Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 25 Sep 2018 18:48:54 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc:     x86@kernel.org, platform-driver-x86@vger.kernel.org,
        dave.hansen@intel.com, sean.j.christopherson@intel.com,
        nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com,
        shay.katz-zamir@intel.com, linux-sgx@vger.kernel.org,
        andriy.shevchenko@linux.intel.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        David Woodhouse <dwmw@amazon.co.uk>,
        David Wang <davidwang@zhaoxin.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        "Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>,
        Jia Zhang <qianyue.zj@alibaba-inc.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v14 04/19] x86/cpufeatures: Add SGX feature bits
Message-ID: <20180925164854.GF23986@zn.tnic>
References: <20180925130845.9962-1-jarkko.sakkinen@linux.intel.com>
 <20180925130845.9962-5-jarkko.sakkinen@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20180925130845.9962-5-jarkko.sakkinen@linux.intel.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Sep 25, 2018 at 04:06:41PM +0300, Jarkko Sakkinen wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> Add SGX feature bits as part of the Linux defined leaf 8, which
> currently contains virtualization flags.  There are currently four
> documented SGX feature bits, with more expected in the not-too-distant
> future.

...

> +static void detect_sgx(struct cpuinfo_x86 *c)
> +{
> +#define _X86_FEATURE_SGX1		BIT(0)
> +#define _X86_FEATURE_SGX2		BIT(1)
> +#define _X86_FEATURE_SGX_ENCLV		BIT(5)
> +#define _X86_FEATURE_SGX_ENCLS_C	BIT(6)
> +
> +	unsigned int eax;
> +
> +	clear_cpu_cap(c, X86_FEATURE_SGX1);
> +	clear_cpu_cap(c, X86_FEATURE_SGX2);
> +	clear_cpu_cap(c, X86_FEATURE_SGX_ENCLV);
> +	clear_cpu_cap(c, X86_FEATURE_SGX_ENCLS_C);
> +
> +	if (c->cpuid_level < SGX_CPUID) {
> +		pr_err_once("x86/sgx: cannot enumerate CPUID leaf (0x%x)\n",
> +			    SGX_CPUID);
> +		clear_cpu_cap(c, X86_FEATURE_SGX);
> +		return;
> +	}
> +
> +	eax = cpuid_eax(SGX_CPUID);
> +
> +	if (eax & _X86_FEATURE_SGX1)
> +		set_cpu_cap(c, X86_FEATURE_SGX1);
> +
> +	if (eax & _X86_FEATURE_SGX2)
> +		set_cpu_cap(c, X86_FEATURE_SGX2);
> +
> +	if (eax & _X86_FEATURE_SGX_ENCLV)
> +		set_cpu_cap(c, X86_FEATURE_SGX_ENCLV);
> +
> +	if (eax & _X86_FEATURE_SGX_ENCLS_C)
> +		set_cpu_cap(c, X86_FEATURE_SGX_ENCLS_C);


Look at arch/x86/kernel/cpu/scattered.c for how to do this properly.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.