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

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Message-ID: <391ad4b0-2011-4d63-8274-9ccb77a5351f@amazon.de>
Date:   Mon, 6 Jul 2020 09:13:29 +0200
From:   Alexander Graf <graf@...zon.de>
To:     Andra Paraschiv <andraprs@...zon.com>,
        <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 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.

> +};
> +
> +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.


Alex



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