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

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Message-ID: <8af490be-01e3-5ba1-a3c1-4de49bf717e5@amazon.com>
Date:   Mon, 6 Jul 2020 16:09:26 +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 11:01, Alexander Graf wrote:
>
>
> On 06.07.20 09:49, Paraschiv, Andra-Irina wrote:
>>
>>
>> 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.
>
> The largest NUMA node CPU count I'm aware of today is 64. Since we 
> limit the pool to a single node, we can't go beyond that. Let's be a 
> bit future proof and double that number: 128. Then we get to 401 
> characters if you pass in every single CPU as comma separated. I would 
> seriously hope most people would just pass ranges though.
>
> So how about we make it 512 for now?

We can set it like this, I changed to 512 and updated the comment as well.

Thanks,
Andra



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