linux-kernel - Re: [PATCH v19,RESEND 01/27] x86/cpufeatures: Add Intel-defined SGX feature bit

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Date:   Thu, 21 Mar 2019 16:16:43 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Neil Horman <nhorman@...hat.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-sgx@...r.kernel.org, akpm@...ux-foundation.org,
        dave.hansen@...el.com, sean.j.christopherson@...el.com,
        npmccallum@...hat.com, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, haitao.huang@...el.com,
        andriy.shevchenko@...ux.intel.com, tglx@...utronix.de,
        kai.svahn@...el.com, bp@...en8.de, josh@...htriplett.org,
        luto@...nel.org, kai.huang@...el.com, rientjes@...gle.com,
        Kai Huang <kai.huang@...ux.intel.com>
Subject: Re: [PATCH v19,RESEND 01/27] x86/cpufeatures: Add Intel-defined SGX
 feature bit

On Wed, Mar 20, 2019 at 03:41:53PM -0400, Neil Horman wrote:
> On Wed, Mar 20, 2019 at 06:20:53PM +0200, Jarkko Sakkinen wrote:
> > From: Kai Huang <kai.huang@...ux.intel.com>
> > 
> > X86_FEATURE_SGX reflects whether or not the CPU supports Intel's
> > Software Guard eXtensions (SGX).
> > 
> > Signed-off-by: Kai Huang <kai.huang@...ux.intel.com>
> > Co-developed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> > Reviewed-by: Borislav Petkov <bp@...e.de>
> > ---
> >  arch/x86/include/asm/cpufeatures.h       | 1 +
> >  arch/x86/include/asm/disabled-features.h | 8 +++++++-
> >  2 files changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> > index 981ff9479648..a16325db4cff 100644
> > --- a/arch/x86/include/asm/cpufeatures.h
> > +++ b/arch/x86/include/asm/cpufeatures.h
> > @@ -236,6 +236,7 @@
> >  /* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */
> >  #define X86_FEATURE_FSGSBASE		( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/
> >  #define X86_FEATURE_TSC_ADJUST		( 9*32+ 1) /* TSC adjustment MSR 0x3B */
> > +#define X86_FEATURE_SGX			( 9*32+ 2) /* Software Guard Extensions */
> >  #define X86_FEATURE_BMI1		( 9*32+ 3) /* 1st group bit manipulation extensions */
> >  #define X86_FEATURE_HLE			( 9*32+ 4) /* Hardware Lock Elision */
> >  #define X86_FEATURE_AVX2		( 9*32+ 5) /* AVX2 instructions */
> > diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
> > index a5ea841cc6d2..74de07d0f390 100644
> > --- a/arch/x86/include/asm/disabled-features.h
> > +++ b/arch/x86/include/asm/disabled-features.h
> > @@ -62,6 +62,12 @@
> >  # define DISABLE_PTI		(1 << (X86_FEATURE_PTI & 31))
> >  #endif
> >  
> > +#ifdef CONFIG_INTEL_SGX
> > +# define DISABLE_SGX_CORE	0
> > +#else
> > +# define DISABLE_SGX_CORE	(1 << (X86_FEATURE_SGX & 31))
> > +#endif
> > +
> >  /*
> >   * Make sure to add features to the correct mask
> >   */
> > @@ -74,7 +80,7 @@
> >  #define DISABLED_MASK6	0
> >  #define DISABLED_MASK7	(DISABLE_PTI)
> >  #define DISABLED_MASK8	0
> > -#define DISABLED_MASK9	(DISABLE_MPX|DISABLE_SMAP)
> > +#define DISABLED_MASK9	(DISABLE_MPX|DISABLE_SMAP|DISABLE_SGX_CORE)
> >  #define DISABLED_MASK10	0
> >  #define DISABLED_MASK11	0
> >  #define DISABLED_MASK12	0
> > -- 
> > 2.19.1
> > 
> Just out of curiosity, would it be worthwhile to separate out the cpufeature
> patches here to post and integrate them separately?  It would at least reduce
> the size of this patch set slightly, as these aren't controversial changes

I can prepare such patch set if that is what people want. I also see a
benefit of single patch though that you can git am and try out. Most of
the changes do not play much of a role without the functionality.

/Jarkko