linux-kernel - Re: [PATCH v14 04/19] x86/cpufeatures: Add SGX feature bits

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Date:   Wed, 26 Sep 2018 14:11:39 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Borislav Petkov <bp@...en8.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, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, linux-sgx@...r.kernel.org,
        andriy.shevchenko@...ux.intel.com,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        David Wang <davidwang@...oxin.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        "Levin, Alexander (Sasha Levin)" <alexander.levin@...izon.com>,
        Jia Zhang <qianyue.zj@...baba-inc.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v14 04/19] x86/cpufeatures: Add SGX feature bits

On Tue, Sep 25, 2018 at 06:48:54PM +0200, Borislav Petkov wrote:
> > +	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.

Thank you. I guess I understand what you want me to do i.e.

+       { X86_FEATURE_SGX1,             CPUID_EAX,  0, 0x00000012, 0 },
+       { X86_FEATURE_SGX2,             CPUID_EAX,  1, 0x00000012, 0 },
+       { X86_FEATURE_ENCLV,            CPUID_EAX,  5, 0x00000012, 0 },
+       { X86_FEATURE_ENCLS_C,          CPUID_EAX,  6, 0x00000012, 0 },

What puzzles me is that I cannot find any call site for
get_scattered_cpuid_leaf():

$ git grep get_scattered
arch/x86/kernel/cpu/cpu.h:extern u32 get_scattered_cpuid_leaf(unsigned int level,
arch/x86/kernel/cpu/scattered.c:u32 get_scattered_cpuid_leaf(unsigned int level, unsigned int sub_leaf,
arch/x86/kernel/cpu/scattered.c:EXPORT_SYMBOL_GPL(get_scattered_cpuid_leaf);

/Jarkko