nitro_enclaves: Add ioctl interface definition

The Nitro Enclaves driver handles the enclave lifetime management. This
includes enclave creation, termination and setting up its resources such
as memory and CPU.

An enclave runs alongside the VM that spawned it. It is abstracted as a
process running in the VM that launched it. The process interacts with
the NE driver, that exposes an ioctl interface for creating an enclave
and setting up its resources.

Changelog

v9 -> v10

* Update commit message to include the changelog before the SoB tag(s).

v8 -> v9

* No changes.

v7 -> v8

* Add NE custom error codes for user space memory regions not backed by
  pages multiple of 2 MiB, invalid flags and enclave CID.
* Add max flag value for enclave image load info.

v6 -> v7

* Clarify in the ioctls documentation that the return value is -1 and
  errno is set on failure.
* Update the error code value for NE_ERR_INVALID_MEM_REGION_SIZE as it
  gets in user space as value 25 (ENOTTY) instead of 515. Update the
  NE custom error codes values range to not be the same as the ones
  defined in include/linux/errno.h, although these are not propagated
  to user space.

v5 -> v6

* Fix typo in the description about the NE CPU pool.
* Update documentation to kernel-doc format.
* Remove the ioctl to query API version.

v4 -> v5

* Add more details about the ioctl calls usage e.g. error codes, file
  descriptors used.
* Update the ioctl to set an enclave vCPU to not return a file
  descriptor.
* Add specific NE error codes.

v3 -> v4

* Decouple NE ioctl interface from KVM API.
* Add NE API version and the corresponding ioctl call.
* Add enclave / image load flags options.

v2 -> v3

* Remove the GPL additional wording as SPDX-License-Identifier is
  already in place.

v1 -> v2

* Add ioctl for getting enclave image load metadata.
* Update NE_ENCLAVE_START ioctl name to NE_START_ENCLAVE.
* Add entry in Documentation/userspace-api/ioctl/ioctl-number.rst for NE
  ioctls.
* Update NE ioctls definition based on the updated ioctl range for major
  and minor.
Reviewed-by: Alexander Graf <graf@amazon.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Alexandru Vasile <lexnv@amazon.com>
Signed-off-by: Andra Paraschiv <andraprs@amazon.com>
Link: https://lore.kernel.org/r/20200921121732.44291-2-andraprs@amazon.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/userspace-api/ioctl/ioctl-number.rst

@@ -328,8 +328,11 @@ Code  Seq#    Include File                                           Comments
 0xAC  00-1F  linux/raw.h
 0xAD  00                                                             Netfilter device in development:
                                                                      <mailto:rusty@rustcorp.com.au>
-0xAE  all    linux/kvm.h                                             Kernel-based Virtual Machine
+0xAE  00-1F  linux/kvm.h                                             Kernel-based Virtual Machine
                                                                      <mailto:kvm@vger.kernel.org>
+0xAE  40-FF  linux/kvm.h                                             Kernel-based Virtual Machine
+                                                                     <mailto:kvm@vger.kernel.org>
+0xAE  20-3F  linux/nitro_enclaves.h                                  Nitro Enclaves
 0xAF  00-1F  linux/fsl_hypervisor.h                                  Freescale hypervisor
 0xB0  all                                                            RATIO devices in development:
                                                                      <mailto:vgo@ratio.de>

include/linux/nitro_enclaves.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ */
+
+#ifndef _LINUX_NITRO_ENCLAVES_H_
+#define _LINUX_NITRO_ENCLAVES_H_
+
+#include <uapi/linux/nitro_enclaves.h>
+
+#endif /* _LINUX_NITRO_ENCLAVES_H_ */