linux-kernel - Re: [PATCH v10 6/7] x86/arch_prctl: Add ARCH_[GET|SET]

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Date:   Thu, 10 Nov 2016 15:38:41 -0800
From:   Kyle Huey <me@...ehuey.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Borislav Petkov <bp@...e.de>,
        "Robert O'Callahan" <robert@...llahan.org>,
        Andy Lutomirski <luto@...nel.org>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Jeff Dike <jdike@...toit.com>,
        Richard Weinberger <richard@....at>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Shuah Khan <shuah@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Len Brown <len.brown@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Dmitry Safonov <dsafonov@...tuozzo.com>,
        David Matlack <dmatlack@...gle.com>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:USER-MODE LINUX (UML)" 
        <user-mode-linux-devel@...ts.sourceforge.net>,
        "open list:USER-MODE LINUX (UML)" 
        <user-mode-linux-user@...ts.sourceforge.net>,
        "open list:FILESYSTEMS (VFS and infrastructure)" 
        <linux-fsdevel@...r.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>, kvm list <kvm@...r.kernel.org>
Subject: Re: [PATCH v10 6/7] x86/arch_prctl: Add ARCH_[GET|SET]_CPUID

On Wed, Nov 9, 2016 at 5:34 AM, Thomas Gleixner <tglx@...utronix.de> wrote:
> On Wed, 9 Nov 2016, Borislav Petkov wrote:
>> +static void init_misc_enables(struct cpuinfo_x86 *c)
>> +{
>> +     u64 val, misc_en;
>> +
>> +     if (rdmsrl_safe(MSR_MISC_FEATURES_ENABLES, &misc_en))
>> +             return;
>> +
>> +     misc_en &= ~MSR_MISC_ENABLES_CPUID_FAULT_ENABLE;
>
> I rather prefer to write this MSR to 0 right away and just enable the bits
> which we really support.

I've gone ahead and done this.

- Kyle