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

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Date:   Fri, 2 Sep 2016 16:09:13 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tom Lendacky <thomas.lendacky@....com>
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 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:

---
--- 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 }
 	};

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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