linux-kernel - Re: [PATCH 2/2] cpu: intel, amd: mask cleared cpuid features

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Message-ID: <500FDDD1.5080805@parallels.com>
Date:	Wed, 25 Jul 2012 15:51:45 +0400
From:	Vladimir Davydov <vdavydov@...allels.com>
To:	Andi Kleen <ak@...ux.intel.com>
CC:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Borislav Petkov <borislav.petkov@....com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] cpu: intel, amd: mask cleared cpuid features

On 07/20/2012 09:10 PM, Andi Kleen wrote:
>> +					unsigned int *msr_ext_cpuid_mask)
>> +{
>> +	unsigned int msr, msr_ext;
>> +
>> +	msr = msr_ext = 0;
>> +
>> +	switch (c->x86_model) {
> You have to check the family too.
>
>> +
>> +	return msr;
>> +}
>> +
>> +static void __cpuinit intel_mask_cpu_caps(struct cpuinfo_x86 *c)
>> +{
>> +	u32 low, high;
>> +	unsigned int msr_cpuid_mask, msr_ext_cpuid_mask;
>> +
>> +	msr_cpuid_mask = intel_cpuid_mask_msr(c,&msr_ext_cpuid_mask);
>> +	if (msr_cpuid_mask) {
>> +		set_cpu_cap(c, X86_FEATURE_CPUIDMASK);
>> +
>> +		rdmsr(msr_cpuid_mask, low, high);
> And please use rdmsrl(), rdmsr() is so 90ies
>
> Other than that patch looks good. I presume it will be useful for
> other things than just migration too.
>
> -Andi
>

Thank you for review, but we've decided to drop this since the kernel 
does not seem to be a suitable place for such "tweaking".
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