linux-kernel - Re: [PATCH v12 06/13] x86/sgx: detect Intel SGX

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Date:   Wed, 4 Jul 2018 20:28:14 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     x86@...nel.org, platform-driver-x86@...r.kernel.org,
        dave.hansen@...el.com, sean.j.christopherson@...el.com,
        nhorman@...hat.com, npmccallum@...hat.com,
        linux-sgx@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Andi Kleen <ak@...ux.intel.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v12 06/13] x86/sgx: detect Intel SGX

On Tue, Jul 03, 2018 at 09:09:52PM +0200, Thomas Gleixner wrote:
> On Tue, 3 Jul 2018, Jarkko Sakkinen wrote:
> > @@ -0,0 +1,54 @@
> > +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> > +// Copyright(c) 2016-17 Intel Corporation.
> > +
> > +#include <asm/sgx.h>
> > +#include <asm/sgx_pr.h>
> > +#include <linux/freezer.h>
> > +#include <linux/highmem.h>
> > +#include <linux/kthread.h>
> > +#include <linux/ratelimit.h>
> > +#include <linux/sched/signal.h>
> > +#include <linux/slab.h>
> 
> The common include ordering is
> 
> include linux/....
> 
> include asm/...
> 
> > +
> > +bool sgx_enabled __ro_after_init;
> > +EXPORT_SYMBOL(sgx_enabled);
> 
> 
> > +bool sgx_lc_enabled __ro_after_init;
> > +EXPORT_SYMBOL(sgx_lc_enabled);
> > +
> > +static __init bool sgx_is_enabled(bool *lc_enabled)
> > +{
> > +	unsigned long fc;
> > +
> > +	if (!boot_cpu_has(X86_FEATURE_SGX))
> > +		return false;
> > +
> > +	if (!boot_cpu_has(X86_FEATURE_SGX1))
> > +		return false;
> > +
> > +	rdmsrl(MSR_IA32_FEATURE_CONTROL, fc);
> > +	if (!(fc & FEATURE_CONTROL_LOCKED)) {
> > +		pr_info("IA32_FEATURE_CONTROL MSR is not locked\n");
> > +		return false;
> > +	}
> > +
> > +	if (!(fc & FEATURE_CONTROL_SGX_ENABLE)) {
> > +		pr_info("disabled by the firmware\n");
> > +		return false;
> > +	}
> > +
> > +	if (!(fc & FEATURE_CONTROL_SGX_LE_WR)) {
> > +		pr_info("IA32_SGXLEPUBKEYHASHn MSRs are not writable\n");
> > +		return false;
> > +	}
> > +
> > +	*lc_enabled = !!(fc & FEATURE_CONTROL_SGX_LE_WR);
> > +	return true;
> > +}
> > +
> > +static __init int sgx_init(void)
> > +{
> > +	sgx_enabled = sgx_is_enabled(&sgx_lc_enabled);
> 
> This is horrible, really. Both variables are global. So what the heck is
> wrong with assigning them directly in the function? 

Fully agreed, does not make any sense.

> Thanks,
> 
> 	tglx

/Jarkko