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

From: Kyle Huey <me@kylehuey.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: "Borislav Petkov" <bp@suse.de>,
	"Robert O'Callahan" <robert@ocallahan.org>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Ingo Molnar" <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Jeff Dike" <jdike@addtoit.com>,
	"Richard Weinberger" <richard@nod.at>,
	"Alexander Viro" <viro@zeniv.linux.org.uk>,
	"Shuah Khan" <shuah@kernel.org>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
	"Len Brown" <len.brown@intel.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
	"Dmitry Safonov" <dsafonov@virtuozzo.com>,
	"David Matlack" <dmatlack@google.com>,
	"open list" <linux-kernel@vger.kernel.org>,
	"open list:USER-MODE LINUX (UML)"
	<user-mode-linux-devel@lists.sourceforge.net>,
	"open list:USER-MODE LINUX (UML)"
	<user-mode-linux-user@lists.sourceforge.net>,
	"open list:FILESYSTEMS (VFS and infrastructure)"
	<linux-fsdevel@vger.kernel.org>,
	"open list:KERNEL SELFTEST FRAMEWORK"
	<linux-kselftest@vger.kernel.org>,
	"kvm list" <kvm@vger.kernel.org>
Subject: Re: [PATCH v10 6/7] x86/arch_prctl: Add ARCH_[GET|SET]_CPUID
Date: Thu, 10 Nov 2016 15:38:41 -0800	[thread overview]
Message-ID: <CAP045Arx_8XLGkrZdj4+ZOKeWhrbVM5CUbNbiPkdWjLQC4YkUw@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1611091425042.3501@nanos>

On Wed, Nov 9, 2016 at 5:34 AM, Thomas Gleixner <tglx@linutronix.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