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From: Borislav Petkov <bp@alien8.de>
To: David Woodhouse <dwmw@amazon.co.uk>,
	Tom Lendacky <thomas.lendacky@amd.com>
Cc: arjan@linux.intel.com, tglx@linutronix.de, karahmed@amazon.de,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	tim.c.chen@linux.intel.com, peterz@infradead.org,
	pbonzini@redhat.com, ak@linux.intel.com,
	torvalds@linux-foundation.org, gregkh@linux-foundation.org,
	dave.hansen@intel.com, gnomes@lxorguk.ukuu.org.uk,
	ashok.raj@intel.com, mingo@kernel.org
Subject: Re: [PATCH v5 3/7] x86/cpufeatures: Add AMD feature bits for Speculation Control
Date: Thu, 25 Jan 2018 22:30:48 +0100	[thread overview]
Message-ID: <20180125213048.yd5cloxh2ttggeas@pd.tnic> (raw)
In-Reply-To: <1516896855-7642-4-git-send-email-dwmw@amazon.co.uk>

+ Tom.

On Thu, Jan 25, 2018 at 04:14:11PM +0000, David Woodhouse wrote:
> AMD exposes the PRED_CMD/SPEC_CTRL MSRs slightly differently to Intel.
> See http://lkml.kernel.org/r/2b3e25cc-286d-8bd0-aeaf-9ac4aae39de8@amd.com
> 
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  arch/x86/include/asm/cpufeatures.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
> index 0a51070..ae3212f 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -269,6 +269,9 @@
>  #define X86_FEATURE_CLZERO		(13*32+ 0) /* CLZERO instruction */
>  #define X86_FEATURE_IRPERF		(13*32+ 1) /* Instructions Retired Count */
>  #define X86_FEATURE_XSAVEERPTR		(13*32+ 2) /* Always save/restore FP error pointers */
> +#define X86_FEATURE_AMD_PRED_CMD	(13*32+12) /* Prediction Command MSR (AMD) */
> +#define X86_FEATURE_AMD_SPEC_CTRL	(13*32+14) /* Speculation Control MSR only (AMD) */
> +#define X86_FEATURE_AMD_STIBP		(13*32+15) /* Single Thread Indirect Branch Predictors (AMD) */

So this leaf is AMD-specific so you can drop the AMD strings above.
Also, let's simplify this as those flags appear in /proc/cpuinfo:

#define X86_FEATURE_IBPB		(13*32+12) /* Indirect Branch Prediction Barrier: Prediction Command MSR */
#define X86_FEATURE_IBRS		(13*32+14) /* Speculation Control MSR only */
#define X86_FEATURE_STIBP		(13*32+15) /* Single Thread Indirect Branch Predictors */

so that we have "ibpb", "ibrs" and "stibp" respectively.

Thx.

-- 
Regards/Gruss,
    Boris.

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

  reply	other threads:[~2018-01-25 21:30 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-25 16:14 [PATCH v5 0/7] Basic Speculation Control feature support David Woodhouse
2018-01-25 16:14 ` [PATCH v5 1/7] x86/cpufeatures: Add CPUID_7_EDX CPUID leaf David Woodhouse
2018-01-26 14:59   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 2/7] x86/cpufeatures: Add Intel feature bits for Speculation Control David Woodhouse
2018-01-26 15:00   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 3/7] x86/cpufeatures: Add AMD " David Woodhouse
2018-01-25 21:30   ` Borislav Petkov [this message]
2018-01-25 21:37     ` Thomas Gleixner
2018-01-25 21:41     ` Borislav Petkov
2018-01-26 15:00   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-26 18:41     ` [PATCH] x86/cpufeatures: Cleanup AMD speculation feature bits Borislav Petkov
2018-01-26 18:45       ` David Woodhouse
2018-01-26 18:49         ` Borislav Petkov
2018-01-26 21:06           ` Tom Lendacky
2018-01-26 21:52             ` Borislav Petkov
2018-01-26 21:59               ` David Woodhouse
2018-01-26 22:10                 ` Borislav Petkov
2018-01-26 23:14                   ` Tom Lendacky
2018-01-27  8:49                     ` David Woodhouse
2018-01-27  9:27                     ` David Woodhouse
2018-01-27  9:37                       ` Borislav Petkov
2018-01-27 10:32                         ` David Woodhouse
2018-01-27 13:18                           ` Borislav Petkov
2018-01-25 16:14 ` [PATCH v5 4/7] x86/msr: Add definitions for new speculation control MSRs David Woodhouse
2018-01-26 15:00   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 5/7] x86/pti: Do not enable PTI on processors which are not vulnerable to Meltdown David Woodhouse
2018-01-25 18:10   ` Dave Hansen
2018-01-25 19:53     ` Dave Hansen
2018-01-25 22:00   ` Borislav Petkov
2018-01-26 15:01   ` [tip:x86/pti] x86/pti: Do not enable PTI on CPUs " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 6/7] x86/cpufeature: Blacklist SPEC_CTRL/PRED_CMD on early Spectre v2 microcodes David Woodhouse
2018-01-26 15:01   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-25 16:14 ` [PATCH v5 7/7] x86/speculation: Add basic IBPB (Indirect Branch Prediction Barrier) support David Woodhouse
2018-01-26 15:02   ` [tip:x86/pti] " tip-bot for David Woodhouse
2018-01-26 16:18     ` David Woodhouse
2018-01-26 21:36   ` [PATCH v5 7/7] " Tim Chen

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