linux-kernel - Re: [PATCH v4 07/18] nitro_enclaves: Init misc device providing the ioctl interface

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Message-ID: <7cd235d0-25a8-5476-985f-3ee7a60ce3de@amazon.com>
Date:   Mon, 6 Jul 2020 10:49:43 +0300
From:   "Paraschiv, Andra-Irina" <andraprs@...zon.com>
To:     Alexander Graf <graf@...zon.de>, <linux-kernel@...r.kernel.org>
CC:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Colm MacCarthaigh <colmmacc@...zon.com>,
        Bjoern Doebel <doebel@...zon.de>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Frank van der Linden <fllinden@...zon.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        Martin Pohlack <mpohlack@...zon.de>,
        "Matt Wilson" <msw@...zon.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Balbir Singh <sblbir@...zon.com>,
        Stefano Garzarella <sgarzare@...hat.com>,
        "Stefan Hajnoczi" <stefanha@...hat.com>,
        Stewart Smith <trawets@...zon.com>,
        "Uwe Dannowski" <uwed@...zon.de>, <kvm@...r.kernel.org>,
        <ne-devel-upstream@...zon.com>
Subject: Re: [PATCH v4 07/18] nitro_enclaves: Init misc device providing the
 ioctl interface



On 06/07/2020 10:13, Alexander Graf wrote:
>
>
> On 22.06.20 22:03, Andra Paraschiv wrote:
>> The Nitro Enclaves driver provides an ioctl interface to the user space
>> for enclave lifetime management e.g. enclave creation / termination and
>> setting enclave resources such as memory and CPU.
>>
>> This ioctl interface is mapped to a Nitro Enclaves misc device.
>>
>> Signed-off-by: Andra Paraschiv <andraprs@...zon.com>
>> ---
>> Changelog
>>
>> v3 -> v4
>>
>> * Use dev_err instead of custom NE log pattern.
>> * Remove the NE CPU pool init during kernel module loading, as the CPU
>>    pool is now setup at runtime, via a sysfs file for the kernel
>>    parameter.
>> * Add minimum enclave memory size definition.
>>
>> v2 -> v3
>>
>> * Remove the GPL additional wording as SPDX-License-Identifier is
>>    already in place.
>> * Remove the WARN_ON calls.
>> * Remove linux/bug and linux/kvm_host includes that are not needed.
>> * Remove "ratelimited" from the logs that are not in the ioctl call
>>    paths.
>> * Remove file ops that do nothing for now - open and release.
>>
>> v1 -> v2
>>
>> * Add log pattern for NE.
>> * Update goto labels to match their purpose.
>> * Update ne_cpu_pool data structure to include the global mutex.
>> * Update NE misc device mode to 0660.
>> * Check if the CPU siblings are included in the NE CPU pool, as full CPU
>>    cores are given for the enclave(s).
>> ---
>>   drivers/virt/nitro_enclaves/ne_misc_dev.c | 133 ++++++++++++++++++++++
>>   drivers/virt/nitro_enclaves/ne_pci_dev.c  |  11 ++
>>   2 files changed, 144 insertions(+)
>>   create mode 100644 drivers/virt/nitro_enclaves/ne_misc_dev.c
>>
>> diff --git a/drivers/virt/nitro_enclaves/ne_misc_dev.c 
>> b/drivers/virt/nitro_enclaves/ne_misc_dev.c
>> new file mode 100644
>> index 000000000000..628fb10c2b36
>> --- /dev/null
>> +++ b/drivers/virt/nitro_enclaves/ne_misc_dev.c
>> @@ -0,0 +1,133 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights 
>> Reserved.
>> + */
>> +
>> +/**
>> + * Enclave lifetime management driver for Nitro Enclaves (NE).
>> + * Nitro is a hypervisor that has been developed by Amazon.
>> + */
>> +
>> +#include <linux/anon_inodes.h>
>> +#include <linux/capability.h>
>> +#include <linux/cpu.h>
>> +#include <linux/device.h>
>> +#include <linux/file.h>
>> +#include <linux/hugetlb.h>
>> +#include <linux/list.h>
>> +#include <linux/miscdevice.h>
>> +#include <linux/mm.h>
>> +#include <linux/mman.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>> +#include <linux/nitro_enclaves.h>
>> +#include <linux/pci.h>
>> +#include <linux/poll.h>
>> +#include <linux/slab.h>
>> +#include <linux/types.h>
>> +
>> +#include "ne_misc_dev.h"
>> +#include "ne_pci_dev.h"
>> +
>> +#define NE_EIF_LOAD_OFFSET (8 * 1024UL * 1024UL)
>> +
>> +#define NE_MIN_ENCLAVE_MEM_SIZE (64 * 1024UL * 1024UL)
>> +
>> +#define NE_MIN_MEM_REGION_SIZE (2 * 1024UL * 1024UL)
>> +
>> +/*
>> + * TODO: Update logic to create new sysfs entries instead of using
>> + * a kernel parameter e.g. if multiple sysfs files needed.
>> + */
>> +static const struct kernel_param_ops ne_cpu_pool_ops = {
>
> Adding an empty ops struct looks very odd. If you fill it in a later 
> patch, please indicate so in a comment here.

True, I already updated this in v5, to have the .get function here and 
the .set one in a later patch.

>
>> +};
>> +
>> +static char ne_cpus[PAGE_SIZE];
>
> PAGE_SIZE is a bit excessive, no? Even if you list every single CPU of 
> a 256 CPU system you are <1024.

It is a bit too much, I was thinking of it while declaring this. I can 
update to 1024 in v5.

Thank you.

Andra



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