Re: [CFT PATCH 2/2] KVM: x86: support XSAVES usage in the host

From: Paolo Bonzini
Date: Fri Nov 21 2014 - 16:58:30 EST

On 21/11/2014 21:06, Andy Lutomirski wrote:
>> > + cpuid_count(XSTATE_CPUID, index,
>> > + &size, &offset, &ecx, &edx);
>> > + memcpy(dest + offset, src, size);
> Is this really the best way to do this? cpuid is serializing, so this
> is possibly *very* slow.

The data is in arch/x86/kernel/xsave.c, but it is not exported. But
this is absolutely not a hotspot.

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