Re: [PATCH v7 6/6] x86/arch_prctl: Add ARCH_[GET|SET]_CPUID
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From: Thomas Gleixner <hidden>
Date: 2016-10-27 22:42:45
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On Thu, 27 Oct 2016, Andy Lutomirski wrote:
On Thu, Oct 27, 2016 at 4:15 AM, Thomas Gleixner [off-list ref] wrote:
Let's just do this right from day one:
static void set_cpuid_faulting(bool on)
{
u64 msrval;
DEBUG_LOCKS_WARN_ON(!irqs_disabled());
msrval = this_cpu_read(msr_misc_features_enables_shadow);
msrval &= CPUID_FAULT_ENABLE;
msrval |= (on << CPUID_FAULT_ENABLE_BIT);
this_cpu_write(msr_misc_features_enables_shadow, msrval);
wrmsrl(MSR_MISC_FEATURES_ENABLES, msrval);
}
RDMSR may be considerably faster than WRMSR, but that doesn't mean it's *fast*.Good point!