vdpa: Define vdpa mgmt device, ops and a netlink interface

To add one or more VDPA devices, define a management device which
allows adding or removing vdpa device. A management device defines
set of callbacks to manage vdpa devices.

To begin with, it defines add and remove callbacks through which a user
defined vdpa device can be added or removed.

A unique management device is identified by its unique handle identified
by management device name and optionally the bus name.

Hence, introduce routine through which driver can register a
management device and its callback operations for adding and remove
a vdpa device.

Introduce vdpa netlink socket family so that user can query management
device and its attributes.

Example of show vdpa management device which allows creating vdpa device of
networking class (device id = 0x1) of virtio specification 1.1
section 5.1.1.

$ vdpa mgmtdev show
vdpasim_net:
  supported_classes:
    net

Example of showing vdpa management device in JSON format.

$ vdpa mgmtdev show -jp
{
    "show": {
        "vdpasim_net": {
            "supported_classes": [ "net" ]
        }
    }
}

Signed-off-by: Parav Pandit <parav@nvidia.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20210105103203.82508-4-parav@nvidia.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Including a bugfix:

vpda: correctly size vdpa_nl_policy

We need to ensure last entry of vdpa_nl_policy[]
is zero, otherwise out-of-bounds access is hurting us.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Cc: Parav Pandit <parav@nvidia.com>
Cc: Eli Cohen <elic@nvidia.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/20210210134911.4119555-1-eric.dumazet@gmail.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 5700baa22356..6b8b4222bca6 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -35,6 +35,8 @@ struct vdpa_vq_state {
 	u16	avail_index;
 };
 
+struct vdpa_mgmt_dev;
+
 /**
  * vDPA device - representation of a vDPA device
  * @dev: underlying device
@@ -335,4 +337,33 @@ static inline void vdpa_get_config(struct vdpa_device *vdev, unsigned offset,
 	ops->get_config(vdev, offset, buf, len);
 }
 
+/**
+ * vdpa_mgmtdev_ops - vdpa device ops
+ * @dev_add:	Add a vdpa device using alloc and register
+ *		@mdev: parent device to use for device addition
+ *		@name: name of the new vdpa device
+ *		Driver need to add a new device using _vdpa_register_device()
+ *		after fully initializing the vdpa device. Driver must return 0
+ *		on success or appropriate error code.
+ * @dev_del:	Remove a vdpa device using unregister
+ *		@mdev: parent device to use for device removal
+ *		@dev: vdpa device to remove
+ *		Driver need to remove the specified device by calling
+ *		_vdpa_unregister_device().
+ */
+struct vdpa_mgmtdev_ops {
+	int (*dev_add)(struct vdpa_mgmt_dev *mdev, const char *name);
+	void (*dev_del)(struct vdpa_mgmt_dev *mdev, struct vdpa_device *dev);
+};
+
+struct vdpa_mgmt_dev {
+	struct device *device;
+	const struct vdpa_mgmtdev_ops *ops;
+	const struct virtio_device_id *id_table; /* supported ids */
+	struct list_head list;
+};
+
+int vdpa_mgmtdev_register(struct vdpa_mgmt_dev *mdev);
+void vdpa_mgmtdev_unregister(struct vdpa_mgmt_dev *mdev);
+
 #endif /* _LINUX_VDPA_H */