linux-kernel - Re: [RFC PATCH v2 05/20] x86: Add the Secure Memory Encryption cpu feature

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Date:   Wed, 7 Sep 2016 09:07:11 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Borislav Petkov <bp@...en8.de>
CC:     <linux-arch@...r.kernel.org>, <linux-efi@...r.kernel.org>,
        <kvm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <kasan-dev@...glegroups.com>, <linux-mm@...ck.org>,
        <iommu@...ts.linux-foundation.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Ingo Molnar <mingo@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Alexander Potapenko <glider@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [RFC PATCH v2 05/20] x86: Add the Secure Memory Encryption cpu
 feature

On 09/02/2016 09:09 AM, Borislav Petkov wrote:
> On Mon, Aug 22, 2016 at 05:36:22PM -0500, Tom Lendacky wrote:
>> Update the cpu features to include identifying and reporting on the
>> Secure Memory Encryption feature.
>>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
>> ---
>>  arch/x86/include/asm/cpufeature.h        |    7 +++++--
>>  arch/x86/include/asm/cpufeatures.h       |    5 ++++-
>>  arch/x86/include/asm/disabled-features.h |    3 ++-
>>  arch/x86/include/asm/required-features.h |    3 ++-
>>  arch/x86/kernel/cpu/scattered.c          |    1 +
>>  5 files changed, 14 insertions(+), 5 deletions(-)
> 
> ...
> 
>> diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
>> index 8cb57df..d86d9a5 100644
>> --- a/arch/x86/kernel/cpu/scattered.c
>> +++ b/arch/x86/kernel/cpu/scattered.c
>> @@ -37,6 +37,7 @@ void init_scattered_cpuid_features(struct cpuinfo_x86 *c)
>>  		{ X86_FEATURE_HW_PSTATE,	CR_EDX, 7, 0x80000007, 0 },
>>  		{ X86_FEATURE_CPB,		CR_EDX, 9, 0x80000007, 0 },
>>  		{ X86_FEATURE_PROC_FEEDBACK,	CR_EDX,11, 0x80000007, 0 },
>> +		{ X86_FEATURE_SME,		CR_EAX, 0, 0x8000001f, 0 },
> 
> If this is in scattered CPUID features, it doesn't need any of the
> (snipped) changes above - you solely need to reuse one of the free
> defines, i.e., something like this:

Ok, that's much easier. I'll do that.

Thanks,
Tom

> 
> ---
> --- a/arch/x86/include/asm/cpufeatures.h	2016-09-02 15:49:08.853374323 +0200
> +++ b/arch/x86/include/asm/cpufeatures.h	2016-09-02 15:52:34.477365610 +0200
> @@ -100,7 +100,7 @@
>  #define X86_FEATURE_XTOPOLOGY	( 3*32+22) /* cpu topology enum extensions */
>  #define X86_FEATURE_TSC_RELIABLE ( 3*32+23) /* TSC is known to be reliable */
>  #define X86_FEATURE_NONSTOP_TSC	( 3*32+24) /* TSC does not stop in C states */
> -/* free, was #define X86_FEATURE_CLFLUSH_MONITOR ( 3*32+25) * "" clflush reqd with monitor */
> +#define X86_FEATURE_SME		( 3*32+25) /* Secure Memory Encryption */
>  #define X86_FEATURE_EXTD_APICID	( 3*32+26) /* has extended APICID (8 bits) */
>  #define X86_FEATURE_AMD_DCM     ( 3*32+27) /* multi-node processor */
>  #define X86_FEATURE_APERFMPERF	( 3*32+28) /* APERFMPERF */
> --- a/arch/x86/kernel/cpu/scattered.c	2016-09-02 15:48:52.753375005 +0200
> +++ b/arch/x86/kernel/cpu/scattered.c	2016-09-02 15:51:32.437368239 +0200
> @@ -37,6 +37,7 @@ void init_scattered_cpuid_features(struc
>  		{ X86_FEATURE_HW_PSTATE,	CR_EDX, 7, 0x80000007, 0 },
>  		{ X86_FEATURE_CPB,		CR_EDX, 9, 0x80000007, 0 },
>  		{ X86_FEATURE_PROC_FEEDBACK,	CR_EDX,11, 0x80000007, 0 },
> +		{ X86_FEATURE_SME,		CR_EAX, 0, 0x8000001f, 0 },
>  		{ 0, 0, 0, 0, 0 }
>  	};
>