linux-kernel - Re: [PATCH v11 07/13] x86, sgx: detect Intel SGX

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Message-ID: <20180611113521.GB22164@hmswarspite.think-freely.org>
Date:   Mon, 11 Jun 2018 07:35:21 -0400
From:   Neil Horman <nhorman@...hat.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     x86@...nel.org, platform-driver-x86@...r.kernel.org,
        dave.hansen@...el.com, sean.j.christopherson@...el.com,
        npmccallum@...hat.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andi Kleen <ak@...ux.intel.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>,
        "open list:INTEL SGX" <intel-sgx-kernel-dev@...ts.01.org>
Subject: Re: [PATCH v11 07/13] x86, sgx: detect Intel SGX

On Fri, Jun 08, 2018 at 07:09:42PM +0200, Jarkko Sakkinen wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
> 
> Intel(R) SGX is a set of CPU instructions that can be used by applications
> to set aside private regions of code and data. The code outside the enclave
> is disallowed to access the memory inside the enclave by the CPU access
> control.
> 
> This commit adds the check for SGX to arch/x86 and a new config option,
> INTEL_SGX_CORE. Exposes a boolean variable 'sgx_enabled' to query whether
> or not the SGX support is available.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> Tested-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> ---
>  arch/x86/Kconfig                | 19 ++++++++++++
>  arch/x86/include/asm/sgx.h      | 25 ++++++++++++++++
>  arch/x86/include/asm/sgx_pr.h   | 20 +++++++++++++
>  arch/x86/kernel/cpu/Makefile    |  1 +
>  arch/x86/kernel/cpu/intel_sgx.c | 53 +++++++++++++++++++++++++++++++++
>  5 files changed, 118 insertions(+)
>  create mode 100644 arch/x86/include/asm/sgx.h
>  create mode 100644 arch/x86/include/asm/sgx_pr.h
>  create mode 100644 arch/x86/kernel/cpu/intel_sgx.c
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index c07f492b871a..42015d5366ef 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1925,6 +1925,25 @@ config X86_INTEL_MEMORY_PROTECTION_KEYS
>  
>  	  If unsure, say y.
>  
> +config INTEL_SGX_CORE
> +	prompt "Intel SGX core functionality"
> +	def_bool n
> +	depends on X86_64 && CPU_SUP_INTEL
> +	help
> +	Intel Software Guard eXtensions (SGX) is a set of CPU instructions
> +	that allows ring 3 applications to create enclaves; private regions
> +	of memory that are protected, by hardware, from unauthorized access
> +	and/or modification.
> +
> +	This option enables kernel recognition of SGX, high-level management
> +	of the Enclave Page Cache (EPC), tracking and writing of SGX Launch
> +	Enclave Hash MSRs, and allows for virtualization of SGX via KVM. By
> +	iteslf, this option does not provide SGX support to userspace.
> +
> +	For details, see Documentation/x86/intel_sgx.rst
> +
> +	If unsure, say N.
> +
>  config EFI
>  	bool "EFI runtime service support"
>  	depends on ACPI
> diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> new file mode 100644
> index 000000000000..fa3e6e0eb8af
> --- /dev/null
> +++ b/arch/x86/include/asm/sgx.h
> @@ -0,0 +1,25 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> +// Copyright(c) 2016-18 Intel Corporation.
> +//
> +// Authors:
> +//
> +// Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> +// Suresh Siddha <suresh.b.siddha@...el.com>
> +// Sean Christopherson <sean.j.christopherson@...el.com>
> +
> +#ifndef _ASM_X86_SGX_H
> +#define _ASM_X86_SGX_H
> +
> +#include <linux/types.h>
> +
> +#define SGX_CPUID 0x12
> +
Agree with Dave, this can just be remoed and you can use the feature macro from
cpuid.h instead

Neil