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Subject: Re: [PATCH v4 01/18] nitro_enclaves: Add ioctl interface definition
To:     Stefan Hajnoczi <stefanha@redhat.com>
CC:     <linux-kernel@vger.kernel.org>,
        Anthony Liguori <aliguori@amazon.com>,
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From:   "Paraschiv, Andra-Irina" <andraprs@amazon.com>
Message-ID: <60d7d8be-7c8c-964a-a339-8ef7f5bd2fef@amazon.com>
Date:   Wed, 24 Jun 2020 17:02:54 +0300
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On 23/06/2020 11:56, Stefan Hajnoczi wrote:
> On Mon, Jun 22, 2020 at 11:03:12PM +0300, Andra Paraschiv wrote:
>> diff --git a/include/uapi/linux/nitro_enclaves.h b/include/uapi/linux/ni=
tro_enclaves.h
>> new file mode 100644
>> index 000000000000..3270eb939a97
>> --- /dev/null
>> +++ b/include/uapi/linux/nitro_enclaves.h
>> @@ -0,0 +1,137 @@
>> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
>> +/*
>> + * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserv=
ed.
>> + */
>> +
>> +#ifndef _UAPI_LINUX_NITRO_ENCLAVES_H_
>> +#define _UAPI_LINUX_NITRO_ENCLAVES_H_
>> +
>> +#include <linux/types.h>
>> +
>> +/* Nitro Enclaves (NE) Kernel Driver Interface */
>> +
>> +#define NE_API_VERSION (1)
>> +
>> +/**
>> + * The command is used to get the version of the NE API. This way the u=
ser space
>> + * processes can be aware of the feature sets provided by the NE kernel=
 driver.
>> + *
>> + * The NE API version is returned as result of this ioctl call.
>> + */
>> +#define NE_GET_API_VERSION _IO(0xAE, 0x20)
>> +
>> +/**
>> + * The command is used to create a slot that is associated with an encl=
ave VM.
>> + *
>> + * The generated unique slot id is a read parameter of this command. An=
 enclave
>> + * file descriptor is returned as result of this ioctl call. The enclav=
e fd can
>> + * be further used with ioctl calls to set vCPUs and memory regions, th=
en start
>> + * the enclave.
>> + */
>> +#define NE_CREATE_VM _IOR(0xAE, 0x21, __u64)
> Information that would be useful for the ioctls:
>
> 1. Which fd the ioctl must be invoked on (/dev/nitro-enclaves, enclave fd=
, vCPU fd)
>
> 2. Errnos and their meanings
>
> 3. Which state(s) the ioctls may be invoked in (e.g. enclave created/star=
ted/etc)

I'll include this info in v5. Indeed, that's useful for the user space =

tooling that interacts with the kernel driver, in addition to the code =

review itself and future refs, to understand how it works.

>
>> +/* User memory region flags */
>> +
>> +/* Memory region for enclave general usage. */
>> +#define NE_DEFAULT_MEMORY_REGION (0x00)
>> +
>> +/* Memory region to be set for an enclave (write). */
>> +struct ne_user_memory_region {
>> +	/**
>> +	 * Flags to determine the usage for the memory region (write).
>> +	 */
>> +	__u64 flags;
> Where is the write flag defined?
>
> I guess it's supposed to be:
>
>    #define NE_USER_MEMORY_REGION_FLAG_WRITE (0x01)

For now, the flags field is included in the NE ioctl interface for =

extensions, it is not part of the NE PCI device interface yet.

The enclave image is copied into enclave memory before the enclave =

memory is carved out of the primary / parent VM. After carving it out =

(when the command request to add memory is sent to the PCI device and it =

is successfully completed), there will be faults if the enclave memory =

is written from the primary / parent VM.

Ah, and just as a note, that "read" / "write" in parentheses means that =

a certain data structure / field is read / written by user space. I =

updated to use "in" / "out" instead of "read" / "write" in v5.

Thank you.

Andra


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