplex
> + * @rss_max_key_size: Maximum size of RSS key.
> + * @supported_hash_types: Bitmask of supported VIRTIO_NET_RSS_HASH_ types
> + * @rss_max_indirection_table_length: Maximum number of indirection table
> + *				      entries.
> + */
> +struct vdpa_net_dev_config {
> +	u8 mac[ETH_ALEN];
> +	u16 status;
> +	u16 max_virtqueue_pairs;
> +	u32 speed;
> +	u16 mtu;
> +	u8 duplex;
> +	u8 rss_max_key_size;
> +	u32 supported_hash_types;
> +	u16 rss_max_indirection_table_length;
> +};
> +
> +struct vdpa_dev_config {
> +	struct vdpa_net_dev_config net;
> +};
> +
>   /**
>    * struct vdpa_config_ops - operations for configuring a vDPA device.
>    * Note: vDPA device drivers are required to implement all of the
> @@ -164,6 +200,10 @@ struct vdpa_iova_range {
>    *				@buf: buffer used to write from
>    *				@len: the length to write to
>    *				configuration space
> + * @get_ce_config:		Read device specific configuration in
> + *				cpu endianness.
> + *				@vdev: vdpa device
> + *				@config: pointer to config buffer used to read to

So I wonder what's the reason for having this? If it's only the reason 
of endian, we can just use get_config.

We don't plan to expose a legacy or transition device, so we can simply 
do the endian conversion in the device.

Then we can stick to the uapi of virtio_net_config and there's no need 
for the VDPA_ATTR_DEV_NET_CFG_XXX?

Thanks

>    * @get_generation:		Get device config generation (optional)
>    *				@vdev: vdpa device
>    *				Returns u32: device generation
> @@ -235,6 +275,8 @@ struct vdpa_config_ops {
>   			   void *buf, unsigned int len);
>   	void (*set_config)(struct vdpa_device *vdev, unsigned int offset,
>   			   const void *buf, unsigned int len);
> +	void (*get_ce_config)(struct vdpa_device *vdev,
> +			      struct vdpa_dev_config *config);
>   	u32 (*get_generation)(struct vdpa_device *vdev);
>   	struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev);
>   
> 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,
>   };