psp: base PSP device support

Add a netlink family for PSP and allow drivers to register support.

The "PSP device" is its own object. This allows us to perform more
flexible reference counting / lifetime control than if PSP information
was part of net_device. In the future we should also be able
to "delegate" PSP access to software devices, such as *vlan, veth
or netkit more easily.

Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250917000954.859376-3-daniel.zahka@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

include/uapi/linux/psp.h

@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) */
+/* Do not edit directly, auto-generated from: */
+/*	Documentation/netlink/specs/psp.yaml */
+/* YNL-GEN uapi header */
+
+#ifndef _UAPI_LINUX_PSP_H
+#define _UAPI_LINUX_PSP_H
+
+#define PSP_FAMILY_NAME		"psp"
+#define PSP_FAMILY_VERSION	1
+
+enum psp_version {
+	PSP_VERSION_HDR0_AES_GCM_128,
+	PSP_VERSION_HDR0_AES_GCM_256,
+	PSP_VERSION_HDR0_AES_GMAC_128,
+	PSP_VERSION_HDR0_AES_GMAC_256,
+};
+
+enum {
+	PSP_A_DEV_ID = 1,
+	PSP_A_DEV_IFINDEX,
+	PSP_A_DEV_PSP_VERSIONS_CAP,
+	PSP_A_DEV_PSP_VERSIONS_ENA,
+
+	__PSP_A_DEV_MAX,
+	PSP_A_DEV_MAX = (__PSP_A_DEV_MAX - 1)
+};
+
+enum {
+	PSP_CMD_DEV_GET = 1,
+	PSP_CMD_DEV_ADD_NTF,
+	PSP_CMD_DEV_DEL_NTF,
+	PSP_CMD_DEV_SET,
+	PSP_CMD_DEV_CHANGE_NTF,
+
+	__PSP_CMD_MAX,
+	PSP_CMD_MAX = (__PSP_CMD_MAX - 1)
+};
+
+#define PSP_MCGRP_MGMT	"mgmt"
+
+#endif /* _UAPI_LINUX_PSP_H */