From: Tom Lendacky <thomas.lendacky@amd.com>
To: Borislav Petkov <bp@alien8.de>, David Woodhouse <dwmw2@infradead.org>
Cc: x86-ml <x86@kernel.org>,
linux-tip-commits@vger.kernel.org, hpa@zytor.com,
gregkh@linuxfoundation.org, tglx@linutronix.de,
linux-kernel@vger.kernel.org, mingo@kernel.org
Subject: Re: [PATCH] x86/cpufeatures: Cleanup AMD speculation feature bits
Date: Fri, 26 Jan 2018 15:06:20 -0600 [thread overview]
Message-ID: <7094ed9b-40f7-ba2b-55a6-cc5ab0b06bb9@amd.com> (raw)
In-Reply-To: <20180126184915.ioqewp56orj2qhrt@pd.tnic>
On 1/26/2018 12:49 PM, Borislav Petkov wrote:
> On Fri, Jan 26, 2018 at 06:45:18PM +0000, David Woodhouse wrote:
>> On Fri, 2018-01-26 at 19:41 +0100, Borislav Petkov wrote:
>>> +#define X86_FEATURE_AMD_IBPB (13*32+12) /* "" Indirect Branch Prediction Barrier MSR */
>>
>> Stray quotes.
>
> No no, those quotes are magical. :)
>
> They don't show the string in /proc/cpuinfo, see arch/x86/kernel/cpu/mkcapflags.sh
>
>>> +#define X86_FEATURE_IBRS (13*32+14) /* Indirect Branch Restricted Speculation */
>>
>> Please don't call it that. Call it X86_FEATURE_AMD_IBRS and leave
>> X86_FEATURE_IBRS to parallel X86_FEATURE_IBPB as the *software* bit
>> which is vendor-independent.
>
> Do we have a X86_FEATURE_IBRS bit?
>
> If so, then this bit should become
>
> #define X86_FEATURE_AMD_IBRS (13*32+14) /* "" Speculation Control MSR only (AMD) */
>
> *with* the magic quotes.
So I like the idea of AMD_IBRS/AMD_IBPB/AMD_STIBP and then use the magic
quotes as appropriate. We could probably use the magic quotes on
AMD_STIBP and set X86_FEATURE_STIBP when we see X86_FEATURE_AMD_STIBP.
Just my two cents.
Thanks,
Tom
>
next prev parent reply other threads:[~2018-01-26 21:06 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
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 [this message]
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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