vdpa: Add support for returning device configuration information

mainline inclusion
from mainline-v5.17-rc1
commit 612f330e
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5WXCZ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=612f330ec56f12c0d099286c45f82d835845f136

----------------------------------------------------------------------

Add netlink attribute to store the negotiated features. This can be used
by userspace to get the current state of the vdpa instance.

Examples:

$ vdpa dev config show vdpa-a
vdpa-a: mac 00:00:00:00:88:88 link up link_announce false max_vq_pairs 16 mtu 1500
  negotiated_features CSUM GUEST_CSUM MTU MAC HOST_TSO4 HOST_TSO6 STATUS \
  CTRL_VQ MQ CTRL_MAC_ADDR VERSION_1 ACCESS_PLATFORM

$ vdpa -j dev config show vdpa-a
{"config":{"vdpa-a":{"mac":"00:00:00:00:88:88","link ":"up","link_announce":false, \
 "max_vq_pairs":16,"mtu":1500,"negotiated_features":["CSUM","GUEST_CSUM","MTU","MAC", \
 "HOST_TSO4","HOST_TSO6","STATUS","CTRL_VQ","MQ","CTRL_MAC_ADDR","VERSION_1", \
 "ACCESS_PLATFORM"]}}}

$ vdpa -jp dev config show vdpa-a
{
    "config": {
        "vdpa-a": {
            "mac": "00:00:00:00:88:88",
            "link ": "up",
            "link_announce ": false,
            "max_vq_pairs": 16,
            "mtu": 1500,
            "negotiated_features": [
"CSUM","GUEST_CSUM","MTU","MAC","HOST_TSO4","HOST_TSO6","STATUS","CTRL_VQ","MQ", \
"CTRL_MAC_ADDR","VERSION_1","ACCESS_PLATFORM"
]
        }
    }
}
Signed-off-by: NEli Cohen <elic@nvidia.com>
Link: https://lore.kernel.org/r/20220105114646.577224-9-elic@nvidia.comSigned-off-by: NMichael S. Tsirkin <mst@redhat.com>
Acked-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NPengyuan Zhao <zhaopengyuan@hisilicon.com>

drivers/vdpa/vdpa.c

@@ -849,6 +849,9 @@ static int vdpa_dev_net_config_fill(struct vdpa_device *vdev, struct sk_buff *ms
 		return -EMSGSIZE;
 
 	features = vdev->config->get_driver_features(vdev);
+	if (nla_put_u64_64bit(msg, VDPA_ATTR_DEV_NEGOTIATED_FEATURES, features,
+			      VDPA_ATTR_PAD))
+		return -EMSGSIZE;
 
 	return vdpa_dev_net_mq_config_fill(vdev, msg, features, &config);
 }

include/uapi/linux/vdpa.h

@@ -23,6 +23,9 @@ enum vdpa_command {
 enum vdpa_attr {
 	VDPA_ATTR_UNSPEC,
 
+	/* Pad attribute for 64b alignment */
+	VDPA_ATTR_PAD = VDPA_ATTR_UNSPEC,
+
 	/* bus name (optional) + dev name together make the parent device handle */
 	VDPA_ATTR_MGMTDEV_BUS_NAME,		/* string */
 	VDPA_ATTR_MGMTDEV_DEV_NAME,		/* string */
@@ -40,6 +43,7 @@ enum vdpa_attr {
 	VDPA_ATTR_DEV_NET_CFG_MAX_VQP,		/* u16 */
 	VDPA_ATTR_DEV_NET_CFG_MTU,		/* u16 */
 
+	VDPA_ATTR_DEV_NEGOTIATED_FEATURES,	/* u64 */
 	/* new attributes must be added above here */
 	VDPA_ATTR_MAX,
 };